Ballistics

[UllyB 1,206]

I need some help to solve a ballistic issue for a weapon/rocket. Everyone here, understands, by now, how a weapon (missile) works in this game. What very few know is HOW to tweak  and WHICH weapon's parameters exactly must be changed in order to get a weapon as realistic as possible. Also, not all new weapons (third party) are set to reflect the realism by their creators.

This is where I come in. I want to make the AS-4 Kitchen missile (KH-22) to work in this game to have a 80-85 succes hit chance from 300km (in reality the weapon can hit a target at 600km). I cut in half the weight of the weapon (5820 to 2910 Kg); I cut in half the max range of the weapon from 600 to 300 km. I also changed the seeker range parameter making it 350 for the max range of 300km. I tweaked the booster and sustainer motor values (in reality the rocket can reach 4,5 times the speed of sound after all) but I can't make it hit a target which is longer than 150 km and I am out of ideas. Is there a way to make it be reliable from 300Km but without changing its weight any further ? Thank you

[tiopilotos 2,519]

Any modder who deals with ballistics should use the missile range simulator which can be found here:

https://combatace.com/files/file/10592-missile-range-simulator/

I have spent much time testing and trying to determine the best values to ensure that missiles will perform as realistic as possible (always taking into account game's egnine limitations). As for Kh-22, I suggest to use the real values in terms of diameter, weight, booster acceleration/time, sustainer acceleration/time etc and then after many simulations you can determine the combination of which subsonic and supersonic drag values best fit with weapon's profile.

As far as I remember stock Kh-22 is capable of destroying ships at 400 km when fired from high altitude. The improved Kh-22M/MA had 600 km range according to wikipedia. As for the hit chance I'm not quite sure what values must be changed for ASM missiles. 

[UllyB 1,206]

thank you for your reply and link. Actually I had no clue that such a tool exists. If you noticed, though, I posted my message in the SF1 series forum. The link you sent seems to be for the SF2 series weapons, which I understand has new data type for missiles and such. My question for you friend is: can I use the simulator for SF1 weapons too or is it useless for anything but SF2 stuff ? Thanks

[UllyB 1,206]

It seems that works for both SF1/SF2...I've run some numbers but something is wrong...at 350kts and 5200kg weight I get distance of 1,5 milion km which is impossible, plus the author said that in simulation is not taken into account the gravity, but in the simulator there is this parameter. I am confused....If you say that you used that tool and it works, could you write down an example , with numbers, to make me understand how it is done , please ? Thank you.

[+guuruu 5,909]

I used these datas :  https://en.wikipedia.org/wiki/Kh-22

[tiopilotos 2,519]

I think these values are quite unrealistic. Let me explain some things taking into account the russian wikipedia: https://ru.wikipedia.org/wiki/Х-22

1. IAS/TAS Ratio has to do with the flight altitude, 0.86 is 10,000 feet (3000m). Maximum range for initial Kh-22 was 300 km when fired from 10-12 km altitude. Shortly after launch the missile climbs to 22 km (75000 ft) and at that altitude accelerates to 3700 km/h (3.5 Mach). So, reaching 585 km at 3000m level flight is even unrealistic for later variants Kh-22M/MA.

2. Maximum speed in your graph is 1447 m/s which is 5200 km/h at 3000m alt. Maximum speed for Kh-22M/MA was 4000 km/h at 22000m. I guess we all know that a missile can fly faster at higher altitudes due to thinner air. So according to this graph the Kh-22 should fly at about 5500-6000 km/h at high altitude! 

3. Sonic speed must be set 343 m/s when the missile flies at surface level. The higher the altitude the lower the sonic speed. This changes at 18 km altitude. Higher than 18 km sonic speed starts increasing.

This is my effort on how to tweak this missile:

However keep in mind that the missile simulator tool calculates speed, range and time for level flight. So at this graph you have a missile reaching 300 km at 0.488 IAS/TAS (22.5 km) altitude. Practically game range should be shorter because Kh-22 is being launched at 10 km alt, climbs at 22 km alt and then at a certain distance from target starts diving. 

In general, determing the correct values for ASM missiles is more difficult and you need to test missile's performance in game again and again because flight profile of ASM missiles is more complicated. Personally when using this tool to determine values for surface to air missiles I test missile's performance in game again and again. Then according to what I have seen in game I keep working using the range tool until I have achieved the best combination between real values and realistic performance. Unfortunately it's an extremely time consuming process.

Edited January 5, 2019 by tiopilotos

[UllyB 1,206]

I tried, it won't work for me, 150+ km is the best I get. I used the real values (real weight is 5820, I checked some weapons packs, no one uses this value, they all use a smaller value: 4820Kg or something) from wikipaedia, for the drag coef I used the values given in the weapon setup. In simulator I get, with my values 141956,47 m. I noticed something else: the loft thing it seems not to work for me, the missile is not going up to the ceiling I set in the weapon sheet (4000m) ; it just dives to the ground after the booster ends. The same with the sustaining motor, it is like inexistent, after booster shuts down, the missile falls like a stone downward in contrast with the situation at 150Km, when it seems that it can lock on target and flies almost straight after realeasing it and dives gently to the target after that.. I can't figure out what I do wrong. If you all say that you get ~ 300Km hit I would really like to see your weapon setting. One more thing to eliminate any confusion: I use WOI/ SF1 environment ONLY, so my weapons are for SF1. I am out of ideas. I need some fresh angles.

PS - my math gave me 0.6136 IAS/TAS at 30.000 feet, how do you get 0.488  ??? I used F-14 to measure the coefficient, cause it's one which shows me the TAS on MFD (IAS=332kts ; TAS= 541kts), so :

332/541 = 0.6136

 

Edited January 6, 2019 by UllyB

[tiopilotos 2,519]

I set IAS/TAS 0.488 because I made simulations for 22 km altitude because that's the max alt the missile reaches before diving to target. In SF1 the ASM function is not present so I'm not quite sure how you will simulate the missile. As far as I remember cruise missiles in SF1 use radio command or semi auto command. These types of guidance don't use loft, so you just fire the missile from high altitude and you hope that there will not be mountains between missile and target.

Send me your copy of Kh-22 missile and I will make some tests using both ASM and semi auto command. 

[UllyB 1,206]

well that explains a lot. Indeed I use for ASM the CGR one instead (I knew that ASM feature doesn't exist for SF1 series) . I didn't know that CGR missiles won't use the loft feature (I think that this is a slip of editor author, it should been greyed the feature when selecting CGR missiles; I wonder now how many of these features won't work for some missile and I don't have a clue which is which), I just thought that something is wrong in settings, LOL

Ok I will send the file once I am home. Thank you for insight and help!

Edited January 6, 2019 by UllyB

[UllyB 1,206]

I solved the problem. First, it was my fault, from the beginning: I was blind because I was with my eyes on all the data from that weapon window and didn't noticed, when testing , that my TU-22M3 had instruments in NM, instead of KM. I always was thinking that those 300 are KM in my mind. I realized the mistake , when switching to a TU-22K, which had instruments in KM, and when I saw 800Km to the target , I realized the mistake I made. Stupid me!

But there is a good side to the story, confusing 300NM with KM I made it fly 590KM and hitting the target. At 10.000m , launching it from 590km and with max speed (full afterburner). I didn't test it yet for lower heights, but I guess it should work, there , too with some digits tweak, for shorter distances. Here's the weapon sheet with the data:

 

I kept max values for Launch reliability, Lock-on chance and Accuracy for testing purposes only, otherwise I would've wasted precious time. I also changed the missile type from CGR to the inertial homing to benefit from the loft feature which is missing for the CGR missile types. The good part, for those who play in big terrains, is that you can fire it from great distance (the accuracy will be a issue I guess if you revert to the realistic 80% accuracy of the missile, though), the not so good part is that you have to tweak it a lot , for lower heights, in medium and small terrains, otherwise it will fly above and it will hit the map "wall" , getting far away over the target. The data , I guess can be retained for people who wants to try higher distances etc.

Edited January 7, 2019 by UllyB

[UllyB 1,206]

UPDATE

I checked launching it,  in the same setting,  from lower heights and things didn't work out too well. The missile climbs to steep and disappears (somewhere in the TK's stratosphere I guess LOL) . One should modify, because of that, the loft and the descent angle (maybe even the Max Loft Altitude as well, we'll see). I will update the info once I get some positive results in my testings.

And here's the KH-22 setting as CGR missile, with 300km hit range tested. I used 10.000m height, 300km missile release, max speed(full afterburner):

 

 

Edited January 7, 2019 by UllyB

[UllyB 1,206]

The KH-22M has a 600km range so, the first one I renamed it. The last one, the CGR KH-22 I leaft it with 300km range as the initial KH-22. i created specific code stations in Tu-22K and TU-22M3 and I can use them both, depending the year. Problem solved, thank you all very much for the support. I wouldn't have done it without it.