"Bret Ludwig" wrote in message

Actually, aircraft engines don't deal with it very well at all. Large
radials deal with it by having a high reciprocating mass, and the 65
Continental class of engine deals with it by low impulse and again a
high reciprocating mass, but geared light aircraft engines have been
largely troublesome. The Continental Tiara was a disaster and so was
the GO-300. The planetary gear case Lycomings were a little more
successful but they were also heavy.

Agreed. Part of the solution, is like I said, stout (read heavy)
crankshaft, along with, as you stated, high reciprocating mass.

Radial engines have stout cranks, plus massive master and slave rods.

A good "car" engine that is suitable for ski boat use is suited to
aircraft use if 1) any resonant peaks in its internal configuration are
figured out first, (the boat will do that!) 2) a proper drive is
selected and 3) propeller loads are transferred to the airframe from
the drive and not the engine itself.

Part of that "proper drive" for boats also use a rubber coupling between the
engine and the transmission, outdrive, v-drive, or prop shaft. The entire
output from the engine turns the rubber, then the rubber turns the drive.
In this manner, there is no metal to metal connection of the engine to the
drive. Every one I have seen uses one, but I'll be damed if I can remember
what the correct name is, at the moment! g Old age, or time of night?

Those units tend to absorb part of the pulse energy, and leaves a way for
the torsional energy to dissipate. They do eventually wear out, and a new
one has to be installed. AMHIKT. Very careful alignment is key to the unit
lasting as long as it should.

One of the more modern solutions is use of a toothed rubber drive belt, to
slow down the prop, and allow for a prop shaft and bearings that can deal
with all of the loads the prop creates. It also allows the belt to flex and
isolate the prop from the engine. They are pretty efficient, and have a 200
hour or more life expectency.

Dave Blanton had no torsional
resonance problems,

Some would argue that! g
--
Jim in NC