[MISSING TRACK FILE] Uncommanded roll.

[Cyborg71]

Anyone else experiencing left roll during wings level pull?

Occurs during pull from level flight to vertical. When the hud tape reaches about +50 degrees slow left roll begins. Pulling over the top results in an offset attitude where rather than looping, an offset turn is pulled during the loop.

 

Yes I'm adding control inputs to try and keep level wings during pull but the roll seems excessive.

 

At first I thought it was my controls. So I set a massive roll dead zone. Brought up the on screen input indicator confirming no roll input. Still happened.

 

Not convinced its a bug. Anything to do with the fuel imbalance issue?

[razo+r]

What's your loadout?

[=Panther=]

Anyone else experiencing left roll during wings level pull?

Occurs during pull from level flight to vertical. When the hud tape reaches about +50 degrees slow left roll begins. Pulling over the top results in an offset attitude where rather than looping, an offset turn is pulled during the loop.

 

Yes I'm adding control inputs to try and keep level wings during pull but the roll seems excessive.

 

At first I thought it was my controls. So I set a massive roll dead zone. Brought up the on screen input indicator confirming no roll input. Still happened.

 

Not convinced its a bug. Anything to do with the fuel imbalance issue?

 

What was your fuel levels?

[Mikaa]

I've noticed this as well, and found a few old posts relating to it, but no concrete answers. Not sure if it's a characteristic of the jet, (based on CG location or asymmetric drag, etc.) but fuel loading doesn't seem to make any difference. I attempted it at 30% fuel, 50% fuel, 100% fuel, and even at the limits of the Fuel CG loading (based off the AL/FR indicator in the cockpit). In the track provided, I set the aircraft up on a 360 Hdg, Full Mil, pointing at the Eastern edge of Kutaisi (visual reference for heading deviations). Starting the pull around 500 KCAS (using only the keyboard arrow keys to eliminate erroneous inputs), positive G throughout the loop, you can see the rolling moment becomes really prevalent over the top as aoa increases beyond ~22 degrees.

 

I also tried this with zero gun ammo, as well as zero chaff/flare to eliminate other variables. Could it be due to the weight of the Vulcan itself that's causing this? The rolling moment seems a bit excessive (requiring ~10%-25% right roll input to maintain heading during a loop), however I've never flown a Viper, so I'm all ears for someone with more experience to chime in and tell me this is how it actually is.

 

Additionally, for a sanity check, I also tested this in the Hornet (50% internal fuel, no pylons, no chaff/flare or gun ammo), and while the effect is still present, the total heading change on completion of the loop is <5 degrees, which is seems a lot more reasonable for any asymmetric internal loading, but I'd love to hear if these are correctly modeled.

F-16 Left Roll Test.trk

[104th_Money]

I have observed this many many times. It is much more pronounced at slower airspeeds especially after the first 90 degrees of loop. The first few times I thought I was just subconciously pulling the stick to the left with max back stick pressure but then realized that it does take noticable stick deflection to the right to keep the wings level.

[Eldur]

I have observed this many many times. It is much more pronounced at slower airspeeds especially after the first 90 degrees of loop. The first few times I thought I was just subconciously pulling the stick to the left with max back stick pressure but then realized that it does take noticable stick deflection to the right to keep the wings level.

 

Noticed the same with the Hornet and it's there in the Viper. Also was thinking it was me or my stick, but I checked the overlay and it clearly takes right roll input on both airframes (clean, fuels balanced) to do an Immelmann or Split S. Same for pulling up to ~60-70°, then turning around and pulling back down through -90° to revers the flight direction. Takes a considerable amount of right stick in both planes, especially at the lower speeds.

[Machalot]

What does the Roll Attitude Hold mode do (Autopilot Roll switch center) if not maintain the roll angle? I have always been confused by that.

[Mikaa]

AFAIK it does, but only within a certain threshold, and of course only while the autopilot is engaged.