RIGHT & DOWN THRUST ?????

[mandtra]

Is there a chart or some resource to help figure the correct amount of right , and up or down thrust? How do you know which way to go to correct flying problems? 50cc and 100cc gas engines and yaks , 540's . One of my planes flies hard to the left and tucks left . but at the prop hub it has 3/16 of right thrust on a DA 50 with 3" stand offs and 1/4" down thrust. I can get it to fly pretty straight with 11 trim clicks to the rudder . So i would assume it needs more right? also I measured from prop to the wing and it was 12 1/2 " left and 12" right.

[Kevin Y]

Is it pulling left when flying straight and level?

[RTK]

Here is a basic trim chart and a real good article by peter goldsmith. If you want your plane to fly the best, I would go through the whole procedure.


http://www.freewebs.com/scrcflyers/P...0Procedure.pdf


http://www.wtp.net/DBEST/trimchrt.html

[mandtra]

yes it is flying to the left in level flight . but it's really bad when i pull it straight up

[Zeeb]

Refer to RTK's post.....

[mandtra]

Thanks a bunch. Great info I printed both out and will start working on it this afternoon.

[exeter_acres]

how much rudder trim does it need to fly straight and level?

[MODE 1]

Mandtra.....The charts you have are very useful for trimming. However before you start any attempt at tweaking the model its wise to ensure the model is built right in the first place or no amount of trimming will resolve your problems. I would suggest taking incidence measurements on wings, stab and fin from all angles first before flying.

As a point of note. One of the guys here in FG had a 100cc Yak with a fin approximately 5 degrees off center.

[mandtra]

It takes about an inch of rudder trim to fly straight

[mandtra]

I checked everything out and the horiz stab was out by almost one deg. everything else was good.

Question though ??????? When I shim the motor to the right for the right thrust , the prop center line is pretty far right and not in the center of the fuse anymore. Should i remount the engine offset so that when the right thrust is applied the prop shaft will be back in the center of the fuse? or if i dont remount the engine will it affect the way it flies?

[MODE 1]

Yep thats correct...When the engine offset is applied the engines center line is off center with the fuse line by something like 7 to 8 mm depending on engine length of course

[MODE 1]

The red line is where the engine center should go on the firewall

[mandtra]

since my engine is already mounted and not offset. what will be the result if i add the right thrust and do not offset the engine?

[MODE 1]

Difficult to say in REAL terms. It could effect the way it tracks or could not. Profile models don't appear to suffer from any negative effects when they're engines are bolted to the side but then again they are not as precise in they're aerodynamic build.

Something is wrong though. A 1" offset in the rudder indicates a problem further up the line.....perhaps more than just engine offset.
The fuse is straight ...right? Its not like a banana?
Both wings and tail are the same distance from the fin post? (not staggered)

[mandtra]

it's a seagull BLING 3D. I have a about 150 flights on it and it has always flown dirty. has always flown to the left and pulled to the top. so far i have kept it trimmed and just flown it as is. Lately I have decided if i cant get it to improve at least by 50% i'm going to scrap it.