Chevy's

[Jess Meyers]

Dan, if this is your interest, contact GM as they may have the data your requesting, we have not done testing on that issue.
Jess

[DanH]

Jess,
GM certainly did torsional modeling of their crank and flywheel, and of their crank and flywheel when coupled to the manual transmission powertrain. They would have done at least these two models because the system is run clutch engaged or disengaged. Your application is an entirely different torsional system.

With all due respect (I do appreciate your pioneering efforts), your posts make it look like you lack any understanding of torsional vibration as it applies to a crankshaft/flywheel/lower shaft/upper shaft system. Can that be true? I find it hard to believe.

If true, the only way you got a successful PSRU system was to keep adding strength (usually meaning weight) until things didn't break. Ignoring an effort to reduce the underlying vibratory loads (which are usually higher than engine oscillating torque) means you built a system that is somewhat heavier than necessary. The method works, but weight has been one of the classic objections holding back acceptance of auto coversions.

Didn't mean to hijack your thread. Lighter and more reliable propeller drive systems are possible. It's gonna take engineering and modern tools. I entered the thread to ask your opinion regarding those tools. I ending up pushing Ross because I know he's smart and has the resources. I hope you won't knock his efforts should he choose to pursue it.

Dan Horton

[Rotary10-RV]

Originally Posted by DanH

Jess,
GM certainly did torsional modeling of their crank and flywheel, and of their crank and flywheel when coupled to the manual transmission powertrain. They would have done at least these two models because the system is run clutch engaged or disengaged. Your application is an entirely different torsional system.

With all due respect (I do appreciate your pioneering efforts), your posts make it look like you lack any understanding of torsional vibration as it applies to a crankshaft/flywheel/lower shaft/upper shaft system. Can that be true? I find it hard to believe.

If true, the only way you got a successful PSRU system was to keep adding strength (usually meaning weight) until things didn't break. Ignoring an effort to reduce the underlying vibratory loads (which are usually higher than engine oscillating torque) means you built a system that is somewhat heavier than necessary. The method works, but weight has been one of the classic objections holding back acceptance of auto coversions.

Didn't mean to hijack your thread. Lighter and more reliable propeller drive systems are possible. It's gonna take engineering and modern tools. I entered the thread to ask your opinion regarding those tools. I ending up pushing Ross because I know he's smart and has the resources. I hope you won't knock his efforts should he choose to pursue it.

Dan Horton

Dan, I don't know about Jess, but I do consider your comments cogent. What may also be a good idea is to start a TV thread in the alternate engines forum. I'm a Mechanical engineer myself, but have rarely needed to do a true tortional analysis. The aircraft drive is a perfect test case. The link to the Lovejoy site is also appreciated, as I am often fumbling around looking for a damper/coupling for lower power stationary mechanisms.
Bill Jepson