DCS 1.5 Autopilot/Airspeed Issues???

[pikmin124]

I'm posting this here because I'm pretty sure it's on my end, and therefore not a bug to report. This issue did not exist yesterday, and the game hasn't updated since. Furthermore, I can't find any references to this issue in the bug reports. If it were an issue with the beta itself, I would imagine it would have been an issue yesterday and for other people.

 

Also, disclaimer, I'm pretty new and only know how to fly the F-15, so testing to see if this issue exists for other planes would require learning to fly said plane.

 

I'm also running the beta through Steam, if that matters at all.

 

Anyway, the autopilot is behaving very strangely. Engaging attitude hold will work more or less, but the plane will slowly roll to the right and the way it responds to stick input seems off. Altitude hold doesn't seem to work at all, and when it's engaged the plane will just pitch down. Disengaging either autopilot causes the plane to abruptly pitch down.

 

Also, when I was recording the track attached below, I noticed that thrust seemed to be behaving oddly as well. You can see that at 30,000 ft at MIL power, the plane won't go above 250 knots IAS, and the acceleration resulting from advancing to MAX power seems very slow (during the bit where I'm catching up to the jet I'm supposed to intercept I'm in full afterburner the whole time). I am pretty new, so I may just have a bad feel for how the plane flies, but I'm pretty sure it's not supposed to behave like that.

 

That's the only time I've noticed anything funny with thrust, but the autopilot issue has persisted across different mission and survived restarts of the game and of my computer.

 

I have tested my copy of 1.2, which I have as a standalone, and everything works fine there.

 

The attached track is me running the first mission of the 'An Eye for an Eye' campaign by Feefifofum. I start playing around with the autopilot once I level out (at 30,000 ft), so you can fast forward to that. The intercept bit (from reaching waypoint 2 to shooting down the target) demonstrates the airspeed thing pretty well, especially when I'm diving after the plane in search of pretty fire and smoke and still accelerating fairly slowly considering. Then I do a bit more with the autopilot on the way to waypoint 5, engaging it then not touching the controls to see what happens. The landing really just serves to illustrate how bad I am at landing, so fast forward through that. At the very end there's a funny thing where the engines take forever to shut down that appears to be bugged as well

 

Any ideas anyone can provide would be great. All I can think of at this point is to reinstall the beta version, and on my internet connection that would be incredibly inconvenient.

 

Thanks

 

P.S. The only thing I did between yesterday and today was disassemble my laptop to clean the fan, but I really don't see what I could have messed up doing that that wouldn't have broken everything, so I would guess the problem is somewhere else.

An Eye for an Eye 01-07 (1-5) (notice autopilot and airspeed issues, and why did engines take so.trk

[HiJack]

Autopilot is bugged for everyone since DCS 1.5 OpenBeta came out. It's a beta so bugs will be there. DCS 1.2 is the released version.

[DarkFire]

The Su-27 autopilot has a really strange bug whereby if it's engaged at anything under 560 Km/h IAS it's completely unstable and produces all sorts of weird roll and flutter effects. I wonder if the F-15C autopilot is suffering from the same sort of problem? Try engaging it at an IAS above 300 Kts and see if that makes a difference.

[Santi871]

The Su-27 autopilot has a really strange bug whereby if it's engaged at anything under 560 Km/h IAS it's completely unstable and produces all sorts of weird roll and flutter effects. I wonder if the F-15C autopilot is suffering from the same sort of problem? Try engaging it at an IAS above 300 Kts and see if that makes a difference.

 

I don't think that's a bug, its a result of relaxed stability. If you read the wikipedia article on it, it says there is no single point where the plane will be stable and as a result it will fluctuate.

[pikmin124]

Autopilot is bugged for everyone since DCS 1.5 OpenBeta came out. It's a beta so bugs will be there. DCS 1.2 is the released version.

 

Really? I could have sworn it worked fine a couple days ago, and I couldn't find any mention of it in the bug reports.

 

I guess I can stop trying to fix it then, haha. Thanks for the quick response.

[GGTharos]

This is normal, and it also means you climbed at too slow a speed. Maybe you're hauling three fuel tanks, too? :)

 

Higher altitude = less air = lower IAS for a given TAS/Mach compared to lower altitudes = less thrust = less acceleration.

 

It's not an F-15 thing, it's an airplane/jet engine thing.

 

 

Also, when I was recording the track attached below, I noticed that thrust seemed to be behaving oddly as well. You can see that at 30,000 ft at MIL power, the plane won't go above 250 knots IAS, and the acceleration resulting from advancing to MAX power seems very slow (during the bit where I'm catching up to the jet I'm supposed to intercept I'm in full afterburner the whole time). I am pretty new, so I may just have a bad feel for how the plane flies, but I'm pretty sure it's not supposed to behave like that.

 

Skip this part. In fact, never show this again!

 

-- Dark Helmet

 

:D

 

The landing really just serves to illustrate how bad I am at landing, so fast forward through that. At the very end there's a funny thing where the engines take forever to shut down that appears to be bugged as well

[pikmin124]

This is normal, and it also means you climbed at too slow a speed. Maybe you're hauling three fuel tanks, too? :)

 

Higher altitude = less air = lower IAS for a given TAS/Mach compared to lower altitudes = less thrust = less acceleration.

 

It's not an F-15 thing, it's an airplane/jet engine thing.

 

Just one tank, and I dropped it before the intercept.

 

I'm aware of how altitude affects performance, but at MIL power at 30,000 ft I should be accelerating when I'm below 300 knots IAS, shouldn't I? In the track I linked I was losing speed in level flight at 200 knots (at MIL power - I had to keep going into afterburner to keep up with an IL-76). I mean according to the manual the flight envelope under those conditions goes up to a little over Mach 0.9, which I believe is somewhere between 300 and 350 IAS.

 

I don't know why it was weird the one time, but I ran that mission again today and everything was fine other than the autopilot thing.

[GGTharos]

but at MIL power at 30,000 ft I should be accelerating when I'm below 300 knots IAS, shouldn't I?

 

Barely.

 

In the track I linked I was losing speed in level flight at 200 knots (at MIL power - I had to keep going into afterburner to keep up with an IL-76).

 

Sounds about right.

 

I mean according to the manual the flight envelope under those conditions goes up to a little over Mach 0.9, which I believe is somewhere between 300 and 350 IAS.

 

I don't know why it was weird the one time, but I ran that mission again today and everything was fine other than the autopilot thing.

 

You might be remembering wrong ... you might have popped the airbrake and not noticed, there's all manners of run things that could be happening :)

[DarkFire]

I don't think that's a bug, its a result of relaxed stability. If you read the wikipedia article on it, it says there is no single point where the plane will be stable and as a result it will fluctuate.

 

True, but I think in this case it must be a bug because the minimum AP engagement speed that produces stable flight is always ~560 Km/h IAS, irrespective of altitude, temperature, wind etc.