ORIGINAL: dksnyder
I am assembling an Oasis electric pattern-type plane (from Value Hobby)
The firewall is tapered to provide some right thrust, but I don't measure and right thrust when the
motor is mounted. I think the factory assembly is sloppy and the firewall is out of alignment.
What is a ''normal'' amount of right thrust?
I installed shims to provide 2 deg, but this ''looks'' excessive....
This is a 3 1/2 lb electric, not in the F3A size class.... but I expect the thrust line adjustments
may be similar.
I will do final adjustment after first flights, but the right thrust does affect how the cowl is installed.
I would like to be close when I install the cowl....
Thanks for any help
Cowled models that have down or right thrust place the engine mount so that the drive shaft is centered just beyond the cowl where it exits.
There isn't a certain amount of thrust that's used. Why? Things like wing position for example affect how much is needed. Designers usually guess whether or not they need it and how much to try on their prototype model. Fly and adjust, then decide what to put on the production models.
2 degrees right is a good start.
Cowls should be straight on a model, btw. If you're wanting right thrust, placing the rear of the motor mount to the left makes that easier. Down thrust? Place the rear higher on the firewall. Drawing centerlines on the firewall help. You'll notice that some motor mounts have marks on their base showing where their centerlines are just for this placement.