Su-25t won't dive

[maturin]

Are you by any chance lowering or raising flaps, when this happens? You'll get a pitch up during those periods that, at the right speeds, could cause issues.

Flaps, no, airbrake, possibly.

 

And it wasn't a nose-up force so much a complete loss of control over the down elevator. The plane was quite stable, and happy to stay in a dive or fly levelly.

 

I only think it wasn't a weird autopilot glitch because it was momentary, and autopilot woes always result in permanent and constant trim changes.

[GGTharos]

http://www.ce560xl.com/files/high_altitude_aerodynamics.pdf

 

I thought those compression effects were manifested as loss of lift? At least on the other part of the wing? :dunno:

[RIPTIDE]

Thanks Bro! :thumbup:

[FlyToRainbowRay]

Hi again. So it turns out that I haven't quite figured out the problem. Was playing some multiplayer and every time I went to dive and attack a target with my vikhrs after being in AP I couldn't dive anymore. Even after only using Lalt+3 to engage and Lalt+9 to disengage. Added a track to see if someone can figure it out. During the track I just used Lalt+3 and Lalt+9 and when I couldn't dive I trimmed the stick forward.

can'tdive.trk

[159th_Viper]

LAlt-3 is emergency leveling mode - will not be able to dive with that mode engaged, unless you momentarily override the AP authority to enable the dive.

[Ironhand]

LAlt-3 is emergency leveling mode - will not be able to dive with that mode engaged, unless you momentarily override the AP authority to enable the dive.

Actually, that's not what's going on. In fact, it turns out he has no pitch up authority either just prior to that with the ACS lights dark.

 

It all happens around 08:02:40-55. He's in A2G mode and has been cycling emergency leveling on and off. Around 02:50 the stick goes forward and puts the aircraft into a shallow dive with the ACS lights dark. When I took over at that point, I was already screwed because I couldn't pitch up. I tried ALT-9 just in case but it made no difference.

 

If you take over after Emergency Leveling is displayed on the ACS panel (sometime around 08:02:55) and let the a/c settle, pitch up authority has returned but you have lost pitch down authority no matter how many times you cycle Emergency Leveling, Baro Alt Hold, etc.

 

 

 

Rich

[159th_Viper]

Ta Rich :)

 

Have not watched the track so I'll do so soonest and attempt to replicate with an independant mission. As an aside, have you per chance been able to replicate without resorting to the OP's track?

[Ironhand]

Ta Rich :)

 

Have not watched the track so I'll do so soonest and attempt to replicate with an independant mission. As an aside, have you per chance been able to replicate without resorting to the OP's track?

No. It'll be this afternoon before I'll have a chance to do that. Just took a quick look at the track and took control at key points (keyboard only--no flight stick,etc) a few times.

 

 

EDIT: And for that matter, I haven't been able to replicate in his track, if I take over before it falls apart. Part of the problem is that I can't quite tell, from the track, whether or not the pitch down at 02:50 is due to a stick input or the ACS. The ACS lights are dark but that could be part of the problem.

 

 

Rich

Edited August 12, 2012 by Ironhand

[Ironhand]

UPDATE

 

I've been trying for about an hour to reproduce it independently without success. It definitely happens in the track--I now have my flight gear hooked up and the result is the same as with the keyboard. There comes a point when, in the shallow dive, there is no elevator up control. Then, after FlyToRainbowRay hits ALT-3 followed by ALT-9, the aircraft more or less levels out and you then have no down authority.

 

However....something else that I wasn't paying attention to but noticed this time...although you have "up" elevator control, that control is jerky. The stick (and elevator) jump to the up position instead of transitioning slowly.

 

 

But, again, I've been unable to reproduce this independently in a single mission. This was recorded in a multiplayer environment. FlyToRainbowRay, is this only happening in multiplayer or has it happened in single player missions as well?

 

 

Rich

Edited August 12, 2012 by Ironhand

[159th_Viper]

I've been trying for about an hour to reproduce it independently without success...

 

Same here.

 

Possible axis conflict somewhere? FlyToRainbowRay, check your Options/Controls/Su-25T/Axis commands and confirm that there are no default axis inputs mapped to pitch.

[maturin]

It happens to me in SP, and although I haven't watched the track, it seems like the exact same issue. Correct autopilot disengage procedure, lights off, loss of (one-way) elevator control in a fastish dive.

[159th_Viper]

It happens to me in SP, and although I haven't watched the track, it seems like the exact same issue. Correct autopilot disengage procedure, lights off, loss of (one-way) elevator control in a fastish dive.

 

Would appreciate a track and exact description as how to go about replicating if you have the chance.

 

Ta

[Ironhand]

It happens to me in SP, and although I haven't watched the track, it seems like the exact same issue. Correct autopilot disengage procedure, lights off, loss of (one-way) elevator control in a fastish dive.

If you still have the track, could you upload it?

 

 

Rich

[maturin]

You have to press record in order to get a track, right? Or does it do it after every mission?

[FlyToRainbowRay]

The pitch down at 2:50 was me trimming the stick forward.

 

It happens in single player too.

 

I checked and there is no default axis inputs mapped to pitch.

 

I hooked up my ps3 controller and was able to move the stick slightly more forward than with the keyboard, but it was still hard to dive. Also, every time I laser a target and hit the "a" key so the autopilot steers toward my target, I can never dive after disengaging the autopilot with "a" key or Lalt+9. I added a track of this happening if you are interested.

can'tdive#2.trk

[Ironhand]

The pitch down at 2:50 was me trimming the stick forward.

 

It happens in single player too.

 

I checked and there is no default axis inputs mapped to pitch.

 

I hooked up my ps3 controller and was able to move the stick slightly more forward than with the keyboard, but it was still hard to dive. Also, every time I laser a target and hit the "a" key so the autopilot steers toward my target, I can never dive after disengaging the autopilot with "a" key or Lalt+9. I added a track of this happening if you are interested.

OK....Just a note, using the "A" key for that is probably a bad idea even though the documentation suggests that as an option. I'd use ALT-6 instead. If I have time today, I'll take a look at this other track.

 

 

You have to press record in order to get a track, right? Or does it do it after every mission?

It records automatically. When you exit the flight, check the window you end up on. Above EXIT, WATCH TRACK, and FLY AGAIN, there's an option to SAVE TRACK and SAVE DEBRIEFING. You want the SAVE TRACK, of course. :)

 

 

Rich

[Ironhand]

Also, every time I laser a target and hit the "a" key so the autopilot steers toward my target, I can never dive after disengaging the autopilot with "a" key or Lalt+9.

This is a procedural suggestion based on what I saw you do in your track rather than having anything to do with the lack of elevator authority. This may help you enjoy things more, especially since you are flying with a keyboard.

 

Turn on the Shkval early and ground stabilize the TV target box somewhere ahead of you. Turn on either Emergency Leveling (ALT-3) or Barometric Altimeter Hold (ALT-4) to stabilize the aircraft--Baro Hold has the advantage that you can still bank left or right while the altitude remains more or less constant. Turn off the AP with Alt-9. Turn on Combat Steering with ALT-6. Your aircraft should now be following the target box. Slew the TV target box in the direction you want to fly--presumably in the direction of your targets and begin searching the target area. If nothing else, you should have a smoother, less harried flight. :)

 

And it'd be interesting to see, if you still have the same elevator control issues with this approach.

 

 

BTW, after I was sure you were experiencing the problem, I took control and experienced it as well. Re-flew, taking control immediately and tried to repeat what you seemed to be doing. Everything worked without any issues. Unfortunately, it'll be several days before I can get back to the sim.

 

Question: what kind of keyboard are you using? Is it wireless, by any chance?

 

Rich

Edited August 12, 2012 by Ironhand

[maturin]

I experience those issues with a built-in keyboard.

[Ironhand]

I experience those issues with a built-in keyboard.

Oh well, that sends that hypothesis up in flames:

 

 

Rich