|Antique Model Aircraft||
Rudder and Tailplane.
The silk on these two components can either be stitched or glued on. Refer to item No. 24. .Should it be decided to stick silk
on, the following method can be adopted for them both.
Cut silk to size, allowing ½ in. overlap all round. Lay component on a flat wood surface, and have handy some drawing pins. Damp silk and place over component, and stick pins in at each corner of silk, pulling tight both ways. Proceed to place more pins in about 2 in. apart, meanwhile pulling silk taut. Run a little glue through silk on to the wire frame and rub round until adhesion is assured. When nearly dry take out pins, and with
scissors clip round edges, allowing 3/16 in. to 1/4 in. overlap. Run glue round inside of overlap, and gently press silk round wire and on to the silk surface. Take care not to disturb the "nearly set" glue.
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Doping Covered Components.
Assuming that you have the cellulose acetate dope and solvents, a camel hair brush is best, and first wash this out in the solvent to remove dust and loose hairs. Well stir dope, the colouring matter in which, being heavier, forms as a sediment at the bottom of container.
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Doping should be done in a warm ventilated room. Apply dope lightly with the tip of brush, and don't go over a patch more
than twice, as it drys quickly and will "pick p." After the first coat, allow quite three hours before applying the second, which will dry leaving quite a glossy surface. When applying first coat rub dope well into the silk with brush.
Do not keep the lids off dope tins any more than necessary, or work near a flame, for dope contains very volatile and inflammable ingredients.
Nosepiece and wheels can also have two coats of dope if desired, or be polished with shellac varnish.
This is composed of two sets of 10 strands, 1/4 in. strip Para rubber, 45 in. long. To make it up, first drive into bench two nails 45 in. apart, and tie end of hank of rubber to one nail. Loop strands up and down round nails, taking the slack out of each strand as it is wound round, until ten strands are
counted. untie first end from nail, cut off last strand to required length, and make a reef knot. Pull tight from each side of knot,
and get somebody to tie a piece of thread tightly each side of reef knot in rubber, which securely locks rubber knot.
Replace strands on nails, and, pulling all strands tight from each end in turn, tie a piece of thread 3 in. from each end round
strands. This keeps them together and of equal length.
Apply rubber lubricant fairly liberally first time on new rubber, and rub it in well.
Fixing Motor in Fuselage.
Get an odd thin stick, 36 in. long, make a notch in one end, and round it tie a piece of string, leaving ends about 4 in. long.
Pass one end of string through loops in the two skeins of rubber, tie, and pass stick through fuselage, pulling rubber after it until in place. Connect motor to hooks at nosepiece and rear end. It is advisable to tie a piece of thread at the neck of each hook, for a skein, when twisted, is apt to creep up the side of the hook and foul the sides of fuselage, eventually slipping off hook.
Articles in back numbers of the "M.E." illustrate methods of constructing an air scr ew, The one used on the "Ad Astra" is 13 in. diam., 22 in. pitch, and is carved from a block of satin walnut 13 in. by 1⅝ in. by ⅞ in. It rotates clockwise as viewed from the rear of machine. Carving an airscrew is a very difficult job for those not used to using woodworkers' tools. They are usually carved with a draw-knife, smoothing down with spokeshave,
and cleaning up with first No. ½ , then' No. 0 glass paper. Finally
the surfaces are filled up with wood filler, and, when that is set,
French polished. The pitch angles on the blades must be very
accurate, and airscrew must be statically balanced. After cleaning, and before glass papering, thread a piece of 18 s.w.g. piano wire through hole in centre. If balanced, blades should come to rest horizontal. If one side should drop, glass paper a little off the rounded side. A. E. Jones, Ltd., New Oxford Street, London, keep a big range of airscrews, and one particularly suited to this machine is type G.B., which has a graduated
pitch. These are beautifully made, and perfectly balanced.