Paul,

I am finding prop flanges come in many flavors.   I contacted MT
props  about an electric C/S  beta able version I wish to
purchase.  Included are the diagrams they sent me.   Notice the
1/2 size bolts.  More robust than for the lighter wooden props.
Notice there is an optional method of the bushing length as well
that is shown on the left side of the illustration.   I am going
with this extended bushing method to insure the best alignment.
This also lets the bushing to take the radial shear loads and
the bolt provides only tension.

For your website files,  A three page report on the advantages
of different metals used in aerospace and why.


http://machinedesign.com/article/comparing-stainless-steel-and-other-metals-1209


Cheers


Doug in Japan

Good work Doug. Thanks for those pdf's.

The bolts are larger due to the smaller bolt circle diameter.
This is the standard CS metal prop flange and the gyro
600 foot pound bending moment  on the prop shaft is  the highest.
The large bolts are there to transfer this bending moment
to the shaft from the prop. This is the same flange that is
on my O-470 with metal 50 pound constant speed prop.

Way overkill for a light weight composite prop.


McMaster Carr has a lot of good info on materials.

http://www.mcmaster.com/#steel/=8s27vw

------------------------------------

Here is another good McMaster site.
http://www.mcmaster.com/#stainless-steel/=8s29sm


Paul Lamar



Doug,
I went through this exercise when adapting 3-blade M/T electric prop to fit
on Tracy's RD-2C drive.  The RD-2C uses 7/16 bolts where the M/T uses 1/2"
(as you've stated).  Tracy was satisfied that 7/16 bolts were more than
adequate, but M/T insisted that I needed 1/2" bolts.  I ended up purchasing
the 1/2" prop bushings and having the flange re-drilled to accept 1/2"
bushings.  They are working fine and I sleep better at night.

Mark S.