Paul, just to keep you in the loop. I've got the Warp Drive
  hub model into the FEA and had a couple initial runs on it.
  I'll have more data in the coming days, just tuning things
  so it all work out right.

  It's been a brutal couple weeks to find time to do stuff like this.

  Jarrett

  Thanks Jarrett. That is good news as it means the cash is coming in.
  Man does not live on work alone. Sounds like your prices are
  a bit too low :)

  Paul Lamar
  --

 Here you go Paul, seems to be well w/in the range as far as I can
 tell.
 Not sure how much cash is coming in.. but the kids are fed and the
 bank says I can keep the house :)

 Just glad I have people whom I can help out.

 Best

 Jarrett


 Thanks Jarrett.

 Good work.

 6 to 8 thousand psi on the stress looks very conservative
 in the torque direction.

 What about the 100 foot pounds fore and aft loads?

 I kept it simple at first to keep down the milling time
 and cost. Probably heavier than it needs to be but better
 safe than sorry.

 After we fly it for awhile I think we can take some weight out
 in selected areas. Got any ideas about that?
 Feel free to modify it as you have the FEA experience.


 Paul Lamar

 The torque loads are included in that FEA [it has both the
 200lb rotational & the 100lb torque load]

 I'll have a look at trimming some fat there, it's pretty solid
 so there is probably some room for material removal. As
 you'd noted leaving it thus, and then trimming later is
 probably a good route to take.

 Jarrett


We have two torques. One fore and aft and one rotational.
We have the rotational data.
The fore and aft torque is caused by the gyroscopic action
of the prop when the aircraft is stalled. At a pitch
rate of one radian per second (60 degrees per second)
it is 600 foot pounds for a 50 pound aluminum prop. I am guessing
that it will be only 100 foot pounds for a carbon blade prop.
That too places a bending load on the prop hub.

In the side view of the prop the gyro torque is around
the center of the hub in a plane passing through the center
line of the engine.

Paul Lamar

Hi Paul,
Do you know of any on-line resources that detail the calculation
involved in the above fore and aft gyroscopic torque specifically
regarding a propellor? I'd like to learn more
about this. Thanx, Dave M

Here is a pdf on the math.
Not on the Internet but this book gives some practical
calculations based on real experience of aerobatic
airplanes. Page 436.

Sky Ranch Engineering Manual. This book presents an excellent
overview of the problems of aircraft engines. It is 500  pages and a
bargain at only $23. There are many details on the materials and
processes used to build a successful aircraft engine. There is a
very good and exhaustive discussion of destructive  torsional
vibrations and fatigue. The telephone number  to buy this book is
(916) 421 7672. The author is John Schwaner. John is highly thought
of in the experimental aircraft community.

Paul Lamar