g-forces at 90 degrees of pitch drops abruptly

Hi folks,

tried this out with nearly all versions of DCS, including the last one v 1.5.7.10872.

Can't say if this relates to other aircraft, since I actually don't fly them (Viggen replaces all of them ... :music_whistling:)

If I fly a looping with constant g-forces, let's say 6g, the g-force abruptly falls down to approximately 4.5g when passing exactly 90° flight path angle.

Note that I try to hold the 6g, by increasing the stick deflection further and further due to dropping speed, but no matter what I do, the g-forces drop there abruptly (like a step-function).

Please don't start telling me that the g-forces would drop because I am getting slow or because of the decreasing influence of gravity, I know this and other effects which could influence the g-meter.

If you dont trust what I am stating here, simply try it out and you will see what I have noticed.

Carefully watch the artificial horizon, and also the g-meter (hard to do but if you make a video, which I am actually not able to, you will see it). I will try to produce a video of the track soon.

In my opinion there is something wrong with the maths at 90° pitch angle ... some Euler stuff or stuff with the Quaternions ... dont know how DCS calculates the flight physics.

But maybe there is only a wrong indication ... hard to say ...

Kind regards,

TOViper

You have tried a loop at different G's?

Like constant 2G or 3G?

Maybe 6G is to much.

Yeah, I tried some different g-forces values. the drop seems to be somewhere around 1.5 g.

What I have to add here is that I am not 100% sure if it relates to 90° flight path angle or 90°

pitch (which differs by the AOA). The drop is abruptly in any case, which makes it look very strange.

I think I have to dig deeper and perform some more test flights when I am at home again.

I also thought about the flight control system, it may change the elevon deflection depending on the actual IAS, which is what I don't know actually ...

I dont have the Viggen but It should be able to keep a 2-3G loop very easy

yes, this is possible of course.

The g-forces can be held at a constant value (with a little training) by increasing stick deflection. I tried out a few values between 3g and 8g. No matter which value I select, the effect was there.

The point is that the g-forces drop abruptly when passing the 90° pitch/flight path. This is - in my opinion - wrong behaviour, and thus I posted it in the "Bugs and Problems" section and not in the general Viggen section of this forum.

Thanks for the report!

Today I tested a few g-force values more, and had the same strange behaviour.

Moreover, the indicator abruptly increases by approx. 1.3 g when going through -90° of pitch/flight path angle.

The situation / attitude of the aircraft doesn't change in this certain moment, thus - the more I fly - the more I think it is really just an indication problem.

I think I will stop here now, and let the pro's check the code :D

Kind regards,

TOViper

Cobra, I just want to add some more information here relating to this problem.

I went for a flight with the MiG-29 and the Su-27 today, and I wasn't able to reproduce this effect. Thus I think it relates to the Viggen only and you have to dig (and not ED guys). :(

Edit: I did this with 1.5.8.

Edit: Same behaviour with 2.5.4.30386

Hello Cobra!

After flying today without using VR, I had the idea of looking to the outside camera view of my loopings.

The passing of the 90° and -90 vertical angles during loopings are "smooth" when looking the g-forces written in the status bar. The needle in the cockpit is performing these jumps I have written above, so it seems a simple indication problem, not a flight model problem.

For me it seems that the g-forces indicator is influenced by the "jump" of the HSI.

Maybe its just a little dirty programming bug, and nothing more. :music_whistling: <<< I would never say things like this ... *shameonme*

Thanks for the report!

Since RagnarDa seems to be in a process of fixing some bugs I thought it might make him look at this bug again I reported a very long time ago and acknowledged by Cobra.

Ok, now I will stop bumping things up, I promise. At least for this month :D

Let's get closer to release candidate, out of f.....g EARLY ACCESS.

Same situation (sim was paused), took two screenshots, one showing 2.6g and one 3.2g

Cobra, tell me please, what is wrong with the flight model / g-meter / core sim?

It must be an indication BUG..

You lose 1,5 G at 90+ and You get it back at 90-

No change in A/C trim or Alpha

HB, this obvious bug is still there, can this be addressed eventually?