Alan Baker wrote:
In article ,
Jim Logajan wrote:

Alan Baker wrote:
The only thing that matter was thrust line.

You've managed to make the same incorrect claim at least twice (that
I've counted) in one thread. Are you sure you aren't overlooking
something?

I'm will to entertain that possibility.

What do you think I'm overlooking?

That the aircraft are moving through a fluid, not a vacuum.

So things like propwash affect a tractor differently than a pusher. In my
own analysis of the two types and their engine on versus engine off
dynamics, the thrust line has not been "the only thing that matter[s]." It
is more complex, and the texts I have handy do not make the situation
appear as simple as you claim.

If thrust line moment arm (relative to the c.g.) were all that mattered,
then the following two bottle rocket firework designs would fly the same
paths, mass, impulse curve, c.g., and thrust moment arm being held the
same:

(A) ----------------+-----+
|=====]

(B) +-----+----------------
|=====]

The attachments to the sticks are made so that the moment arms relative to
the c.g. are otherwise identical, but in (B) the thrust is opposite its
usual direction. Now in a vacuum I would expect them to fly the same paths
and would be surprised if they didn't do that. But in a fluid like the
atmosphere? Would you expect them to fly the same or different paths?
Frankly, I would be surprised if they did fly the same - but as I don't
have any fireworks handy at the moment I haven't gone outside to have fun,
er, run experiments to observe their behavior.