Mayfly (oz7426)

About this Plan

Mayfly. Free flight sport biplane model, for Mills 1.3 power.

Quote: "MAYFLY was designed and built primarily with a view to providing a model of pleasing semi-scale lines which would serve well for general sports flying. Things, however, did not altogether work out as planned, as the model ultimately proved itself as possessing a performance closely approaching that of a contest model! Powered by a Mills 1.3 cc (Mk I), it has a climb which is quite remarkable for this type of model; spiral and longitudinal stability of a high order; and a very satisfying glide.

The construction is robust and a high degree of 'knock-off ability' has been incorporated in the design. Several times during the last season the model has collided with the usual and ever present obstructions at Fairlop, viz, motor-cars and motor cycles, etc, and has on occasions appeared to disintegrate as a result. Spectators have, however, been astonished to see her in the air again a few minutes later! In almost all weather the model has afforded the writer many hours of delightful flying.

Fuselage: This is built on the usual basic box-frame principle. Build the two sides on plan, separate when dry and cover each fuselage side with the 1/16 in sheet from top longeron downwards. The cabin can be sheeted after erection of the two sides. Erect the two sides by assembling them on formers 4 and 5. The sides are parallel between their two formers. Complete the rest of the structure in usual way. U/C blocks must be strongly cemented in place. Complete all internal fittings before fixing the 1/8 in sheet flooring. Cut slots for lower-wing tongues accurately. The leading edges of the lower wings butt against the front of the mid-cabin upright of the fuselage and the line-up of the slots must be parallel with the appropriate portion of the lower longeron which, in turn, is parallel with the datum line.

When fixing the fin-dowel block, assemble in place with a length of dowel in the paper tube to ensure that the fin, when assembled will be dead vertical in the block.

Cover all the balsa panelling and decking with plain tissue and the underneath from former 5 with Model-span. Give two coats of clear dope, except the decking which should have one coat. Finish in colour dope as desired.

Undercarriage: Bind and solder the 14-swg. piano wire compo-nents, not forgetting the 20-swg hook for rubber bands across the front legs. Form and solder the components with the prongs fitted into the tubes to ensure that the prongs fit into tubes when completed. Cement in the balsa fillets then cover the whole unit with calico, using generous liquid glue (not balsa cement) well rubbed into the balsa and round frame edges, one side at a time overlapping to other side. Cover the inside first. Finally, cover with plain tissue overlapping as above, dope and colour dope to match fuselage. 21 in. Caton airwheels were fitted to prototype.

Upper Wing: First form main-spar and dihedral brace on plan to give Id' dihedral. Then build both centre sections together with tubes and dowels in place..."

Update 12/04/2016: Replaced this plan with a clearer copy, thanks to TonyP.

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