rotors were at one time believed to be the next big thing in air-driven
propulsion. They would replace cloth sails on boats and fixed wings on aeroplanes. I
remember seeing such fantastic contraptions in magazines like Mechanix Illustrated
and Popular Mechanics back in the 1960's and 1970's. The
sails and wings were actually built on experimental vehicles which can be found in a
Google search on
Flettner rotor. They operate on the
which is where a lifting force is generated by a spinning sphere or cylinder moving
through the air (or water, or any fluid), thereby causing an unequal pressure to
build on opposite sides. I had a Magnus rotor kite as a kid in the late 1960's that
was made of thin, molded plastic. It flew pretty darn well if I remember correctly.
This curiosity-inducing control line model designed by Roy Clough exploits the Magnus
rotor effect. It is more of a novelty proof-of-concept platform rather than a stunt
or scale model.
Flettner-Type Rotor Wing-Control Line Model
You'll Find It Fun to Fly This Flettner-Type Rotor
Wing Control Line Model
Nothing hard about this project! Best of all it's a great flyer.
By Roy L. Clough, Jr.
This novel control line model gets its lift from a pair of whirling Flettner-type
rotors which spin automatically in flight.
Easy to build and fly, the model is practically crashproof because the rotors will
keep turning whether the motor is running or not.
Although the model moves along at a fairly good clip in normal flight it can be made
to practically hover on the upwind side of the circle if the nose is raised a bit. Center
of gravity location in relationship to the rotor axis is not very critical so a wide
variety of small engines may be used without altering the model. It is important, however,
to have the control line guide set to allow the model to nose slightly out of the circle,
the same as for any ukie.
Construction Is of the Profile Type.
Fuselage is cut from medium hard 1/4" sheet balsa. Motor mount is a plywood disk held
rigidly in place by blocks cemented on either side. Landing gear may be held either between
the plies of the nose disk or simply be set in a groove in the face of the disk and held
in place by the rear of the engine tank. Control horn and bellcrank are of the 'Tee'
or Firebaby type which are the best for profile fuselages.
A short wing stub fills the center section. A cabane strut on each side acts as a
brace. This provides support for the 3/32" wire rotor axle and allows a clear wash-way
to the tail surfaces. If you run the rotors right up to the fuselage sides their interference
will make elevator control uncertain at low speed.
Construction of the rotors is simple, but should be followed closely for best results.
The open center design was chosen after experiment with several types indicated this
design allowed the best forward speed maximums and minimums. It is essential that the
rotors be mounted as shown, so that the rotation is to the rear at the top. If the rotors
are installed backwards the model will not lift since the rotor thrust will be downward
instead of up.
The line guide is soldered to the tip of the inboard axle and is bent slightly to
the rear to insure the correct amount of nose-out without the necessity of a separate
When you have your rotor-wing craft in operation, get a friend to snap a photo for
the magazine. American Modeler pays $10 apiece for the individual "shots" used with its
Full size plans for Flettner-Type Rotor Wing on Plan No. 357 from Hobby Helpers. 770
Hunts Point Ave., New York 59, N. Y. (50c).
Flettner-Type Rotor Wing Control Line Model Plans
Posted October 20, 2018