Model Aeroplane Notes

Auckland Star, Volume LXIII, Issue 287, 3 December 1932, Page 3 (Supplement)

Model Aeroplane Notes

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YELLOW-BIRD FUSELAGE MONOPLANE. NEW ZEALAND RECORD-HOLDER. Here is something that model aeroplane enthusiasts throughout New Zealand have been waiting for a considerable time. I am giving you herewith the plans and full constructional details of W. B. Mackley's record-breaking fuselage monoplane. You will remember that this machine actually flew for five minutes 03 seconds recently in Auckland, coming to rest near the top of a high pine tree. The actual duration derived by the propulsion of the rubber motor is in the neighbourhood of two to two and a half minutes, but so skilfully has this machine been designed that it acts just like a modern sail-plane when the rubber winds out, and, taking advantage of any uprising currents gracefully soars aloft while there is the slightest breath of an upwind to support it. Constructional Details. The fuselage is actually symmetrical in section, there being the same curve on the top and the bottom longerons. The, whole machine is constructed from balsa wood, with the exception of the propeller, which is carved from light white-wood such as spruce or kaliikatea. The Fuselage. Draw the side view of the fuselage, full *ize, on a smooth board and procccd to build up the first side, using modelmaker's pins to keep it in position. Do not pierce the longerons AA, but place a pin on each side of them so that they arc held in the correct place. Now insert all the bulkhead frames B2 to 812 in place, fitting them carefully and cementing into place. If a little cement gets

bound and cemented to cross bulkhead No. 3. The undercarriage stmts arc of composite construction, a piece of balsa Jby J being used. A eaw cut a bare 1-16 is cut down the leading edge and a thin silver of bamboo glued firmly into place. This gives a great deal of extra strength. The strut is now streamlined and sanded to a fine finish. The axles we made of 25 gauge wire and shaped as shown. They are bound and glued to the strut, the U shape preventing any twisting action. The wheels arc slipped on and the ends turned up.

The spring shock absorber is very important. It is made from 25 gauge piano wiro to the shape shown. A small U on each end is again used to bind it about one and a quarter inches down the strut. Make both the absorbers at once and see that they are the same. Bind the absorber to the fuselage longeron under upright No. 4. The wheels are built up from a 1-32 three-ply centre disc, with shaped sides of balsa as shown clearly in the diagram. The Tail. Draw the tail plane out full size, and from a light thrce-plv template cut out all the ribs, bunching them tight together and sanding until they are all the same. Pin the main spars, which are rounded on their outside edges, to- a board, and cement the ribs in flat side down. The tips are now cut from a sheet of half by 1-16 balsa and cemented into position. Now make the cutouts in the rib to take the centre spars, which are 3-32 by 1-16 bare. Now fit the centre spars; these being on the rounded side help to keep the paper out and improve the finished shape. The Rudder and Fin. This is drawn out on a board, and is quite flat in section. Take the fin first. The bottom member is made of

•on to the baseboard it does not matter as the completed side may be lifted later on by running a razor blade underneath it. Now without removing the first side build the second 'side up, right on top of it. in this way you are assured of getting both sides exactly. alike, in the drawing the last bulkhead 813 ha« been omitted for sake of clarity, but it must be inserted before the side frames are lifted off. Now proceed to put in the top cross bulkheads. This is a ticklish job, but with a little patience a good job can be made. The top and bottom bulkheads 84, 5, and 0 are fitted first, and pinning may have to be resorted to to keep them in place, but very Light rubber bands used here will simplify the job. The nose bulkhead frames are now inserted. These were also left out in the drawing for the sake of clarity to show you just how the Jiose block fits in. Fit the nose and tail top cross bulkheads and gradually put in all the rest, cutting each one to length as you proceed. Make sure that the whole fuselage is square and true. At this stage any tendency to warp may be corrected. !Now put in the diagonal bulkheads at the nose. Any pins and bands can now be removed and your skeleton fuselage is complete. The -nose block F can now be shaped from a solid lump of balsa, details of which are shown in the accompanying drawing. The Undercarriage. The first step is to shape up the wire to which the undercarriage struts are attached. This is shaped as shown, and

one-eighth by 3-32 balsa, and the uprights 3-32'bv 1-10. Pin the straight sides on to the board and cement in the cross pieces, which are 3-32 by 1-32. The round corners are cut from sheet 3-32 thick. The rudder is now made up in exactly the same way. The hinges are two pieces of fine aluminium. The uprights: are slit with a razor blade, the aluminium pushed through both the rudder and the fin and turned .slightly, leaving a slight space. Cement firmly. The Wing. Draw this full size. Make up the ribs as per instructions given about the tail. Be very careful to use this section, as upon it depends largely the success of

the finished model. The ribs axe made from 1-32 hard balsa. The wing is made in one piece. Owing to the peculiar shape of the airfoil section it will be necessary to raise the leading edge line. Pin down the trailing edge and cement in the ribs. The tips are now steamed over a kettle spout. They are made from bamboo, and cemented into place, pinning until dry, and then removing the pins. Now place the strengthening wing tip struts into place and cement. When dry, cut small Vs in the main spars on the top edge, and gently break the spars upward. Try and not break right through. Pack up the tips two and a half inches, and cement at the centre, allowing it to dry. Now cut the notches in the ribs, and lit first the top centre spar, and thou the bottom one. In the plan accompanying these notes, half the wing is shown. Super-imposed on this you will sec a frontal view of the wing assembly showing clearly the amount of dihedral angle. Actually the tips should be 2A inches higher than the centre. Covering. —A very important part of the procedure. Use liquid glue for attaching the paper, running the lube along the spar or longeron, as the case may be, and smoothing out any surplus spots with your linger. Keep a wet rag and a towel handy. Stretch the paper on, being very careful to smooth all crinkles. Always remember to cover opposite sides, that is when doing the fuselage, cover the top and bottom and then the sides. When the paper is on and the glue quite dry dope the paper surface all over using a medium to strong dope. Assembling.—After all parts are covered and doped the assembly is gone on with. The tail unit, of course, presents the most difficult part. This is held into position by two blocks, a small one in front and a large one at the rear, shaped as shown. The front block is neatly streamlined to prevent eddies. Cement the blocks on to the fuselage first. Then cement the tailplane on top and finally fix the rudder in position. The main wing is held in place by a rubber band passed around the fuselage as shown.

Tlie Propeller.—The propeller is cut out of a solid block, and shaped as described in previous notes. The rubber motor is composed of six strands of J x 1-32 rubber or twelve sc.ands of J duration strip. This should be well lubri■cated in order to get the maximum turns. A very slack motor is' used, being at least four inches longer than the distance between the rubber hooks S and T. If when flying the model it is inclined to go up and stall, move the wiug slightly until the correct adjustment is found/ The "Yellow Bird" monoplane should not weigh more than 2£ ounces finished. Note.—The accompanying diagrams are made exactly a quarter full size.

"YELLOW BIKD" MONOPLANE — LIST OP PARTS. Letler. Name. Material. Size. No. A Fuselage longerons Balsa 1-16 sq. x 21 4 B Fuselage bulkhead frames Balsa 1-16 sq. 52 .C Wing spars Balsa 1-16 sq. x 26i 2 D Wing centre spars Balsa 3-32 x 1-16 x 26i 2 E Wing ribs Hard balsa 1-32 thick x 4 15 F Nose block Balsa 1 x 5-8 (shaped round) 1 G Undercarriage struts Balsa, bamboo I x 1-8 xsi 2 inlaid H Rudder and fin frames Balsa 1-16 x 3-32 4 J Rudder bottom member Balsa 1-S x 3-32 1 K Elevator tips Balsa 4 x 1-16 x 3} 2 I, Fin cross members Balsa 3-32 x 1-32 '.) M Wing tip struts Balsa 3-32 x 1-16 6 N Wing tips Bamboo 2 O Tail spars Balsa 3-16 sq. x 13 2 P Tail centre spars Balsa 3-32 x 1-16 x 13 2 Q ' Tail ribs Balsa 3 1-S xi x 1-32 9 R Tail block Balsa .1 3-S x 7-16 1 S Rear hook Steel wire 25 gauge I T Propeller spindle Steel wire 20 gauge 1 TJ Propeller Balsa 12 x 11 x 3-8 1 V Shock absorbers Steel wire 25 gauge 2