Dream (oz16958)

About this Plan

Dream. Free flight sport model. Low wing layout. Wingspan 17 in.

Quote: "A low wing model for KP-01 electric or CO2 motors. Dream, by Eric Marsden.

Several years ago, a friend of mine tidying his attic, uncovered a book from his youth, on model aeroplanes for boys by Rigby (Charles?). I had assembled a Rigby model published in two weekly parts in 'Modern Boy', roundabout 1933 or '34, a kind of landplane version of the Supermarine S6B, and had managed to get flights of as much as twenty or thirty feet with it. Rigby generally managed to get nice lines into his models, so I borrowed the book and photocopied the illustrations and drawings, with the intention of getting a set of lines on which to base a model suitable for the KP 01.

I enlarged a side view from a photograph of the Supermarine type model, and got out the enlarging dividers to make my working drawing, but after three attempts I only had three quite ugly side views and I still do not understand how I managed to convert the side view from the book into such an unlovely side view on my board.

So I scrapped my nostalgia and decided to create my own 'dream' of a low-winger comming up with the model you see here. Of course it looks a bit like a 'this', and a bit like a 'that' - after sixty years of looking at aircraft that is bound to happen -but when I drew it, there were no full-size kites in my mind at all - only what a two-holer with inverted engine might look like. T

The original model - still flying - was built before I had properly explored the capabilities of the KP 01 and so it was built as lightly as possible, compatible with decent life and serviceability. This led to error - I used 3/32 sq longerons and kept the tail light, since the tail moment is reasonably long, but found that with the KP 01 in one piece, the model was nose heavy, requiring 7 grams of modelling clay in the fuselage by the sternpost. I don't like the hammerhead effect that such a set-up can produce, but the model flew very well in this form for three or four years. During this time the other snag with 3/32 sq longerons became apparent - they were not suited to the weight of my thumb, and our friend Cyano de B had to be employed once or twice.

So, I would suggest that Dream be built with 1/8 sq fuselage structure, which will provide both a better start towards initial balancing and a much more handleable model.

Eventually, I took out the tail ballast and separated the 50mAh cells from the motor unit of the KP motor, mounting them on a 3/8 x 1/8 piece of balsa, which I plugged into the battery socket of the original 01 and rebalanced the model by sliding the cells back and forth until I had a fair glide. The nominal saving of 7 grams was probably already lost as result of odd repairs, but until last year at Moddle Willup, she was still flying well.

An unplanned arrival by another model in a kind of mating frenzy, led to my stripping the wing for repairs and recovering. As result of this, all the warps with which I was familiar, have gone and I have a new set, to which I am not yet accustomed, but on the one occasion on which I took Dream out this year, she still showed a fair willingness to fly.

Do build the downthrust and sidethrust into the motor bulkhead, but use short lengths of silicone fuel tubing as mountings - about 3/16in. long -behind the motor lugs. By making the 2mm screws a tight fit in the threads made in the ply forewall, these pieces can be squeezed for fmal trim adjustments of the thrust line for just the flight pattern you want. To cut the threads in the ply, if you haven't got the 2mm tap, take a screw, and solder it into a piece of brass tube and file three flats to a taper on the screw. Tap the hole but do not enter your tap to full thread -just nearly - and the screw will force its way to create a fairly tight fit. Run a drop of thin cyano into this thread, and wiggle a thin wire to spread it around, and this should harden the threads sufficiently for practical use.

Despite all my care, I have a problem in tissue covering models. For some mysterious reason, my port wings tend to finish with slight wash-out, a Good Thing - and my starboard wings tend to have wash-in, and this is Not a Good Thing - making trimming for decent flights a bit tricky. The rudder trim tab is of great value in this regard.

Finished weight of Dream was under 100 grams for me - since my balance is one of those semi-circular postal scales held in the hand, I don't care to be more exact - but with my little GHQ Sportster, and my Gordonou-Leseurre 482 I learned that too low a wing loading is a recipe for lost models, so now aim at reasonable powered flight, followed by a glide which would require a serious thermal to take the model away. This year my wife has made me promise not to climb trees, so such considerations are of more importance than formerly. "

Dream from Aviation Modeller International, August 1996.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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