In article 40057c28$1@darkstar,
(Mark James Boyd) wrote:

Alan Baker wrote:

Project Dog Whistle. LOL

And Bill rightly points out that if the thrust
is behind the CG, any yaw at low speeds means
a ground loop on takeoff unless the tailwheel is
firmly tracking.

No it doesn't. The thrust is always directed through the centre of mass.

It's position of the main wheel with respect to the CM that matters for
a ground loop...

Alan Baker

Correct. I'm mixing apples and oranges. In our Sparrowhawk design,
the engine(s) thrust is through the center of mass, so this
doesn't matter.

I wonder about the Genesis mock-up, where this may not be the case.

How can it really be otherwise?

And what's more, a ground loop is cause when the main wheel -- ahead of
the CM -- develops a sideways force which causes further yaw, which
causes larger sideways force, etc.

Even mounted off the CM laterally, and engine would still be fixed to
the fuselage and hence the yaw force would be *constant*.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."