flyrotary@lancaironline.net Mailing List Archive

Agree. Any kind of composite will likely have a radically different rate of expansion with heat. I'd bet more money on welding up the lightening holes in the flex plate, and an engineer friend has already nixed that idea. Note that the cracks seem to start in the lightening holes. When I found one that wasn't cracked, I polished the edges of the holes with a small Scotchbrite wheel before I installed it, with the hope of removing any stress risers that were created in the punching/forming process.

Did I or anyone else mention that Tracy's last design (for 2 rotor/wood prop use) eliminated the damper plate and direct coupled the input shaft to a racing flywheel (instead of the flex plate)?

Charlie

On 10/30/2018 12:42 PM, argoldman@aol.com wrote:

Joe,

I am a little concerned with this approach-- not that it won'd work but adding material with all kinds of different coefficients with the hope of strengthening may possibly have the opposite effect. For example adding carbon to fiberglass has the problem that in the failure mode, when one of the substrates gives out, it transfers an instant load to the other with sometimes catastrophic results, which might not have been seen with the failure mode of one of the substrates by itself.

Not knowing much about this, I sure would like to have a real engineer do an evaluation of the addition of the carbon.

Rich

In a message dated 10/30/2018 12:31:55 PM Central Standard Time, flyrotary@lancaironline.net writes:

I have tried to search the archives and found part of the story.

I think it will take a while to find all of the emails.

Found pics of Dave’s broken flexplate.

The pics of Dave’s flywheel are very disturbing.

It appears that the destructive stresses occur between the counterweight bolt circle and the torsional damper bolt circle.

If a good flexplate could be modified to strengthen the areas could this be a fix?

Clean the flexplate in the area of the bolt circles and perform a layup of carbon fiber on both sides.

A layer of Eglass would be placed between the carbon and steel flexplate to prevent galvanic reaction.

The mounting plate for the RD-1C would have to be shimmed the thickness of the carbon fiber.

Has anyone thought about this?

Joe Berki

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