Davis DA9 (oz16679)

About this Plan

Davis DA9. Radio control scale model. Wingspan 38-1/2 in.

Quote: "THE DAVIS DA9. An exercise in minimalist Quarter scale. DR Mike Hawkins was searching for a model that would be easier to scrutinise by airport security officers. The DA9 at 38-1/2 in span fitted the bill perfectly!

In 1995 I took my Bucker Student from Bangkok to Las Vegas for the Quarter Scale Association meeting. It required a box 57 in long and weighed 22 kilos. With a number of incidents affecting airline security it seemed politic to try for something a little smaller this year. When I saw the Davis DA9 at the Sun 'n Fun EAA Fly-In at Lakeland Florida not only was it the most exciting aeroplane that I had seen but its small size seemed an answer to my transport problem.

I just had to build it and was referred by Ken Shugart, the pilot of the DA9, to Contact Magazine who had a constructional article on the aircraft written by Leeon Davis, the designer. This included a small three view and with the photographs that I had taken, I was able to draw up plans for the model.

At 38-1/2 in span it was rather smaller than the usual minimum 96 in span required at Las Vegas but it is true quarter scale and as I write, my entry has been accepted. The box in which it now resides is 44 in x 15 x 13 and the whole thing with tools and equipment weighs 13 kilos.

As a non-member of the SMA I never thought I would be able to combine the pleasures of small models with Quarter Scale, but the DA9 does it.

The full size aircraft is a hairy little beast and not for the faint hearted; so it is with the model. A wing loading of 36 ozs/sq ft seemed a bit high but as it has turned out, is quite acceptable. Think of those ducted fan F 104's that manage perfectly well!

A good 40 provides plenty of power and the construction is straight forward for anyone who has built several scale models. The wheels are rather small and I have not tried to fly it off grass as yet. I would not like to try a hand launch!

Small models build more quickly and cost less than large ones although they are less stately in flight. The only time that I saw the real D A 9 fly it was not stately at all. It was disappearing upwards at a remarkable rate of knots. It would have been possible to make the structure considerably lighter by using 1/16 planking instead of 1/8 but this is much more difficult to build with an accurate surface and had I done so, the model would never have survived an unexpected accident that spoilt my entire day.

Construction: Wing: The first wing that I built was sheeted with 1/16 balsa. The sheets were joined by putting a strip of Sellotape down the join, running slow CA glue into the join and then putting the sheets back flat on the bench until set. They were sanded, flat on the bench but a couple of weeks after finishing the model I noticed a slight trough at the join in spite of my care. When it became necessary to build another wing I had some rather hard 1/16 sheet which weighed the same as some softer 3/32 sheet. So I used the 3/32 with slightly smaller ribs and this time it has kept its shape.

Each wing panel is built separately, flat on the bench, with the ribs threaded onto the aileron torque rods before assembly to the spars. The tags on the rear of the ribs keep everything straight while the upper sheeting is applied and allowed to dry out thoroughly. The width of the sheeting on top is 8-3/8 in. I suggest you use a really hard piece for the rear 3/8 in as this will have to form the thin trailing edge of the wing. The panel can then be removed from the board..."

Davis DA9 from Flying Scale Models September 1997.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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