Wilco/Feelthere Airbus "breaks" away from FD

[mike113]

I have the Wilco Airbus Deluxe Volume 1 on FS9. I have this issue where I climb on managed mode and everything seems to be going well.I switch from TOGA to CL at 1500' and it maintains 250 below 10K' and accelerates to 280 for climb. On more than one occasion the aircraft just disregards the FD and starts climbing up to 20+ degrees. The FD is attempting to correct this by demanding a downward pitch the but the aircraft/autoflight is just not listening, it's like the aircraft just wants to keep pitching up! I have to disengage AP and FD, keep downward pressure on the stick and re engage FD and AP and hope it listens which it usually does until it possibly happens again, sometimes it happens again and I take the same steps. My GW is around 150K lbs starting my flight with about 24K lbs of fuel. My pitch is 05 down and the weather and there is a cross wind of 26 kts. It also happens when weather is cleared.

One thing that concerns me is that my CL power (EPR, N1) is set too low. I have been over this with various people about the flex temp affecting CL power but if it's only for Flex take off then HOW is CL thrust calculated????


I am wondering if this could this be a bug with the app or can the wind change in FS9 be that significant to throw the aircraft off by that much?????Does flight sim have updrafts?


OR is this just something that happens in all aircraft?? I understand that autopilot isn't perfect and might get knocked off now and then but this seems very extreme..

[jomni]

I don't have that particular plane but it sounds like the it is trying to find a climb rate that maintains the target speed. Or maybe I'm wrong. Is the speed being held constant during the climb? How's your throttle during the climb? If you claim that the CL N1 is slow, then it makes no sense for the autpilot to make the plane climb up as you will lose more speed that way. I would think it's a bug in the Wilco plane.

[wdscobie]

can the wind change in FS9 be that significant to throw the aircraft off by that much?????

yes. FS wind shifts are not correctly modeled. a plane going from wind blowing in the same direction as the plane (ie, 'pushing the plane) to wind going suddenly in the opposite direction (ie, 'on the nose') results in a aircraft speed increase (ie, pitch up by autopilot to correct the 'overspeed' situation. wind going from on the nose to on the tail results in aircraft speed decrease and a pitch down command.


the airbus climbs fine. i've not had issue with climb since before the aircraft was released ... more the five years ago.

OR is this just something that happens in all aircraft??

yes

the best fix is to use one of the addon real-weather programs that will moderate how quickly, and therefore slightly improve, FS wind speed direction changes. the payware version of FSUIPC will also moderate FS wind direction changes.


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[mike113]

Yes the speed is constant during climb. I feel the CL n1 can be it a bit low however can be fixed lowering the pitch.

I am starting to take my CG into account. I noticed that my CG for these flights were about 15 which I believe is too low. I normally shift most of the weight to the back to get my CG closer to 20, is that ideal? Can anyone enlightening me more on CG and what the optimal value is?