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| Weapon Speed After Burnout http://jkpeterson.net/forum/viewtopic.php?f=6&t=2529 |
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| Author: | Centurian57_369th [ Sun Jul 03, 2022 10:33 am ] |
| Post subject: | Weapon Speed After Burnout |
All right, so in the past we've established that the speed listed in "Flight Speeds" on the "Missile Info" tab on ordnance is the speed in ft/sec after the fuel is expended. Until then, the weapon maintains the max speed in the "Movement Info" tab, which is in mph. So now the question arises, "what is a good post burnout speed?" Obviously, FA isn't smart enough to maintain that weapons will gradually lose speed so this just becomes a catch all "final speed," if you will. In some of the initial setups that I made, I was using around 50% of maximum speed but I am finding that this is just too slow, especially on AAMs that have modifiers for sea level reductions. Where I've found stats showing "average speed" for a weapon, I've always used this number but for those that don't, I'm thinking of a band-aid solution. Any thoughts? Maybe 75%? |
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| Author: | CAG Hotshot [ Tue Jul 05, 2022 02:23 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
I don't think you are correct here... FA does have many factors that influence missile performance after burnout... drag and how fast the missile loses its energy... |
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| Author: | Centurian57_369th [ Tue Jul 05, 2022 10:18 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
Here are two videos, one with 46% modifier at 0KFT and one with 100% modifier at 0KFT. Both have 100% at 20KFT. Missile is set to 2000 kts powered and 1000 kts unpowered. In the first video, you can see the launch and the missile not quite hitting the 2000 kts because we're at 10KFT in the video (cruise altitude is set to 40 aka 10KFT). Once you hit burnout, the missile slows down to the final speed and remains that speed constant until it starts to dive on the target. There is an instant loss of around 55 kts, likely the result of the maneuver to the dive. Then a slow increase in speed as it dives. But then we see another, even more drastic loss of speed (more maneuvers? lower altitude?), followed by an even more rapid acceleration before impact (maybe the dive?). The missile is set to go down to 1KFT at a cruise distance of 20 and 10KFT at a cruise distance of 78. https://www.youtube.com/watch?v=gMl01JymQi8 In the second video, you can see the missile going right to 2000 kts because I have the 100% modifier at 0KFT. Just as before, there is an initial speed loss - this time around 50 kts - and a gradual acceleration as it dives. Then the more drastic reduction (even more drastic than before actually) and the same increase in speed. I fired two missiles on this one instead of 1 so that we can watch it again but the performance is identical. https://www.youtube.com/watch?v=8aYfJr-shCI So, at best, this is what I can ascertain. 1. Weapons go to max speed upon launch 2. Weapons go to final speed upon burnout 3. Weapons will gain speed in a dive 4. Weapons will lose speed in a maneuver I surmise that if a weapon climbs it will lose speed if it is unpowered. So, push comes to shove, the burnout speed remains a critical factor. Missiles won't lose speed just flying along but the burnout speed obviously is going to factor into the missile's speed upon diving, climbing, or maneuvering on the target. Ergo, if I were to just set it to 50% - as I did in this test case - it makes missiles (primarily we're talking AAMs here) ultimately easier to defeat. Missiles such as the AIM-120 have a very short burn (< 10 sec) with no sustainer. They're flying high and diving so they maintain their energy really well. In a few test scenarios in DCS, which seem to model the AIM-120C-5 very accurately - they're maintaining over 2000 kts at quite far distances. Actually, it appears on missiles like the AIM-120C-5 that energy isn't really a problem when it comes to range but rather battery life on the seeker. It's only around 85 - 90 sec. They still have a lot of speed but speed's useless if your seeker is dead. So ultimately, for a missile such as a long-range, "low drag" AAM like the R-77, like the AIM-120, like the Meteor, we would want much less of a penalty to the burnout speed than something say higher drag like the AIM-7, AA-6, or AA-10. Presumably the AIM-120A/B with the original Sparrow fins would fit into the "higher drag" category. In this regard maybe 80 - 85% of burnout speed is better for the lower drag and 67 - 75% for the higher drag. Then for dogfight missiles now what because they typically have very short burns (< 5 sec) and bleed speed fast as they maneuver. Almost like they should be closer to 100% at burnout and then let the maneuvering kill the speed instead of the "final speed" factor. |
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| Author: | CAG Hotshot [ Fri Jul 08, 2022 00:07 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
Try firing out to very edge of max range where it has a low probability of hit % set, with a large exist time, and see what it does... And I have no idea what KFT means... and why is there so high a speed with missile burnout? Shouldn't that be set to 0 since the missile no longer applies thrust? If you really want to test missile burnout speeds make the missile visible on radar and watch it on your RWR and see if it slows down after burnout. It should show a steady decline of speed after fuel is exhausted... |
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| Author: | Centurian57_369th [ Fri Jul 08, 2022 00:16 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
CAG Hotshot wrote: Try firing out to very edge of max range where it has a low probability of hit % set, with a large exist time, and see what it does... And I have no idea what KFT means... and why is there so high a speed with missile burnout? Shouldn't that be set to 0 since the missile no longer applies thrust? If you really want to test missile burnout speeds make the missile visible on radar and watch it on your RWR and see if it slows down after burnout. It should show a steady decline of speed after fuel is exhausted... KFT is just me saying 1000 feet. As for everything else, I mean all of that is basically answered in my post and videos. if you put it to zero, missile's going to go from 2000 knots at motor to 0 at burnout. |
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| Author: | CAG Hotshot [ Fri Jul 08, 2022 06:19 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
Centurian57_369th wrote: CAG Hotshot wrote: Try firing out to very edge of max range where it has a low probability of hit % set, with a large exist time, and see what it does... And I have no idea what KFT means... and why is there so high a speed with missile burnout? Shouldn't that be set to 0 since the missile no longer applies thrust? If you really want to test missile burnout speeds make the missile visible on radar and watch it on your RWR and see if it slows down after burnout. It should show a steady decline of speed after fuel is exhausted... KFT is just me saying 1000 feet. As for everything else, I mean all of that is basically answered in my post and videos. if you put it to zero, missile's going to go from 2000 knots at motor to 0 at burnout. Sorry I cant see anything other than two launches. I cant see anything else. Make the missile trackable on radar then record a video showing it on the RWR to see if it slows down or not. |
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| Author: | Centurian57_369th [ Fri Jul 08, 2022 09:23 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
After the launch, the missile gets targeted and provides the range & speed data. |
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| Author: | CAG Hotshot [ Fri Jul 08, 2022 11:09 am ] |
| Post subject: | Re: Weapon Speed After Burnout |
I didn't see much of that because I viewed it on my phone... All I saw was a set pace for negative closure speed which means your missile was flying at the same speed and not decelerating at the end. Of course a straight line shot like that for an antiship missile from higher altitude to low altitude, where it follows a direct path to the target isn't going to slow down much because it loses altitude over the course of its flight and regains some lost energy (known as "smash"). So it's a bad example... Again you should make a missile shows up on RWR and use an air to air missile like a sparrow which has a lot of drag from its large fins and actually tumbles over at the end of its flight as it runs out of energy if the target is able to extend outside the missile's range after its fired, but lock is maintained on the guidance radar. |
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