Mini Minx (oz15108)

About this Plan

Mini Minx. Rubber sport model. Wingspan 24 in.

Quote: "HOW BIG A MODEL can you get out of one stock sheet of balsa? Well, without making a hollow stick fuselage with tissue-covered flying surfaces, this 24 in design must be close to the ultimate from a single sheet of 1/16 x 4 x 36 in balsa. Nothing extra was used except wire, a 7 in plastic prop, celluloid wheels, a scrap of tissue, a cocktail stick and a stub of tube for the shaft bearing. Plus, of course, a small amount of cement, dope, and rubber.

Apart from the wing root and ribs, everything is straight lines, making the transfer to balsa simple, since very little tracing need be done; a 12 inch steel rule is really essential for cutting out.

Pick a soft sheet of balsa to keep the weight down and if there is a slightly harder edge, try to arrange to use this for the narrow strips needed for the fuselage. Cut out the wings, tailplane, fuselage bottom and fin; you will probably have to butt join a small triangle to make up the fin.

Make up the two fuselage formers B1 and B2 over the drawing, trimming off ends when the cement has set and erect on the fuselage base. Use a matchbox to ensure that they are square and also to square up the nose side panels. Fit the two top longerons at the nose, the wing mount (two pieces angled to the dihedral angle) and the rear top spine and tail panels.

Complete by cutting spacers to length and inserting, including the rear rubber anchorage and the top nose panel. The extra spacer between the longerons on top is only needed if the longerons are very soft. Bend the undercarriage and cement in place, adding a patch of tissue (paper hankey type will do) with cement rubbed through, to reinforce.

Lightly sand the fuselage to remove any irregularities, then cover each side with one piece of tissue, with a third piece for the nose top. Lightly watershrink and, when dry, apply a thin coat of dope. Sand the tailplane and fin thoroughly and cement to fuselage, checking that they are exactly horizontal and vertical respectively. Add the sub-fin.

Drill for the motor peg (twirling the cocktail stick will probably do it) and cut the stick to length. Also drill just in front and behind the wing mount at a shallow angle and cut two pegs from the rest of the stick, cementing firmly as these take the wing retaining band(s). Laminate the noseblook from odd scraps of 1/16 making the rear lamination a good plug-in fit in the fuselage nose. Cement in a stub of 20 or 22g aluminium tube, or cement a cup washer on the front and rear to make a shaft bearing. Bend up a 22 swg wire shaft to suit the propeller and cover the hook with rubber tube or the sleeving slid off a piece of electrical flex.

It is best to dampen the wing panels lightly and pin them down over the ribs, or if this is too fiddly, over a couple of pencils laid end to end at about 1/3 chord position. Allow to dry, then cement the ribs in place, skewing pins through from the top so that the panels can be laid flat and the leading and trailing edges pinned down until the cement is thoroughly dry (overnight).

Sand the roots to a close fit when one wing is flat on the board and the other has its tip raised 5-1/2 in. Cement them together thoroughly, leave to dry, then sand all over.

One loop of 1/4 in rubber 10 in long provides the power. Lubricate, then hook on to prop shaft and wrap a small rubber band or a couple of turns of knitting wool round. Find the other end and wrap this too, to leave a 1/4 in dia loop. Dangle down fuselage and find the loop with the motor peg.

Attach wing with one modest rubber band doubled, or two small ones and check balance is about 1-1/4 in behind leading edge at wingtips. (The original weighed 23 grams without rubber and balanced exactly right).

Add a little plasticine or tape on a panel pin or small nail at nose or tail if necessary, then glide test. Try power flights with about 80-100 turns, breathing on rudder to warp it (or crack and cement it) if needed.

Performance on 250 turns or so may well surprise you!"

Supplementary file notes

Article.

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