Jerry-
The only thing keeping my engine where it belongs is a
2x4. This
worries me, since I share the hangar & my airplane gets
moved around
when I'm not there. So, to answer your question, getting
the rear mount
was my #1 project. I do have the local guy who could
fab it
for me --
he's ready to whip it out for me quickly once given the
right
measurements but he doesn't weld, so I'll have to find a
welder too.
Mark here is a photo of the prototype strut bracket. Two
things to
note: one, the inside measurement is 1" which is also the
outside
measurement of the rod end. You may have to file the inside
faces of
the bracket to get a smooth fit. Secondly, the bracket is
off set
toward the pilots side about an inch to clear the pan bolts so
that you
can get a wrench on them. check to make sure it will still
line
up with
the firewall bracket. If it will do the job, I will
complete the
welding and send it to you. You will have to enlarge the
bolt holes
(Rod End) in the bracket. Also, the bolt holes that attach to
the pan
will have to be enlarged (presently drilled for 1/4 inch.) I
am not
set up yet to make the final version but it will be
similar to
what
you see here. Lastly, there is a lip on the pan that will have
to ground
away in the area of the bracket. I do have an extra Barry
washer. Jerry
P.S. It is heavily constructed. If you want to drill a few
lightening
holes, go for it.
Jerry -
Thanks - I'll drive out to the hangar tonight after work & check
clearances & whatnot and get back to you.
Mark
Well, the hard point itself doesn't allow for any offsetting at all.
The bolt hole is dead-center & there is no structure anywhere else
(e.g., toward port) to tie into. The rod ends don't look like they
would support any kind of angle to the strut. Further, the prototype is
set up for bearing from underneath.. Based on the photo, it looks like
the mounting brackets don t extend out enough to allow a strut to come
down from the top.
So - it looks like this bracket won't do the job for my installation.
Thanks, tho.
Mark
What is the matter with coming up from the bottom Mark
as in this 3D?
Coming down from the top is not out of the question.
That big 1/2 inch shank on the rod end can take some bending loads.
There are ways around it. Do me a favor and use a fish
scale hooked to the back of the engine to measure the force
required to level the engine when you have a prop on there.
Or if you don't have a prop yet you can hang the weight of
a prop off the prop flange. This will tell me precisely
where the CG of your engine is so I can calculate the exact
loads on the rear motor mount.
Also are you thinking of replacing the oil pan? If so
a bracket suitable for coming down from the top can
be incorporated in the back panel of the oil pan.
Paul-
The design of the M2 has the fuselage forward top skin taking torsional
loading from the engine. The 5th hard point is part of this & the
designer prefers that it be used when mounting a high power engine.
He's ok not using it up to about 220HP at the prop. So I was pretty
happy to dedicate it to the rear engine mount. And, of course, Jerry
has already built a perfectly lovely engine mount, so the idea of
mucking about with it to add additional tubes for the rear mount don't
satisfy. Finally, I was liking the strut with rod ends design because
it would make it trivial to adjust thrust angle should it be necessary.
You are right that much of the weight is already carried by the SBeam.
We picked the engine up by hand & were suprised how far forward the
redrive brought the CG, even without a prop. I don't think a prop will
result in a CG at the SBeam, but it won't be all that far off.. I will
get a scale & measure the weight at the rear. I'll add weight to the
prop flange if anyone can tell me what a 3-bladed prop weighs.
I was not planning to replace the pan. I agree it's shape is a
nuisance, and that it will be difficult to drain oil from once the
radiator is mounted. But I wasn't seeing a compelling need to replace it.
Mark
I just sent and oil pan alternative. Move the ears over to the center
of the pan and space them far enough apart to clear the center pan bolt.
The 1/2 bolt going through the pan ears and the rod end will
take considerable bending load no problem. You will
then need short spacers between the rod end and the pan ears on
each side. The same trick will work on a Jerry Hey style
steel bracket.
Paul Lamar
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