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Ataka Questions


AeriaGloria

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I have tried to learn everything I can about these ATGMS. But questions remain. I hope someone can help

When they first came out with Ataka, I checked rocket motor power and drag specifics in the LUA. 

 Per the formula for specific impulse to reach Newton-seconds of power, using the fuel weight, acceleration time, and impulse values in LUA, brought me to 

Shturm: 

Booster: 43,120 N for .05 seconds, 1 kg of fuel.

Boost stage; 7,597 N for 2 seconds, 6.46 kg fuel.

Sustain stage: 2,400 N for 3 seconds, 2.94 kg fuel

Ataka: 

Booster: 43,120 N for .05 seconds, 1 kg fuel.

Boost stage: 6,503N for 2 seconds, 5.5 kg fuel.

Sustain Stage: 3,503 N for 3 seconds, 4.3 kg fuel

Ataka, despite being 37% heavier, has 14% less first stage thrust and 46% more sustain thrust. This is done by shoveling more fuel into sustain and less into boost, decreasing boost burn rate and increasing sustain burn rate. This makes sense to deal with increasing range of a heavier missile by allowing it gradually build up speed better. 
 

This site, https://thesovietarmourblog.blogspot.com/?m=1#kokondesign

Is where I get most of the following information and the source of all following quotes. It Gives 45,000 N peak thrust for the booster for the Shturm over .065 seconds. 5,500-7000 N for the Boost stage, and 1,800-3,600 N for the sustain stage. Both are relatively close to the range, with only Shturm going over the boost stage range. 

For the booster itself, this site states “On the 9M120 "Ataka", the ejection engine was upgraded to a new model with 15 rear nozzles, but retaining the same 9Kh182 fuel charge. This modification allowed the engine to develop a stronger impulse, necessary to launch the heavier missile at the same velocity as the lighter 9M114.” yet it gives no sources, and I cannot find any pictures of the Ataka with the booster attached in order to corroborate. And in DCS, Shturm and Ataka have same number of nozzles and thrust 

The part where I compare the engine thrust? The website mentioned earlier, also references a textbook with a surprising mention, that Ataka and Shturm have identical motors “According to the textbook, "Конструкция Средств Поражения, Боеприпасов, Взрывателей И Систем Управления Средствами Поражения: Конструкция и функционирование ПТУР" (Design of Weapons, Ammunition, Fuses, and Control of Destructive Devices: Design and Functioning of ATGMs) by the Penza Artillery Engineering Institute, the 9M120 shares the same engine as the 9M114.“

Perhaps by same engine, this textbook does not exclude the possibility of re shuffling the ratio of boost to sustain fuel mass, and changing mass flow to reach same 2 second limit of boost stage and 3 second limit of sustain stage. But it makes me wonder how ED came to the different engine rocket thrust figures? 
 

This website also makes another astonishing claim, that I cannot find a backup for in other English literature.Indeed, in accordance with the goals of OKR "Ataka", the only difference with the 9M120 was in the implementation of a new tandem warhead with a powerful precursor charge, and minor modifications in the launch circuit due to the new fuze of the warhead. Everything else, from the radiocommunications equipment, to the rocket engine, to the steering mechanism, and even the fuselage itself, is the same as the "Kokon".

If this is true it brings a couple questions to the table. If they only differ in warhead, where does the extra 1 km of range come from? Is the aerodynamic benefit of the longer tandem HEAT warhead that reduces drag coefficient, and a combination of the increased inertia and shuffled around engine power allowing it to lose speed slower despite a slower max speed? But if this is Al so is true, becuase of the aerodynamic advantages of the tandem HEAT warhead, why do the 9M120F and 9M220O have 6 km range as well despite having same warhead shape as Shturm? The article does point out that some components are different between Shturm and Ataka, such as the gyro coordinator, but that it is unknown if those confer any differences at all. 
 

   In fact, as the Shturm has a higher speed then Ataka, and having same 17.6 second battery, means it should reach 6 km same as Ataka. Doing tests in DCS show that Ataka despite its slower speed; it’s grater inertia allows it to decelerate slower, and is actually traveling faster at 6 km compared to Shturm. Since the rotation rate is often tied to airspeed/time since motor shutdown, the faster rotation rate should be more accurate as it can make faster more precise corrections (in real life). 
 

  Perhaps Russia decided to relax the restrictions/standards a bit, and give 9M120F and 9M220O a 6 km range same as Tandem HEAT, vying on the proximity fuse and thermobaric warhead to mean accuracy was less of an issue. Or perhaps the boost/sustain stage was truly different in Ataka series, and did confer serious benefits. 
 

  And if Ataka And Shturm are identical save for warheads. Why is Ataka 11.5 kg heavier, when the tandem HEAT/thermobaric warhead is only 2 kg heavier then Shturm warhead? Where can the other 9.5 kg possibly come from? And 9M220O warhead is shown to be same weight as Shturm warhead in DCS LUA, 5.4 kg. Yet 9M220O is same weight as Tandem HEAT/thermobaric Ataka. I wonder if something else is going on? 

  Lastly, while the tandem HEAT warhead may provide less 0 lift drag. It also has four vanes/strakes, presumably to help balance out the longer/heavier warhead with extra lift. Yet in DCS LUA all Ataka and Shturm has same Cx/drag coefficient. Perhaps ED thought it would be negotiable when you also add in the lift-induced drag caused by the vanes/strakes? 

  Anyways these are just some thoughts. And did not think these were a rigorous or clear cut enough to put in “bugs and issues,” as these are merely questions and inferences coming from data that isn’t always directly sourced or concretely backed up. 
 

Thank you for reading, and please let me know any thoughts you have or knowledge of what may be going on behind the scenes with these missiles 

 


Edited by AeriaGloria
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