About this Plan
Monocopter. Profile free flight helicopter model.
Quote: "Simple, single-rotor design that flies -and flies! Monocopter, by Bill Hannan.
Building a Monocopter can offer hours of free flight fun with little investment in time or materials. This helicopter is simple, with only one rotor blade and no belts, pulleys, or other intricate parts.
Although it is a profile design of the Italian Agusta A-109 Twin, it can be built with another design if the layout is similar.
Before building, make a copy of the plans to preserve the originals, and when selecting materials, remember that weight is a performance enemy in any aircraft, but especially in helicopters.
CONSTRUCTION. Cut the Monocopter's motor stick from a stiff, medium-hard strip of 3/16 x 1/8 balsa. Glue a short section of balsa to one end to act as a spacer for the rotor-shaft bearing.
The bearing is a section of 1/16-inch diameter aluminum tubing. Cut it to length by rolling it under a single-edge razor blade, then snapping the tube along the scored line. Smooth the end with a fine file and sandpaper.
A Peck-Polymers nylon thrust bearing can also be
used. For either tube bearing, roughen the outside for better glue ad-hesion.
Bend the rubber-motor retaining hook from thin music wire, then roughen it and insert it in the lower end of the motor stick. Wrap both the rotor-shaft bearing and retaining hook with strong thread and secure them with glue. Glue the fuselage, which consists of Vis and 1Jsx1/16 inch strips. Pin the strips in position while the glue dries.
Cut the fuselage covering directly from the plans. Apply color with fiber-point pens. My Agusta was white with red ornamentation.
ROTOR. Cut the rotor hub from hard 3/32 sheet balsa. Drill a small hole for the rotor shaft. Make sure it is square with the hub so the rotor will run true. Carefully cut away one corner to form the mounting face for the rotor blade. Use 1/32-inch diameter music wire for the rotor shaft. Make the bends in proper sequence, forming the hook for the rubber motor first.
Next, slide the shaft through the motor stick bearing, and add brass or teflon thrust washers, then the rotor hub. Make a right-angle bend in the shaft above the hub using the plans as a guide. Make another right-angle bend in the end of the shaft arm to help retain the counter-balancing weight. Bind the shaft arm to the rotor hub with thread and glue.
Shape the rotor blade from 3/32-inch sheet balsa. An exact airfoil is not critical, but a suggested section is shown. The model will perform without washout but twist some in to give the blade tip less incidence than the root.
ASSEMBLY: Make the counterbalance from a length of electrical solder evenly wound onto the end of the rotor shaft arm. Adjust the balance horizontally. A drop of glue will secure the solder in position. Glue the fuselage framework to the back of the fuselage cov-ering and weigh it down to prevent warping. Then glue the motor stick firmly to the lisx1!36 inch portion of the fuselage frame-work. Moving the fuselage position up or down relative to the motor stick will alter the model's flight path.
FLYING: Add a drop of oil to the rotor bearings. Power requirements will depend on your model's weight and testing site. With low power the model can be flown in a fairly small room. Too much power can cause the Monocopter to hit the ceiling. Start with a single loop of 2 mm rubber.
A long loop of lubed rubber winder-wound can yield impressive results in a large indoor site. During the recent West Baden indoor championships, Charles Sotich proxy-flew a Monocopter 80-feet high for over 40 seconds. Outdoors, with more power, the model can fly much higher.
EXPERIMENTS: The Monocopter invites modifications! Improve the balance. Add or subtract from the counterbalance weight to affect vibration. Bend the rotor counterbalance arm slightly forward and down for better dynamic balance.
There you have it, the world's simplest helicopter. Why not give it a whirl?"
Direct submission to Ouuterzone.
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