Double Dutch (oz9201)
About this Plan
Double Dutch. Radio control sport biplane model for small field flying.
Quote: "Compact airframe, bags of power. Steve Holland's formula for stunning aerobatic performance... he basic ideas behind the 'Double Dutch' design are: (1) The model would have to fly slowly so as to enable hand launching from and landings into rough pasture. (2) Because of the above, the model would need to have a very gentle low speed stall. (3) The plane would have to be small for transport by motor-cycle. (It sits on the topbox fully rigged and causes a few funny looks as cars are overtaken by a plane). (4) The model had to be capable of aerobatics. (5) I also wanted the finished result to look like a full-size acrobatic plane i.e. bright colours and sponsors' adverts, etc., to help get away from the toy-like look.
The above facts all pointed to a vintage model's flying habits but most vintage subjects are large and not especially acrobatic. The only way to get a largish area into a small span was to make the model a biplane. This also helps with the slow flight requirement as the slot effect of the two wings helps to keep things controllable at slow speeds. The original model was very acrobatic and would fly quite slowly but it was very heavy and would flick roll if it was hauled off the ground too quickly. A second model was made with a lighter wing loading and a slight change to the tip section and mild washout added. This has led to an aeroplane which, in fresh winds, can be landed with no ground speed at all, and in really windy weather the landing roll is backwards! If you watch full-size aircraft of this type fly you'll notice that they fly on about l/3rd throttle and only open up to full throttle at the start of vertical manoeuvres, then shut off at the top of loops, etc., so there is not need to tear around the sky all the time flat out. The engines used so far have been an old HP61 and Super Tigre's wonderful Como 51 with a 10x6 or 11x5 prop.
Aerobatics tried so far are stall turns, tail slides, slow rolls, figure eights, knife edge, loops, inverted, four and eight point rolls, spins upright and inverted, avalanches and clover leafs. Landings with a biplane can be bouncy affairs if you don't get them quite right. The best approach is using elevator to control speed and flair out with the throttle. Landings are very easy in small fields as the high drag enables steep, slow approaches - quite different to the 40-powered kippers..."
Double Dutch, Radio Modeller, October 1987
Direct submission to Outerzone.
Supplementary file notes
Article pages, thanks to RFJ.
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User commentsMade this soon after the plan was originally released. A very good and well respected flyer for perhaps your 3rd plane. Capable of small field aerobatics. Flew for many years using a Merco 61. Now I have another plan, another will soon be flying. Have fun.
DJO - 17/11/2021
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