reported ACFT Roll Characteristics

[Mohawk16]

ACFT is showing a negative static roll characteristic at the 100-120 roll mark, causing the ACFT to want to roll upside down during CMF.  ACFT is neutral static during this roll.  Request this is updated.  Occurs even when cyclic is re-centered to neutral (hence negative static tendency).

 

Additionally, ACFT does not appear to have a “nose tuck” tendency in the >30 degree roll.  The Apache, much like most helicopters, displays a weather-vane effect and will tuck into the left or right turn at this angle with no aft cyclic or thrust increase.  Current characteristic has ACFT conducting essentially a translation slide in the turn instead of a heading change towards the ground.

Edited March 22, 2022 by Mohawk16
Update “static” to “negative static”

[BIGNEWY]

Hi

please include track replays from your tests and if possible PM me your evidence ( if publicly released data ) of this behaviour. 

We will investigate. 

thanks

[bradmick]

I can confirm this. Back when we used to do High/Low G's we would perform an initial aft cyclic pull to achieve +2.0G +/- 0.2 G and then forward cyclic looking for +0.2G +/- 0.2G. The maneuver was initiated at 130knots, during both the aft cyclic pull and forward cyclic pull the aircraft was stable in roll. Currently in the existing FM, the aircraft will depart from controlled flight with a high speed forward cyclic application, which is definitely not the expected behaviour.

[BIGNEWY]

Thanks for the reply Bradmick

[comcat]

I also agree that the weather-vane effect is missing. the aircraft just slides sideways instead of turning towards the movement direction. at a certain speed it the rolls sideways violently. it should turn towards the sideslide, to give a good quick sideways missile evasion maneuver.

 

 

I have just under 6000 h on real Helicopters.

[bradmick]

Recorded the following track file. In it I perform 3 high/low-g's, I ensure a FLT > SET page is displayed in order to display the G-Meter. Before each sequence I reset the G-meter to ensure i'm hitting the marks of 2G and 0.2G. You can see the aircraft violently rolls left in each low-g situation, where she remain stable about the roll axis.

rollDepartureTest2.trk

[BIGNEWY]

Thanks, added to my report. 

 

[Strannix]

Hye,
This week i ve got the chance to put your AH64 module in the hands of my father. He was the Tiger helicopter test pilot for 15 years so he 've got really good knowledges in term of helicopter physics irl and in a simulator. 
I 've showed to him a phenom that's i found very strange that's you can look in the attached video. It's very simple to reproduce, you just have to go level and push the cyclic to put negative Gs then the aircraft will engage a roll to the left. He explained to me that kind of phenom can't happen on a chopper with more than 2 blades rotor. Only the uh 1 must show a reaction like this and it is link to the mast bumping danger.
 

 

[ddc196]

I'm pretty sure this is a known issue and the team is aware. 

[Scaley]

Yep, already bug reported in the bugs sub-forum.

[S. Low]

My report from weeks ago:

 

A better report than mine from weeks ago and it includes an SME track file:

 

[BIGNEWY]

merged posts

thanks