About this Plan
Rotoriser. Unorthodox free flight single-rotor flying machine.
Quote: "YOU could call it a free flight, single rotor blade helicopter and you wouldn't be wrong. The Rotoriser is a model you should build when you are in the mood for something simple and exciting. Ken Willard's Rotoriser.
The Rotoriser is a free flight fun machine. It won't win any contests, nor will it set any records, but you'll have more fun with it than you'll have with many other flying machines, simply because it's easy to build, easy to launch and fly, and, by varying the trim lab on the stabilizer, you can get a wide variety of flight patterns.
The concept of the Rotoriser was developed originally by Charles W McCutchen back in 1954 [and published as the Charybdis (oz5275) flying machine]. Various designs based on the concept have been published at times, principally in European magazines. The one which appears here, with some minor modifications which I have added, was designed by a young man in Florida. I saw the machine in Vince Arias' Hobby World, was intrigued, and figured that you would be equally fascinated by its flight capabilities.
The design concept is generally called the 'McCutcheon Machine' after its inventor. However, I chose the name Rotoriser because, if you happen to get the .049 reed valve engine going backwards and try to fly it, you'll soon find out that it's a 'Rotorooter.' (Apologies to the sewer pipe cleaners, of course.) But you won't do that, will you?
Constructing the Rotoriser. Construction is so simple that you can build it in one evening and fly it the next day. So let's make one.
First, assemble all of the various components in a convenient location near your workbench. The bill of materials lists what you will need.
Make the main rotor blade out of the piece of balsa which is 1/4 x 4 x 36 inches long. Shape the sheet into a flat-bottomed airfoil as shown in the full-size cross section on the plans. Cut a slot in the center section of the main blade, 2-1/2 x 1-1/8. Insert the end of the 1/4 x 1-1/18 x 1/2 inch hardwood motor arm into the slot on the main blade and glue it in place. Reinforce this center section joint with a piece of 1/16 x 4 x 4-1/2 inch plywood, glued to the bottom. Then further strengthen it by covering that section with fiberglass cloth wrapped around it and resined in place.
Make the engine mount by gluing the 1/2 x 1-1/2 x 1/8 basswood biockson the end of the motor arm. Shape them to the contour shown in the plans. The photos show a metal mount, which is optional..."
Quote: "Hi Steve - Here is Ken Willard's Rotoriser from MB issue 03-84. A bit different to be sure but it has a wing and a prop making it an 'official' aircraft. I'm not to sure where to put the pilot! A few anti-dizzy pills before strapping in might also be in order. My modeler mind wonders if an electric power with speed control and micro servo controlled trim tab is feasible .... hmmm. It would really keep people on their toes as the 'flying machete' took to the air. If the blade doesn't get you the counter weight should."
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User commentsI made one of these and flew it in a schoolyard, it was a stable flier and could be made to climb by adjusting the trim tab. It was a six foot blade in the air, impressive.
weehaw - 22/01/2014
Hi Steve - Totally shocked – I went to look at a gent's 'hangar sale' today and he had one of these in good shape on top of the pile. I had just seen the design in Outerzone a couple of days ago – what are the odds of that happening? It’s like the aliens were directing met there. Did I buy it? Of course.
PGregory - 17/09/2014
I built one of these based on plan from 1/2A projects book of Ken Willard designs. It is a hoot to fly, and never fails at pleasing a crowd. A couple of notes: The center part of the wing is mostly dead weight... consider lengthening motor stick and only keeping the outer 2/3 or 3/4 of wing. This will also shift moment of blade outward, which will reduce coning. My balsa wing is bit prone to spitting. Consider covering it with light tissue with tissue grain running chordwise. This may end up lighter than trying to fill the balsa grain for a smooth finish. As shown, the engine thrust line is not tangent to rotation, as would be optimal. This also causes fuel in integral tank to move forward (toward crankcase) once up to speed, but rearward due to acceleration as rotor spins up. This makes it difficult to get the thing to run on partial tanks, as needed to prevent losing it. A decent solution is to angle the engine mount so that the crankshaft is tangent to rotation. Note that due to thrust of engine, and drag of wing, the center of rotation under power is a bit forward of wing LE, not where pivot hole is shown. The pivot hole is near the CoR when autorotating. G-loading causes considerable leaning as the rotor spins up. I had to set the needle sloppy rich (barely able to stay running) in order to have enough power to fly when spinning. Uniflow venting would help some, but venturi suction still has to lift fuel the length of pickup tube under G loading. A pen-bladder tank setup and FF fuel cutoff timer would be very advisable. A tall launching pole is needed if there is more than a faint breeze. The wind causes the rotor to tilt downwind when on the pole, so it 'slides' downward once free. The dynamics allow it to self level, once it is moving with the wind, but some altitude is needed for this to happen. De-thermalizer isn't really needed. Under autorotation, it performs about like a D-T'd fixed wing.
kevbo - 04/01/2019
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