Mistakes with the “hump”; rudder cables, instrument panel & seat
Arranging to meet up with the modellers at North Weald I loaded my roughly-carved blue foam SE 5 hump in the car and headed off. It was a nice sort of day if you discounted the wind, which was more than either microlight fliers or model fliers would want and after checking the aircraft tie-downs I met up with Richard, a pleasant and helpful chap.
The model club occupy a hut on the airfield similar to, but larger than, the one from which we run Saxon Microlights. They have a very nice workshop complete with a band saw and a lathe, some good large work benches and a goodly variety of hot wire cutters. Already there was a chap putting, what seemed to the finishing touches to a very beautiful model of a Mig 15 (I think). He pitched in to help straight away, so I’m afraid that we interrupted his painstaking work. Both of the lads looked at the piece that I’d brought and it was apparent that I’d made several mistakes in my ignorance of blue foam work. I’ll pass these on in the hope that it may save somebody else from the same errors.
Firstly I’d used ply for my end formers, this may have worked but I’d not taken the trouble to get the edges sufficiently smooth. Ideally I should have used alloy to allow the hot wire to glide around the ends, if not then the ply would ideally be as smooth as it was possible to make it. Secondly, for something so sharply tapered it would have been far better to have made it in two pieces to glue together later. Before we started I was warned that this may well, due to the drag on the wire, give a sway backed finish. My last mistake was to glue the sections together using epoxy, it’s not structural said the man, PVA would have done. The other advantage of PVA apart from being easier to use is that it cuts similarly to the foam so causing no localised drag on the wire.
The first side went quite well with the drag marks that I’d been warned of but nothing too much. The second side though lived up to its billing, the epoxy slowed the cut in the centre and left me with a hollow that will have to be filled.
Still I’d spent the morning in pleasant company and I’d learned a lot but I finished the day with a hump that needed a bit more work and at least one area of my ignorance diminished. So I moved forwards on two fronts, that can’t be bad, I ordered some more microballons for my filler and moved on.
The next job to progress was to replace the old rudder cables with new. This, after fitting the static pipe forward to the rear of the instrument panel position and rigging the seat belts, would mean that I could fit the seat. This would be handy as at present I have had to keep moving the seat about to keep it out of the way, because I’d had to attach the upper seat straps (and thus the seat) when fitting the tank.
I have made up control cables before, but only for the training simulator that we use at Saxon, I thought a bit more of a thorough look was called for. So I resorted to that invaluable resource, the EAA Instructional Videos. Sure enough all the information was there and not for the first time I blessed their generosity in making this available to everybody. I was intending to use the “economy “tool for compressing the Nicopress swages and from reading the “Big White Book” on inspections and much else by the FAA, I purchased the simple little gauge to check them.
Then I made up my first cable, a success! All I have to do now is to find a tape to prevent the ends from unravelling that doesn’t fall off and how to prevent the little spiky ends from sticking in my fingers, it didn’t happen to the bloke in the video.
(Written March 2015)