Twin-kle - Twin engined sport model for single channel or 2 function proportional radio control. For 2x .049 to .06 engines.
Quote: "TWIN-KLE should actually have been built a long time ago, in the days of super-regen and rubber driven actuators but, perhaps fortunately, it did not materialise in three dimensions until early 1971. I first had the urge to build a twin-engined radio controlled model after watching one fly at Doncaster ten or more years ago (Jim Bridgewood's modified ‘Sixgun' with manual pulse rudder) but the sketches drawn at the time did not re-emerge until recently, and any resemblance to the original is now purely co-incidental.
The model was built quickly, since I deliberately kept it structurally as simple as possible, feeling that the twin engines provided sufficient complication. The original uses Pecon 5 on rudder and elevator, and is powered by a pair of Cox TD 049s - relics of my free-flight contest days. When the time came for the acid test, the model was despatched from a hand launch (rough field conditions) with both motors at full song. A moment's panic followed while it headed for the ground, and then I grabbed for the stick with my launching hand (being a mode 1 flier). A liberal application of up produced a 45 degree climb with no apparent diminuition of speed. After a couple of minutes I had it trimmed out, and took time to breathe again! The model proved faster than I had expected, but was by no means a wild ride. One motor was stuttering badly, and thus the second moment of truth arrived. As the port motor cut out I pushed in full right trim, and found that I still needed a little right stick. However, everything was perfectly controllable and the model climbed well on one motor. The second cut was followed by a routine (if fast) approach and normal landing (ie bumpy in the rough grass). Subsequent flights were carried out from a runway and the take-off and landing proved to be a pleasure to be-hold.
The only modifications made have been to fit larger subfins, so that single-engined straight flight is achieved with full trim and no stick pressure, and to install clunk tanks once I realised the acrobatic potential. The aircraft is extremely lively with the TD's at 38oz all-up weight. Provided that lead-lined balsa is not used, two Babe Bees or QZ's will be quite adequate, although you should be prepared to land with one running if it is sick. Single-engined performance with the TD's leaves nothing to be desired, being similar to a Junior Falcon (oz8144).
Should anyone feel like fitting 07's or 09's, by all means proceed, but please sound the four-minute warning first. Be assured however that such steps are not necessary, since two motors seem to give a much more zippy performance than one of twice the size. No doubt there is some inscrutable scientific reason for this, probably related to the relative efficiency of the airscrew discs. However, I just accept it!
Building points: The structure is utterly conventional and the plans well annotated, and since this is not a beginner's model (it is too hot) the following then is merely a sum-mary of points of interest. Do not neglect the ply reinforcements where shown on the wing..."
Twinkle, RCM&E, September 1972.
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