fixed pitch oscillation aggravates at AOA limit by just holding the stick and throttle to IDLE

[DummyCatz]

Here's a bug in the CAT I limiter:

By just performing a max effort pull to the AOA limit and reducing the throttle to IDLE, the aircraft developed an aggravating pitch oscillation by itself and eventually overshot the AOA limit and resulted in a deep stall. This dangerous behavior is not listed in the dash-1 manual.

Viper AOA oscillation.trk

[darkman222]

Thank you for posting this. I observed this oscillation behavior, with a possible deep stall, since the 2.9 update with the new G onset modelling.

I did not have the time to reproduce it yet. But the oscillations can also happen on very low altitude with a very low fuel state. Below 1.500 lbs I remember.

[DummyCatz]

Time history of NASA FLCS control system A performing 1g stall, for example:

Ref Figure 18, NASA TP-1538, https://ntrs.nasa.gov/api/citations/19800005879/downloads/19800005879.pdf

 

[BIGNEWY]

This has been sent to the team for investigation. 

thank you

[TunisianRaptor]

[razo+r]

I guess it's similar to this one?

Edited December 21, 2023 by razo+r

[BIGNEWY]

threads merged 

[BIGNEWY]

we have found the issue and it should be resolved in a future update

thank you 

[BIGNEWY]

I have just tested a fix internally and it will be in a future patch. 

thank you