Bryan wrote:

   The truck most days will  hold 50 miles per hour on a 5% grade
  The last big failure was on a 8 to 9 % grade at about  35 miles
per hour.  Now with that said we are overlooking ( IMHO ) 2 important points

1.  The diesel engine in front of the gear set has a very nasty
torque pulse and it gets worse under load. Picture someone
with a 5 lb hammer beating on your gear set all day.

2.  The failures usually occurr at gear change- the shock load
finishes the job the load and the hammer started.

I do not know how to account for those factors in your calculations.
But my gut feeling is that you should be fairly safe with the 6
planet set up as you are under constant (compared with a truck)
load and a steady torque load with the prop.  The only shock loading
would be in the event of some other mishap like a prop strike. You
might ask the transmission guys if the gear set in the latest Ford
products behind the 7.3  power stroke are the same as the
E4OD.  The newer transmissions are very bullet proof at
much higher horse power than the E4OD ever thought of being.
   Hope this contributes something.  Bryan in Princeton B.C.

It sure does Bryan and thanks for the hard data.

Paul Lamar

I think there is one additional important point, the torque.  
Since in aircraft we are at a much higher RPM the torque is much lower.  
It seems to me that more cycles of lower stress would be better on the 
life-span than fewer cycles of high stress. 
 Just a guess:  I'm a Doctor, Jim, not an Engineer.

Dave Leonard

Yes Dave I mentioned that. Did you read all your messages first? :)

Paul Lamar

**************************************************************************
Subject:     Ross Redrive failure mode
Date: Tue, 27 Jan 2004 16:06:08 -0800

Paul,
I can't remember exactly but I think Tracy's assessment was a max of 250hp
as well - I would like to know how he arrived at that assessment.
I believe it might confirm your own figures/assessment, but he may arrive at
his conclusion by another route.
BTW what is the HP rating of the Ford Pick-up.
George (down under)

250 HP turbo diesel as I recall. Of course that is at a relatively
low RPM so the torque is super high. Probably well over 500 ft pounds.
As Bryan said... that is a factor in gear life. The torque on a 3 rotor
will be about 240 ft pounds max. With a TURBO 3 rotor it depends
on the boost.
 
Paul Lamar
**********************************************************************


 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.