Are we talking about thrustline or are we talking about AOA of the wing?
My view on thrustline is that it needs to be in the direction the model is flying. I know that this isn't a universally accepted idea but it's the one that makes the most sense to me.
The only way to adjust the AOA is by shifting the CG. When your model already weighs 7 grams without ballast then there's not much way to do this. My tendency would be to try a farther back CG based on the flight attitude I saw. This would involve moving the wing posts forward. I didn't have time for anything that involved.
I also think that shifting the CG rearward on the model with the built-up wing might be beneficial. The design program shows better times with a forward CG but that doesn't guarantee that real life performance is going to match the prediction. As flown yesterday the model has a static stability margin of 74%. This is probably more than any other model I've flown. Moving the CG back with the built-up wing would just be a matter of moving the 2 gram ballast from the nose to somewhere else and retrimming. I didn't have time for this either.
Neil - The last motor used was 2g x 17" wound to 2080 turns and .9 in-oz and backed off to 1760 turns and .30 in-oz. You're giving up a lot of potential time if you don't teach them to wind to maximum and back off to an appropriate launch torque. My models will usually barely maintain cruise if wound to 500 turns. I think you've just told us the reason for the short flight times you're experiencing.
----- Original Message -----
From: Kurt Krempetz
To: Indoor_Construction_at_yahoogroups.com
Sent: Sunday, December 03, 2006 10:37 AM
Subject: Re: [Indoor_Construction] LittleSquare finally earns its wings!
Hi,
The angle of attack is another variable which I
didn't give much thought too. It could explain the
un-expected observation.
Thanks,
Kurt
--- dgbj_at_aol.com wrote:
> "The wood wing had a significantly better sink rate.
> I expected that it
> would fly on less torque than the built-up wing, but
> it didn't work out that way."
>
> The wings may not be operating at the same attack
> angle in glide and under
> power. You may be able to adjust thrustline position
> and angle to get the wood
> wing to fly at the same attack angle as in glide and
> it should improve.
>
>
> [Non-text portions of this message have been
> removed]
>
>
Kurt Krempetz
__________________________________________________________
Cheap talk?
Check out Yahoo! Messenger's low PC-to-Phone call rates.
http://voice.yahoo.com
[Non-text portions of this message have been removed]
Received on Sun Dec 03 2006 - 09:10:33 CET