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Moon shot missle 1.5.5


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I was playing the instant intercept mission for the SU-27, took a missile hit that blew my wing off, used the launch override and fired a number of missiles off in different directions.

 

One of the R-27ER missiles that I fired pretty much straight up in override mode, just kept going and going...I was at 8k altitude, it was accelerating until it hit a max of about 80,000 meters then all of a sudden started to bleed speed in space,fell back towards the ground, re accelerated to about 3000 kph until around 10k drag slowed it way down before it hit the ground. I am going to try to repeat it, I got a picture somewhere to. Worth looking into or is this a known behavior that is being worked on?

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I fail to see how this is an issue, missiles have a LOT of potential energy in their rocket motors. Without air resistance they definitely go like a bat out of hell.

 

No way that a missile fired at 8k straight up will reach 80k altitude (72k climb). Even if there would be zero air resistance there is still gravity... And to me it sounds like the rocketmotor did not stop burning till 80k since it was still accelerating. There is no way the rocketmoter of a R-27ER will burn that long

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It would be trivial for somebody who is good at math (not me) to figure out the max altitude the missile could theoretically reach if the atmosphere didn't exist.

 

But all of my intuition says that a missile fired straight up should go extremely high. Especially a 27E, which is a very fast, long range missile even at low altitude.

 

Also, it would be very nice if we could make absolutely certain we're not interpreting "k" to mean "a thousand feet" or "a thousand meters." Please use km or ft to prevent confusion.

DCS modules are built up to a spec, not down to a schedule.

 

In order to utilize a system to your advantage, you must know how it works.

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First off, missile talk. An AIM-7E has a mass of 197Kg, and a motor mass of 42Kg(https://forums.eagle.ru/showthread.php?t=131806&highlight=missile+mod) making a Motor/Mass ratio of 0.213198

The AIM-7M has a mass of 231Kg and a motor weight of 62Kg ratio of 0.2684

The R-27ER is a missile based on the same category as the 7m, but with basically more propellant, so it is safe to assume the fraction is AT LEAST of 25%

 

 

 

I did my own test with a mach 1 (1480km/h=411m/s) launch at 8km (26299'=8015m) , level. The max speed the missile reached was 2421KTS IAS (2662 KTAS = 1331m/s)

Now, the drag from a constant altitude launch > the drag of a missile launched vertically, so I will not consider the drag, as it is already capped over what the missile will experience vertically.

The energy given by the missile was 1/2*(350*0.75)*[1331^2-411^2]=210346500 J (assuming missile mass = Launch*0.75) This considers the energy given only to the missile itself, without the energy used to transport the engine that hasnt burned yet. [Aka minumum]

 

Now, assuming constant G[maximum value] and a mass of 350[maximum value] we get 350*9.81*h=210346500 h=61262m, making a final height of ~70 000m, with an initial launch speed of 0, and assuming the missile brings the engine the whole way up!

 

So, i've made VERY rough approximations that REALLY reduced the missile's performance, yet it still managed to get pretty close to your altitude, so it makes a lot of sense to me.


Edited by Ktulu2
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Upgraded version : if we consider the mass M, the mass of the missile without the engine, we get :

 

1/2*m*[1331^2-411^2]=9.81*m*h

thus h=81684m

 

Thus max height 88000m...

 

This is legit, as the energy needed to accelerate and make the engine climb would be lost as it was burned!

 

EDIT : This however, is with an approximation of drag, as I said, FOR THE ACCELERATION ONLY, I forgot to say that earlier, sorry, taking the rest of the drag into account takes MUCH more calculus, and while I could do it, i'm entering my finals...so yeah...


Edited by Ktulu2
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It was not online so that rules lag out. I have been really busy with school/finals so I haven't had a chance to check back. When I said 8k altitude that a high estimate btw 7-8k was the launch altitude. It was gaining energy in a vertical climb to 80k.... I got the screenshots, ill post them in a bit.


Edited by zxarkov

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i7 3930k @ 4.7GHz | GTX 980 Ti | 16GB G.Skill 2133 Quad Channel | Samsung 850 EVO SSD | Win7 ProX64 | CH Fighterstick | CH Pro Pedals | CH Throttle | BenQ XL2730Z 1440p

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First off, missile talk. An AIM-7E has a mass of 197Kg, and a motor mass of 42Kg(https://forums.eagle.ru/showthread.php?t=131806&highlight=missile+mod) making a Motor/Mass ratio of 0.213198

The AIM-7M has a mass of 231Kg and a motor weight of 62Kg ratio of 0.2684

The R-27ER is a missile based on the same category as the 7m, but with basically more propellant, so it is safe to assume the fraction is AT LEAST of 25%

 

 

 

I did my own test with a mach 1 (1480km/h=411m/s) launch at 8km (26299'=8015m) , level. The max speed the missile reached was 2421KTS IAS (2662 KTAS = 1331m/s)

Now, the drag from a constant altitude launch > the drag of a missile launched vertically, so I will not consider the drag, as it is already capped over what the missile will experience vertically.

The energy given by the missile was 1/2*(350*0.75)*[1331^2-411^2]=210346500 J (assuming missile mass = Launch*0.75) This considers the energy given only to the missile itself, without the energy used to transport the engine that hasnt burned yet. [Aka minumum]

 

Now, assuming constant G[maximum value] and a mass of 350[maximum value] we get 350*9.81*h=210346500 h=61262m, making a final height of ~70 000m, with an initial launch speed of 0, and assuming the missile brings the engine the whole way up!

 

So, i've made VERY rough approximations that REALLY reduced the missile's performance, yet it still managed to get pretty close to your altitude, so it makes a lot of sense to me.

 

 

And I told my Calculus Teacher I'd never use the stuff outside of school. :music_whistling:

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I tried this out in Instant Action and managed to get a few missiles to pass 80,000m (263,000ft). Launched them from about 20,000m (70,000ft). Hit 'em right in the mesosphere. ;)

OrbitMissiles.trk


Edited by SignorMagnifico

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So I had some time to waste and tried to see how the thread was still alive, so 2 things :

1) Why do you guys think this is wrong? Anything aside from guts?

2) I made a nice little graph showing the max altitude the missile should be expected to reach if there was no atmosphere at the moment the engine was out (so WITH acceleration drag) considering variable G. Of course, these will be a couple tens of thousand meters off, but should get the point across. (of course, this is based on what I posted above)

 

H[1]=Launch altitude, H[2]=Max altitude, all in meters.

 

attachment.php?attachmentid=152907&stc=1&d=1481001073

MissilesTopAlt.thumb.jpg.d8e36b2f4fefa7cf634495dc28dbc03f.jpg

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