Twisted: Week 60 - Elevator Hexes and Air Inlet

Hours to date: 562.0

Been a bit lazy last week - doing stuff around the house rather than working on the plane - no good.

Stepped it up again this week though.

Tidied up the root ribs on the tailplanes and put the reinforcing carbon roving around the fiberglass hexes. These hexes will get bonded into the elevators and slide over the metal hexes in the tail - so must be a perfect fit with no play.

I found I had to 'peen' the edges of the rivets on the metal hexes as they stick up a bit. Also found I had to file the edges on a few as they were not perfectly in line with the raised part of the hex.

6 layers of roving are needed, I waxed everything on and around the metal hexes and taped up the area of fuselage that is nearby.

After wrapping the roving round tightly I put a strip of peel ply over that - then used a strip of clear plastic around that and finally a strip of duct tape. This made sure that the roving would stay wrapped securely.

Worked out okay - it's best to take off the hexes after an hour or so and give the metal hexes a twist to make sure that no resin has dripped in there and bonded them in place. Then push the hexes back on to set.

After about 5 hours I took them off again and did a 'knife trim'. Something I have read about but not done up to this point. Basically you just wait until the resin has pretty well set but not completely hard and then it is dead easy to trim off the excess carbon for a neat finish on the edges. Works a treat!

I also did a bit more 'donkey work' with body filler on the tail, fuselage, and the spar tunnel.

I also bonded on a glass reinforcing tape around the canopy surround where the fuselage and safety cell join. Body filled it too - looking good.

Finally because I was getting bored with the smell of the body filler and sanding I decided to start on making a male mould for the oil cooler air inlet.

Using the urethane foam blocks I previously micro-ed together and starting with a template that I had printed out on the computer I was able to rough out the shape with a Stanley Surform. (I think this better known as a rasp?)

After that it was sanding with 80 grit and then 180 grit sandpaper to get the shape I was after.

Lots of fun but very messy stuff this urethane. I had to stop every now and then and vacum up the mess.

Doesn't look too bad - I'm not 100% happy with the shape but will leave it for a bit and see how I feel.

After I am happy with the shape I will add a slurry layer of micro and some fumed silica which should make a nice hard surface which is still easy to sand. Then just sand that until it is perfectly smooth and put some mould release on it - most likely I will use PVA (different to PVA glue). Then it will be good to use for laying up on - the foam will be carved out from the inside once the part has set - thereby destroying the mould - but I don't think I'll need to make more than one of these so thats less work than making female moulds.

I also received a missing part of the kit from the factory - it is for the integrated tailwheel and will replace the lower tail area - this will then be wide enough to accomodate the tailwheel and it's turning clearance.