G'day Folks,
I finished a rather difficult stage of my Stearman tonight. I'd read of a few methods on here on how to reinforce a firewall & racked my brain about how ya can do any of 'em, what with the tight space & lack of visibility. I've got a fairly big hand (see pics) & tentatively tried to put it through the frame that holds the fuel tank. No way I thought. If I could get it in there I probably wouldn't get it out without breaking something. I'd already decided the plan would include two vertical pieces of hardwood on the inside firewall so I started cutting them to shape & hoped some ideas about how to fit them would germinate in the meantime. I think I was sanding some globs of glue off the stock firewall reinforcement using a long thin piece of ply as a sanding block when I realised my whole hand had gone inside! Oh no! But to my relief I found, if I twisted my hand & mouth in exactly the right way I could not only get it out, but put it back in with relative ease. Next problem was not being able to see anything if my hand was in there. I cut the handle of a 1/2" craft paintbrush in half & screwed it back together at 90' so I had a brush with a bend in it. I put a small rectangular cosmetic mirror against the firewall & standing the fuse on it's nose, I practiced painting epoxy in reverse perspective with this brush. My hand was outside the space & I could see what was going on. It wasn't pretty to watch by any means but I convinced myself I could do it for real. I painted epoxy on the difficult bits first, then unscrewed the brush handle to give me a straight short handled brush to do the bits I could see without the mirror. So I got the two peices glued in ok & while they were still curing I made a thinned batch of epoxy & wetted a dozen or so strips of carbon fibre tape on the upper firewall joint. This was the only place I could manouver the brush with enough dexterity to do a half decent job. After all this touch cured I made a couple of batches of thinned 5 minute epoxy & tipped them in stages around the rest of the firewall joint, holding the fuse at a 45' nose down attitude & rolling it axially until the resin cured in a nice fillet. I also put a fillet along the inside landing gear mounting plate & applied a few strips to the outside of the gear mount. Now I think I can get back to the instruction book again & start mounting the tail feathers.I've posted a few pics. I wanted to make sure the firewall was strong because i'm using a DLE 30.
Mick