Alan Baker wrote:
In article ,
"Morgans" wrote:


"Morgans" wrote


Doubtful that you would ever notice a difference in a 4" change, but if it
originally has downthrust, and you move the prop lower, you would take
downthrust out, but not much. 1/2 degree, perhaps? Hardly enough to be
able to change, I would think.

Dang, it, I got it backwards. It would theoretically need downthrust
_added_.

Think about it. A seaplane with an engine up on a pylon has up thrust, so
when you add power, that the nose does not go down as much.

Wit the center of drag higher than the engine, you have down thrust so added
power does not lift the nose as much, so going higher, take down out; lower,
add down.


Read this. Read it again and again until you get it:

Don't take moments about anything other than the centre of mass.



Why?

I mean specifically, how else would you even FIND the center of mass?

What difference does it make whether it's center of mass or center of
the axles?

Or leading edge of the wing?

Or a point 1" in front of the tip of the spinner???

The numbers for the moments will certaintly look different, but they
all relate to the same spot on the aircraft...




--

Richard

(remove the X to email)