OK, time for a long over due update.
Muffler fitment problem still unresolved. No doubler in the tube for the present setup so moving the mount will be no problem if I have to. Still can't figure out how there could possibly be a 4.5 cm discrepancy in the mount holes..
Control stick and top mounted, roller throttle, still unresolved. My stick broke after using too much force to get the throttle to work. Nice idea, but not enough leverage. I also broke the 3D printed throttle body. Wrong material used, I guess. I wanted something different and less 'snaggy' things in the cockpit but tried and tested wins out this time I think.
So, what to do next.
I decided to have another go at covering my fin and skeg only this time, I thought I'd go for a much cheaper material than the Lycra I initially used. I also decided to have some form of firm backing on which to press as I force the resin into the weave. This led to purchasing a sheet of insulation foam from Bunnings and cutting it to fit inside the framework. First thing I didn't like was that the board is 30 mm thick and the tube diameter is 20 mm. I don't have a hot wire knife as yet so re-shaping it was going to be a problem.
This weighed in at 5.78 lbs (2.6 kg's)and I thought it might be too heavy so I took a tip from a couple of home builders in the states who have used spray foam to complete their roof insulation (www.youtube.com/channel/UChhBsM9K_Bc9a_YTK7UUlnQ) Anyway, this is how it is going.
Spray foam expands about X3 and needs to be confined so I purchased some white board and a load of clamps. Now, in order that the foam didn't stick to the board, I first wrapped the frame in Clingfilm and then clamped on the front and back boards, the front one having access holes. I burnt matching holes through the film with a pointed soldering iron.
Now comes the fun part. Just how much foam does one squirt inside. Oh well, trial and error time. After all said and done , nothing ventured, nothing gained. I thought it was going well after spraying in the evening, but next morning..........
Over done it me thinks. Time to clean it up a bit. Ah, just remembered, foam needs moisture to fill out and set so I squirted a small amount of water mist into each aperture before filling with foam.
The film worked well and the boards came off easily. However, the coverage didn't go too well but will be usable I think. So press on.
This final image is after I had reworked the foam some what. The main problem was that the boards, clamps and stiffening batons clamped across the fin fill, did not prevent the boards bowing outwards and thus ending up thicker than the tube by about 4 mm both sides. By taking to it with a fine cut saw, a small Surform rasp and glass paper, I took off all the high points. Filled some voids and then taped over the tubes so that the resin doesn't stick to the tubes. You never know if this lot has to be removed at some future time. BTW, Instead of c/film on the fin, I just sprayed my boards with cooking oil. Worked well and didn't effect the foam at all.
Now I'm going to keep you all hanging as I choose a cheaper material (Lycra is about $35 per meter), and work out a better way to mix resin and harder. I've decided that I won't be repeating this process on the other flying surfaces (filling with foam, that is) but will try another idea and a lighter hand to boot.