About this Plan
Dynamo. Power duration model, for 1/2A engines.
Quote: "Contest winning 1/2A free-flight contest model. 45-inch wingspan and simple as can be for ease of construction and flying - suits all .8 cc (.049 cu in) engines. Dynamo, by Tony Young.
THIS DESIGN STARTED life in 1960, when a 1/2A PAAload fuselage was made to use a Wakefield wing and tail for the Northern Gala. It was not flown in the comp as the wing was irrepairably broken. A one-ounce wing is not strong enough to carry 11 ounces of inverted model when a 'kind soul' places it upside down to stop it blowing away in the strong wind! With the PAA pilot and weight removed, it became a fairly potent open 1/2A weighing approx 6 ounces, powered by a Thermal Hopper. All three competitions entered were won, at the South Coast, Croydon and Surbiton Galas.
At left is the original Dynamo, housing prototype Dydesyne Dynamic 049 diesel engine. Far right shows (top to bottom) tailplane retained in normal position by thread and rubber band strainer (see picture two) linked to dowel projection from fuselage. Dethermaliser fuse burns through rubber band strainer to release the tensioned tailplane to position seen in picture three. Note also the position of the engine timer in picture two.
Early in 1961 the plan version was created, changing the wing from undercambered to speed up the climb, also simplifying the built-up PAA load fuselage, but keeping the same rigging angles except for changing balance in that the CG was moved forward and dihedral was reduced. Powered by a prototype Dydesyne Dynamic .049 diesel, it weighs 6-1/2 to 6-3/4 oz, and was flown in five contests during 1961, placing in all of them as follows: 1st at the Midland Area Rally; 2nd at Northern Heights Gala and Devon Rally; 3rd in the Croydon Gala; and 2nd in the SMAE contest.
Wings are best made first as they can be covered and doped and left to age whilst working on the rest of the model. They are quite straightforward and amply strong, provided good straight grained wood is used on the spars. Should added strength be required, the inner panels could be webbed between the two rear 1/8 in x 1/16 in spars using 1/32 sheet with the grain running vertically.
On the fuselage, make up the pylon unit (pylon and two or three formers) and bearer unit (bearers and two formers) align these on one fuselage side then stick the other side on, add the tank then top and bottom covering. Tony uses diesels mostly and makes his tanks out of celluloid toothbrush tubes, cutting it to the length required, adding a top, bottom and vents all of celluloid, using cement as the adhesive. If a glowplug engine is used, a metal tank must be fitted.
When the bearer unit is cemented to the fuselage side, the weight of the motor must be considered, the short nosed version is for a motor weighing 2-1/2 oz, and the long nose for a 1-1/2 oz. Nose length must be varied for motors weighing between these amounts. Finish the model before finally drilling the bearers so that one can slide the engine to locate the CG. correctly.
Check the glide first, packing the trailing edge of the tail until there is just a suspicion of a stall turning right; this is cured later after the first power flights, but acts as a safety measure, ensuring that the model will recover from any position.
Trim the initial power pattern from a 2 to 2-1/2 sec motor run at full revs, launching the model at about 80 degrees. This length of engine run is quite long enough to find out which way the model is turning. If the model has been built true, it should be going straight with the wash-in on the wing slightly rolling the model to the left. Balsa strip should be stuck on the fin trailing edge until the model does approx two turns in 10 sec, turning to the right.
Once the power turn is definitely established to the right, the glide can be adjusted, removing the slight stall tendency - and now you're set for the first 1962 1/2A event! "
Dynamo, Aeromodeller, January 1962.
Direct submission to Outerzone.
Supplementary file notes
Article pages, thanks to RFJ.
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