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-   -   Engine Mount Thrust Plates (https://www.rcuniverse.com/forum/questions-answers-154/642113-engine-mount-thrust-plates.html)

stevehord 03-22-2003 09:24 PM

Engine Mount Thrust Plates
I am experiencing a "ballooning" effect with my PT40. I have had to reattach my whole tail assembly in the past 2 months because of a wreck and since this time have not been able to keep the trim for my elevator within range. The trim slide on my Futaba T6XA radio for the elevator is pushed to the top, yet my PT40 still balloons when I try to fly level. I have reset the subtrim and trim on my radio and also adjusted the elevator throws on the plane, however it still won't fly level too long. Would an engine mount thrust plate help this? Any other suggestions for this condition?

Thanks ahead of time,
Steve Hord

Hircflyer 03-22-2003 11:38 PM

Engine Mount Thrust Plates
Try installing shims under the trailing edge of the wing. Start with 1/16 ply and experiment.
Have you the correct amount of downthrust put in?

mscic-RCU 03-23-2003 12:26 AM

Engine Mount Thrust Plates
Sounds like you have the stab incidence incorrect, since this happened since you made the repair. I agree with Hircflyer, try shimming the trailing edge of the wing up to create negative wing incidence to counter act the ballooning effect.

stevehord 03-23-2003 01:12 AM

Engine Mount Thrust Plates
Thanks, Hircflyer and mscic. Is this correct; since I have a removable one-piece wing on the PT40 should I simply start adding shims on the trailing edge area, beneath where the wing sits? This makes sense and is simple enough I'll give it a try.

Thanks again,
Steve Hord

Ernie Misner 03-23-2003 02:50 AM

Engine Mount Thrust Plates
Hi Steve,

How's the balance after the repair work??? If you do determine that the back of the wing needs to be jacked up, there is a slick way of getting a new fit. Put handiwrap on the bottom of the wing, and make yourself a new wing saddle with an epoxy/microballons mixture. When dry it will pop right off and the epoxy overhang will sand right off.

If you decide to try shimming the engine with downthrust, Ernst makes slick little wedges for thrust changes. They have 'em at the hobby shops. They go between the mount and the firewall. Much better than washers!


MinnFlyer 03-24-2003 03:06 PM

Engine Mount Thrust Plates
Yep, check the CG first, since that's the easiest. Then borrow an incidence meter from a club member (if you don't have one) and check that.

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