rodders

Hello,
I have an old style 87" Extreme flight Yak and now that I have started to use it a bit, it does pull to the left on vertical climbs.
Please bare with me with this question!
The amount of right thrust is pre set on the firewall, so if I put some packing pieces under the right hand hand "stand offs" it will cause the right thust to increase but the centre of the propellor is now to the right t of the aeroplane centre line. Will this counteract the increased right thrust angle, as the thrust from the propellor is acting to the right hand side of the aircraft center line, pulling to the left?
So maybe it is easier to ask if the centre of the propeller should remain in the aircraft center line, irrespective of the propellor angle? Do I also need to move the engine mounting holes to the left as I increase the right thrust to keep the propellor on the centre line?
What is the correct method, not the simple one.
Rodders

GalenB

My Feedback: (18)

I would start by reading this... It's an article on trimming by Peter Goldsmith.

http://www.mini-iac.com/Portals/57ad...20trimming.pdf

matus777

Rodders make sure your plane is trimmed properly for hands off flight. I like to trim the turn out with rudder then trim the bank out with ail. if needed and then do your other mixes last. It's not unusual to have the plane go left in a vertical after climbing for some period of time....400-500'.....correct with a bit of right rudder.

Also if you really want more right thrust you will have to add shims to the left side of the mount not the right side. The EF Yak is set pretty good from the git go......why not have someone (with more experience) have a look-see and let them trim it for you before messing with the thrust line?


The post above has all the info you need....good luck!

rodders

Matus,
Sorry, I did mean to put the packing under the left hand set of stand offs and not the right ones as I wrote down earlier.
So once I have put the shims in the right side, should I displace the engine to the left to keep the prop on the center line?
I am quite a good pilot, but have got bored with prop hanging, flat spins, etc and am working on pattern flying and noticed that the plane pulls quite heavily to the left.
I have also reset the main wing incidence as it was flying with a lot of left aileron trim to keep level, not a problem for general flying but no good for consistant pattern flying.
Rodders

Mastertech

My Feedback: (31)

Or just mix in some right rudder to high throttle. I have mine trimmed neutral at cruise, right rudder to high throttle and a bit of left to low throttle.

rcplanefan

My Feedback: (2)

The method nearly everyone uses for trimming right thrust is to add shims under the left side of the engine. Yes, this will cause the engine centerline to be offset slightly to the right. But it will solve the left yaw problem on uplines. Typically, 2 to 3 degrees is what is required for nice, straight uplines on aerobatic models. Your EF Yak is an excellent model and should require about 2 degrees if you are powering it with a good engine. Slightly more if the engine is lacking a bit in power or you are running a 3-blade prop (a couple of washers should be what you need).

Ken