Re: [Paparazzi-devel] AoA and high altitude flying

[Reto Büttner]

Hi Chris

I have flown my eHawk over 4000m AMSL with the same control parameters
as at low altitudes. I have not observed any negative behaviour at
high altitudes. See:

http://www.youtube.com/watch?v=_m8ZR9XWuQ4

As a full scale glider and motor pilot flying at high altitudes I do
not recommend increasing AoA at high altitudes. The correct
compensation for thin air is higher flight speed. When measuring
flight speed aerodynamically (pitot tube) this is done automatically.
When measuring flight speed with GPS you should target higher ground
speeds at high altitudes.

Are you flying electric or gas powered?

Cheers, Reto

2011/11/16 Hector Garcia de Marina <address@hidden>:
> Hello Chris,
> how are you measuring/estimating the AoA?
> Regarding to your question, AoA is absolutely needed for stability
> (actually, it is an angle w.r.t. stability axes), on the other hand you need
> to know, at least, the CL (AoA) and CD (AoA) profiles of your aircraft.
> Increasing the INS pitch neutral in my opinion may won't work as expected,
> as the AoA depends on your relative velocity vector, which is independent of
> your altitude.
> Héctor
>
> On Wed, Nov 16, 2011 at 6:36 PM, Chris <address@hidden> wrote:
>>
>> Hi.
>> I want to ask if it is a good idea to add some AoA compensation for high
>> altitudes in
>> Paparazzi control loops.
>> From my long range tests i found that when flying in higher altitudes the
>> plane speeds up considerably
>> by increasing throttle often to 100% possibly because the AoA set during
>> the setup flights (close to ground) is not enough any more to keep the
>> aircraft from loosing height without increasing throttle (speed) in higher
>> altitudes above 1000m.
>> I was thinking something like increasing the INS pitch neutral to say one
>> degree per 1000m.
>> Any ideas or opinions welcomed.
>> Chris
>>
>>
>>
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>
>
>
> --
> Héctor
>
>
>
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