On Tue, 02 Dec 2003 12:57:49 GMT,
(Corky Scott) wrote:

On Mon, 01 Dec 2003 17:20:55 GMT,
(Corky Scott) wrote:

The PSRU was the one thing he felt should be done
by people who knew how to do them, and contracted NIS to develop one.

To make a long story short, the PSRU did not work well and things have
been in litigation for a while. Making a PSRU to handle 120 to 180
horsepower is one thing, making one to handle over 400 horsepower is
something entirely different.

Corky Scott


Thanks Corky,

I appreciate the info.
As I see it (and I don't know squat about PSRUs except their goal) a
high ratio PSRU as used in a turbo prop which has a very high ratio
(planetary) is easier to build than say the 2:1 or 3:1, BUT the
planetary also has the advantage in being used on an engine without
pulses being inherent in their operation.

The life of a PSRU on a piston engine has to be complicated. It not
only has to handle linear torque and thrust, but virtually any other
imaginable angle as well. Then it has to be designed to avoid any
resonances with those power train pulses AND take the positive and
negative torque without beating the snot out of the gears which means
next to nothing for slack (which brings its own set of problems).
Helical, double helical, spur, planatery...each with it's own set of
pluses and minuses.

BUT, didn't the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
those engines had very short TBOs too. Then again they weren't
exactly babied either.

Also...How did the guys make out using the Olds chain drive in the
Legend? It "appeared" to work great for at least a short time, but
they were running 400 to 500 HP through a chain that was used in a
drive train that only had about 200 HP on the other end. When I
talked to the one guy at Oshkosh some years back he thought it had
plenty of reserve.
I always like that airplane. Last I saw it had a turbine up front.

Sorry, that should be NSI.

I know when he used the original "so called" chevy big block aluminum
based engine he felt the front web was the weak spot. Course that was
right after planting his IV_P off the end of the runway when the web
broke. (or did he make it back on that one?) At any rate the web
broke and it was a high pucker factor.

That sucker sure did go though. The only thing that would have been
able to beat him from Lakeland to Oshkosh would have been a jet and it
would have had to have been a direct, non stop flight.

You'll have to fix the return add due to dumb virus checkers, not spam
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair?)
www.rogerhalstead.com

Corky Scott