Mounting fiberglass spinner

[julietsix]

I have an RV-3, O-320-E2D 150 HP newly rebuilt, Warnke prop, plane was built in 1976. The aluminum spinner developed a crack, I stop drilled it once, but it kept cracking. I stopped flying it, posted here for advice, and based on the input decided to get a new spinner from Van's rather than attempt repair.

I was a little surprised that the spinner I got was fiberglass, but that's fine. It looks good, and I think it will fit on my old spinner mounting hub (made out of aluminum), but I am seeking some advice on mounting it....

1. Can I just drill holes for the mounting screws, or must I put some kind of metal sleeves or reinforcement for the mounting screws?

2. Based on experience I have in the past working with fiberglass/epoxy sailplanes, I was planning on using a couple of different sized hole saws to cut the leading and trailing edge radius' for the prop blade cutouts, and then use a drum sander on my drill motor to finish off the cutouts. I know that I must securely mount the spinner so it won't flex or move during this procedure. Does anyone have any better ways to cut these prop blade cutouts?

3. Can I just seat the fiberglass directly to the aluminum spinner mounting hub, or must I use some kind of wear tape? The inside face of the fiberglass spinner that woudl seat up agains the aluminum spinner mounting hub does have the raw epoxy surface with the cloth weave texture, no gelcoat or other surfacing. I suspect the epoxy is harder than the aluminum and might wear it, but I don't know if I need to be concerned about this.

4. Any special tips or tricks on how to align the spinner precisely? I would hate for my plane to have the wobblies....

5. I do have a hole drilling tool, which should allow me to precisely match up the drilling of the spinner to the existing mounting holes in the spinner mounting hub.... Any tricks on using this thing? It seems simple to me, but I thought I would ask.... You know, I only want to drill these holes once!!!

Thanks,
Jim Hogue
RV-3 N1428Z
Mustang II N71CB

[Ron Lee]

I never put anything between my spinner and the back flange (?). I also have another bulkhead that is attached to the front of the prop and reinforces the fiberglass spinner.

[Hawkeye7A]

I did this recently on my -7A kit. You should have a rear bulkhead(spinner backplate) and a forward plate mounted on the front of your prop. Make a template out of thin cardboard(back of a legal pad works well) and trim it for a good fit around the blades. Make two marks at the rear of the spinner dome 180 degrees apart and trace out the window from your template on both sides. I used a 3" cutoff wheel in a die grinder for the rough cuts (the same one that is used for cutting the canopy) followed by a 1" cutter in a Dremel and then a couple different sizes of sanding drums to fill out the shape in the corners, etc. Lots of builders use countersunk screws with Tinnermann washers to secure the dome to the bulkheads but I chose to go with trusshead screws to keep the holes in the fiberglass smaller and I believe there may actually be more metal to glass contact to minimize the chance of the dome shifting. Hope this helps.

[julietsix]

Thanks for the info, I mounted the new spinner today, it was a piece of cake. I basically did it pretty much as you described, Hawk, it came out fine. I think I will fly a dawn flight tomorrow, I've been on the ground too long....

Cheers,
Jim Hogue