Thrust Line

[Samyguy]

Hi Guys

   I'm finishing a UL Eagle,  What height is the thrust line?
And from where is it measured ?

            thanks Calvin

[Dan_]

The thrust line in a direct drive engine is the center line of the crankshaft.

In a real slick airplane with high power the designer may have to account for the effects of vertical CG and drag vectors when considering thrust line. 

The drag sums and vertical CG resolve to a 'netural point'.  In a low drag high power machine or a gyro copter, the closer the thrust line is to the neutral point the less effect changes of power will have on longitudinal stability. 

In the case of the LE, I have heard no reports of a tendency to pitch up or down or enough yaw that a rudder trim tab would be necessary.

It flies like an airplane is supposed to.

[Samyguy]

thanks for response. I'm looking for the thrust line for the airframe.
Reason being I got a second hand build I'm finishing.
And the wing is considerably higher than most LE's
So I wanted to know where to start, and adjust up or what ever to make it fly right.
I've flown pushers before, don't want to feel that again.

[karmarepair]

I'm looking at the LE-XL plans, and I do NOT see a dimension. I'd guess it's 11 inches ABOVE the LOWER longeron as measured from the LEVEL section under the seat.  I also don't see a good way of raising it, short of rebuilding the fuselage, from station 2 forward.

[Dan_]

And the wing is considerably higher than most LE's
So I wanted to know where to start, and adjust up or what ever to make it fly right.
I've flown pushers before, don't want to feel that again.

How much higher..?

I had a Kolb.  I was practicing power out landings.  When I went full power it forced me to touch down from about 5 feet.

Full power would cause a pitch up in your case, shirley you could never get that much of a violent pitch change in a L.E. that would fly.

Your best bet may be to go ahead and build it and see how it flies.

Even with the Kolb, as long as you knew what was going to happen you can get used to it and compensate.

You may be looking at changing the engine height an equal amount as the wing, but like I say -- I would doubt it but you may want to run it by Leonard.

Keep us posted...

[Samyguy]

That's kind of what I have been finding reading in the tech sites.
Just wanting to check with what the practical man had to say.

thanks Guys