Sep 21, 2013

Estimating the UMLACA Range

If this is your first time here, I recommend starting from the conclusion page.


In this page several methods are used to estimate the range of the rocket used in the chemical attack ("UMLACA"), resulting in a final estimate of 2.5 km. The methods:
  1. The model design was entered into a rocket simulation software. Two engines were examined - one smaller than the real engine, and one larger. This resulted in a range of 2.0-2.5 km.
  2. For verification, designs of four other rockets with known ranges were entered, giving results accurate within 20%. Additionally, the parameters of engines in the simulation were compared to known military rockets, and were shown to have the same efficiency.
  3. Two videos of launches of a similar rocket model were analyzed, resulting in a range of 2.2-2.3 km.
  4. A comparative analysis to another rocket of similar size, while not accurate enough to provide a range estimate, proves that the UMLACA could not have been launched from the Syrian army bases north of Damascus, as frequently claimed.
  5. An analysis indicating rockets of this design are intended for short-range missions.
  6. A full bottom-up analysis of the rocket, estimating its range at around 2.5 km.
  7. A calculation placing an upper theoretical limit of 3.5 km if the rocket is assumed to be subsonic, as implied by its design.
  8. Most importantly, this page has seen thousands of visits over several weeks, and no one has provided any evidence that contradicts this estimate (here or anywhere else). If you have it, please share.
  9. Update - The same conclusion was later reached by two experts: Theodore Postol, a Professor at MIT (quoted in the Hersh report), and Richard Lloyd, a warhead technology consultant (quoted in the Brown Moses blog, and later in the NY Times). It was also later confirmed by the UN to be a "fair guess".

Method 1 - OpenRocket Simulation

Note: Method 5 below is considered a more reliable simulation. Feel free to skip this section.

Following the advice of Amund Hesbol, I used the OpenRocket simulation software to simulate the path of an UMLACA.

Here is my design:

I made the following selections:
  1. All measurements according to the UN report.
  2. 2mm steel for the material, which is my estimate based on the main body remains found in impact sites. The engine tube is much thicker, but when I tried 5mm the rocket lost control.
  3. Added 60 kg weight to the body (the weight of sarin).
  4. Added a plastic nose to improve aerodynamics (about 10% improvement to distance)
  5. Motor (in gray): Cesaroni Technology Inc. 21062-03400-IM-P
  6. 40 degree launch angle, which gave the maximal distance.
This resulted in a 100 kg rocket with the following trajectory:

So exactly 2 km.

It should be noted that the motor does not fill the entire tube (in length nor diameter). I tried stronger motors but they seemed to be too strong for the poor aerodynamic design and the rocket started to spin mid-air. Following the discussion with L.K. in the comments below, I realized I could optimize the fins to make the UMLACA stable even with a large engine. So I picked an oversized engine (Contrails Rocket 06300P) and optimized the fins, resulting in the following design:

The simulation now gave the rocket a distance of 2.5 km.

To assess the general accuracy of this simulation software, I ran simulations for 4 artillery rockets with known distances, including a Falagh-2 333 mm rocket, and got results that are accurate within 20%.

Update: Several people have raised the concern that the civilian engines in the simulation may be less powerful than military engines. Scarlet Pimpernel found some great information on the total impulse (the aggregate of force impacted by the engine over its burn time) and the propellant weight of 3 military rockets (different versions of Grad). They show the same efficiency as the civilian engines in the simulation, proving this is not a concern.
See the full discussion in the comments.

Rocket design files are available here.

Method 2 - Videos Analysis

In an anonymous comment below, I was referred to this video from December 2012 (Update: the video was removed, if anyone has a copy, please share):

It unmistakably shows a real UMLACA launch with a conventional warhead. It is described as a rocket shot from Mazzeh airport into Daraya (Update: Brown Moses managed to prove the source is Mazzeh airport). I took the following screenshots:

Since we have video and audio for both launch and impact, we can use the sound delay to estimate range. The sound delay for launch is 4 seconds and for the impact is 3 seconds, and speed of sound is 340 m/s. If we assume the rocket passes exactly above the camera, this comes out to 2.4 km, or 2.2-2.3 km if we assume a slight angle (as seems to be the case).

Of course, to trust sound delay we must ensure the audio and video are not out of sync. This is ruled out at time 0:04 when the sound of the camera movement is heard in sync.
These numbers also match well the distance from the center of Mazzeh to the center of Daraya.

It should be noted that while this does not indicate a maximum range, it does give an indication of the typical range.

Update: Brown Moses has found another video of a conventional UMLACA. Unlike the previous one, it does not show the launch so it's harder to use it for range estimation. However, the cameraman seems to be below the Apogee, as was the case in the first video, and the time delay from the impact site is 3.5 seconds - also similar. So this adds another indication that the typical range is around 2.5 km.

Update 2: HRI found another video of a conventional UMLACA launch.

This one was taken near the launcher so we can estimate the distance more accurately, and can more easily verify there is no sound delay. The delay between the flash and the sound is 5.5 seconds, which gives a range of 1.9 km.

Brown Moses tweeted to Amund Hesbol that the range for the lighter sarin warhead should be longer than the HE version seen in the video. This makes perfect sense, so I prepared a simulation for the HE version. Using TNT's density I reached a warhead weight of 170 kg (including the steel casing), which is 100 kg more than the sarin warhead. I then optimized the fins and nose as done for the sarin version, and got this:

This reached a range of a bit under 1700m, which is a ratio of 1.5 to the sarin version. So applying that to the 2.2-2.3 km range from the video, we get 3.2-3.4 km.

Three things to note about this calculation:
  1. The software chose to place the fins at an extreme angle of 15 degrees, probably since this is the only way it would stabilize. Since we know the fins are not slanted in the real UMLACA, we can assume the designers managed to stabilize it some other way - and indeed it seems very stable in the video. If substantial energy is lost to spinning it would mean a lower ratio than 1.5.
  2. The longer warhead also allows for a longer engine. If this was done, it would also result in a ratio lower than 1.5.
  3. If the sarin version was a refilled WP warhead that wasn't redesigned for the lighter load, it may have lost some range to drag and instability.
This all makes me uncomfortable assigning a 3.5 km range to the sarin UMLACA, but since this is based on too much speculation, I will leave it as is.
Update: See Method 5 below, which invalidates this calculation. The sarin version does not have a longer range, since it also has a smaller motor.

Method 3 - Comparison to Falaq-2

For people who find the calculations here too complex or don’t trust the results, I thought of the following thought experiment:

Let’s compare the UMLACA to the Falaq-2 from Iran, chosen because its launcher was once speculated to be the inspiration for the UMLACA launcher:
  1. They are roughly similar in length and diameter.
  2. The Falaq-2 warhead is a bit heavier: 117 kg compared to around 90 kg for the sarin version of UMLACA (including the two large steel plates).
  3. The Falaq-2 engine is much larger. To calculate its volume I’ll assume a length of 90cm (from the diagram), and 7mm width of the casing, resulting in an internal radius of 16 cm. So the volume is: Pi*0.16*0.16*0.9 = 72 liters (0.072 cubic meters).
  4. Based on the UN report and photographs, the UMLACA’s engine volume would be Pi*0.055*0.055*1.34 = 12.7 liters. (18 liters if the engine extends into the warhead).
So, if the Falaq-2 range is 10.8 km, what would be its range if we were to shrink its motor by a factor of 5.6 (or 4) and ruin its aerodynamics? Of course hard to tell exactly, but it’s hard to imagine it being anywhere near 8-9.5 km, which is the distance to Syrian Army bases that are currently claimed to be the source.

Method 4 - Comparison to SLUFAE

Two prominent features of the UMLACA are the oversized warhead and non-aerodynamic design. There are very few rockets with similar design, with the most similar one being the US SLUFAE minefield-clearing rocket, described in this patent. In this related patent it is described as having a range of 700 meters.
While not something that can be used to directly estimate the UMLACA range, it indicates that rockets designed in this manner are intended for short-range missions. If anyone knows of a medium or long range rocket with a similar design, please share - so far none were found.

Method 5 - Full Bottom-Up Analysis

Since some people are still not convinced, I decided to do a full open calculation. Its importance is in providing detailed insight into the calculations and sensitivities, thus increasing our confidence in the accuracy of the result.

To keep a safe margin, we will assume a few ideal conditions:
  1. The engine extends all the way into the warhead.This is calculated below to be 1.83 m.
  2. Launch angle is optimized for distance.
  3. Trajectory is perfect. The rocket does not lose energy to spin or wobbling.
  4. Highly efficient rocket fuel with specific impulse of 2345 Ns/Kg (the highest I could find for an atrillery rocket).
  5. Engine container width of only 2.5 mm, allowing for more propellant. Update: Brown Moses has pointed out this image which shows the engine has an additional casing. Together their width is 10 mm, and the propellant's diameter is 100 mm. The calculations below were updated to use this number.
  6. Engine burn time of 3 seconds, as seems to be the case in the Liwa Al-Islam videos, and here.
The big question is the drag coefficient of the UMLACA. Some coefficients can be seen here and here: A long cylinder, like the UMLACA's warhead is 0.82. To this we should add some friction drag caused by the engine body and the drag of the fins. An exact estimate is relatively complicated, but according to this rocket design guide fins account for 20-40% of total drag (page 27), which would mean a coefficient well above 1. In comparison, a model rocket is estimated at 0.75, a bullet at 0.3, and a typical artillery rocket at 0.36-0.39 (subsonic; page 39 here). An interesting finding from this guide is that rectangular fins (like the UMLACA's) have higher drag.

Adding a nose cone to the UMLACA may somewhat reduce drag, but no remains of a nose cone were found in any of the impact sites, and the images captured by Brown Moses here don't seem to have one. 

The lack of a nose cone and the non-aerodynamic fin design are another indication that range was a low priority in the UMLACA's design process - probably since it was specially designed for the Syrian civil war, requiring large warheads at short ranges. It is however interesting to note that in the video of the experimental giant UMLACA a small cone was added (noticeable immediately after launch). In a screenshot from this video we can see it is very flat, so its effect on drag should not be significant. It also shows the sharp change in diameter behind the warhead - another indication of the low priority the engineers gave to drag and range.

So a realistic estimate of the drag coefficient would be over 0.9, and an optimistic one would be 0.75.

We can now estimate the range, by feeding all the assumptions and measurements into a simulation model. This simulation calculates for each second of flight the rocket's velocity and angle, by adding the acceleration caused by the engine (based on the amount of propellant burnt every second), and deducting the effects of gravity and drag (calculated using the drag equation). It is available here for public review.

A drag coefficient of 0.75 yields a range of 3.0 km, with the following trajectory:

A drag coefficient of 0.9 yields a range of 2.7 km, with the following trajectory:

If we use more realistic estimates of 1.0 drag coefficient, 2100 Ns/Kg impulse and 5% loss to inefficiencies, we reach a range of 2.3 km:

Update: We have received an analysis of the UMLACA's drag from a notable expert in rocket artillery. His estimate: "With a nose cone, the drag coefficient would be around 0.6-0.7, without a cone around 1.0-1.2. Please remember that the coefficient refers to the largest diameter of the cone, that is 350 mm, not 122 mm" (He used the 350 mm diameter reported elsewhere. The actual is calculated below at around 370 mm).
The expert may not provide an official response without his employer's approval, which we will try to obtain.
Using the lowest estimate of 0.6 with the optimistic specific impulse (2345) yields a range of 3.3 km, indicating that even with a nose cone, the rocket could not have been launched from regime-held territory.

It is interesting to note that in these simulations the rocket's velocity approaches the sound barrier. Since it is unlikely that the UMLACA was designed for supersonic speeds, these trajectories give us a theoretical upper limit on its range. In other words, any theory claiming a range beyond 3.5 km is based on highly unlikely assumptions (i.e. supersonic speed or very low drag). Specifically: The drag coefficient needed to bring the UMLACA's distance to the 9.6 km claimed by HRW is 0...

When entering the details of the HE version of the UMLACA (170 kg mass, 2.23 m engine), we get a range that is longer by about 100 m. This means the positive effect of a larger engine exceeds the negative effect of having a larger mass.

Next let's examine a White Phosphorus UMLACA, which is probably what the sarin rockets were originally designed for. White Phosphorus has a high density of 1.823, compared to 1.09 for sarin, which results in a 40 kg heavier warhead. Surprisingly, its range is similar to the sarin version. This is possible since the rocket's mass affects its trajectory in two ways: It resists the engine's force during acceleration, and resists the drag force in deceleration. It is therefore possible in some cases to add weight to a rocket and extend its range (imagine a paper ball being launched from a cannon). This may indicate that the UMLACA was indeed originally designed for the heavier White Phosphorus warhead.

So 3.5 km is our theoretical limit, and 2.5 km is a realistic estimate.

Response to Analysis at Brown Moses

The Brown Moses blog published an UMLACA range analysis by John Minthorne, a mechanical engineer, reaching estimates of 3.3 to 15 km.

First thing - Awesome. The goal of this blog is to reach a conclusion through open discussion, and having another professional analysis adds great value. I hope this will start a fruitful discussion that will together help reach a consensus. I will do my best to be open and not get attached to my previous statements, and hope John will do the same.

Let's start with John's critique of my analysis:

  1. "Assuming very short burn times (and wrongly stating that such an assumption is conservative). Drag increases as a function of more than the square of the velocity, and as a result the thrust of the rocket motor over time is a crucial consideration."
    Response: Not sure to which analysis this relates, but the most recent analysis (method 5 above) uses a burn time of 3 seconds, which is what is seen in the Liwa Al-Islam videos (also here). Claiming that the UMLACA has an optimal thrust curve is highly doubtful when the rocket is obviously not optimized for range (e.g. high diameter, thick steel body, discontinuity in shape, non-aerodynamic fins). However, for calculating an upper theoretical limit, I don't mind assuming this is the case. So far a few experiments I did with thrust curves hardly affected range, and in the OpenRocket models provided by John, the effect seems to be about 5%. This is probably since longer burn times also mean longer flight times, which result in more gravity impact.
  2. "Using hobby rocketry engines as the basis of design. By extension, underestimating the propellant mass and specific impulse."
    Response: This was shown to be incorrect. In the discussion below with Scarlet Pimpernell three Grad rockets were shown to have a specific impulse that is similar or lower than the OpenRocket engines.
  3. "Miscalculating the center of drag, severely underestimating the rocket's stability."
    Response: I assume this relates to Method 1 above. I haven't checked yet but agree that this could be the case. However, Method 5 assumes an optimal trajectory with no loss to instabilities and reaches a similar range.
  4. "Failure to consider wind direction, elevation above sea level, or air temperature."
    Response: Wind and temperature were indeed ignored since they have negligible effect. Elevation was incorrectly ignored in Method 1, but this was corrected in Method 5. 

Next, here are my comments to John's analysis:

  1. Propellant Mass - Here I believe I found a major oversight. John assumes that all of the engine's volume is filled with fuel. This is never the case. A large part of the volume is composed of voids designed to control the thrust curve (see examples here and on page 35 here).
    By comparing the propellant mass of the largest engines in OpenRocket to their volume, I found the average portion of volume used is 0.62 (assuming 2.5 mm casing and after filtering engines with special thrust curves that can be below 0.5), with the highest being 0.69. I assumed 0.65 in Method 5, but will gladly update it based on reliable evidence.
    Just to prove the UMLACA is not filled to capacity: Typical burn speeds of propellants ("regression rates") are below 10 mm/sec. This would mean that if the UMLACA was filled to capacity, its engine would take over 3 minutes to burn (and would probably never take off).
    Another small correction: The UN report gives a rocket length of 2.04 m (1.34 + 0.7), from which the booster charge and nozzle should be deducted. I estimated 1.8m for the engine length, and 1.9m in the optimistic scenario.
  2. Specific Impulse - 2550 Ns/kg is an extreme example. The analysis of the three Grad rockets mentioned above shows a range of 1937-2272, and the largest engines in OpenRocket and ThrustCurve are 1966-2272.
    Together with the overestimation of the propellant's mass above, this results in a Total Impulse value of 90000 Ns, which is twice my most optimistic estimate of 46000.
  3. Environmental Considerations - Generally agree. Small correction: Elevation in Zamalka is 700m, not 760.
  4. OpenRocket model - A few minor corrections: (a) According to the UN, warhead diameter is 360mm and not 350mm. (b) Body tube length is 1.34m and not 1.55m. (c) Sarin weight is 60kg and not 50kg (56 liters). (d) The warhead's inner tube is missing. (e) The two thick steel plates on both sides of the warhead are missing (around 10mm?). (f) The thick steel blast plate is missing (over 70mm). Images here.
  5. Fin Layout - I like the idea of adding the ring to the fins' area.
  6. Drag - This is the most important part of the calculation. First, as shown above there are good reasons to assume no nose cone is used: (a) There doesn't seem to be one in the videos we have, (b) no remains were found in any impact site, despite minor damage to all other parts, and (c) other features of the UMLACA were not optimized for range (high diameter, thick steel body, discontinuity in shape, non-aerodynamic fins) so there is no reason to assume this was done for the nose cone.
    Even if we do assume a nose cone, OpenRocket's drag coefficient estimate of 0.21 is wrong. As mentioned above, a typical aerodynamic artillery rocket is 0.36-0.39. A coefficient of 0.21 would imply an outstanding (and maybe impossible) aerodynamic design, which is definitely not the case here.
    Update: Amund Hesbol has communicated with Sampo Niskanen, OpenRocket's developer, who explained OpenRocket was not designed to simulate rockets with a non-standard design like the UMLACA, and therefore the drag calculations "may be way off".
    Since there seems to be a bug in the drag calculation module, I suggest we use the spreadsheet in Method 5 above from now on, instead of OpenRocket. It also allows more visibility into the calculations.
Additionally, the analysis has the following shortcomings:
  1. No sanity checks are given for the assumptions made in the simulation. For the results to be trusted, they should be applied to known artillery rockets (e.g. as I did for Falaq-2) and show that they give the true results. John - would be great if you can prepare a few.
  2. It ignores the two videos we have, in which the UMLACA flies less than 2.5 km, despite its trajectory not being exceptionally shallow or high (as evident by the rocket's apparent velocity and sound level).
  3. It fails to explain how a rocket with a significantly smaller engine and worse aerodynamics than the Falaq-2 manages to travel a longer distance (15 km compared to 10.8).
Summary: John Minthorne's analysis overestimates the engine's total impulse by a factor of 2, and the drag coefficient by a factor of around 4. Once corrected, range estimates should be similar to all other analyses.

Once again, I'm excited that this discussion is happening. John has improved on my analysis in several points, and I hope that he too will incorporate the feedback I provided, leading to an overall better and more reliable result.


In the comments to his post John responded to my review. My response:

Gravity drag is less significant for a blunt-nosed rocket with a Cd of around 1. Any thrust that would accelerate a more streamlined body to above ~M0.8 is wasted on the extremely high drag forces. For lower Cd's, the length of the thrust curve does indeed become a less significant of factor.
Response: For the sake of argument, I'm fine with assuming an optimal thrust curve. However, the Liwa Al Islam video and this new video clearly show a burn time of 3 seconds, as typical to artillery rockets.

The fins did not seem bad to me.
Response: Page 20 of this guide discusses fin shapes, with rectangular being the least efficient. I assume the UMLACA uses rectangular fins since they’re the easiest to produce, indicating range was never a goal.

260 s is a high but plausible specific impulse for a solid rocket. Using literature to identify performance criteria is a more robust means of analysis than comparing with a single model of rocket or comparing with specific impulses of a few hobby rockets.
Response: Page 36 of this rocket artillery guide gives a specific impulse range of 210-250s (2060-2452), and one example of 239s (2345). We should not use theoretical limits of propellant fuels - only those that we actually know were used in rocket artillery. Additionally, Zandbergen gives a range of 240-260s for the highest grade fuel, but also a density range of 1660 to 1855. There is no reason to assume that fuel that reaches the highest impulse also has the highest density. When calculating a theoretical upper limit, it's ok to take a combination of high assumptions, but they should be plausible as a whole. I suggest using 239s (the highest we have so far) and a density of 1750, when calculating an upper limit.

Unfortunately Sasa Wawa's spreadsheet treats Cd as a constant, which is not valid for speeds above M0.7. This is not problematic at subsonic velocities, but is a problem when comparing results with a supersonic projectile such as the Grad.
We appear to agree that the rocket is effectively stable.
Response: I agree. I will stop comparing to Grad's Cd, thanks for correcting. Small correction: According to the graph on page 41 here of a typical artillery rocket, Cd only takes off at 0.8-0.85M, not 0.7M.
By the way, it shows the subsonic Cd of an aerodynamic rocket as 0.36-0.39, which again makes the 0.21 estimate for the UMLACA highly implausible.

For ~60 second flight times, ignoring wind will generate over 5% error.
Response: Agree. If we ever get to 60 seconds, we can take wind into account. But I doubt this will be the case once we agree on the other parameters.

Technically, purely end-burning rockets do exist though I agree that the UMLACA is not an example. I did consider the volume ratio and ignored it as insignificant, but I should have noted and justified this assumption. Please note that hobby rockets have much lower volume fractions than heavier rockets; Zandbergen suggests a Kv of 0.8-0.95. More specifically, a dual-thrust configuration such as I proposed can have excellent volume fractions; see Himanshu Shekhar's Burn-back Equations for High Volumetric Loading Single-grain Dual-thrust Rocket Propellant Configuration for a more involved analysis. For the curves I proposed (roughly 5:1 boost:sustain thrust ratio), a Kv of 0.95 is appropriate. While 10mm/s is a quite typical regression rate, as I alluded in my report the rate can be varied by around an order or magnitude. It is indeed quite plausible to design a rocket of the dimensions described, with a volume fraction near unity and a burn time on the order of 30 seconds.
Response: Page 35 of the artillery rocket guide states that most engines are star shaped, with the alternative being multiple tubes. The theoretical discussion is interesting, but our goal is finding the maximum plausible range for the UMLACA - not the range that the world's best rocket scientists could get it if they worked on it for years. Claiming that the Syrian Army designed a rocket where the body has a discontinuity in diameter, yet somehow decided to maximize range by using a grain structure and propellant that were never used in the history of rocket artillery, is not constructive to our goal.
If we want to claim volume use above 0.7, we should be able to show at least one artillery rocket where that is the case.
Also, I could not find where Zandbergen suggests 0.8-0.95. John – could you please quote it?

Another contributor suggested that all military rockets have multiple, tubular grains; this is demonstrably false.
Response: Agree, the guide states the star shape is more popular.

The dimensions were based largely on the HRW report. The UN report goes out of its way to point out the dimensions are approximate.
Response: Good point. So let's do our own calculations:

Body length is 136 cm:

Plus 6 cm here:

The warhead's internal tube is 67 cm (I estimate 2 cm loss due to the measuring method), plus 2 cm of the steel plate:

of which at least 7 cm is lost to blast plate. Let’s assume 8 cm.

The booster charge is after the blast plate, so no need to deduct it (which means the warhead length is actually 75-80 cm).

So total length of engine: 136 + 6 + 67 + 2 - 8 = 2.03 m

Which is very similar to John's initial estimate. However, we need to take the nozzle into account. I couldn’t find the exact measurements, but a quick review found that nozzles have a length-diameter ratio of around 2.5. So for a 100 mm internal diameter, this would indicate a nozzle length of 250 mm. This estimate is verified in these diagrams of Grad rockets, which have a slightly larger diameter and nozzle lengths of 280-285 mm. 
The image below shows that the nozzle protrudes a length of around half diameter, leaving 200 mm inside the body. This means the propellant length is 1.83 m, which is what we should use from now on.

Update: Brown Moses pointed out this image which clearly shows the propellant diameter is 100 mm:

Amund Hesbol prepared this video illustrating the engine and external tube, as seen in the image above.

Update: Here is another video by Amund which shows the dispersion mechanism. It is illustrative only - actual liquid dispersion would be sideways. More details in the comments.

My impression is that none of these mass or dimensional adjustments (save external diameter, which appears to be within the margin for measurement error) have a significant impact on ballistics. Would you agree?
Response: The 10% shorter engine length is definitely significant. The missing steel parts would affect mass significantly, but possibly not range. The radius of the steel plate is seen below as 18.5 cm. This is nearly a 12% difference in area., which may have significant effect on drag. The reduction of propellant diameter to 100 mm should have a dramatic effect on range.

For reasons listed above, the spreadsheet is not accurate for velocities above Mach 0.7
Response: As shown above, significant changes only happen at around Mach 0.8-0.85, which we currently assume the UMLACA does not reach, so the spreadsheet is valid.

John then discusses drag calculations in length, ending in a conclusion that without a wind tunnel or wind tunnel simulation, it's hard to reach an accurate result. I agree and don't see a point in discussing each item in detail, but I would like to respond to the following claim:

I think a subsonic Cd of less than 0.25 is plausible for the munition with nose cone.
...The Falaq-2 is a different rocket. It travels at supersonic speed and has a heavier payload. There is no reason to think that two very different vehicles must have ranges proportional to any superficial characteristic such as launch mass. As discussed above, the UMLACA with a nose cone may have subsonic drag performance comparable to a rocket with more "streamlined" appearance.
...It probably is possible to select a thrust curve that propels the Falaq-2 more than 10.8 km. The designers probably did not do this for other reasons, such as time-on-target and accuracy. This does not mean that it is implausible that a modified Falaq-2 could hit a target 15 km away.
Response: The claim here is that the UMLACA can indeed take the same payload farther with an engine that is 4 times smaller, but this is because the Falaq-2 engineers didn't optimize for range. This statement is extremely problematic. Even if the Falaq-2 had other considerations, there must have been someone in the history of rocket artillery who wanted a design that can take a 100 kg warhead to 15 km with such a small engine. Why did no one do it before? Why do all artillery rockets have exactly the same design? It should be clear that if the UMLACA's Cd was 0.25, we would have seen this design everywhere. 
We have above an example of a standard rocket with a subsonic Cd of 0.36-0.39. The UMLACA's design is dramatically different than the norm, with features that are obviously not optimized for range. It's Cd must be much much higher than 0.39.
Update: According to the expert opinion we just obtained, the lowest Cd we can reach with a nose cone is 0.6. More details in method 5 above.

So to sum up the next steps:
  1. Unless we have evidence that there was ever an artillery rocket that had a specific impulse above 239 s, propellant density above 1750, and propellant volume ratio above 0.7, these should be the parameters we use. It's perfectly fine to build an optimistic scenario, but it can't be based on the UMLACA engineers making breakthroughs in rocket science.
  2. Propellant length should be changed to 1.83 m, warhead diameter to 360-370 mm, propellant diameter to 100 mm, and extra mass added according to the missing steel parts.
  3. Getting a reliable estimate of the UMLACA's drag coefficient. Anyone who can help with this - feel free to jump in.
  4. OpenRocket can be used for simulations without a nose cone, but the spreadsheet is preferable. Once we have an estimate of the UMLACA's Cd with a nose cone, we can enter it to the spreadsheet for a reliable range estimate.
John - would be great if you update your estimates for the version without a nose cone. And once again, thank you very much for your contributions.

Conclusion: The UMLACA used to attack Zamalka has a range of around 2.5 km.


  1. I'm pretty sure 2.2kg of sarin goes into the warhead. Do you realize how much 60kg of sarin really is?

    1. I think you are confusing with the M14 140mm rocket. This calculation refers to the 360 mm rocket, which carries 56 liters of sarin.

      You can see a description of both in the UN report.

  2. First of all good try although:
    1. How do you know the parameters of the engine (motor)?
    2. Have you tried to modify your design (for example - tail fins) in order to get 9km?
    3. Have you tried to simulate other rockets (to compare "real" and "simulated" range)....for example Falagh II rocket :D (expected maximum range 10,8 km).

    1. Thank you!

      1. I just tried several engines of a size similar to the tube, and used the ones that were most successful.
      2. I used the actual measurements of the tail fins, so no need to modify them. I did optimize a few other things (like adding the nose).
      3. See the update above: yes, and it worked well.

      Would be great if you run your own simulation from scratch and share your results.

    2. Just to make sure, I tried the Falagh-2 specifically. I couldn't get it to stabilize, so I had to add fins. It then reached 11.5 km.
      I also did an automatic optimization of the UMLACA fins as you suggested and its effect on distance was 1-2%.

    3. See the new update above. I think you'll like it. Thanks for the idea!

    4. I didn't understand. Then, if you simulate a Falaq-2 launcher, the distance is 11,5km? And with one launcher do you get 2/3km?

    5. Indeed seems like I was unclear on that. The sanity simulation was of a Falagh-2 333mm rocket, not the Falaqh-2 launcher.
      I corrected the post accordingly.
      Thanks for the correction.

    6. I still can't understand :P
      Wich with launcher do you get 2/3 km? I meant, the UMLACA "always" reachs 2/3 km despite the launcher?
      What do you refer with the previous comment "It then reached 11.5 km"?
      What is "sanity" simulation?
      It's important for me because the HRW image has been used as "final proof" and if UMLACAs rests shows that had been launched from 3km... it's a big discovery (all big media points the militar base).
      Sorry for the noob questions, but I wanna understand all pretty well :)

    7. In the simulation, distance is not affected by the launching platform. I think that also the case in reality: launchers are used for accuracy, safety and efficiency, but they do not increase distance. It's not like normal artillery where all energy is impacted at the launch site.

      "It then reached 11.5 km", means once I added fins to stabilize the rocket, the real Falagh-2 rocket is spin stabilized, probably using an appropriate nozzle configuration. I did it with fins instead.
      I updated the post to make that clearer as well. Thanks for pointing it out!

      I think it is pretty clear at this point that the HRW calculation (which was based on UN hints) is complete nonsense. Probably the first time in history that "all big media points" report nonsense ;-)

    8. Thanks for the answer! :)
      All clear for me, continue with your great (and needed) work!

  3. Can you publish your RKT files for your optimal design?

    1. done. see bottom of post.

    2. Thanks,

      I'm just starting to lean the package. However,

      The Falaq2 sanity file has centre of pressure in the nosecone and well ahead of the centre of gravity. The file may be broken?

      The CP should always be behind the CG for a stable rocket (according to my ages old Amateur Science rocketry pages)

      Your model for the oversized UMLAC has the payload mass as an override of the casing mass. It probably won't make a difference but you could use a separate mass element(s) for the payload to refine the design

    3. Indeed wrong file. Updated.

  4. Thanks for this.

    My criticism of the model design are

    1. Wall thickness and material. 2mm steel seems arbitrary. changing that to say 1.5mm results in a 25% weight reduction - as would using aluminum alloy.

    2. The rocket detail seems problematic. The various photos I've seen appear to have a longer rocket inside the payload container, topped with what seems to be a solid metal cylinder perhaps 10cm long? That makes the rocket motor including nozzle about 1.98 metres.

    3. How did you select the motor and burn time? Simply changing the grain profile or changing the size of the oxidiser particles makes a significant difference in thrust and burn time. All things being equal a very short burn time will give better range in that type of trajectory (gravity effects) - complicated by needing a heavier casing.

    4. Why did you select the launch angle of 40 degrees?

    5. How did you calculate your mass-override for the payload container?

    Good work anyway! Thanks!

    1. Thanks for reviewing my work!

      1. This was my best estimate. Feel free to change it and report. I don't think it's too important since 75-80% of the weight is the sarin and the engine.

      2. The question of whether the engine goes inside the internal tube was not answered yet. I took two extremes which cover both cases well. Note that the 'oversized' version is much longer and wider than the best case.

      3. I tried several motors until I got the best result. Feel free to suggest another motor.

      4. 40 degrees gave the longest distance.

      5. 56 liters of sarin weigh 60kg, to which I added the 12kg estimated by the software for the container.

    2. I was browsing the HRW report and spotted this

      "The rocket is of a non-aerodynamic design and possesses a novel spin stabilization mechanism located just above the nozzle. The non-aerodynamic design of the rocket indicates that the rocket would be relatively short ranged and not capable of accurate targeting."

      They also mention Mezzeh airport as a likely source for the 140mm rocket - as I independently suggested.

      "Two witnesses told Human Rights Watch that the August 21 rocket attack on their area came from the direction of the Mezzeh Military Airport and the nearby Syrian 4th Armored Division base, which are located respectively four kilometers and five to seven kilometers from the site of the attack"

    3. The details in this report are bad ballistics; I'd go so far as to say they're actually wrong. Spin stabilisation is not used for a munition of this calibre and is either imparted on launch or by canted fins. In addition, the small fins are to small for total fin stabilisation which makes the airfoil very important in the stability mechanism of this rocket. The airfoil imparts drag and helps with lift but does not impart spin.

    4. The details in this report are bad ballistics; I'd go so far as to say they're actually wrong. Spin stabilisation is not used for a munition of this calibre and is either imparted on launch or by canted fins. In addition, the small fins are to small for total fin stabilisation which makes the airfoil very important in the stability mechanism of this rocket. The airfoil imparts drag and helps with lift but does not impart spin.

  5. hello.
    there is interesting video with such a device from which we can estimate its ballistics.
    imho i do not see reference to this video in Moses blog, may be you can send it to him?

    i copy my post from another forum, where i m making such estimation using simply the newton's laws :)
    may it help you.
    i also estimate such device as low-ranged and with very bad accuracy

    rocket started at 1 sec, and sound heard at 4.5 - so 3.5 sec delay - about 1.1 km.
    sound of impact we listen at 0.24 - so we have flight time at least not more than 23 sec.
    because we cant see impact, at least one second for delay we can subtract = so we have 22 sec of ballistic flight.

    1.using formula for altitude and time of falling body - h = gt^2/2(for one half of trajectory) we have
    t = 22/2 = 11 sec of falling
    altitude = 9.81*11^2/2 ~= 10*1210/2 ~= 600 m (accurate calculation gives 593.5 m).
    so altitude in this flight was = 600m

    2. let calculate the vertical speed at impact - v = g*t (where t=11 sec)
    v= 9.8 * 11 = 108 m/s

    3. let we calcullate full speed of missile. it depends on flight distance (approximately 1.5-2.0 km), or start angle...hmm 45-55 degrees.

    im boring to do all calculations here but we can estimate full speed not greater than 150-200 m/s.

    from missile mass we can caclulate the full propulsion momentum = mass*speed... hmm approximately 150 kg*200 m/s = 30000 kg/m/s.

    for missile of mass 100 kg(CW), we ll have starting speed 300 m/s.
    calculation of max range at such a speed - do youself pls

    i can't comment the idea that CW missile has bigger propulsion. at least it is something new.

    i got some ballistic calculator and found that
    at 300 m/s at most optimal angle 45degrees in vacuum this misille will have
    1. max range - 9.1 km
    2. flight time at max range - 43 sec.

    remark - this missile has not aerodynamic nose - so we can substract at least 1 km, and i was too optimistic for propulsion momentum...

    at 300 m/s it is practically supersonic! but with such flat nose... it is quite new word in "supersonic engineering".

    interesting that that at speed of sound(330m/s) ballistic missile has range 11.1km and flight time - 47.5 sec.

    1. Sir, that is an amazing find! Thank you!
      I will update the post immediately.

    2. The timing estimates will certainly be wrong, Video players quite often play audio out of sync with video - sometimes up to 1 second. You can;t tell without the equivalent of a clapper-board.

      We have also seen the SAA uses smaller oversized rockets based on 107mm bases so we don;t know if this is a 107mm or 120mm or any other size.

    3. my calcualations about altitude and speed on impact are correct - because there delta of sound marks is used, so any possible "shift of player" is eliminated.
      the same for sasa wawa estimations - where he is using delays to estimate distance. error of the beginning will compensate error of the ending.

    4. I can't help thinking there is a problem in the theory.

      If the sound and video events were from the same place there would still be a problem using deltas. We can't estimate range without having an absolute timing reference on the sound lag.

      Having different start and end locations complicates it even more- too much for my brain this early.

      sasa wava says the absolute delta is 0.04 seconds (above). While that may be true for him, it may not be true for you. Players often have different lags between audio and video though I'm guessing he's put it into a video editor to analyse it.

    5. Charles,
      You are indeed correct that audio lag would cause the calculations to be meaningless. However, I ruled that out by noting that at 0:04 we see and hear the camera being moved in sync.
      I see my post wasn't clear on that. I will clarify it now. Thanks!

  6. HD-version of the Daraya-video here, courtesy of @BrownMoses:

  7. From @Brown_Moses on Twitter just now:
    One thing to note, the warhead on the HE version shown in the video would have weighed up to three times as much. So that managed to travel 2.5km with that huge payload, so the sarin version could travel further based off that.

    Thoughts on this?

    1. very strong point. let me check.

    2. The payload Sarin is around 55% of the missile weight of 110+ kg. (60 kg in the model)

      Changing to HE might add another 120kg if the container was filled completely making overall weight 230 kg compared to 110kg

      Modified range would be 1100m and flight-time of 16 seconds. i.e. range is about half a Sarin version.

      However there is no certainty a full load would be used.

    3. Another point is that Ammonium Nitrate based explosives are actually less dense than Sarin. The bulk density of the Prill is 0.8 and the additional oil and sensitisers wouldn't bring the density much above 1.0

      The only video of an unexploded HE missile shows a powdery granular explosive.

    4. And a final point. TNT has a density of 1.65 so 55 litres of TNT weights 90 kg compared to 60kg of Sarin.

      The model shows a range of around 2200m and flight-time of 23.5 seconds.

      So overall not much difference from the Sarin 2500m and 26 seconds.

    5. I ran more simulations and updated my distance estimate. Thanks for pointing this out!

    6. sasa wawa,

      TNT has a density of 1.65 solid, less if powdered. Therefore 55 litres would weigh 90.65 kg. or 30.65 kg more than your estimate for sarin of 60kg.

      Your update 4 says it would be 100 kg heavier which is incorrect.
      Your figure of 170 kg for the warhead should be 112 kg.

      This assumes the warhead is the same volume for both the HE version and the CW version - which should be easily verified by examining the dud HE missile being disassembled on video. If you are trying to use the blurry photos of the Darayya missile to posit a longer payload cannister, you need to consider whether it has a nosecone and whether it is the same diameter.

    7. Charles,

      I used the 1050 mm estimate for warhead length mentioned in the HRW report, which they based on Brown Moses. I'm not sure how it was calculated, but it seems to about match what we see. If you can get a better calculation that would be great.

      I also think the HE warhead is a bit lower diameter than the WP/sarin. Let me know if you find any indication of that as well.

      Thanks for helping out!

  8. Have you tried this with a ring airfoil around the fins? It will likely add drag and thus more stability but will also helps with lift. It makes up for the lack of canted fins.
    Also maybe worth trying different sizes of solid explosive burster in the warhead. All reports have assumed the warhead is filled completely with liquid sarin but this is not necessarily the case. There maybe a ballast weight in there.

    1. I don't think this software supports the ring. Feel free to use my files and try yourself.
      I did not assume it's full of sarin - the volume calculation assumes the tube goes all the way in, as described in the UN report.

    2. Scarlet,
      You seem to have some Rocket Science background. Would you mind preparing your own analysis so I can add it here?

    3. Scarlet PimpernelThu Sep 26, 09:27:00 PM

      I can't seem to get the program to work on my computer but will keep trying or try a different one!
      Another couple of points that I think are worth mentioning:
      1. The large metal plate at the top end of the rocket motor inside the warhead should help with stability of the UMLACA.
      2. A liquid payload is likely to decrease rocket stability.

      Keep up the good work!

  9. why you are talking about sarin - it is FAE warhead, and direct prototype is american M130(exactly of this diameter)-
    also look this-

    1. Please read my analysis here:
      The UMLACA was designed with a conventional warhead and a White Phosphorus warhead. I did not find any evidence for FAE. If you can find any, please share.

  10. Amazing and innovative work! This should have been done before reaching official conclusions based on prejudicies.

    Now it's just funny how everybody is desperately trying things so as you obtain the "correct and acceptable" result of 9km. Physics resist official narrative though.

  11. Sensitivity analysis of your model says flight time is strongly affected by launch angle. I don't think you can use the video timings alone to infer flight characteristics of a CW variant nor even the HE variant.

    The tail-fin shape is not critical. Mostly tailfins are designed to withstand handling damage. All that really matters is their surface area and moment relative to the CG at various stages of flight.

    Sensitivity analysis of your model shows a variety of tailfin designs can work and have little effect on range or flight-time using different surface areas. Inherent stability only requires CP behind CG at all stages.

    1. I'm not sure I understand why the video timing cannot be used to infer even the HE range.

      I use the tail fins only to get the rocket to stabilize. It otherwise quickly crashes to the ground before completing its fuel or loses energy to instabilities in flight.

      I added the HE model to my files. Perhaps you can help improve the model.


    2. The video timing gives A HE range. Differences in launch angle give dramatically different ranges and flight times. This is expected as the missiles are ballistic and changes in launch angle are used to alter range (in fact for most practical ranges there are two different launch angles and flight times to achieve the same distance)

      I simply state that you can't rely on the video timing of that flight alone.

      Separate from this, the HE and alleged CW versions have different markings on the rocket tube, not the payload. This indicates to me they are different motor types.

      Finally, as I noted before, the HRW report mentions a 'novel spin mechanism'. I haven't spotted what that is, and I don't know what variants it applies to.

    3. Well it would still give a minimum range. Specifically here it seems like the rocket is taking an optimal trajectory so it's also the maximum range.

      I'm pretty sure the HRW report refers to the unique fin design with the ring.

    4. 1.unique fin design is obvously the ring on fins. :) not take fins shape into account because i m sure this simulator uses some analytic formulas and sometimes gives unstable solutions in configurations he can't calculate properly.
      3. but basically calculations are good with reasonable error.

    5. also the general lack if such design is the flat nose and bottom of the warhead. it brings very high air resistance, so if motor of reasonable power accelerated the rocket to high speed, after motor fuel is off - rocket will lose her speed very fast tо 100-150 m/s. so variant with light warhead and powerful motor won't have significant range. may be 1 km longer than heavy variant.

    6. Alex,
      Thanks for the response. You seem to have good understanding of the subject. What is your background? Could you give a more detailed analysis that I can add to the post?

    7. higher education in physics of elementary particles :) and strong computer science background.
      i stil did not downloaded simulator, but seems there is no room for detailed analysis.
      that's me, who gave you reference to the video of a full rocket flight in aleppo.
      there i gave my estimations using simply the Newton laws, without air resistance.
      general hint here is - this design obviuosly is deep subsonic(flat nose and bottom), and it's reasonable courier speed is about 100-150 m/s.
      but for such s speed without air max distance of ballistic flight is about 2-3 km. with air it will be obviosly less.
      and details can't change this whole picture.

    8. if you need the better understanding of your graphs, look at speed graph behavior, and acceleration since motor is off - it will show you the force from air resistance of such design. good aerodynamic design will show slow decrease of horisontal speed, but this design will show high decrease.
      also look at trajectory at impact end. you ll see impact angle.
      compare this angle with missile impact angles on videos.
      at least in video, where un inspectors are investigating one missile in Ghoota, this angle is about 45 degrees. but must be about 60 or greater. so or missile changed vertical angle after impact, or was launched from short distance (about 1 km) at angle less than optimal(your 40 degrees).

  12. Good point about the markings, Charles. It's been assumed earlier that the red and black numbering referred to types of munition - HE, GB or even FAE. But we know that the payload itself is color-coded. Here is one of two known UMLACAS with a yellow band around the payload. The second documented UMLACA with an intact container has a black band which may indicate a removed marker:

    1. Unfortunately for my theory your first video shows the same number '900' in black on the motor body and on the payload body.

      However that could be the usual military dumbing-down approach "always put a 900 motor on a 900 body boy!".

      The yellow band appears to have some other significance.

  13. It certainly does. Can't believe I missed that. Oh well.

  14. Great contributions from Alex. To me this looks like rock solid evidence. It's impossible for the UMLACA to travel more than 2-3 kilometers. Sasa: When you update the article, it would be good if you wrote a little bit of context/background in the intro. People who have no idea what an UMLACA is, are left clueless.. A little bit about the HRW-report, "9km-range", something like that.

  15. Sasa, i downloaded simulator and tried your UMLACA design. But I changed some parameters and model.
    1. i took nose cone type - conical, with small height - practically flat - 1 cm
    2. i added "transition" detail between warhead tube and motor tube, with short lenght - about 1 cm.
    3. in simulation i set wind speed = 0, and turbulence = 0, to simplify the "atmosphere conditions"
    may be i changed something else(it was my first try) but i got distance - about 1.7 km.
    Imho Transition detail is essential for simulation, else there is some hole.

    1. Interesting. Can you share the file?

    2. it's my model with cone nose and Transition block, also there is some powerful motor i found in list. I slightly increased diameter for motor section, to fit the motor. and still it is about 2 km, despite quite big speed at the start - 271m/s. as i said this design after motor burnout has very high air braking and decreases speed quickly.

    3. When applying optimization to the nose cone and fins it can get to over 2.3km. I think we should always optimize even if we get weird results, because we should assume the real designers knew what they were doing and didn't suffer from the stability problems etc. that we may have in our simulations.
      Also note that your motor has a very short burn time, which is very different than what we see in the videos.

  16. One way of estimating the range would be from the flight time of the rocket. As far as I can see, the December 2012 video with the UMLACA fired from Mazzeh airport into Daraya shows the full flight path. I estimate the flight time to be about 20 seconds.

    For simplicity, I will make calculations with an idealized artillery shell fired in vacuum. The engine running during flight might give a longer range, but that would have to be determined through simulation. Air resistance will decrease the range.

    The projectile will have the longest range when fired at a 45 degree angle. The 20 seconds flight time means 10 seconds going up and 10 seconds going down. The terminal downward velocity after a 10 second drop will be g × 10 s = 10 m/s2 × 10 s = 100 m/s. The vertical distance traveled will be 500 meters.

    With a 100 m/s initial (and terminal) vertical velocity and the 45 degree angle the horizontal velocity will also be 100 m/s. This does not change during the flight. The 20 second flight time would give a maximum range of 2000 meters.

    From the video it seems that the rocket is fired at a higher angle to achieve a shorter range. This will increase the flight time. Consequently the flight time at the maximum range would shorter then the 20 seconds we observe, thus the range would be under 2000 meters.

    In yous simulation you should consider 20 seconds the absolute maximum flight time. If your rocket flies longer than that, then your engines are too strong or your payload too light. From your simulation I cannot read a flight time. How long is it?


    The CIWCL team is studying the gas "attack" at our research wiki A Closer Look on Syria. The Ghouta attack now has about 20 subpages. We will be following your work closely.

    1. The assumption of vacuum is not a good assumption. The missiles have significant drag.

      The missile simulation used by sasa wava is a better approximation to flight time and has 40 degrees optimum launch angle to account for air resistance

      It would help your understanding if you downloaded it and the different models sasa wava has provided. You should then alter parameters like launch angle and payload weight.

    2. Charles. I did same calculations in vacuum (I posted it in this page as Anonimous) but estimated flight time as 22 sec. max altitude was 600 m, etc.
      "Estimation in vacuum" - is most optimistic for distance, altitude, range, because there is no braking force from air. Draft is essential for "aerodynamic bodies with wings" - kinda birds, airplanes, gliders...not such a bombs, kinda stone.

    3. not draft...but drag, of course. :)

    4. Petri,
      Welcome and thanks for the contribution!
      My 2 km simulation flew 23.7s, The 2.5 km was 26.7 s
      However, I think your calculation makes too many assumptions. How can we support the 100 m/s estimate for example?
      I've spent a few hours at the Closer Look site. Some of the information there was very valuable (and added to reports), while some were outrageous claims not based on any evidence.
      I don't see how I'll ever have the time to review all of it, so if you think you could filter for us only relevant and reliable evidence, that would be of great help.
      Thank you!

    5. 100 m/s is not estimation, but simple calculation. if gravity constant for earth surface is 9.8m/s^2,then to calculate impact speed, you need simply multiply 9.8 m/s^2 * 10 sec(half of flight time obtained from video). so impact speed is approximately 100m/s. but without air. it is quite close to real speed, with air, because this speed is deep subsonic.
      for estimation it is quite enough. because our goal is not to calculate accurate abilities of such design, but show that he cant fly more than 3 km with any reasonable motor. of course, with buster of the Space Shuttle it could fly long. but seems it is not our case.:)

    6. I think I understand now. So this could help estimate range from the videos, but would still not help us extrapolate from the conventional UMLACA videos to the sarin ones. Right?

    7. if we know the mass of this thing, we can quite accurately estimate full motor moment... then or we can find the motor in simulator with such moment, or simply recalculate formulas for warhead of another mass.
      but because we already have simulator, it's better to use it.

  17. sasa wava - your model downloads are not up to date. You refer on the page to using a Cesaroni Technology Inc. 21062-03400-IM-P but the download models have a Contrails Rocket 06300P which has a higher total impulse - and is also greater in diameter than the known rocket tube.

    1. Yes, this is the 'oversized motor' i mention. The files are right - I'll update the text.

  18. Scarlet PimpernelMon Sep 30, 11:34:00 PM

    Sasa wawa I've been having a play with this program this evening and have designed an UMLACA based on a 90kg mass override. The rocket motor dimensions I have modeled, as far aspossible, on the 122mm. Unfortunately the program does not have the correct size engine, and there is no method to include that tail ring, but even without these and using only a small engine, the simulated rocket will fly 3km. With an oversized engine it will fly as much as 6km.
    I hope you like it!

    1. Scarlet, Thanks for sharing.
      Unfortunately you have a bug there: You have 7 engines occupying the same space. This thing could probably get you the moon... (-:

    2. Scarlet PimpernelTue Oct 01, 12:37:00 AM

      It should be one rocket engine but with a cluster of 7 propellant grains not 7 engines but I'll double check tomorrow!! The 122mm utilises 7 'sticks' of propellant in it's motor, hence the 7 nozzles.

    3. Scarlet PimpernelTue Oct 01, 12:41:00 AM

      It should be one rocket engine but with a cluster of 7 propellant grains not 7 engines but I'll double check tomorrow!! The 122mm utilises 7 'sticks' of propellant in it's motor, hence the 7 nozzles.

    4. it's ok to have 7 engines (although i doubt that is the case in the umlaca). they just can't occupy the same space.

  19. Just read my last 2 posts - shouldn't do it before going to bed! Here is a better explanation:
    As Open Rocket is a program for model rockets, you are technically right - there are 7 engines in this design. However, most engines for model rockets are comprised of only 1 grain of propellant. There are a few high powered exceptions but even those are only 4-5 grains. Consequently, the program gives you the option to 'cluster' your engines.
    Charles are put together some excellent evidence that appears to show the rocket motor of the UMLACA comprising a 122mm rocket motor. This makes a lot of sense as it would rapidly increase production numbers whilst keeping costs down which is ideal when you've been fighting a war for 2 years and your resources are running down. (Bespoke rocket motors take a lot of R&D work - ask any amateur rocket enthusiast!)
    The 122mm rocket has a rocket engine comprising 7 grains of propellant, not 1. This is much simpler to make as you can avoid casting inside the motor - makes sense for mass produced munitions. The motor is also much longer than most of the rocket motors in the program.
    What I was trying to demonstrate was that your UMLACA rocket simulation, due to the confines of the Open Rocket program in this scenario, is underpowered and realistically will likely have a further range than you have been able to show.

    1. 1. this motor works only 2 sec - visible from the video. it motor is "long" and constists of 7 "grains" (don't know what is grain here) - seems it have to work longer?
      2. the thing is obviously subsonic - rough estimation of video gives about 150 m/s. so can quite easy, estimating the mass - get the full motor momentum.
      3. thing with such flat nose simply can't be supersonic, it will be unstable, and will decrease speed very fast.
      so key arguments here, against long range - short time of motor work, and subsonic design - flat nose and bottom.

    2. it's possible that military motors would be a bit stronger due to better materials, but this would be a 20% change not 600%. The purpose of clusters is just a shortcut for defining multiple motors for the same rocket. The UMLACA has just one motor, so its simulations should reflect it.

    3. grad 122mm motor has very low smoke, practically unvisible.
      interesting that turkish 122mm T-122 Sakarya rocket, has big smoke, like in UMLACA video, and works about 2 sec also.

  20. I completely agree with your points 1 and 2. The only additional comment I would make is that you cannot always tell visually how long a motor is working for as once the grain is burnt through the thrust reduces hugely but some small left over shards will continue to burn visibly whilst having a negligible effect on the thrust. This would imply that the motor produces thrust for less the visible 2 secs. (A grain is basically an individual 'stick' or particle of propellant. They are burned in parallel.)
    The point I was trying to make was that the simulation software is designed for model rockets that generally use motors consisting of 1 grain of propellant, usually black powder. It is highly likely that most or all of the motors in the simulation software are like this. Some of the larger ones may have additional grains but not as many as 7.
    Black powder, or another potassium nitrate mix, is used in model rockets because of its consistent burn but it has a relatively low energetic output in comparison with propellants manufactured for larger commercial rockets. Indeed, the propellant in the 122mm rocket, is likely to be a double base propellant of sorts - a mixture of nitrocelluose and nitroglycerine which is far more energetic.
    In summary, any motor used for a simulation using the Open Rocket software is highly likely to be under-powered when compared with a 122mm rocket motor which is bigger, contains more burning surface due to the 7 grains, and is likely ignited from the middle of the motor to burn propellant in both directions. All these factors together are likely to result in a much bigger output from the the 122mm motor over a shorter time period than would be seen in a model rocket simulated in Open Rocket. The thrust would be far greater and consequently the range would be increased. So, if sasa wawa is getting 2-3km with his rocket on a model engine, in reality, if you were to substitute the model engine for a 122mm rocket engine, it would likely go much further.

  21. I've just found some figures to demonstrate the above comment.

    In Open Rocket, the largest engine is a Contrail O0630. The programme states that the maximum thrust is 12271N with an average of 7341N. By way of a comparison, the mean thrust of a 122mm rocket is 23600N.
    (Ref: World Academy of Science, Engineering and Technology
    Vol:72 2012-12-21)
    If these figures are correct, then the 122mm rocket has a thrust approximately 92% higher than the maximum motor thrust of the largest motor in the simulation programme. If we assume, for ease in this case, that the average number is also the mean number for the Open Rocket program, then the difference increases to 221%. Unfortunately the thrust cannot be measured on a linear scale but it does demonstrate that the UMLACA is very likely to have a slighter larger range than can be demonstrated using the Open Rocket program.

    1. Interesting stuff.
      In order to compare motors they should of course be of similar size. The Grad 122mm is indeed of very similar volume to the Contrail O0630. So that's good.
      Next, we should compare total impulse, and not just average thrust. The contrail has a burn time of 4s, while I think Grad is 1.5s (please verify), so total impulse is just 20% higher for the grad.
      I think in our simulations we should use motors that are 30% oversized, and we should be good.

    2. The O0630 rocket is not the largest available in Open Rocket.

      For my extended simulation I used the Ceaseroni 025,000 engine with total impulse 30,907 and burn time of 1.25 seconds. There are other motors with a lot more total impulse.

      The 025,000 is a far better match to the Grad than the hybrid 6300 which has a ~5 second burn. Faster burn means higher altitude and longer range - at possible expense of accuracy.

      My extended simulation with a HE load got a range just under 2,000 metres.

      Next, there is no such thing as a 122mm Grad. The missiles come in at least 4 different sizes from one manufacturer alone. Considering how many different manufacturers there are and how many variants I think it's impossible to quote spec-sheets. All that can be done is try and match the physical dimensions of the grain and find a burn-time that matches visual observation - certainly under 2 seconds for the ones I have seen.

    3. Thanks for the corrections!

  22. This comment has been removed by the author.

  23. Im no expert, but understand that there is a relation between a rockets inititial speed, the altitude it reaches, the range and the speed of impact. So the further they go, higher they fly, the harder they crash. I therefore assume that the remains of the mystery 330+ found on ground in Ghouta also could tell a lot about their range? Pictures from impact sites show missiles damaged by impact of course, some bent, other with body quite intact. Calculations for a short 2 km range ( in other post above) stipulate a impact speed at 100 meters pr second or 360 km pr hour. If you extend the range I guess impact speed would increase accordingly, and the rocket wreck would be even more damaged? To me it looks like the rocket remains we see on the ground do not fit into the picture of a crash at a speed of several 100 kms pr hour? But as I said, I am no expert:)

    1. Interesting direction. It's hard to estimate how much damage such a structure would absorb at a certain velocity. If anyone knows how to do it, please share.
      Also, the velocity of these rockets is severely limited by their poor aerodynamics.

    2. The simulations take into account air-drag. Depending on a number of factors the terminal descent is steeper than the ascent, but slower.

      In one simulation I ran, vertical velocity got up to 500m/s (supersonic) at the end of the thrust period. That fairly slowly (logarithmically) changed to -250 m/s (subsonic) at impact.

  24. I think we could be in danger of going down a large rabbit hole with this. There are so many variables involved with rocket flight that we could be here for a long time.

    Charles, you are right when you say there is no such thing as a single 122mm GRAD. I just picked one model at random to try and demonstrate the differences between model rocket engines and more powerful commercial type ones.
    The main conclusion to draw from all this is that the idea of maximum range for the UMLACA should not be absolute. If a possible launch site is, for example 1-2km, outside the Venn diagram drawn on a map, but it is in the right direction, we should not exclude it and make sure it is included in any subsequent analysis.

    1. We have several independent indicators that the UMLACA can not fly over 3.5 km. It's ok to add 20-30% to the 2.5 km from simulations because of better engineering (and that was indeed the gap between the simulated conventional UMLACA and the video), but it's hard to justify more than that.
      I don't think deploying 7 motors in the same space simulates any realistic physical situation, and should not be used to allow for a longer range.
      Am I missing something?

    2. Wohoah! I didn't mean for that simulation to confuse you as to what I've been talking about previously. Keep it as mutually exclusive and completely separate! It does indicate that the UMLACA could be stable with a much stronger engine though ;-)

    3. Oh sorry. Then I misunderstood.
      So why do you think the multiple indications we got for the 2-3.5 km range are not reliable?

    4. Sasa it's worth bearing in mind that one of the models of extended range 122mm is very similar in thrust to 4-5 of those motors put together - and that's within a 122mm calibre, not 152mm. That would give you a range of approx 4-5km; the program suggests it would also be stable. I just don't think you have enough evidence in a few videos and a model rocket program to make a definitive statement on UMLACA range. You have a ball park figure - which is a great start - but as Charles points out, we have no idea which 122mm is likely being used as the motor.You have to keep an open mind.
      As an aside, clustering is also a very real concept with amateur rocket enthusiasts and not just a short cut for the Open Rocket program.

    5. It has higher thrust, but on a much shorter time, so the total impulse is not too different. and total impulse is the main contributor to distance.
      There's no way you can get an engine of similar volume to generate 4-5 times more thrust over the same period of time.

    6. Total impulse is absolutely the main contributor to distance with model rockets as the distance they usually refer to is altitude. However, if you're after horizontal distance, then you need a rapid and powerful burn to push the rocket as far as possible.
      Many people have correctly alluded to the non-aerodynamic shape of the UMLACA which means as soon as it reaches it's "all burnt" stage, it will likely plummit downwards quite rapidly, exhibiting more of a mortar profile at this point than one of an FFR. So, tactically, you may need it to go as far as possible before it plummits - hence the need for a higher thrust.
      In answer to your second point, see here:

      Sasa, you've done some really good work so far on this UMLACA and I really don't mean to make things difficult for you. I think the range you have is realistic. All I am trying to do is make the case that it could, and may, fly further than you think: I don't want you to lose any possible leads you may dig up by discounting them because an UMLACA is alleged to have flown, say 3-4km, in a particular scenario.

    7. P.S. In the above post, I meant rapidly in terms of distance not time. Bad choice of word - sorry!

    8. No need to explain yourself - If we can show UMLACA has a higher range, that's very important information that needs to be taken into account, and a great contribution.

      I guess I'm just not understanding your claim. Would you mind explaining why you think the real engine could impact a distance that's significantly more (i.e. over 30% more) than an engine of a similar volume from the simulation?

    9. Sasa, This is why:

      Charles's Cesaroni O25000:

      3 models of GRAD 122mm:

      Note that the diameter for the Cesaroni excedes that of the 122mm, although the length is only 140.7cm. Unfortunately there is no length given for any of the rocket motors of the GRAD 122mm models shown so we can't do an accurate volume comparison. However, all 3 are far more powerful motors than the Cesaroni. Given that the rocket engine on the UMLACA ends almost at the top end of the warhead, I suspect that even the extended range 122mm rocket motor shown would fit into it.

      Hope this helps.

    10. Great sources. Exactly what I was looking for. Thanks!

      So let's analyze the propellant mass and total impulse in the 4 cases:
      1. Cesaroni: 14.5 kg => 30794 Ns (ratio 2124)
      2. Grad: 20.5 kg => 39700 Ns (ratio 1937)
      3. Grad M: 25.6 kg => 51400 Ns (ratio 2007)
      4. Grad 2000: 27.4 kg => 62250 Ns (ratio 2272)

      I think it's clear from this that there is no need to assume significantly more distance in reality compared to the simulations. No?

    11. Scarlet,

      The "Grad" is manufactured by a number of different companies. They vary in performance due to different grain lengths as well as different nozzles.

      Physical inspection of grad models shows they are segmental. That is they're made up of multiple short sections screwed together to make a longer rocket. My assumption is that grain length determines overall rocket length and range and that various models use different numbers of segments to get a particular grain length.

      The 300mm+ missile appears to have a 1.98 metre grain and nozzle. That is quite a bit shorter than many 122mm rockets but could easily be made up with less segments and what looks like a custom nozzle.

      The best modelling assumption is to have a rocket of the same grain volume and with a short - sub 2 second - burn time.

      I'm trying to find out how to add custom motors to the package and will report back.

    12. Charles,
      It looks like you're doing some good analysis there. It's worth noting that grain shape is also vital when determining rocket motor measurements as it affects the surface area available for the burn and thus significantly impacts on the thrust curve measurements. For example, older Soviet rocket systems often used a cluster of 7 grains shape inside the motor casing but newer models nw apear to use a single star-shaped grain. Propellants is such a huge area and was what I was referring to when I mentioned the rabbit hole It's fascinating though so I hope you do enjoy the research.
      Did you account for the warhead and fuze in the measurements? The actual motor is segmented but should be somewhat shorter than the figures given in my references.

    13. The grain shape is what causes different thrust curves. High surface areas lead to shorter burn times.
      Ultimately the effect of burn time on distance is minor in comparison to total impulse.

    14. Sasa

      I'm not really following your analysis there. Could you explain?

    15. Above post was referring to the volume measurements.

      Re: burn time, It's actually important when dealing with horizontal distance as opposed to vertical distances as this is when errors will occur with the rocket's trajectory. With vertical distance, as height increases, wind and similar forces decrease, so you can keep plodding on upwards with a lower thrust. This doesn't work horizontally as you're always fighting the wind, or similar. Think of it as more of a marathon as opposed to a sprint. High thrust is important with horizontal distances. Hope that makes sense?

    16. What do you mean by 'volume measurements'?

      I agree that burn time has an effect. It's just a minor optimization that's not relevant to us. We want a rough estimate of the range.

    17. Scarlet,

      I disagree re vertical/horizontal.

      Vertical has a constant negative force of 9.8 N per kg. A slowly burning motor may be so weak as to have little or no vertical acceleration against gravity. The classic example is the Grasshopper

      A fast burning rocket will have huge acceleration vertically and will achieve very good altitude. A slow burning rocket will have far less thrust in proportion to gravity despite firing for longer and will get much lower altitude as much of its upward thrust is negated by gravity.

      Horizontal there are no opposing forces other than wind drag. It makes far less difference if the rocket is fast or slow burning.

    18. I agree that an extremely slow burning rocket will get nowhere, but that's an extreme. Can't see significant differences between 1s and 4s for distance.

    19. Charles, Sorry I was being too simplistic. I should have said 'after weight has been taken into account' and not used horizontal but 'rocket trajectory.

    20. Sasa

      As you alluded to before, range of a rocket motor is given simply by the ratio of fuel weight and volume of motor : warhead. i.e. weight and volume of propellant:warhead.
      So, bigger motor = longer range. The 122mm models on the webpage I posted are all bigger motors and will therefore go further with the same warhead.

    21. Sorry, I think I lost track of the discussion. Is there currently any claim we need to evaluate that the UMLACA range can go beyond 3.5 km?

    22. Just to follow up on the Specific Impulse (Total Impulse per Kg propellant) discussion above, here are details of three more of the largest Cessaroni motors:
      Impulse 40960 Ns, Propellant Mass18610 g => 2200 Ns/g
      37148, 17700 => 2099
      30605, 13950 => 2194

  25. Can you show this place on google maps (or ask Moses)?

    The same place —

    1. Looks like a BM-21 attack from Mazzeh airport.

    2. Seems to work Grad
      But much more interesting where this house is located where the video was conducted.

    3. They say Darayya, which is next to the airport.

    4. Daraya too large district. I would like something similar to the impact #197 in Zamalka — building accuracy.

    5. by matching the mountain skyline and the buildings, i'd say it's:
      33.466650° 36.228534°
      but not really sure.
      why do you need it?

    6. Why? See

    7. I'm sorry. I don't follow. Could you explain in more detail?

    8. No problem.
      If we know the location of the operator, we can accurately determine the direction of the launch of the rocket and its landing place (two sides of a triangle and the angle between them). Therefore, the fly trajectory search easy and fast (the third side of the triangle).

    9. Great work!

      Based on the 20 s flight time I said the maximum distance was 2 km. The rocket seems to be fired in a high trajectory that does not produce quite as long a range. You say 1812 meters. You would now have to run this in a simulation and make the flight times match.

    10. "You say 1812 meters"

      This is not a real distance - this is only algorithm for calculation.
      Sorry, but I do not know the location daraya cameraman.

      p.s. You can look at umlaka with grad engine in my blog, if you want.

  26. I have found out to create custom motors for the simulation.

    The actual file, called in this case 0my_O1980sim.eng is stored in


    This is a hidden directory so you may need to turn on view hidden directories either in the directory properties or in control panel as a global setting.

    Text between >>>>>>>> is what is in the .eng file

    0my_O1980sim 122 1980 0 45.0 70.0 0myMotor
    0.1 60000.0
    0.3 60000.0
    0.5 60000.0
    0.7 60000.0
    0.9 60000.0
    1.1 60000.0
    1.3 60000.0
    1.5 60000.0
    1.7 0.00

    0my_O1980sim - Name of the motor
    122 - Diameter in millimeters
    1980 - Length in millimeters
    0 - Delay
    45.0 - mass (Kg) of the propellant
    70.0 - mass (Kg) of the total motor including propellant and case
    0myMotor - Manufacturer name

    The rest of the file are ordered pairs
    time {space} thrust in Newton

    You can have any number of thrust lines but the last entry must be a 0

    I can't find any obvious info on thrust curves for 107mm and 122mm rockets so any advice appreciated.

    1. because in our case, time of burning is about 2 sec, you can assume than thrust curve is constant. Curve is unmeaningfull, because all the role plays the total motor impulse.

    2. I think that's what my sample shows....

      constant thrust for 1.5 seconds at approx 300m/s/s for a 200kg rocket.

      It's very ballpark waiting on hard data.

    3. if acceleration in your simulation was 300m/s/s then it is something wrong...motor is too powerful.
      because obviously in video rocket does not exceed speed of sound - 340 m/s. we do not listened shock wave, also imho this design will be unstable or/and rocket damaged at supersonic speed.

    4. As I said, ballpark.

      Other motors of similar size (that fit the rocket tube) produce maximal vertical velocity of 500m/s.

      The thrust and thrust curve data are very important which is why I asked for them.

      However, we have some very basic parameters available including burn time, flight time, and estimated range. Simulations that match those data do involve a super-sonic phase in the flight.

    5. vertical velocity or full velocity? if vertical is 500, then full if about 2M or above - it is simply wrong selected motor.
      All of you under influence of Scarlet's idea to fit some advanced motor and tube.

    6. I simply fitted a motor of the same size and approximate burn-time with a missile of the right weight.

      The rest is physics.

      How about you run some models and publish what you think are the correct results?

      You'll be very surprised!

    7. imho, idea that motor must fit the length of the tube is wrong. tube in warhead section is just constructive element and motor is shorter. tube itself is long not to fit the motor, but for flight stability.(the longer tail, the stably flight)
      correct results for light warhead are 2.5-3 km max, imho :)
      to have more distant device designers would take into account its aerodynamics. but they obviously missed it.
      so they did not take care about long range.

    8. None of the simulations I've seen for different variants have ever exceeded 2500m.

      The 3500m is sasa wava reacting to a Brown Moses comment.

      My simulations of the heaver bigger engined HE variant didn't get over 2000m. I have no reason to expect the lighter CW model with a smaller engine to have significantly different performance.

      2500m is the absolute max for all simulated variants that I know of.

      But again, run your own simulations! see what's important!

    9. may be you just hint me what is important there? at very beginning (before Sasa simulator finding and mine - of video with full flight), i estimated the rocket as short range, and optimistically gave a range 2.5-3.0 km max.
      simulator simply approved this estimation.
      it was my reaction on a some well known claim that during bombing, rocked flied about 9-10 km from some SAA base.
      but obviously such design can't do it.
      also i think it is not CW desigh, but something kinda FAE bomb, which is very effective in urban area.
      but who and how poisoned people there - stil is a question for me.
      i ll run simulations, but not just now. because have not a lot of time now.

    10. Also you can use rse-file (see "20 seconds of flying Eskimo")

    11. Upd. More reduced engine thrust (avr. 10kN):

      • payload 90kg (TNT) 45° — 20 s, 1500 m.
      • payload 60kg (Sarin) 45° — 23 s, 1650 m.

  27. Sasa, given the (alleged) pending reply by a mysterious engineer retained by Mr. Higgins, you may want to consider doing a few more sanity checks, including the M--14 rocket, and compare them with reported ranges, to corroborate your UMLACA range findings.

    1. The Update 9 above pretty much closed the deal. Anyone claiming above 4 km has some mistake in his calculations. If the engineer won't find his mistake and publish the results, I'll now be able to point it out the mistake immediately.
      You can try any sanity check yourself. I did the M14 and got the correct range of 9+ km. This assumed a drag coef of 0.3 and an optimal mass (since I couldn't find the real mass).
      Feel free to try more.

    2. sasa,

      I've read the analysis on BM. In my view it is rubbish! The burn times as you point out are ridiculous.

      I'm planning to put together a detailed rebuttal but I'd prefer not to do it as a comment here as it will take a bit of text. Possibly I can send it to you as a document to insert on this page?

    3. sure. sasa1wawa on gmail. thanks!

  28. sasa,

    I have been collating a variety of data on the Ghouta incident for use in a number of analyses including potential UMLACA range.

    Specific data of interest is METARS (Aeronautical weather reports) for OSDI - Damascus airport. This is much more fine-grained and accurate than an anonymous 'weather underground' source.

    The wind speed and direction, corrected to local time and SI units are at

    The relationship of OSDI to Ghouta is shown at

    Actual METARS are

    OSDI 211200Z 28008KT CAVOK 37/06 Q1008
    OSDI 211100Z 32008KT CAVOK 36/08 Q1009
    OSDI 211000Z 00000KT CAVOK 34/09 Q1009
    OSDI 210900Z 31006KT CAVOK 33/11 Q1010
    OSDI 210800Z 25006KT CAVOK 31/14 Q1010
    OSDI 210700Z 25004KT CAVOK 28/17 Q1011
    OSDI 210600Z 29006KT CAVOK 25/18 Q1010
    OSDI 210500Z 26006KT CAVOK 23/19 Q1009
    OSDI 210400Z 26006KT CAVOK 21/19 Q1009
    OSDI 210300Z 25008KT CAVOK 21/19 Q1009
    OSDI 210200Z 22012KT CAVOK 21/18 Q1009
    OSDI 210100Z 21012KT CAVOK 21/17 Q1009
    OSDI 210000Z 28010KT CAVOK 22/18 Q1009
    OSDI 202300Z 24006KT CAVOK 23/17 Q1009
    OSDI 202200Z 27004KT CAVOK 24/15 Q1009
    OSDI 202100Z 28004KT CAVOK 25/14 Q1009
    OSDI 202000Z 27002KT CAVOK 25/07 Q1009
    OSDI 201900Z 34002KT CAVOK 27/07 Q1009
    OSDI 201800Z 34008KT CAVOK 28/05 Q1008
    OSDI 201700Z 34008KT CAVOK 30/06 Q1007
    OSDI 201600Z 32012KT CAVOK 33/08 Q1007
    OSDI 201500Z 33012KT CAVOK 35/07 Q1006
    OSDI 201400Z 25004KT CAVOK 37/07 Q1006
    OSDI 201300Z 23005KT CAVOK 37/04 Q1006
    OSDI 201200Z 22006KT CAVOK 36/07 Q1007
    OSDI 201100Z 34004KT CAVOK 35/10 Q1008
    OSDI 201000Z 25002KT CAVOK 35/06 Q1008
    OSDI 200900Z 24004KT CAVOK 33/14 Q1009
    OSDI 200800Z 24004KT CAVOK 30/17 Q1010
    OSDI 200700Z 28004KT CAVOK 27/18 Q1010

    The elevation of OSDI is 660m. Atmospheric pressure at OSDI would be around 918 mb given the MSL pressure of 1009 mb

    What is significant is that the wind-speed and direction are collected at 10m agl. This is not the wind speed and direction seen at immediately higher altitudes. In particular the wind veers with altitude as well as increasing in speed.

    In my professional experience, the wind direction hundreds of metres above ground level at night in an inversion can be nearly 90 degrees to that on the ground. It is never closer than 30 degrees.

    Assumptions of UMLACA range based on ground level observations are plain wrong. In most cases the missile is driven sideways and achieves little or no extension in range.

    Again in my professional experience, using OSDI data is a reasonable analogue for weather in Ghouta.

  29. Your update from the expert mentions a diameter of 350mm not 360mm as seen on other non Ghouta missiles.

    I also note this post uses measurements of a missile that was not from Ghouta. There appear to be subtle but distinct differences between the Ghouta missiles and your measured subject. In particular the motor nozzle detail shows a protruding nozzle in the Ghouta missiles that is not present in the measured unit.

    There is also the difference in motor tube diameter which is variously drawn as 120mm ID by Brown Moses and 120mm OD by the UN inspectors. The measured unit has an OD closer to 130mm and is likely 133mm.

  30. I think its possible that the rocket motor inside that there gray tube is a modified/variant of a 122mm rocket motor of some type. Just like the US M130 SLUFAE the UMLACA rocket motor may very well be a MIL-SPEC production item that has been some what modified (removed fins etc) to provided propulsion for the UMLACA rocket. My best guess is its a modified 122mm rocket motor. I posted much more detailed info on this possibility in the BM blog; Who was responsible for the Aug 21st attack, 16 Sep. GW I also agree with mostly everything you, SW, and a few others have concluded about the UMLACA's max range.

  31. Charles,
    I wouldn't put too much weight to the different measurements reported. They are all based on deformed remains, so some discrepancies are expected. I think the measurements done above using Brown Moses' images are pretty reliable.
    As to diameter, the image just added above pretty clearly shows the tube is 120 mm, and the engine slides inside it having an external diameter of 110 mm and internal diameter of 100 mm.

  32. Jody - See the comment above regarding diameter. I can't see how a 122mm would fit inside.

  33. I hear what your saying about the diameters listed/discussed but I still don't believe they are completely accurate and may be off by as much as 5mm for the outside diameter of the gray tube. Trust me when I say I have looked at every possible image/angle/measurement and I still have my doubts but of course I could very well be wrong also. At little on my background, 27 years EOD, and we ALWAYS used inside and outside calipers/and a few other unique tools to get precise measurements (down to a gnats ass). I have seen similar measurement mistake made by so called experts way to many times to count. What we need conclusively is proper measurements or maybe the UN inspection teams will come across a stockpile of actual unfired UMLACA 's and associated components in Syria, which I assume eventually will happen.

    1. I just realized the image I was referring to was not attached. Here it is:

      I think it is pretty reliable for diameter estimation. No?

    2. I am assuming that from what you see its about 115mm in that photo but its not. Hint, you must look very closely at the photo. The actual outer diameter of the gray tube (rocket motor housing) is about 10mm larger. 115mm + 10mm = 125mm.

    3. I just reread jodys post on BM, and the observations of the rocket engine are very precise and valuable. So far they have gone unnoticed, unfortunately. We know the SAA have a lot of Grad-rockets, and in an improvised device you take what you have - theres no time or money to invent something exotic, or to buy something expensive. So what type of Soviet/Russian made Grad is a likely candidate?

    4. sasa,

      Your photo is not definitive. It's measuring the rocket nozzle not the body. There is no reason to believe the nozzle has the same diameter as the body and it may well be narrower.

      This image shows a larger diameter

      And this image shows the outer circumference of 420mm -> 133mm OD

      I agree with Amund that a 122mm Grad rocket motor is most likely.

      Also can someone give a URL for the jody wave posting on BM?

    5. I enhanced the dud HE-vid, and took out a frame where they have removed the casing and are unscrewing the nozzle. A lot more detail come to light, and I'm very curious: Are we looking at a Grad here?

    6. Heres a comparison with a technical drawing of the 9M22U Grad. I would guess the indent between the nozzle and the rocket body is where the spring-fins used to be. No need for them in the UMLACA.

    7. Here's my understanding of the build:
      The engine is 105mm (internal 100mm) and 1.83m in length. I won't be surprised if this is some standard engine. It could be a Grad - don't know what's the internal diameter there.
      It is screwed into a 2.03m steel tube with fins of external diameter 125mm (internal 105mm), and a nozzle is added.
      The tube slides into the 360-370mm warhead (either WP or HE) through a 130mm tube (internal 125mm), the entrance is here: and the end of the warhead tube here:

      Charles - note that there is no nozzle in that image. We can see all the way to the other side of the tube.

    8. sasa,

      Excluding US/European models there are three standard diameters.

      107mm - standard artillery rocket with nozzle designed to spin
      117mm - Chinese rocket for "worker bee" launcher (nozzle unknown)
      122mm - standard artillery rocket with fins and a straight-through nozzle

      Your photograph appears to show a converging nozzle end-view that terminates in a ragged internal edge you can see light through - the remains of the venturi? The nozzle material is distinct to the gray structural housing that supports the fins.

      122mm Grad missiles come in a variety of constructions. Some have a slightly smaller OD with integral skin adaptors to fit the standard 122mm launch tube.

      At least one (Indian) manufacturer supplies units made up of segments screwed together and have a screw-on nozzle / venturi, one or more fuel sections, and then a screw-on warhead. They sell different models with different numbers of segments and range.

      Regarding assembly and assuming a 122mm rocket. I suggest that it's assembled from the payload backwards. The payload cannister manufactured complete. Then a 122mm rocket is inserted into the central tube cavity. Finally a 133mm OD casing with fins is pushed over the 122mm rocket as a sleeve and bolted onto the payload section, imprisoning the 122mm rocket.

      The rocket motor section on the 122mm rocket is narrower than the main body to allow for spring-out fins, so any measurement at the base would necessarily be narrower diameter than the main body.

    9. Charles,

      I'm pretty sure the nozzle fell off and we're seeing all the way down the tube unobstructed. You can clearly see the heart shaped end of the tube, as seen from the other side here:

      Also the other end also seems to measure 125 mm external, so I think we need more evidence to claim the mid section is 133.

  34. GW, we are pretty much in agreement and my OD est: is most likely on the low side a few millimeters. Also, I agree that the nozzle OD is smaller then the rocket motor OD. I have attached a document that is probably the best single open source material available on rocket artillery. This document covers most of the basics and provides some information very relevant to this discussion.

    Tittle; The Rocket Artillery Reference Book:

  35. sasa,

    The photo at

    Shows a 420mm circumference which is 133-134mm diameter

    Assuming the measurement is out by 10mm - unlikely - then the diameter would still be 130mm.

    You can't get more accurate than a circumference measurement without going to calipers. It certainly beats eyeballing against a ruler - where parallax is a factor and which always produces a lower measurement than actual.

    I think it's quite conclusive that the substantial part of the motor tube is at least 130mm diameter and likely 133mm.

    Also, note, the 122mm designation is the launch tube ID, not the missile OD. The missile is likely to be around 120mm OD to allow for manufacturing tolerances and dirt/ice contamination.

  36. Note that we're generally in agreement on the numbers: 130 mm OD for the warhead tube.

    Here's my estimate again:
    The engine is 105mm (internal 100mm) and 1.83m in length. I won't be surprised if this is some standard engine. It could be a Grad - don't know what's the internal diameter there.
    It is screwed into a 2.03m steel tube with fins of external diameter 125mm (internal 105mm), and a nozzle is added.
    The tube slides into the 360-370mm warhead (either WP or HE) through a 130mm tube (internal 125mm), the entrance is here: and the end of the warhead tube here:

  37. sasa,

    The only motor that fits a 105mm dimension is the 107mm rocket. Again, the 107mm designation is the tube ID, while the rocket OD would be 105mm. It is just possible that a composite motor was made up of individual fuel segments screwed together (the 107mm rocket is made up of motor, fuel, and warhead segments that are screwed together). However a completely new nozzle assembly would be required and the fuel composition and grain shape altered to keep the maximum pressure to within original 107mm specs.

    However that is not congruent with a 130mm tube. It would imply either an outer wall thickness nearly 15mm or there is a gap.

    The more likely scenario is a narrow motor section - perhaps 105mm - on a 120mm body as seen in the Grad. That allows room a substantial fin base as seen. The outer wall thickness on the substantive body would be around 5-6mm which is about right for its job and would not add too much weight in the wrong place by moving the CG backwards. That thickness would also allow the tube to bend as seen in the Ghouta photo. That would not be possible if the tube had 15mm walls. (Note, the rocket motor is probably a tight fit to the tube as seen in the HE unit disassembly.)

    The tube is not a pressure container as there is at least one photo showing a weld-line indicating it was rolled from sheet and welded into a tube. The outer tube function is to hold the fins in place without vibrating too much. The inner motor takes care of all pressure containment.

    The only place I have seen any reference to the 105 mm motor is some 'expert' contribution to Brown Moses. Do you have any positive independent evidence the substantive body of the motor pressure container was 105 mm - as compared to the motor assembly?

    1. First, I see my previous message was wrong. You were referring to the engine tube, and I was referring to the warhead internal tube. I also see some of my calcs were wrong.

      Ok, So here is what I currently think. Let me know if you disagree.

      This image shows the blast plate, which is definitely unharmed. It is 133 mm

      So the warhead tube is probably 135 mm ID, 140 mm OD.
      BTW - You can see here that circumference calculations are inaccurate, since it gives an OD of 159 mm instead of 140 mm here:

      Into the warhead tube we need to slide the engine tube. The entrance is 125 mm, as seen here:

      So the entrance is smaller than the warhead tube ID (i guess heat isolation?).

      We also know it is 125 mm on the nozzle end:

      So it's 125 mm OD on one end and needs to slide in a 125 mm hole on the other side. I find it hard to justify a larger than 125 mm OD in the middle.

      The rocket tube is around 107 mm ID, to which we fit the engine which is 105 mm OD, 100 mm ID.

      What do you think?

    2. I still think the engine sections are standard 122 mm GRAD sections.

      On the outer tube there is a weld between the 174 mm long fin section and the rest of the tube, implying that the fin section can be of thicker metal. (7 mm?) Also note that the fins are not welded to the tube on their full length but only to this thicker tube.

      Assembly of the rocket is like in a GRAD: the fin section is held place by screwing the nozzle into the first engine section. In the UMLACA it would mean that the engine sections are pushed in from the top and the nozzle is screwed in from the bottom. The engine is held in place in the tube by the thicker fin section now squeezed between the engine and the nozzle.

    3. I agree that the rocket motor is most likely a 122mm GRAD or a close variant. If you notice the bolt/s between the fins. These bolts appear to screw into the thick ring about 1.5 inches forward from the end of the rocket motor nozzle and are one of the components that may hold the rocket motor in place in the tube. There are a few photos that show these bolts have sheered off due to rocket ground impact forcing the rocket motor rearward. I suspect that these bolts are one of the mating components that not only help hold the rocket motor in place within the tube but also help prevent the rocket motor from torqueing/twisting/spinning within the tube. I posted more details on this way back when on the BM blog.

    4. I prepared a little flick for you guys. Measurements of UMLACA based on Brown Moses-footage. I've got technical drawings of the Grad, but without measurements. ID UMLACA 125mm. OD on the Grad is 122mm in this version.

    5. Amund - Awesome. Added to the post. Thanks!

    6. Petri - Interesting idea. Do you have indication of the diameter of a typical Grad engine? Is there anyone that manufactures them separately?

    7. Amund,

      Nice graphics (far better than my belated attempt with QCAD)

      However it seems likely the tail tube and fins pushes over the motor fuel tube and nozzle assembly from the rear. Possibly the nozzle is inserted last from the rear, but the fuel tubes can't be.

      jody wave's description below sounds like a very good analysis.

    8. This graphic shows the detail of a 9M22u missile. It shows in particular the attachment of the fore-part of the motor to the fuel section. (This may be what Amund is working off?)

      What is interesting is that the motor venturi appears to be made in two parts screwing together at approximately the middle / narrowest pat of the venturi. The fore-part flares to almost full 120mm diameter where it screws into the fuel section. The rear section also flares.

      It may be possible to work out the minimum diameter of the motor by counting pixels and comparing to the 120mm outer bush diameter.

      (There's a technical name for the joiners between fuel sections and between them and the payload which escapes me now)

      Also of interest is the main body tube is slightly smaller diameter than the 'joiner rings' which will be approx 120mm OD.

    9. Yes, I've got that drawing. It's the best illustration I've found so far. BTW: If someone know russian - it would be nice to have the legend translated. I'll rework the animation based on input here - Also, I like the reverse engineering idea - to actually show how the thing is assembled.

  38. I think you should make a new post - named "An examination of possible rocket motors in the UMLACA" or something. The scrolling here is killing my index finger.

    1. Try this (-:

  39. He he. Obviously you're not on a mac. So this is The End? Nah. Don't think so.

  40. REF;
    There are other videos/pictures that also show what I am going to attempt to describe.
    Amund; nice little video, now if you could make one showing how they assemble all the UMLACA components.

    Sasa, let me talk about a few possible reasons why the warhead central tube is of larger size then the rear tube section. Also, I believe there very well may be/should be a rocket motor to warhead mounting/mating fixture that we can't see inside the forward portion of the warhead inner central tube section. Additionally , the warhead central tube section consists of two separate tubes and when the rocket motor is inserted there are three tubes in the warhead section. The tail section only consist of only two tubes an outer tube and the inner rocket motor tube. This is complicated to explain and you will need to use the Ref; video to see what I am trying to point out. The best starting point is to freeze frame at the 43 second point. Here goes.
    1. The warhead section central tube consist of two (inner and outer) tubes before the rocket motor is inserted.
    a. The inner warhead tube is apx 130mm OD. This inner tube is what the rocket motor is inserted into.
    b. The forward end of this tube has a heavy metal plate as its end cap. This end cap can be seen in the pictures you referenced. I believe that on the reverse side of this cap (no visible) there may be a mounting/mating fixture for securing the warhead to the rocket motor. Visualize how a 122mm GRAD type rocket motor and its associated warheads are connected and you will understand.
    2. The outer warhead tube is apx 140mm. This tube is welded to the inside of the warhead baseplate.
    a. This outer warhead central tube contains the inner warhead tube and is also used to structurally tie the warhead base plate assembly, burster assembly, and nose assembly together (I also explained this part, in detail, way back when on the BM blog).
    3. When the rocket motor is installed in the warhead there will be three tubes. To actually see this go to the referenced video and freeze frame at 43 seconds. You will notice that the rocket motor tube is the inner most tube, visible were it snapped off. The inner warhead central tube is also visible but you must look closely. The outer warhead central tube again is welded to the inside of the warhead baseplate. Next get a straight edge and line it up with the rocket motor tube vertically, then line up the straight edge with the inner warhead central tube vertically, and last line up the straight edge vertically with the outer central warhead tube. The three warhead tubes listed from smallest to largest.
    a. Rocket motor tube; apx 122mm.
    b. Inner warhead central tube; apx 130mm
    c. Outer warhead central tube; apx 140mm

    1. jody,

      I think it is likely there is some type of insulation between the 140mm tube and the 130mm tube - basically to protect the payload. It's also not clear how the thrust from the motor is transferred to the 140mm tube and thence to the payload and fin assembly. Possibly it's done at the base-plate direct to the payload?


      It is very likely the motor 122mm OD is actually 120mm so as to fit inside a 122mm launcher tube.

      There will also be one or more shear bolts to hold the complete missile in the launch tube till full thrust is achieved. Where they are is interesting because the fin assembly is smaller diameter than the payload.

    2. GW; Yes I would think they would coat the inside of the outer and/or inner central warhead tube with insulation. Typically you don't see a rocket motor extend into the warhead/payload section like we see on the UMLACA. Basically its a piss poor design. Below I will attempt to explain how rocket motor internal chambers are insulated, to the best of my ability. I don't think asbestos is used much anymore and this technique is old school. There are more modern methods to accomplish these tasks but this will give you the general idea.

      1. Rocket motor internal columns (chambers)normally have a coated layer (liner) between the rocket motor inner metal column (chamber) surface and the propellant.

      2. Normally this type of linear is composed of a mixture of asbestos-fiber-epoxy or similar materials.

      3. This material is normally sprayed in the rocket motor chamber while the chamber is spun. This type material functions as a liner/insulator.

      a. Case bonded propellant grain; First-the rocket motor chamber is coated with asbestos-fiber-epoxy. Second-the propellant grain/igniter is inserted into the rocket motor chamber while the coating is still wet. Finale-once the coating cures the propellant grain has effectively bonded to the inner rocket motor case and can't be removed.

      b. Non-case bonded propellant grain; First-the rocket motor chamber is coated with asbestos-fiber-epoxy. Second-the rocket motor chamber with asbestos-fiber-epoxy coating is cured. Finale-the propellant grain/rocket motor chamber is coated with silicon or similar type lubricant. The propellant grain/igniter is seated in the rocket motor chamber and secured in place (normally by attaching the nozzle assembly). None-case bonded propellants can be removed from the rocket motor chamber (in my field we call this stripping a rocket motor).

  41. Amun, If I can just add a little bit, I hope without complicating matters and not too much duplication of jody.

    It seems to me the rear fin support ring is thick metal. It has the fins welded to it and it also surrounds and holds the motor assembly.

    The next element is the outer ~130mm tube between the fin ring and the payload flange. It is lighter construction with a longitudinal welded seam and it is welded at the base to the fin ring. Its function is to support the fin ring and fins and provide a degree of stiffness. Let's call it the fin attachment tube. The far end has an attachment flange.

    Internal to the fin attachment tube and fin ring is a 120mm motor that is anchored to the fin ring but is isolated from the fin attachment tube. There is probably a small air-gap due to the poor tolerances of a welded fin attachment tube.

    The flange assembly at the base of the payload is in three parts. Internal 130mm tube flange, fin attachment tube flange, and payload flange.

    The internal 130mm tube is structural and takes the motor thrust and transfers it to the payload flange and fin attachment tube flange. It's stronger construction than the fin attachment tube,.

    The payload cannister consists of an outer case, an inner ~140mm concentric tube. and plates joining them together including a base flange. The entire assembly is liquid-tight.

    The assembly process is:

    - Insert the 120mm motor into the internal 130mm tube and flange
    - Slide the fin support tube over the motor and align with 130mm tube flange. Bolt motor in place in the fin support ring.
    - Slide the payload over the internal 130mm tube and bolt together with the 130mm tube flange and the fin support tube flange.

    (gawd! that's complicated! I hope I understand what I wrote)

    1. I can't find any picture where the fin support ring is clearly visible - please link! There are small holes between the fins for screws - holding the rocket in place much like a lampshade. I'll go through everything later today and start modeling. I will try to mimic the assembly as closely as possible. Fun project!

    2. Amund,

      Appears to show a ground down weld (or possibly a braze) between the fin support ring and fin attachment tube. It matches the point that the fins cease to be welded to the fin support ring - though they continue up the fin support tube for a short distance but are not welded.

      The image is not definitive but it's consistent with a wall-thickness change at that point.

      The end view at

      Shows the very thick tail fin support ring as well as some type of liner between the ring and the motor nozzle.

      The motor support tube axial weld can be seen at

      There are better images available though.

      I'm not sure if I mentioned it, but the 140mm payload tube is likely lighter gauge than the 130mm internal structural tube

    3. I made two cross-sections of the layering - one for jody, one for Charles. Is this what you think?

    4. CW sorry about the GW.

      The construction of the warhead inner central tube does appear to be made of heaver metal than the warhead outer central tube. In the referenced video stop frame at 1:02. This is the only image I have found that clearly shows the rear portion of the warhead inner central tube and it also shows a snapped off rocket motor within this tube. I am not sure if this tube is removable from the warhead/payload area and I also would like to know if there is a treaded adapter for rocket motor to warhead attachment contained in its forward end. Also agree on where your going with the fin section construction.

    5. I'm trying to keep the design for the rear end/rocket casing separated from the warhead for now. Charles, can you check if this how you think the rocket casing is layered? Sorry, jody - I accidentally deleted my album (and your comment) on G+.. Have a look at the new cross-section.

    6. Amund, good start and my best guess is that your measurements may be slightly on the low side by maybe 1mm to 3mm. I do agree with CW that the warhead inner central tube may be of slightly thicker/heaver construction than the warhead outer central tube.

    7. REF:
      Some more fine points and a possible unidentified component of the UMLACA.
      The referenced video shows exactly how the rear rocket motor tube forward adapter mates with the rocket motor tube adapter on the rear of the warhead base plate. You must zoom into 200+ to best see this. Stop frame at 31 seconds and you can see clearly two female channels in the adapter ring. The shallow or outer most channel mates with the small raised outer most lip located on the warhead baseplate adapter ring (stop frame at 102 seconds). The deeper inner most channel on the rocket motor tube adapter ring mates with the warhead inner central
      tube lip that extends out of the inside of the warhead rocket tube adapter assembly (stop frame at 102 seconds).

      What might the component be that is laying just in front of the rocket motor. Notice the color, diameter, and apparent damage from explosive blast forces. I have an idea what it could be but any inputs would sure help.

    8. Nice find! The component is the "bicycle pump component" that was investigated a while back on BM. No conclusion then, but in most graphics its placed in the warhead mid-section.

      About the rear tube: It's mindboggling how thick the metal is (5-6mm) in the rear end/fin support, and how thin it is (2-3mm) where it meets the warhead - yet there is no apparent change in the outside diameter. The rear end looks perfectly straight in all media I've seen. The fins are perfectly rectangular and welded on in a simple manner. They are also straight. I don't get it. But then I'm not an engineer.

    9. Amund, sorry I posted the wrong video on the possible unidentified UMLACA component. One more try.

    10. Sorry I'm not replying. You're just moving too fast for me. But I am following the conversation, and will update the posts once you reach an agreement.

    11. Amund, CW's posts above pretty much nails the rear tube and fin construction. Keep in mind the nozzle assembly most likely has a smaller OD then the rocket motor OD. This additional space allows for the extra thickness of the rocket motor mounting tube fin assembly section.

    12. I agree that there is a pronounced thickening of the tube in the fin section. It's weird how smooth the surface is, though. But from certain angles I see a shift in the surface. For the purpose of proving that a 122mm rocket is a good fit in the UMLACA, it doesnt really matter. I've prepared a new vid, showing one part of the assembly.

    13. OD on nozzle assembly: This frame shows the different ODs of the nozzle quite well. It is slimmer in the end, so the images with measuring tape showing 105mm are not surprising.

    14. BTW: I've previously enhanced a part of that video like we did with the Al Liwa-films. There is new light on the HE-warhead also!

  42. This comment has been removed by the author.

  43. OK, here goes. A rough assembly of the UMLACA with Grad rocket.

    1. Thanks! But hang on - I've made a new version with a more detailed fin assembly. I've tried to emulate the seamless, thicker attachment - with fins sticking out on both sides. The devil is hiding in the details.

    2. Very nice thanks! Good detail.

      Also, just to support my contention that the fin support tube is welded thinner metal, see this video of its big brother showing a mid-span weld.

      I think the larger missile perhaps uses a bigger transport rocket? But there nothing obvious in the 150-160mm(?) range.

    3. wow! amazing vid! We've never seen imagery this clear of the launcher. Very interesting! The first thing i notice, in the poster frame - is the "bicycle component" - its actually inserted in the outside of the "unknown port". Yes, I think the thickness of the tube (small UMLACA) is around 3mm. And I agree, the large one has a bigger rocket. Luccum made a very instructive GIF animation on

      Now, I've made a new version of the animation with more detail in the warhead. I've placed a light container around the small TNT-charge, so the charge is placed between two solid steel parts. If done correctly, I think this design would force the explosion laterally, thus opening the cannister from the top without doing much damage to the front parts - which is also what we see in the remains of the rocket. What do you think?
      Have a look here:

    4. Amund, excellent demonstration and you are really good at this animation stuff. There are some other components that go into the warheads forward burster tube assembly but its way to complicated to explain.
      Amund, here is a new challenge for you. Make an animation of a UMLACA chemical warhead functioning in the airburst mode (Height of Burst ?). The following are some key events in the functioning sequence to try and capture.
      1. Fuze, booster, burster functioning; Show flash coming out of the nose fuze well and the fuze being ejected forward.
      2. Show forward portion of the outer warhead skin bulging outward as the burster functions.
      3. Show outer warhead skin starting to separate from warhead nose plate and show the warhead nose plate being ejected forward.
      4. Show the warhead outer skin continuing to separate outward in (6?) equally sized rectangular pieces and show the initial outward dispersal of the chemical agent.
      5. Show the 6? pieces of the outer warhead skin separating from the warhead base plate in a outward/slightly rearward directions and show the chemical agent cloud continuing to expand outward.
      6. Show the rocket motor assembly and warhead baseplate/central tubing impact the ground and the continued outward expansion of the chemical agent cloud.
      Note; Good luck and if you can do this than maybe later you could do the same with a FAE and HE warhead.

    5. Thank you! This is what i do for a living, I think the best contributions come when people use their professional experience, not just their innate tendency to speculate or conspire. This is a good challenge you bring forward. I've already been thinking about how to animate the bursting cannister etc - its doable, but don't expect something overnight. The physics engine in the software I'm using is great, but this type of simulations is complex - especially something like the CW agent cloud. It takes time and effort, but I hope to simulate some of the stuff in your list over the next couple of weeks.

  44. Video

    Has what may be an additional instance of the 300mm+ missile.

    Asides from the obvious errors in dimensions of the missile (e.g. 14:16) there is an interesting perforated round steel dish - perhaps 200mm diameter (5:51). Any idea what that is?

    Also, the video clearly shows the longitudinal weld in the fin support tube at 5:54.

    1. Yeah, noticed that. Never seen before. Any ideas?

    2. Great find CW. This video shows a few more components of the warhead burster assembly/housing and how these additional pieces of the puzzle may fit together. The Eskimo weapon system seems to have a number of different type warheads and these different type warhead most likely also have different type boosters/bursters. A good example of what I am trying to convey would be the FMU-26/B fuze. This fuze has two interchangeable boosters (FZU-1/B and FZU-2/B) depending on application desired and warhead type selected. The FZU-1/B booster is low explosive (propellant) and is used to open thin skinned munitions so that the payload can be dispensed/dispersed. The FZU-2/B booster is high explosive and used to detonate high explosive warheads. I think we may find that the Eskimo chemical warhead uses a low explosive burster ( very large CAD/propellant driven cartridge). I also think we may find that the Eskimo high explosive warhead uses a high explosive booster/burster.

      The following is my best guess about these new components contained in the video and how they may be assembled (Reference; 18 seconds and 5.48 to 5.54). The components that I will attempt to describe are located in the forward portion of the Eskimo warhead. These are some of the components that fill the void between the forward end of the warhead rocket motor central tube and nose assembly, structurally connecting them together(other components are still missing). This gets a little complicated

      1. The approximant 200mm diameter of the component at the 5.48 to 5.54 mark of the video is accurate and consistent with some other components (burster tube/housing assembly components) that I described way back when in the BM blog.

      2. I believe the component at the 5.48 to 5.54 mark of the video is a very large CAD/propellant driven cartridge in the fired/expended condition. This cartridge has five large vent holes that are used to vent the gases in a predetermined direction.

      3. I believe the component at the .18 second mark is the burster housing (breach) that contains the cartridge. This housing also has five large vent holes that are mated to the cartridge vents holes. This housing is one of the major components that help tie the warhead rocket motor central tube and nose assembly together. The video does not show the end cap that encloses the open end of the breach chamber where the cartridge is installed. The info I posted way back when on the BM blog show this breach end cap (I think), approximately 200mm diameter and explains how it may connect to the forward portion of warhead central rocket motor tube.

    3. This comment has been removed by the author.