> > Well, my install of an S-Beam with the RD1C is not going smoothly.
After receiving the correct flex plate, it was only another 5
minutes before I ran into additional serious problems.
> >
> > In the attached photos, you can see 3 issues I am grappling with.
The first is that there is a significant interference between the
RD1C's damper plate bolts and the channel in the S-Beam. As you
can see, the bolts would require a much larger channel to go
through. I have not yet measured the interference, but a quick
look indicates a widening almost to to edges of the u-channel. I
am very concerned that this widening would weaken the S-Beam to
the point where it could no longer support the engine in a 6-G
landing without buckling.
> >
> > In the second photo, the next problem is apparent. Tracy's design
calls for the starter to be mounted at approximately the 5:30
position. In the case of an S-Beam, this access is completely
blocked by the S-Beam itself. Given that Tracy has minimized the
material in his mounting plat design, I think it will be a
challenge to find a starter mounting position without redesigning
the mounting plate from scratch -- not something I am wild about
doing. I think this starter position issue was a known-issue from
a few months back, but can't remember what the final solution was.
> >
> > Finally, I see in the photos of another S-Beam installation (not
sure whose) that Tracy's spacers in the RD1? have been replaced by
individual steel tubes. While it is necessary to replace the
spacers due to the S-Beam using 2 of the bolt holes, I am
unconvinced that steel tubes will provide equivalent torsional
resistance compared to the blocks of aluminum which are present in
Tracy's base design. I wonder whether it will be necessary to
fabricate blocks which span alternate bolt holes.
> >
> > So, I am at a dead stop once again. I am not seeing any solutions
which don't involve serious reworking of the RD1C mounting scheme,
including compromise of the strength of the S-Beam. Any ideas on
what to do about my dilemma?
> >
> > Mark
> >
> > Since I am not at the hangar right at the moment
> > I can't measure my damper plate to see what happened. In other
words I don't have my damper plate in front of me at the moment.
It is 60 miles
> > away unfortunately. The damper plate and bolts should clear the
top flanges.
> > Could you measure that radius to the center of damper bolts for
me. From
> > bolt hole center to center will also work as it is a perfect
square. Also please measure the OD of the ring gear for me.
> >
> > Don't panic we will fix it. I think the steel bushings were
welded in a bit too low in the beam. The left side steel bushing
can intersect the top flange with no loss in strength. Probably
my fault on the drawing. We can make a new beam for you with the
steel bushings in the right place. We will move the bushings up
a bit. That will move
> > the beam down a bit. No cost to you. Sorry about that.
> >
> > The starter reposition was a known issue. I will modify Tracy's
1/2 inch
> > adapter plate for the side mounted starter no charge. You will
have to send me your plate.
> >
> > The mounting beam is more than adequate for torsional strength as
the prop torque of about of about 560 foot pounds max (assuming
the p- port engine
> > is generating 200 foot pounds max and the psru is 2.8:1) goes
directly into
> > the beam and then into the rubber motor mount bushings. Round
spacers could
> > be used in the rest of the holes if you wish. Never the less on
the right side a 1/2 inch rectangular plate spacer can still be
used between
> > the right most hole and the upper right most hole.
> >
> > Paul Lamar
> >
> > Looks like a screwed up big time. Long story but way back when we
decided to do this motor mount I did not have a real good drawing
on Tracy's adapter plate as I was using ACAD V12 for DOS at the
time. Tracy was using something else. I never tried loading his
DXF file into Rhino until now but Rhino, bless its little heart,
had no trouble
> > with Tracy's DXF so I was able to read the dimensions by zooming
in.
> >
> > Here is the worst case fix. Just a couple of .065" ears on the
top of the beam for the left bolt. This is looking at the plate
> > from the engine side. Right bolt can recessed and centered on the
top flange. I am not sure until I get your dimension whether we
will have to go this far down with the beam.
> >
> > I guess Jerry did not have Tracy's gear box at the time to check
the fit.
> >
> >
> > Here is how Al Gietzen relocated his starter.
> >
> > Paul Lamar
>
> Paul, the S-beam fits my engine and Tracy's gear box perfectly. I
have published about a million pictures of it, so I won't send more
unless you ask me too. I am not saying I did not make some error
in construction, but the S beam I sent to Mark was bolted on the
front of my mock up engine without problem. I took the measurements
for the bushing holes directly from the end iron housing ( jigged up
in the mill and used the readout (.xxxx) for the measurements).
Jerry
>
> Did you have the dampener on the flex plate Jerry?
> Maybe Tracy changed the size of the dampener plate.
>
> Paul Lamar
Jerry is correct that the s-beam fit the engine correctly -- the bolts
slid in perfectly. And, after removing the flex-plate ears, the flex
plate was dead-center of the s-beam channel. The flex dampener plate
also fits inside the channel comfortably. The gotcha is the bolts
which attach the dampener plate -- those aren't close to fitting.
I will perform all measurements today. I will also remove Tracy's
mounting plate, but leave the dampener & sbeam on so I can get some
good shots from head-on of the bolt interference. I'm not sure if
repositioning the bolt holes in the sbeam upward can eliminate the
interference -- it might be that the upper bolt hole can't move far
enough up. In any case, I will measure & photo as necessary to be
able to calculate this.
On another subject, I have found a prop which can be used for the
engine testing. It is off another Mustang II & should have the exact
bolt pattern as on the RD1C. Couldn't fly it (wrong pitch for the HP)
but am I correct in believing it would be a sufficient load to prevent
the engine from over-speeding?
Thanks, guys-
Mark
Lowering the beam and adding ears on top for the spacers will work for
sure.
We have come up with another solution that might work. We will narrow
the upper flanges to 1/4 wide and add a strip of 1/4 inch 4130 on top.
Also turn the bolts around with the nut towards the engine. I think
that will give us a bit more room for the 1/4 inch flange modification
based on this picture. Jerry is checking this idea as we speak.
No problem on the prop. When the tips approach supersonic it is like
running into an RPM brick wall.
Paul Lamar
Looks like all we will need is a couple of notchs Mark. The reduced
flange width can then be reinforced with a tiny pieces of steel around
the notchs. Sorry about all this. My fault for not making
a better detailed drawing.
Paul Lamar
Ok, I have driven out to the hangar & measured things galore.
Naturally, I left the paper with all the measurements at the hangar. BUT
- since I have a habit of doing boneheaded things like this, I also took
photos with the rules in place. And these I have!
Since there are so many hi-rez photos for this, instead of killing
everyone's email I have posted them on my web site. Here are the
links to view them:
http://www.supinski.net/IMG_2251.JPG
http://www.supinski.net/IMG_2252.JPG
http://www.supinski.net/IMG_2254.JPG
http://www.supinski.net/IMG_2255.JPG
http://www.supinski.net/IMG_2257.JPG
http://www.supinski.net/IMG_2258.JPG
http://www.supinski.net/IMG_2259.JPG
http://www.supinski.net/IMG_2260.JPG
http://www.supinski.net/IMG_2262.JPG
http://www.supinski.net/IMG_2263.JPG
http://www.supinski.net/IMG_2264.JPG
http://www.supinski.net/IMG_2265.JPG
http://www.supinski.net/IMG_2269.JPG
http://www.supinski.net/IMG_2270.JPG
Paul, all the measurements you asked for are there. Also, I reversed
one of the bolts & showed how it looks on both sides. The measurement
for the ring gear is off my wrong year gear. It is the same diameter as
the correct one tho.
Assuming that some rework is going to be necessary, I brought the
sbeam and Tracy's mounting plate home with me.
Thanks,
Mark
You are not alone Mark :)
I think we have it figured out. Jerry assembled his and found
the problem. Here is the solution. Find a tig welder
locally and send me the bill. My fault for not catching this.
Cheaper than shipping it back and fourth.
Paul Lamar
Hey,
Those look like nylocks... How does everyone feel about their use in the
engine compartment?
Regards,
Matt-
castellated nuts would be better. So far there are hundreads of
hours of use with no problems however.
Paul Lamar
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