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-   -   Trimming issues? (http://www.rcuniverse.com/forum/giant-scale-aircraft-3d-aerobatic-110/11152782-trimming-issues.html)

ceecrb1 07-12-2012 10:48 AM

Trimming issues?
 
I have a goldwing/redwing 30cc MX2.. which I love to bits..
However... when carrying out any "elevator up" manouver (loop, etc) it will yaw left.

I have found that I even have naturally starte to add right rudder on any manouvers...
Its not "violent" biut after a complete loop (large) I do end up very far away from where I "should be"

Its really screwing up basic manouvers such as loop, fig8 even just going into vertical for a stall turn etc..

I've tried to give a mid-range trim.. ie not too far forward that I cant do any 3d playing, but not too far back that its completely wild.

Ideas?

ROGER RUSSELL 07-12-2012 11:09 AM

RE: Trimming issues?
 
1 Attachment(s)
Read and follow the attached file.
They are from Peter Goldsmith.

ceecrb1 07-12-2012 01:11 PM

RE: Trimming issues?
 
yeah i've read that.. and I cant see the problem I am talking about....... pull on the elevator and it yaws....

Bass1 07-12-2012 03:24 PM

RE: Trimming issues?
 
Do both elevator halves have the same amount of travel and perfectly in sync with each other?

speedracerntrixie 07-12-2012 03:45 PM

RE: Trimming issues?
 
When you pull up elevator it is drag and will want to slow the airplane down. This puts more load on the prop and increases your torque value. This torque is pulling the nose to the left. Very common with high powered scale aerobatic airplanes. You can reduce this effect by running a tad more right thrust and/or a smaller dia prop. The test I do is from 1/2 throttle, pull vertical while flying away from yourself and being a full throttle by the time you have true vertical. Note which way the airplane pulls. If it pulls left right away or pulls left before climbing 100-150 feet then add more right thrust. Also at the start of the manuver you should be wings level, very easy to have one wing low and not see it.

ceecrb1 07-12-2012 04:14 PM

RE: Trimming issues?
 
Yeah I can guarantee that wings are level.. this is a long running problem and I've tried it over and over to make sure.
I can visually see it yawing left as it raises the nose.... its most pronounced doing a large loop... once in a vertical climb it stays there... its only when I raise elevators..

yes I've checked the elevator throws with a digital level..

I'm most inclined to agree with the drag letting torque have more effect... seem possible..

I know I COULD just mix rudder into the elevator.. but I'd rather fix it aerodynamically have have things smoother than fight against aerodynamics all the time... plus that mix would later mess around with any hover corrections or similar manouvers....


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