Snowflake (oz11003)

About this Plan

Snowflake. Free flight model for Jetex 50 power.

Quote: "A 15-1/2 in flyweight for Jetex 50 designed by Ron Armstrong.

UNIQUE FASCINATING and relatively cheap as Jetex flying is today, the following given to this branch of the hobby is far less than would be expected. Few Jetex models are to be seen on the flying fields, particularly contest duration designs; but as it is our policy to cater for all modellers and their individual interests, we introduce to our plans range this month a design that will most certainly satisfy the needs of the contest minded Jetex flyers, dwindling though they may be.

The original model, built in 1954 for the Belfast MFC's Annual Boxing Day competition, started off life with a flight of 1:35 on a 10-sec motor run. A second much lighter version was built and proved very successful by taking first place at the PAA Festival in 1955, with an aggregate ratio of 19:1. The most recent success has been first place in the SMAE Jetex Cup 1957, with an aggregate ratio of 27:1, being lost on its last flight.

The fuselage is constructed from med hard 1/8 x 1/4 strip, the 1/4 in being tapered to 1/8 at the rear. Motor pylon is of 1/8 sheet and is cemented perfectly upright onto the fuselage nose. A small piece of1/16 ply is cut 1/8 wide to fit onto pylon top. Positions of screws are marked, and the ply has two fine holes drilled through. The ply is then cemented in position on the pylon. One piece of thin asbestos sheet covers the pylon and fuselage nose; this is achieved by cementing sheet to one side of pylon/nose, folding over and cementing down on the other side. A second layer of asbestos should be cemented onto the pylon top, before clip is finally screwed down, as considerable heat is generated by the latest Jetex fuels.

A point worth mentioning here, is that the 50C motor will only fit correctly into the clip after the gas deflector ring has been removed. This will slide off after the application of a little penetrating oil. Note that the 'lip' of clip is towards the rear and not forward as usual. It is also bent downwards slightly and provides a more positive method of retaining the motor in the clip. The 1/16 x 1/4 strip wing mount is cemented to the fuselage and gently cracked down the middle. Gussets from 1/16 x 1/4 strip when cemented in place should then give wing mount correct dihedral angle. The complete fuselage can now be sanded and rounded off to a streamline section and the 1/32 fin added.

The wing and tailplane are so simple as to require very little explanation. For the modern modeller who Ms yet to use bamboo in a model, we would say that the wing tips can be made from stripped down garden canes.

As regards covering, the wing and tailplane are covered with lightweight Modelspan, watershrunk and given one coat of 50 percent dope/thinners. Both these parts must be pinned down to prevent warps. The original model was trimmed to fly in a tight left-hand spiral by warping the tailplane and using nu sidethrust on the motor, however, by warping the rudder and using sidethrust (easily obtainable by bending the motor clip 'prongs' inward or out, as the case may be), variations in flight pattern can be obtained.

Assembling the model for flight, the wing is secured to the fuselage by one rubber band crossed underneath the fuselage and around the motor pylon as shown on plan. D/T fuse fits under the band around fuselage and presses against the asbestos sheet. When band is burnt through, the wing falls away from fuselage but is retained by a thread of cotton."

Snowflake, Aeromodeller, November 1960.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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