Firefly (oz10065)

About this Plan

Firefly. Rubber competition model. Wingspan 31 in.

Silver medalist, Model Engineer Exhibition.

Scan from DBHL, cleanup by theshadow.

ref DBHL-5706.

Direct submission to Outerzone.

Update 16/9/2025: Added photo [main pic] and article, thanks to Andrew Longhurst.

Quote: "The Firefly. This 1937/8 design was an early effort by the legendary Ted Evans of Jaguar, Vansteed & Clipper fame. Ted started out as a coachbuilder for Mulliners, a firm that made bodywork for Rolls Royce cars. Sometime in the 1930s, aged around 30, he was made redundant as a result of poor demand for posh motors. He decided to follow his hobby by setting up a shop which he called Super Model Aircraft Supplies of Northampton. In that shop he sold plans and kits for his own designs, some of which were his rather complex signature Wakes. However, he had some simple designs for those poor souls who did not have his exacting craft background. They included the 24ins Link (oz15797) and this one, the 31ins Firefly.

Mike Kemp first drew our attention to it in his great biography of Ted first published in SAM Yearbook 4 and since serialised in Free Flight Quarterly issues 50, 51 and 52. He viewed this design as an important precursor to the wartime lightweights. It looked to me like it might fly a bit as its slimmed down Clarke Y wing section usually works well on this size of model and the whole thing seemed well proportioned.

Ted cut the structure down to the minimum and there was one aspect I was worried about. The 1/16 x 1/8 balsa trailing edge was not likely to be stiff enough to resist the tissue tension and would likely bend creating an uncontrollable warp. I wanted to keep the section exactly as designed so resisted the temptation to enlarge the TE. As luck would have it, I found the remains of a beautiful sheet of 1/16 Bass (Lime) wood which I used decades ago to make some dolls house furniture and sliced a couple of strips from that.

One slight design mod I made was to put the wing on conventional goal post rails rather than have the wire supports bound to the wing spars as per the original model. Such an arrangement causes mayhem when tightly packed into a box with some other models and then lobbed into the back of the car. I also lightened the undercart somewhat as on the original it's battleship standard. The prop is carved from balsa and looks very elegant with its elliptical Larrabee style blades although dating from about the time the celebrated professor was born.

In the end it didn’t take long to build and for the first time since flying power in 2012, I built a lightweight below 60g…just: 

Weights:  Fuselage 24.5, Wing 16.5, Tailplane 4, Prop 14.5, Total 59.5g

Ted was clearly at pains to ensure builders got some good flights because he specified that the CG should be in the centre of the wing. As the wing is swept this still leaves things a little ambiguous. But we won’t be critical as this is one of the first rubber designs published in the UK to give any guidance whatsoever in this regard. He also states that packing under the TE of the tail will be required which is just as well seeing as there is no sign of any decalage.

Initial flight tests on the rec. showed the Firefly stalling with the CG slightly too far back. I had placed the Tomy at the extreme rear expecting it to be nose heavy but this turned out to be rubbish, Ted knew best. Some days later the Tomy was relocated under the wing. Pending that minor alteration, I packed up the front of the stab a little and with 1mm right thrust it was off and away showing a great glide considering it’s a freewheeler.

Next outing, with the designated 50% CG, we were able to get more turns on and the only adjustments were some left up tail tilt to stop the right glide tightening when the need for extra right thrust became apparent. The motor was 30g in 12 strands of 1/8, but I was not able to get it up to full torque as the old kite became a little unstable. A 10 strand motor of about 27g will be better as the climb was huge on the 12 strander even limited to 80% turns.

Everyone thinks Mick Farthing invented the British lightweight but Mike thought Evans with his Firefly pioneered it. And so, rather unexpectedly, we have an absolutely fab flyer. It joins the Dyne Dewfly as a pre-war under 34 ins design with post war performance. Why struggle with its contemporary, the KK Ajax when you can build one of these?"

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