Thorp Air Command - T18.net

Here is an interesting link on refinishing wood props:
http://www.thompson-aero.com/index.php? ... &Itemid=32
Here is the link to Thompson-aero's home page on wood props:
http://www.thompson-aero.com/index.php? ... &Itemid=32

Good information for wood prop owners, I'm wondering what the best epoxy
for wood would be?

That's a good question, and one I'm dealing with.
I have a Hendrickson 68x68 prop, and it has fiberglass wrapped tips.
One blade has a fiberglass delamination it the trailing edge, about 3/8" chord, and 4" span, about 2/3 of the way out the blade.
I'm considering heating & reforming the 'glass, then rebond & clamp. I've been using West System Epoxy for all my fairings & plenums on the RV-8, so that's what I'll use.
After that, varnish with whatever the logbook indicates was used during refinish maintenance in the past. I think it was eurethane varnish.
If the reform & rebond doesn't hold up, I'll have to remove the offending little patch of glass, clean to wood, and lay in a new patch, then refinish and ballance etc.

You can reform fiberglass with heat? I'd like to get the warps out of large surfaces on my cowling and wing tips. Anyone, please tell me more.

Les Krumel,
Albuquerque

Les: I am not a "fiberglass man", but I have had some success with heating the stuff and taking out a few "bumps." I think the key is just enough heat to bend and or shape it and not enough to start the stuff to separate. I would heat it and place a couple of pieces of wood on each side and clamp it until cool. I hate the stuff and would pay double or triple for a carbon fiber cowl, tips and pants with a nice smooth finish !

RB

I tried heat from a heat gun.
I didn't like the results. However, my prop had a unique delamination. The trailing edge of the fiberglass cover on the tip had come loose, the delamniated section was about 1/2" wide & 4" long, It started about 1/2" outboard of the inner edge. The prop had been operated in this condition, so centrifugal force had acted on the loose edge.
When I applied heat, the oxidized epoxy just turned brown. It didn't really get sticky or anything. Also, a tear appeared near the inboard edge mentioned above.
I carefully cut out the delaminated strip with a dremel tool using a cut off wheel, and hand worked the wood with needle files until I had clean smooth wood and no loose or frayed fiberglass edges.
I then used West Systems Six-ten (610) which is dispensed from a caulking gun tube. I didn't use the mix nozzle, the amount was so small. It mixes to a consistency of vaseline or a bit thicker. It stayed in place on the prop, and formed well with wood hobby sticks (tongue depressors to us old guys).
A day later, I filed and sanded the high spots, then brushed on some Minnwax Spar varnish, looks fine.
A week later, my hangar mate scratched the trailing edge of the other blade while putting his plane away, so I got to do it a second time. Now I have Minnwax Spar Varnish in a spray can for less than $10. I'll try that next time.

Hangar mate owes you case of beer ! Expensive beer !

RB