The legs were made from wire provided for the fixed undercarriage option on the TopFlite DC3 which I built back in 2000 - can it really be eleven years ago!! The offset bend in the leg was already formed so all I had to do was to make the 90 degree bend for the axle and bend the top of the leg to allow for the mounting angle of the retract unit.
The wire is 5/32in (about 4mm) so a piece of brass tube was epoxied over the top to bring the diameter to 5mm to match the hole in the retract. Finally a flat was ground to accept the 3mm securing screw.
The fairings are shown on the plan simply as pieces of card secured to the u/c leg with tape. I felt that I needed something more substantial, and also wanted to avoid the complication of making a forked leg and possibly not being able to remove the wheel. The fairings are made from 1/64in ply with 1/16 ply side plates. The 3mm bolt which secures the leg is on the pivot point of the retract so by shaping the ply side pieces, I was able to atttach the top of the fairing using these 3mm bolts (the trunnion is thoughtfully threaded on both sides). At the bottom end, ply tabs engage with the axle either side of the wheel. One benefit of this arrangement is that, by loosening the 3mm bolts, the leg and wheel can be removed, leaving the fairing in place.
The fairings are wrapped around a 3mm balsa former visible in the pictures below. There then followed much fiddling around with silicone tube spacers to get the fairings aligned, both in the extended and retracted positions.
The RC Timer motors are quite compact and are unusual in having such a short shaft, meaning that there is no option but to use the case-mounted prop driver. The driver is nicely machined from a light alloy but, with the back hollowed out to fit over the bearing boss, it looks a little fragile. Time will tell.
When I came to fit the spinners, another problem arose with the prop drivers - they are slightly radiused where the shaft meets the base and so the brass reducing inserts prevented the spinner backplate from sitting back against the face of the prop driver. I also found that the twist on the prop blades meant that the prop boss wouldn't sit back against the spinner backplate either. However, serendipity came to my rescue and by swapping the nylon prop reducer and the flanged brass spinner reducer, everything fitted perfectly.
The last issue was getting the spinner adapter nut to fit the prop driver - it went on about a couple of turns and then jammed. I think the prop driver has a 6mm thread and the spinner may be 1/4in. Easing a 6mm tap into the nut was enough to allow the nut to nip up tight and finally it could all be assembled for a test run. As you can see, the distance from firewall to spinner backplate is quite small.
I used a couple of strips of 3/16sq basswood to help align the retract former and the firewall. Then, once the nose former was added, planking could start.
The planking was from 3/32in balsa - I find that 1/16in is just too difficult to work with. By chamfering the planks slightly, a good fit can be achieved and after a light sanding, I usually paint the planking with dilute PVA glue. This tends to ensure that the planks are well bonded to each other and so minimise the need for filler. I did need quite a bit of filler though where the planks meet the wing surface.
The underside of the nacelles were built to align as closely as possible with the retracted fairings. Because there wasn't room to extend the top of the fairing up into the nacelle, I have had to accept a bit of a gap in front of the retracted fairing but hopefully, it shouldn't look too bad in flight.
Cowl construction is fairly self explanatory - if somewhat time consuming and very messy!
