Recover and Repairs

You asked for it here it is. (In my opinion)

I have used over the years the poly fiber process, superflite system II, and on my own aircraft randolph dope. Of the the 3 I prefer the randolph.
I use a croix turbine and 2qt. pressure pot. I have sprayed dope with a binks suction cup gun and the problems you have is getting enough dope on the surface, big enough air compressor to keep up when spraying a large surface.

Now some specifics: I started with 2 brush coats if nitrate dope, 3 cross coats butyrate with silver, sand with 320 grit, 3 more cross coats silver, sand again, 1 and 1/2 cross coats white dope, sand, 2 and 1/2 cross coats color, sand, 1 and 1/2 cross coats final color. All silver and color is mixed to 24-26 seconds with a #2 zahn cup.( combination of retarder and thinner.) Final color is 40% retarder, 35% dope and 25% thinner it ends up being 19-20 seconds on a #2 zahn cup. The final color application with the croix is done as fast as I can spray.(large surface, smaller surface I wait just a bit.) What I mean is on a wing I spray on a coat of dope and go reload and spray again 3 times. What I ended up with is a shine that looks like it was rubbed. Tapes are visible and the weave is just filled.(yes I know too heavy for a working cub but I'll have to sacrifice.)

My opinion of the different systems: Poly fiber will be less labor but the finished product won't be as nice. A lot of guys around here used to do the build up with Poly fiber and then spray Randolph dope for color. That has all changed now that Poly fiber has changed their process manual. They say if you use any top coat besides their's that it renders the STC null and void. As far as aerothane I'm not a big fan of using Polyurathanes on fabric because of the cracking issue and the fact that it is a bitch to repair.
Superflite system II see above on polyurathanes. One other issue the dope versus polyurathane debate is your ability to operate a spray gun. You better have your head screwed on straight with the urathane or it will make you look like a fool in no time.

I hope that helps some of you.

Matt

PS I have 450 hours covering and painting my cub.

Fabric options

I think you are right on as far as Dope vs Poylfiber vs Superflight or Airtech polyurathane systems. My current Cub has cenconite with dope and flying it in the bush I have had sticks through the tail feathers and ripped the bottom out once. The dope system is very easy to repair (and for me thats a big one). The Cub I am just finishing I went dope with a polyurathane top coat and just the normal hanger rash is @#$% to repair. The new Cub I am just now starting (today) I will go with dope for the main body and just do the stripes and cowl in polyurathane. Crash

What's the life of each of the different types of fabric? When does fabric need to be replaced (before the end of its projected lifetime), ie, number or size of patches?

Polyester fabric properly protected from UV rays will last a long time. One of the primary reasons for a recover is to inspect/repair the aircraft superstructure and replace hardware( cables, pulleys and such). Additionally, the longivity of the fabric job has a lot to do with the level of craftmanship with which it was applied.pak