Spectre - Radio control aerobatic model, with flaps.
Quote: - "SOME of you may remember seeing my first flapped model, Mother's Worry, which is still flying very well. This was a test-bed for flaps and it taught me a lot, from the fitting and operating of them to the handling in the air. That model handles beautifully with a small amount of flap, for both slow flying and landing but, with any more than about 30 deg. flap it becomes a little difficult to steer and does not want to come down, even in calm conditions. These few undesirable characteristics made me decide to sit down and (please don't laugh) *design* a model for flaps.
The new aircraft had to have all the handling qualities of Mother's Worry, which will do the whole schedule of manoeuvres, is very fast yet can be so docile. I stuck to the basic set up ie areas, incidences, airfoil, etc but chose to turn the wing round, in other words, to taper the wing at the leading edge instead of the trailing edge. My own reasons for this are that a backward tapered wing is much more stable in strong gusty wind and consequently grooves better. I also wanted to try the flaps on a straight trailing edge so as to get a more even spill of air. Again, I wanted the new flaps to give me drag at high speed and lift at low speed; this meant a smaller area flap with plenty of movement.
Now, if Dave Platt will excuse my pulling his ideas to bits, Dave built his flaps into the wing in such a way that when they are lowered, they cause much more lift than drag and he gets a kiting effect, even with his 811b. model. This is because there is no air spill at low speed. Think of a parachute; if it was not for the hole in the top to allow the air to spill out, the chap on the other end would find himself floating insteading of sinking. (Still friends, Dave?)
The ailerons are of the usual variety with the closing 'V' at the bottom and hinged from the top. The flaps are hinged at the bottom and, when closed, conform with the wing section. The full amount of flap used can be seen in the photographs. This amount is required for slowing the aircraft down and, as the speed decreases, you raise the flaps to about half this amount for the landing. On a dead flat calm day, all the flap can be used for landing.
As you can see, I am using Kraft KP-6 proportional and reading the amount of flap in use is very easy, by having a scale marked on the transmitter. It would be a little more difficult with reeds but, with practice, would not be impossible. I have got used to watching the aircraft and gauging how much flap is required without referring to the transmitter... "
Spectre, Radio Modeller, June 1967.
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Article pages, thanks to RFJ.
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