>   Hi Brian,
 >   Something didn't sound right about sandwiching ANYTHING between the
 >   prop flange and the drive flange, so I went out to my workshop and
 >   looked at my Hartzel props. Sure enough the spinner bulkhead is
 >  attached
 >   to the OD (outside diameter) of the prop flange. Its an elaborate setup
 >   but, the bottom line is there is DIRECT CONTACT of the prop flange and
 >   the drive flange, no bulkhead, no RTV, no aluminum disks, no carbon
 >   fiber or fiberglass. I have 2 props --a 2 blade & a 3 blade-- both are
 >   done the same. Hope this helps. Dave M
 >
 >
 >   >Dave,
 >
 >   >Would it be possible to send a photo?
 >
 >
 >   >Thanks,
 >
 >   >Brian Trubee
 >
 >  Hi Brian,
 >  Photo would not show much. Take a look at the attached sketch. It's not
 >  to scale but all the parts are there. If you need sizes or more info
 >  just shout. Dave M
 >
 >
 >  My Spitfire came with the Spinner and a front and rear flange. Showing
 >  the rear flange between the prop and prop hub, the front on front of the
 >  prop. Prop bolts holding all this together. Is this an improper
 >  installation?
 >
 >  Bob Mears
 >
 >  The smaller three rotor torque pulse is a positive while the additional
 >  average torque is a negative. What is the back plate made out of? If
 > aluminum
 >  you will probably be OK.
 >
 >  Paul Lamar ...No rotor no motor.
 >
 >  The Rotary Engine NewsLetter. Powered by Linux.
 >  ACRE NL web site. http://www.rotaryeng.net
 >  Youtube key word UTUBPLEASE
 >  Copyright 1998-2008 All world wide rights reserved.
 >
 >

 If the prop is aluminum, the bolts can be torqued plenty for this to work fine.

 This is really the normal spinner installation on all of the
 fixed-pitch Cessnas, Pipers, etc.  A backplate  (and sometimes a front
 plate) held in place by the prop mounting bolts.  Usually with drive
 lugs splined through the flange - offering more bearing surface for
 the torque loads in the prop and spinner.

 The c/s props have spinner backplate mounting flanges that don't use
 the same fasteners as which hold the prop to the crankshaft - like
 Dave M depicted.  I suspect part of the reason for this is that
 there's a high pressure oil connection made by attaching the prop to
 the crankshaft.  Adding the spinner backplate to this stackup seems
 like you'd eventually get leaks at this connection.


 Regards,

 Matt-

Replying to my reply..

I have a spinner from this outfit on my 182.  I notice that all of
their bulkheads (back plates) appear to be composite, so that's
probably okay..

http://www.tcbcomposite.com/parts2sm.htm

I imagine what makes this work is the area being crushed is relatively
large - lowering the peak pressure.

Compare the transverse compressive strength of carbon rod (idealized
composite, but in its weakest axis - what we're talking about here):
50MPa

http://www.goodfellow.com/csp/active/static/A/Carbon-Epoxy_Composite.HTML

To aluminum: ~270MPa for 2024



Matt-

What is that in psi Matt?