Cowl mounting in Pitts rubber conversion - RC Groups
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Nov 10, 2001, 05:13 PM
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Cowl mounting in Pitts rubber conversion

It's crunch time. This Pitts Special rubber conversion looks to be coming in somewhere in the low to mid 11oz range.

My next big puzzle is mounting the nose plate/cowl. I want to be able to remove the motor and gearbox without tearing the plane apart. Any suggestions?

Also, the interplane struts are CA'd to the bottom wing. How would you secure them to the top so both wings are removable?
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Nov 11, 2001, 04:55 AM
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buzzsaw 46's Avatar
Would it be possible to put some ply plates behind the Firewall and screw the cowl/ motor on or did you want a cleaner attachment?? Looks good so far. What did you and up using for covering??
Nov 11, 2001, 09:24 AM
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That's a definite possibility. The other option I was considering was to follow that MAN article on the Dumas Bearcat and use rubber bands, but I was afraid that would weigh too much. I'm looking at an all-up weight of 11-12oz, right in line with the projections from Tom Hunt's article, had he also used a rudder.

Ah, I forgot the particulars:
Herr Engineering Pitts Special rubber freeflight kit
Covered in red So Lite
Graupner Speed 300 on an MPI 4.5:1 gearbox
Castle Creations Pixie 7 speed controller
8-cell 720 mAH NiMH
1x Hitec HS-50 for ailerons
GWS Pico flight pack parts for everything else.
Nov 11, 2001, 10:17 AM
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Gerald's Avatar
I'd use small wood screws to mount the cowl. Glue some small squares of 1/8" lite ply behind the front former C4/C7 to make hardpoints for the screw threads to cut into. Two should do it. I was going to suggest to hide the screws somewhere in the cooling vents but you already have those cut out. What did you attach the gearbox to? Did you use any ply for that? Well if there is no ply on the back of the nose block you will need to add another couple of small squares for the screw heads. Drill two holes in the balsa part of the nose block, one on each side, large enough to clear the screw heads. Then inset the small plywood squares (or disks) into the back of the nose block so they are flush and centered over the holes. Drill smaller holes in them to clear the screw shaft. The screw heads will bear against these. You can cover the exposed holes on the outside of the nose with your covering material to hide them if you don't plan on removing it frequently.

If you want to make the top wing removable you can glue some short 1/32 birch ply stubs vertically into it. Use tiny screws and nuts such as #00-90 to attach the struts to the stubs.
Last edited by Gerald; Nov 11, 2001 at 10:27 AM.
Nov 11, 2001, 12:02 PM
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Rotten Robbie's Avatar
On my Herr Super Cub conversion I used a #2 screw in each of the engine air intakes. I put a #2 blind nut in the former directly behind the cowel.

Think about doing the wing struts differently. Make the permenent attachment to the upper wing. It does not have to be rigid. You could use small hinges. Attach the strut to the lower wing with a screw from the bottom. But make the strut go into a hole/slot in the upper surface of the lower wing.


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