Sparkler (oz15315)

About this Plan

Sparkler. Radio control sport model for electric power.

Quote: "Sparkler. A simple electric sportster designed by Dennis Simpson, described by Ian Peacock.

A bit of background: I first encountered Dennis when he wrote to me to tell me about his 72in span twin 'Simtwin' powered by two power units filched from defunct Acorns Cessnas. I was, to say the least, sceptical that such small power plants could cope with such a large and heavy model. Upon invite, Dennis brought his model to my house, and, brave fellow that he is, offered it to me to fly, and fly it certainly did with inverted, rolls and loops well within its flight envelope.

Dennis always seems to be pushing out into areas where there is little previous knowledge or experience. Just one such area has resulted in 'Sparkler'. He once more wrote to me enquiring as to whether I had any experience of smaller electric motors - I hadn't - but that didn't stop Dennis whose thoughts ran along the lines of just how small, simple and cheap can an electric model be?

Consequently a handful of light balsa was obtained, the Fleet micro radio ripped out of his previous model and construction begun. The pod and boom 'micro-light' style just came about as doodles began to take shape and the exacting science of aerodynamics resulted in a glider-like section, drawn round the sole of a wellington boot, in the time honoured tradition! The end result was magic! An all-up-weight of a scant 25 oz produced a wing loading of a very respectable 13-1/2 oz/sq ft, and the flight performance was more than adequate.

Getting cracking: Structurally the wings are reasonably typical with 1/4 x 1/8 main spars top and bottom, 1/4 x 3/8 leading edge and 1-1/4 x 1/4 pre-shapred trailing edge. There is no dihedral, the wing being built in one piece flat on the building board.

It is the thin sheet that tends to make the wing marginally different. All of the wing ribs are from 1/32 sheet and don't need to be any thicker. Please don't beef them up - it only adds weight. Once the 1/32 x 3/16 cap strips are added top and bottom, these light, thin ribs take on an amazing rigidity.

Centre section sheeting occupies the lower side of the wing with the cap strips on the outboard ribs running from leading to trailing edge. The upper surface, however, has leading edge sheeting (also from 1/32 sheet) and centre section sheeting, the caps strips only featuring on the rear part of the outboard ribs. Scrap sheet and soft block are fitted within the centre section prior to sheeting to make the servo box and to provide internal support for the wing dowels..."

Sparkler from Radio Modeller, May 1987.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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