how to set/check engine thrust angle
 

On the used Cherokee arf I just bought the engine is mounted in a clamp type motor mount.
It looks like it has allot of right angle to it.
I was going to take it off and mount on my test stand but I'm not sure if it will go back on in the same position???
as opposed to drilled holes which of course would put it back in the same position


wether its clamp in or drill in mount , 2 degrees (as instructed for my Tiger 60 I'm building) is not allot.

What do you use to check this angle?

How about bolting a straight edge in place of the prop and checking to see if its parallel to the LE of the wing?
I would have to figure out what 2 degrees is but at least there would be something I could measure?

steve

RE: how to set/check engine thrust angle
 

The best way to check engine and wing incidences is with an incidence meter or gauge. To do this I have built jigs so wing and tail incidences can be positioned properly so you have a baseline or datum to work from. This allows you to setup the thrustline according to specifications in relation to the wing and horizontal stab. After the airplane is setup properly in the jig I check where the engine thrust is set and make adjustments as required.

RE: how to set/check engine thrust angle
 

H'mmm this sounds like I would have to buy something which goes against my instincts! :D

Part of what I enjoy in doing this is figuring out a way to do it without spending money. Although my wife doesnt think that is the case!;)

I'm thinking I should be able to get it "in the ballpark" ???

Thanks

Steve

RE: how to set/check engine thrust angle
 

What you suggested would be exactly what I would do. In ballpark is fine for engine thrust.

RE: how to set/check engine thrust angle
 

I guess you could wing it so to speak. If you can find the thrustline and level it you might be able to determine the angles. I find my incidence meter very sensitive, there isn't a great deal of movement to change things an extra degree or so. Its kind of like licking your finger to find the wind direction vs having a wing sock. Close but no cigar IMO:eek:

RE: how to set/check engine thrust angle
 

Multiply the lenght of the staright edge by 0.03492; that will be the difference in distances of each tip to the leading edges.

Example:

For a straight edge of 24", with a hole in the center installed like a propeller, the measured distances from the extremes to the leading edges should have a total difference of 0.838" for 2 degrees.

RE: how to set/check engine thrust angle
 

Great info! Over my head but I understand the concept and I can measure .838 with some degree of accuracy!!
Just what I needed Thanks!

Steve

RE: how to set/check engine thrust angle
 

Popriv, look at this web page.
http://www.uoguelph.ca/~antoon/hobby/trim.htm

RE: how to set/check engine thrust angle
 

more great info, thanks. I'll have to print out and bring to the field..

Steve

RE: how to set/check engine thrust angle
 

Great help as always guys, thanks heaps to all who contributed
Sidekick

RE: how to set/check engine thrust angle
 

.838" 12" from the centerline of the engine? That sounds like way too much. Double check your math, you may have missplaced the decimel.
edit: Well it's not the math using the figures you gave my calculator comes up with the same number. Just sounds like way too much, that's over 3/4 of an inch. Just guessing I would think it would be more like .1"-.2", but that is just a wild guess.