Pierce Nichols wrote:
> > I think
> > there would still be a slight lateral force, but not the yaw/pitch
> > torque that would occur with base-mounted engines.
>
> I don't see how -- please explain.
Well, let's rotate the vehicle 45 degrees, to make the ASCII
art easier - assume we're looking down from above.
<B
^
A D
C>
Let the symbols ^<> indicate the horizontal component of each engine's
thrust. (A is firing 100%, B and C are firing 50%, and D is shut off,
as in the previous example).
So the vertical component of A's thrust, unbalanced by D, will tend to tilt
the vehicle in such a way as to lift the corner where A is mounted... this
is the same 45 degree yaw-pitch maneuver we were considering earlier.
The vertical components of B and C will combine to produce
a lifting-but-not-tilting force. The left-pushing (in the
image plane) horizontal component of B's thrust, combined
with the right-pushing component of C's thrust, will produce
a counterclockwise-rotating torque, but will cancel out as far
as producing a net translational force (i.e., we're not pushing
the vehicle either to the left or to the right).
However, what's the horizontal component of A's thrust going to do?
It produces a torque that cancels that of B+C, but it's also going
to push the vehicle "B-ward" (i.e., toward the top of the page in the
ASCII art plane). If the engines were base-mounted, this is the force
unbalance that would produce the "cross-maneuver" torque discussed
earlier... with the engines mounted at the CG plane, there will still
be a side force even though it's not producing a yaw/pitch torque.
-dave w
_______________________________________________
ERPS-list mailing list
[EMAIL PROTECTED]
http://lists.erps.org/mailman/listinfo/erps-list
