reported Wingtip flex incorrect direction during roll.

[Deano87]

Hey all.

 

I've just been flying with wingtip mounted AMRAAMs and I noticed that the wingtips are flexing in the incorrect direction during roll. In fact the reverse of what they should be.

 

 

If we look at the jet in the picture above you can see that the jet is initiating a right roll. Notice the following things, on the upgoing wingtip (left wingtip) the leading edge is being bent down, on the downgoing wingtip the (right wingtip) the leading edge is being bent up.

 

This makes sense from a physics point of view because the AMRAAM protrudes a long way beyond the wingtips and as such the centre of mass of the missile is near or even beyond the leading edge of the wing and and will naturally bend the leading edge in resistance to the roll direction.

 

If you look at the tip bending in DCS with AMRAAMs fitted (can't comment on empty or Aim-9) its going the opposite way from above and to me doesn't really make much sense.

 

Thoughts?

 

I can try and get some screenshots from DCS Tomorrow.

[JTFF - Raph]

+1 Here as you can see on the track, on the first left rolls, it's inverted, after that I do some "yoyo" with negative G's and everything is okay.

 

Wing flex issue.trk

[bkthunder]

Yeah that's true! Nice find!

[BIGNEWY]

Reported for review by the team

 

thanks

[JTFF - Raph]

Wrong position of wingtip (wingflex issue)

 

Hi, the external fuel tanks are giving a strange behavior to the wing flex, as you can see. When loaded the wing tip is pointing to the top (own aircraft view only), when they are not loaded the wingtip is is in good position.

 

The issue is only visible on your own aircraft.

 

On the first picture you can see the wrong angle between the 9x and the amraam.

On the second picture, you see the issue on your own aircraft and not on the wingmen as I said before, but you can see the difference.

Third picture shows the regular position.

 

 

 

 

Edited January 25, 2020 by FrM | Raph

[JTFF - Raph]

One more screenshot (front view). One this one we see the difference between 9X and AMRAAM pylons.

 

Edited January 26, 2020 by FrM | Raph

[Gnadentod]

Not sure if it has to do with the wing flex or the model itself but yes, the second most outer weapon mounting points are pointed slightly upward in comparison to the others. Eagles eyes.

 

Screenshot related.

[Svend_Dellepude]

https://forums.eagle.ru/showthread.php?t=258640

 

related i guess.

[BIGNEWY]

merged threads, could be related, the team are looking into it.

 

thanks

[FusRoPotato]

I was really impressed with wing flexing physics when I got this module, until I realized that when the F16 rolls, especially with AMRAMMS on the wingtips, they twist the wrong direction!

This is according to structural twist resistance designed into the wing against lift direction for lift stability by controlling I-beam widths in specified sections in the first 7 wing spars, moment produced by control surfaces, and CG/Inertia of the payload itself. They all contribute to a twist in a stabilizing direction opposite of what is presented graphically in DCS. When I roll left for example, the right wing twists upwards. It should twist down initially. I know some of you might think that's not obvious, that a wing should lift the right side of the plane up, but that's not how wing twist works. The control surface does that work. The wing was designed to dynamically work against it.

It's a minor bug sure but probably easy to fix.

Edited May 28, 2022 by FusRoPotato

[Tholozor]

Already reported: 

 

[FusRoPotato]

That appears to be a different issue.

[Tholozor]

Bignewy mentions in-flight wing flex.

[FusRoPotato]

I'm not reporting a wing flex issue, I'm reporting a wing twist issue. There's a difference. It's a separate problem that was not mentioned in that thread. Luckily the fix should be much easier. The direction just needs to be negated for each wing animation. They are simply backwards.

Edited May 30, 2022 by FusRoPotato

[FusRoPotato]

Actually found some footage of sharp rolls with AMRAAMS loaded on the wingtips.

 

 

 

[dorianR666]

On 5/29/2022 at 1:25 AM, FusRoPotato said:

I was really impressed with wing flexing physics when I got this module, until I realized that when the F16 rolls, especially with AMRAMMS on the wingtips, they twist the wrong direction!

This is according to structural twist resistance designed into the wing against lift direction for lift stability by controlling I-beam widths in specified sections in the first 7 wing spars, moment produced by control surfaces, and CG/Inertia of the payload itself. They all contribute to a twist in a stabilizing direction opposite of what is presented graphically in DCS. When I roll left for example, the right wing twists upwards. It should twist down initially. I know some of you might think that's not obvious, that a wing should lift the right side of the plane up, but that's not how wing twist works. The control surface does that work. The wing was designed to dynamically work against it.

It's a minor bug sure but probably easy to fix.

 

i think you should post this in the F-16 section, rather than this DCS world section.

that place gets much more attention

 

https://forum.dcs.world/forum/333-bugs-and-problems/

[BIGNEWY]

threads merged, this has been reported.

thanks

[Cydrych]

Noticed this today. When pulling high G and the wings bend the left wing LEF develops a kink near the RWR antenna. The right wing doesn't do this. The kink goes away and the LEF goes back to normal when not pulling G.null

[BIGNEWY]

This is reported and I have merged the threads. I will bump the report internally. 

thanks