gGys i recently picked up a 40 size u-can-do and let me tell you its great but what im having a problem with is the cowling being parallel to the backplate of the spinner. I mounted the 0.S. 70 per instructions but when i look (from the side at the front of the cowling around the prop shaft its not parallel to the backplate of the spinner its a real eye sore. I had thought about loosing the upper mount bolts until it lowered the engine enough and then put washers behind the upper two mounting bolts to compensate (maybe 1/8th inch most is what im needing) to put the two parellel to each other. my question is this if i lower the mount will it hurt the plane at all by doing so like make it fly bad or wrong or should i just accept that the cowling isnt perfectly parallel to the backplate any suggestions would be greatly appreciated oh and by lower the mount i mean basically pivot the mount by the two bottom screws to bring the front of the engine down some

Usually what you are seeing is the built in engine mount incedence. Adding washers between the engine mount and firewall will change that incedence and like you are thinking about doing, it will cause the plane to go nose up when you cut the throttle

i was thinking more nose down seeing as adding the washers will be making the front of the engine go down

It will go nose down under power but when you suddenly chop power all that down pull is suddenly gone so the nose will come up quickly

More times than not I have found that you can use the cowl as a general guide to help you with proper engine incidence. Meaning that if the backplate of the spinner is not flush with the front of the cowl then it very well could be that your incidence is off on the engine anyway and it needs to be adjusted.

Personally I would be more concerned with proper incidence of the engine than the cowl and cone matching up perfect. If after setting the incidence correctly and still finding that the cowl doesnt match perfect you can make adjustments on the cowl. If you put down a sheet of sandpaper you can very carefully sand an incline into the back of the cowl so that it matches the angle of the spinner. But I would only do that after finding the exact incidence on the engine and testing it in flight.

Also, with some of the planes that I have built there have been things that I thought were a real eyesore (a wrinkle in the monokote, a fingerprint on the inside of the canopy, etc) I always think that I will go back and fix it but once I get it to to the field and fly it for a few weeks I realize that I dont really notice the ¨eyesore¨ so much anyway.

>>> Personally I would be more concerned with proper incidence of the engine than the cowl and cone matching up perfect >>>

This is usually correct. The highly aerobatic planes like the Funtana series and others have right thrust and sometimes down thrust also built into the firewall. The engine should be mounted square to the firewall, nothing else. (if the firewall was installed correctly at the factory) Do you know why right thrust is needed?

Ernie

I'm with Ernie. Virtually all 3D planes have at least a little right thrust. You need it in a hover. Get the engine correct with the firewall and then adjust the cowl.