This is a winner. Losing the strut is no big deal since the ability
to fine tune engine pitch is retained.
People who are new to this list would be amazed at the five year
history of the evolution this design. Paul has probably drawn a
hundred iterations. Over time, the engine mount got better,
slowly,
but it has not been easy. This mount is light, incredibly strong,
and it is OUT OF THE WAY of other engine components like the
exhaust
system. This engine mount was engineered by Paul, without
compromise. Even though I have asked him on many occasions to fudge
just a little, to make things easier, most of the time he did not
seem to hear. Other times when he definitely did hear, I received a
smoking e-mail setting down the law.
This engine mount is designed to provide space to put the
radiator
under the engine with a properly shaped intake plenum. To do
that,
the oil pan had be redesigned and it has become a functional
part of
the engine mount both because it is the anchor for the rear
beam and
because of its shape. Anyone can just buy the engine mount
and get
on with his conversion. No big deal now, but to those of us
who have
had a part in bringing it to where it is today, this last
iteration
is MAJOR.
Paul, if you have time, in the attached drawing change the center
section to 6.5 inches as we discussed and also indicate the angle
between the arms and the center piece. I want to start
building the
fixture for this piece tomorrow. Thanks, Jerry
More views please...
Thanks,
Matt-
MORE VIEWS???? :) What perspective did you have in mind Matt?
Here are some shots of Bob Whites earlier version.
http://www.bob-white.com/log/index.html
We did not need the P51 style side beams then but they were key
to implementing the new design with the rear MM beam.
Paul Lamar ...No rotor no motor.
Thanks Paul,
That's what I was looking for. Kind of freaky to see the v-shaped brace
supporting the rear of the motor mount. If that were to carry more than
the calculated load, flexing of the v puts bending loads on the main
fore-aft trusses. Hmm. I'm sure it's fine. Just looks funny.
Is Bob White's airplane the only one so far to fly with this kind of
motor mount setup? I haven't heard whether it's electric motor smooth...
Matt-
It won't flex much as there is only 50 pounds max static
and probably less depending on the weight of the prop and thrust.
The CG of engine/PSRU/prop combination is just about right over
the schertz beam therefore the two front mounts take
the vast majority of the load. At max thrust (400 pounds) there
is a small moment (about 200 ft pounds) that unloads the rear
mount. Net load is then upwards or about 60 pounds up.
Not counting Questair Ventures? These mounts in essence
are the same. As far as I know Bob White has the only one flown.
Several others are close to flying.
I also designed a different style mount on John Slade's airplane.
It is called the Bushing in Firewall type.
It was a bit difficult to get him to build it like the
plans but eventually he fixed it. John claims it is smooth.
The idea here is to use the rubber bushing to reduce the stress
concentration in composite firewalls when bolts are used.
Speaking of smooth Perry Mick's engine is bolted solidly
to the airframe. NO RUBBER BUSHINGS.
Paul Lamar ...No rotor no motor.
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