Shamrock (oz14485)

About this Plan

Shamrock. Radio control sport aerobatic model for .61 four-stroke or .45 two-stroke engines and 4 functions.

Direct submission to Outerzone.

Quote: "Hi Steve, Attached is another of Radio Modellers two coloured 'Super Plans' from 1990,"

Update 9/4/2023: Added article, thanks to RFJ.

Quote: "Hands up all those with a Laser 61 or similar four-stroke tucked up in a drawer, bought like mine in a mood of extravagance for a scale job then abandoned with eventual demise of the model. Well, dig it out - it's time to put it to good use!

Being a keen sports acrobatic type flier I wanted a pleasant, quiet but reponsive model of the midwing variety. There being nothing around that took my fancy I decided to design my own around the Laser. This allowed me to fit everything into the fuselage with sufficient latitude to get the CG in the correct position without resorting to adding weights. The relatively short nose length, coupled with the long tail moment, was chosen deliberately to offset the extra weight of the Laser. Propeller used was a 12-1/2 x 6 Graupner which gave more than enough urge for vertical manoeuvres, although a 13 x 7 Zinger proved very quiet and almost as good vertically.

Flying: The interesting bit first! I always read this bit first on any plan feature, even if it is printed at the end because, let's face it, you want to know how well it flies before you part with your money!

After an aborted first flight (see later excuse - er, I mean reason) subsequent flights proved very successful indeed. Only a small amount of up-trim was required. Inverted requires just a light pressure on the sticks to maintain height. All manoeuvres appear to be possible - rolls, inside or outside loops (round and square), spins upright and inverted with recovery within half a revolution, vertical eights, etc. The stall is a long time coming and the prototype only tipped slightly to the left so you have to be a real clod to get into trouble. Watch out for dead stick landings though if you haven't got much height; the plane flies everything at a nice leisurely pace which is fine until the engine stops.

Construction: Start by cutting the fuselage sides from nice, light, straight-grained sheet, as closely matched as possible, together with the 1/32 ply doublers.Glue the doublers to the side using Evo-stik or similar, making sure you end up with a right and left hand side. Make the formers F1, F2 and F3 as indicated and mark centre lines front and back to aid alignment. Glue stringers in place and then glue Fl and F2 in position to make the basic box. When dry, pull together at the rear and chamfer until the width is approximately 3/8in, then glue making sure all the centre lines line up.

Cut the top sides and chamfer lower edges where they meet the lower sides and glue in position. When dry, sand top edges to give maximum gluing area and glue on top sheet. Now fix the U/C plate in position and sheet the floor back to F2..."

Supplementary file notes

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