Twiddler. Twin Jetex-powered sport helicopter model.
Quote: "Try this little whirly-bird for real flying fun with 2 Jetex 50 units. Twiddler, by Ray Morse.
It is Ray Morse's aim to try to advance the design of the model helicopter, and during the past few years he has conducted a series of experiments in spare time from his normal duty of running a fine holiday camp on the Broads. Working on one's own is a slow uphill job, however, in the end patience is rewarded, and the design shown here is the result of a long series of tests.
This little helicopter employs the Clough type pivoted rotor blades, but instead of being powered by a diesel on rotor hub, it is driven by twin Jetex 50 B units. As far as we are aware it is the first to use Jetex power with the Clough blade system and we think you will agree that this little machine is not only pleasing to the eye, being reasonably scale-like in appearance, but it also offers several virtues on account of its small high-revving rotor, this being only 15 in diameter with four blades, as you will note. High revs make for increased gyroscopic stability, markedly noticeable in strong winds, as well as greater jet efficiency operating at higher speed. Another advantage is that the jet units are carried on the piano wire extensions of the blade pivots, thus deleting the separate beam mounting as used on the two-blade helicopters.
Details opposite are half-size, but for those who prefer actual size details a 2s 6d plan is available.
Begin by shaping the fuselage lower block from balsa and cementing at right angles to 1/4 sq balsa rotor mast support, then sandwich in between 1/32 med sheet balsa sides, cementing together along tail boom. Fill cockpit back, also top and bottom of the fuselage with 1/16 sheet. Attach the 1/32 sheet in hard balsa tail vane with aluminium wire or strip. The skid under-carriage is made as follows. Cut the two skids from 1/16 sq bamboo, heating ends to form upturned tips in candle flame. The 20 swg wire legs are formed after heating to cherry red to assist bending. Cement skids to legs and bind with fine cotton. Glaze cockpit with thin acetate sheet after adding interior details to cockpit such as seat and stick.
Rotor: The four blades are cut from 1/16 med sheet balsa, and sanded to section as shown, keeping trailing edge as fine as possible. Attach mass balance weights and all pivot bearings with cement, afterwards binding with tissues or strips of Jap silk. Mass balance weights are made by looping the end of 20 swg wire, binding with fuse wire, then building up with soft solder to streamline form. Finish with emery cloth, or better still, file to shape in the lathe if you have one. Be sure to make all the weights identical, otherwise the machine will fly in banked circles at low altitude, due to unequal feathering. The bearings, of approximately 0-024 inch sheet aluminium are formed with clips to press into balsa. blades when cementing. Assemble rotor hub upside down on a scrap block of wood for location..."
Twiddler, Aeromodeller, July 1958.
Direct submission to Outerzone.
Article pages, thanks to RFJ.
Did we get something wrong with this plan? That happens sometimes. Help us make a correction
Do you have a photo you'd like to submit for this page? Then email email@example.com
* Credit field
The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.
This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
© Outerzone, 2011-2019.
All content is free to download for personal use.
For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.
Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.