Bug Report: Missiles @ 20G half way vs NON-manuvering BVR target

[RvEYoda]

Here's a behavior I noticed testing missiles. Happens _every_ time :P

 

Enemy starting head-on above you, shooting about 30 nm out bvr (120C for example).

 

NON-maneuvering target flying straight!

 

About a few seconds after the missile has burned out and has good speed, all of a sudden it does a 20 G turn and loses ~30% of its speed for no reason vs non-maneuvering target :)

 

Ideas?

Track



Mission

 

 

 

.

Edited March 21, 2016 by =RvE=Yoda

[HiJack]

What about the Russian missiles? Same?

[will-]

this is nothing new..... does anyone play single player and watch missiles behavior?

 

I asked about this awhile ago and was told missiles have AFM and working as intended. I personally find it strange to see them act the way they do when in flight, nose pitching every which direction.

[DarkFire]

What about the Russian missiles? Same?

 

Not seeing exactly the same thing with Russian missiles. I just did a test where I launched an R-27ER (Vlaunch was ~2.0M) at 12,200 m and the target was at 2,500m approaching me at 650 Km/h. Launch range was roughly 35Km.

 

The missile did a hard ~9G nose-over and headed down towards the target but then flew the rest of the distance at -0.8G and +12 degrees alpha.

 

I'll post a track & ACMI later when I figure out how to get Tacivew working with 2.0 and 1.5.3...

[AussieGhost789]

+12 alpha? You sure that wasn't -12 pitch? o.O

[DarkFire]

+12 alpha? You sure that wasn't -12 pitch? o.O

 

Hmm it might have been actually. I'll check later after I've had some sleep... 3:30 am here in London :yawn: :sleep:

 

EDITED TO ADD:

 

OK, I've got Tacview working with both versions now so here are the stats from my R-27ER missile test. At the point of launch:

 

MY AIRCRAFT (Su-27):

ALTITUDE: 12,524m ASL

SPEED: 2,136 Km/h TAS = 2.01M

G LOAD: +1.2

STORES: 2 x R-27ER, 2 x R-73, ~8,000 Kg fuel remaining.

 

ENEMY AIRCRAFT (C-17A):

ALTITUDE: 2,500m ASL

SPEED: 646 Km/h TAS = 0.54M

G LOAD: +1.0

STORES: ~100% fuel.

 

I launched a couple of seconds after reaching Rmax, at which point I was exactly 56Km from the target = 34.8 miles = 30.2 Nm.

 

At +5 seconds after launch the missile stats were:

SPEED: 4,699.8 Km/h TAS = 4.42M

G LOAD: -7.7

AOA: 2.3 degrees.

 

At +10 seconds after launch:

SPEED: 5,268 Km/h = 4.93M

G LOAD: +1.0

AOA: 0.0 degrees.

 

At +20 seconds after launch:

SPEED: 3,789.5 Km/h

G LOAD: +0.8

AOA: 0.1 degrees

 

So it looks like the R-27ER flight profile is something like this:

 

Edited March 22, 2016 by DarkFire

[GGTharos]

What you guys are seeing is not a bug in the strictest sense of the word.

 

For the 120, it is the loft algorithm: It was implemented for the SFM missiles which did not lose speed in turns, and it is a very simple algorithm which does not take this fact of physics into account.

 

There is a lofting algorithm which is far more efficient; it isn't secret but implementing it in the game is not a trivial exercise.

 

In general, IMHO guidance needs to be overhauled so that it can accommodate any new algorithm or sets of algorithms (some missiles will use multiple algos). I'm sure ED will get around to it at some point.

 

So again, what you're seeing is not a bug: It's old implementations being inappropriate for the new FM, that's all.

The loft algorithm is no longer appropriate. PN guidance very broadly applies, but possibly not in the form implemented right now for all missiles - for example, RF missiles can use more sophisticated PN than IR missiles due to more target parameters being available as input into the algorithm.

 

There are also energy preserving PN modifications that you might expect to see on AIM-120, R-77 and most modern versions of some SARH missiles, eg AIM-7P, possibly R-33's.

 

More interesting path-shaping algorithms may be appropriate for certain SAMs ... and those algorithms are available as well.

 

But it's all a LOT of work.

 

So like I said ... no bug. Just an artifact of progress.

[SinusoidDelta]

It's not really an artifact IMO.

 

If what you've explained is accurate, it's a great example of software entropy and technical debt.

 

And that's all I have to say about that.

[DarkFire]

All good. Hopefully enhanced missile dynamics & guidance are on a list of stuff to update somewhere...

[winchesterdelta1]

It's old implementations being inappropriate for the new FM, that's all.

 

That is all. Move on guy's. Nothing to see.

[ShuRugal]

That is all. Move on guy's. Nothing to see.

 

move on Guy's what? Onto which things belonging to Guy shall we move?

[kolga]

move on Guy's what? Onto which things belonging to Guy shall we move?

 

:megalol: