Tomboy Senior (oz12755)

About this Plan

Tomboy Senior. Radio control sport model for Mills 1.3 power.

The original Tomboy (oz285) was a classic Vic Smeed FF design at 36 inch wingspan, first published in Aeromodeller, Nov 1950. This here is an enlarged later version at 48 in wingspan, for RC assist.

Quote: "Tomboy Senior, by David Boddington. Vic Smeed's classic design enlarged to 48 inch wingspan for 1.3 to 2cc engines - R/C optional.

It is incredible to realise that the Tomboy Design has now been around for the best part of sixty years and that the model and the designer are still going strong. Always a free flight favourite, as witnessed by the Middle Wallop Hilda Baker Tomboy events, it has now had another new lease of life with the Tomboy 3 radio control competitions - you can find more information on these events in the April 2007 (Update for 2008) issue of RC Model Flyer.

The original 36 inch wingspan Tomboy has the advantage of being compact, easily transported, it will fit in any car and won't break the bank in building costs. When fitted with a Mills .75cc diesel engine the performance, even with lightweight two-function radio fitted, is quite brisk and with a full compliment of the 3cc fuel tank it will achieve a considerable height. If that altitude is then enhanced by finding a thermal the apparent size of the model diminishes to the extent that some of us visually challenged old b**"**s are having a problem in seeing its altitude. Having a model a little longer and a little lower down should ease that problem, although the real reason is to have another model to fly in competition with our fellow enthusiasts.

Similarities: increasing the Tomboy by 30% presents very few problems, it returns the same basic structure and design and the 3/16 wood components are upped to 1/4 in. The few minor modifications include:

1. A slightly reduced dihedral.
2. Engine bearers extended to the second bulkhead.
3. Sheeting under the nose omitted to allow easy access to the engine butts for thrust line adjustments.
4. Height of undercarriage reduced by 1/2 in, it was getting a bit stalky.
5. Wing centre section top sheeting extended one bay each side
6. Nose area reinforced with 1.5mm plywood side plates
7. Allowances made for radio control - although it is equally suitable for free flight.

If you are just building the Tomboy Senior as a sports RC model, any engine from a 10 to a 15 glow, or the equivalent diesel will do, having a throttle equipped motor will give more flying options. I don't recommend fitting ailerons, for them to be effective you would have to severely reduce the dihedral and it wouldn't then have the same Tomboy'character.

Tomboy Senior competition: For flying in the competition the model must be built exactly as per plan and must be powered by a Mills 1.3cc diesel with a standard tank. The engine can be an original Mills (Mills 1 or 2) or an Indian Aurora, Irvine, or other replica, but no modlifications to the engines are allowed. A Graupner 9x4 grey propeller is to be fitted, an operable fuel cut-off is optional. 2-1/2 in diameter balloon wheels are to be fitted and the model must be fabric covered ie 'Tex' materials or nylon, etc. These rules are intended to give, as far as possible, an equal start, model-wise, in the compeitton and to place the emphasis on flying skills - plus a bit of luck!

All clear? Good, clear the bench and let's get building. I prefer to cut out all the parts before commencing construction, inducling sanding the edges of formers and ribs and bending the undercarriage; which is still sewn and epoxied to the fuselage former in the time-honoured way. One further piece of advice; The model will almost certainly finish tail heavy, so keep the rear end and tail surfaces as light as possible..

Fuselage: Where there are curvatures in the longerons, I prefer to laminate them, using two pieces of x 1/8 x 1/4 and dampening them before bending. This not only makes the forming of the curves easier but, with a liberal application of PVA glue between the laminations makes for a stronger and more stable structure.

Protect the plan with clear plastic film and pin and glue the longerons and uprights in posit ion„ it is also helpful if you have also determined the radio layout at this stage.. My recommendation is (as shown or the plan) to have 1/4 square hardwood side rails to which is screwed a 1.5mm ply plate housing the receiver, servos and switch. Keep the installation fairly high in the fuselage so that it is easy to access it from the wing seating area; the switch is actuated by a piece of pianowire projecting through the fuselage side. Because of the tail heavy tendency, the battery should be positioned as far forward as possible.

With the first side assembled and the glue set, remove it from the building board, reverse it and protect the top with clear film. The second side is then built directly over the first, producing a 'good' external surface for the left and right hand sides..."

Tomboy Senior, Model Flyer, May 2008.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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