Mailing List lml@lancaironline.net Message #53496
From: <Sky2high@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Fw: Spinner Backing Plate
Date: Fri, 20 Nov 2009 20:01:15 -0500
To: <lml>
Bucky,
 
You failed to mention whether it is for a fixed pitch prop (bolted to the crank flange or hub extension) or CS prop (bolted to the hub with standoffs).  In any event, a spinner without a forward bulkhead (especially an unbalanced glass one) puts incredible work-hardening stress on the back plate.   Unfortunately, fixed pitch props have nothing to support a forward bulkhead while the CD piston cup allows one to construct such a support. 
 
If you wish to create a carbon back plate, use the current one as a male plug to create a female mold.  Then it is just a matter of laying in the carbon cloth and carefully vacuum bagging the setup.  Remember to make it strong enough to withstand the flexing.
 
Another thing that can be done is to build a carbon flange inside the aft part of the spinner to match the back plate and attach the spinner with machine screws through the back of the back plate and thru the flange to nut plates. 
 
Have fun,
 
Grayhawk  
 
In a message dated 11/19/2009 3:03:21 P.M. Central Standard Time, buckyw@sbcglobal.net writes:
 

I have a prop. spinner backing plate with 500 + hrs. I found cracks around the mounting holes ( at the prop hub ).   I did not install the doubler kit sold by Lancair.   I know this is an ongoing problem for many other builders as the plates crack with or without the kit and sometimes with less hours.
My question is this-- has anyone made one out of carbon fiber for the 320/360 series with a constant speed prop? I know Brent Reagan made one for his LNC4, but we all know Brent can make anything.
I would appreciate any input  positive or negative, about fabricating one out of carbon fiber for the 320/360 series.
Thanks,
Bucky Whittier
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