Originally Posted by
jester_s1
You guys have been so helpful so far on this project. I had to move my engine box back to accommodate the muffler on my engine, so now I am unsure how the thrust angles should be set up. The plane is a Midwest Extra 300s 27% scale.
Also, any advice on incidences would be appreciated. Is this a 0-0-0 kind of plane or do they usually fly better with some up wing incidence and down thrust on the engine? I am using an SD-10 radio so I can set up whatever mixes I need to if that's a factor.
Make your own downthrust angle measurement device. Get a 3/4" square stick, about 10" long and drill a hole on one end to fit the engine shaft. On the outside of the hole, parallel to it, pin a weighted string (sewing thread works fine) and let it hang down towards the opposite end of the stick. On the opposite end, scribe several angled lines in 1/2 degee increments which start at the pin hanger point.
With stab at zero, hang the instrument on the engine shaft and secure it. Let the string hang and let it find the downthrust angle....
Remember the MattK rule for angles, 1/4" deflection of a line in 14" of span, equals 1 degree. For right thrust determination, measure the distance from tail post to each prop tip. Assuming a 14" prop diameter, you have 1 degree of right thrust for every 1/4" length difference...QED!