1/3rd scale comper swift build
By Simon tweedale
Always liked the swift, don’t know why because its ‘pug ugly’ really, but still we all have our crosses to bear! Saw this plan in one of the Traplet mags and just had to have it. The plan (if you can call it that) is on 4 sheets and coming out at 96” span is exactly 1/3rd scale, the full size only measuring 24ft span. The plans are based on the original prototype Swift – G- ARXX which had a pathetic 35hp horizontally opposed twin and would barely become airborne. Apart from a brief experiment with a slightly more powerful (50hp) radial, nearly all of the 41 Swifts built had Pobjoy 7 cylinder radial engines. ( the last three having a DH gypsy engines known as Gypsy Swifts) . This is where my problems started as I decided to make a Pobjoy engined swift. This differing to the plan somewhat has been the reason for the ‘long term project’.
Air racing was popular in the early thirties and probably no other aircraft, built in such small numbers, has ever broken so many records and won so many prizes. With No forward vision the swift was reported to be a ‘handful’ on the ground, also having a fixed tail skid and no breaks. Once airborne the Swift was said to be a delight, you more ‘strapped it on’ as oppose to sitting in it!
The original swifts’ wings were capable of being folded back so they could be towed behind a car, and also for ease of storage. Needless to say my model will not incorporate this feature. I learnt early on with the build that if I didn’t stop messing about with it, it was never going to get off the building board.
Pictures :-
1. Both side frames assembled – not easy getting pins through spruce!
2. Front cabin assembled – note bottle shaped formers. These ‘tee’ pieces are where the wings will be attatched.
3. Shows the rear fuselage formers ready for assembly.
4. Shows bottom of front fuselage .
5. Fuselage showing the rear spruce sides joined to the front cabin assembly.
6. Shows front cabin assembly stringers before plywood sheeting is applied.
7. Fuselage nearly all completed (ha ha). Note rear stringers on top of fuselage curve gently from rear of cockpit to tailplane.
8&9. Shows underside of front fuselage being sheeted with 1/2 “ sheet. This is razor planed off to give a smooth surface. Note that this curves in all directions.
10. Shows fuselage with dummy engine installed. The engine that will be going in the Swift is a 36cc MVVS petrol. The dummy engine had to be built around this so is not quite to scale. Building a fully exposed dummy radial is a large project in itself and had me burying my head in my hands alot! But there comes a point when you think that it has to do, otherwise the model will just not get built.
11. Tailplane assembly, built from 16th sheet core with half ribs on either side. Built 2 of these the first set having ¼ square balsa leading edge. This didn’t really work so I made mk 2 with 2 pieces of 16th obeche laminated to make the leading edge, this was much better.
12. Fuselage with dummy engine. Note that the front end forward of the undercarriage is glass-clothed. This is because on the full size Swift all this is sheet metal, housing the fuel tank etc. Much more work to do on this section yet.
13. Undercarriage traditionally built with piano wire, bound with fuse wire and soldered. The plans show extremely detailed drawings of the working undercarriage as per full size with bungee springing. Again a compromise had to be struck hence the piano wire. (stick to what you know)
14. Showing top cabin assembly where wings will attatch. This is not shown on the plans so this is all my own design. I think I will put a short 1” tube through this section and have the wings sliding on with retaining screws holding it all together as per my SIG Cub. The wings are strutted.
Next ---- The wings!
