IT WILL NEVER WIN a prize for beauty of design or appearance, but the Bensen Gyro-glider (or the powered Gyro-copter) is a first class flying machine—not a toy.
During World War II the German navy towed a similarly designed craft high in the air behind surfaced submarines to increase the range of vision of their observers. The Royal Air Force used them as gliders to drop men and equipment behind enemy lines.
Since 1953, the Bensen Air craft Corp. of Raleigh, N. C., has produced and sold thousands of kits for its Gyro- glider (and Gyro-copter) to flying enthusiasts all over the world from Alaska to New Zealand.
One reason for this popularity is that if you can ride a bicycle you can learn to fly the Gyro-glider. It’s that simple to control, and it will not stall nor go into “spin” dives.
A second important reason for the Gyro-glider’s popularity is that when used only as a towed glider, no license for the pilot or the machine is required! After mastering the glider, you can easily qualify for a Federal Aviation Authority license to fly the Gyro-copter (powered conversion of the glider) if so desired.
All you need do to acquire this privilege is to pass a medical exam and a written exam on the Civil Air Regulations, followed by a flight proficiency exam consisting of three takeoffs and landings in the Gyro-glider, or towed Gyro-copter. Any licensed FAA instructor can give this exam without requiring dual flight instruction.
You’ll be operating on a student pilot license. A third, and most important reason for the Gyro-glider’s popularity is that it is designed primarily to be built by hobbyists from materials and kits consisting of simple parts that are easily bolted together like an Erector set!
Since the greatest cost of building any aircraft is for labor, you can readily see where money can be saved by doing all or most of the fabrication work yourself. For us to present complete plans, construction details, and flying instructions would require upwards of 300 pages of space.
However, if the photographs and drawings arouse your sincere interest, you’ll be able to proceed at “full speed ahead” simply by ordering large-scale plans, materials, or complete Build It Yourself Gyrocopter kits with instruction manuals from Bensen Aircraft Corp.
You’ll find kite ranging from $319 for a Hydro-glider to $1095 for a Gyro-copter, including a reconditioned 72-hp Mc Culloch air-cooled engine.) If your funds are limited, you can even start by buying raw materials in lots as low as $10, plus $2 for special packaging and handling.
Since you really need three persons to safely operate the glider — one to drive the tow car, one to relay the pilot’s hand instructions to the car driver, and the pilot—it might be smart to organize a club. With three (or more) club members, the cost of complete kits is minimized for each member.
Before getting into actual construction details I want to point out that raw materials can be purchased from many sources, but as an experienced pilot I strongly suggest that you “go Bensen, all the way.” The selection of materials for rotary-wing aircraft is far more critical than for any other type of aircraft.
This is because structural vibrations, generated by the rotor, can easily lead to destructive fatigue failures if materials do not meet prescribed strength, elasticity, section modulus, and mass factors. Strength alone is not enough.
Every nut and bolt, as well as all other materials available from Bensen, has been care fully analyzed for function and strength. Complete drawings and strength data of all materials have been supplied to Federal Aviation Authority (FAA) headquarters in Washington.
This data is available to any FAA agent you might contact later when you come to licensing the converted Gyro-copter (powered model) after having acquired some flying experience on the glider model.
Your pocketbook is the main limiting factor when you consider building a Gyro-glider or copter. You can buy the basic glider kit for $369 and fabricate every part, or you can mix kits and order some parts in finished or semi finished form.
If you plan to convert your glider to a licensed (amateur-built, Experimental category) copter, it is important that you fabricate a good percentage of the parts or else the FAA might decide it is not amateur-built and refuse to license it in the Experimental category.
The Gyro-Glider consists of three parts: the airframe, the rotor head, the rotor. Only the rotor head requires accurate machining, because it contains ball bearings. The rest can be built with hand tools and the usual hobby workshop equipment.
A drill press is desirable, although some builders have turned out good work with a hand electric drill. If you lack equipment, remember that you can buy some parts already finished (or semi-finished), as you’ll see when you get the free brochure already mentioned.
Unlike the conventional home-built airplane with its complicated built-up fuselage, wings (ribs and spars), tail units, and fabric covering requiring months of spare time work to construct, the Gyro-glider can be constructed in about 100 to 120 man-hours.
Two men should be able to construct the Build It Yourself Gyrocopter in about two weeks. The airframe consists simply of the keel tube (-1 on plan and perspective drawing), axle tube (-2 on plan), and the mast tube (-3 on plan).
All are made from 1/8x2x2-inch aluminum square tubing (6061-T6 aircraft grade), which is cut to the overall lengths shown on plan. Starting from the left ends of each tube you’ll note that holes are drilled in the tubing at various intervals on the four sides of each tube.
Note also that the holes are identified as A, B, C, and D. A refers to holes of ¼-inch diameter; B to holes of 3/16-inch diameter; C to 5/16-inch diameter, and D to 1-inch diameter. The latter is found only on the bottom (side 3 on plan) of the keel tube.
Note the transfer fixture and punch shown in the lower right section of the plan (reproduced in reduced form). Supplied with the kit, this device greatly simplifies the locating, and punching (marking) of the desired holes in the tubing, assuring the proper edge distance of the holes.
In use, simply select the side of the fixture with the proper hole size desired, slide it to the measured point on the tubing, insert the transfer-punch, and strike it with a single, firm blow of the hammer as shown on the plan.
Repeat this procedure on all sides of the square tubes, on both edges. You now have the hole points marked for drilling. (There are two unused 1/4-inch holes in the mast and three in the keel tube which are provided for possible future engine attachment.)
As shown on the plan, a good quality 10-foot steel tape can be stretched across the full length of the tube and held in place with a C-clamp to facilitate the use of the transfer fixture when lining up the desired hole locations. Drill the centered holes (with the indicated proper-sized drill) through one side of the tube only. Use a drill press when possible.
Simplicity of assembly is seen here in this Build It Yourself Gyrocopter. In above image sequence, keel, mast, axle are fastened together. Wheels, bracing, head plate are added. Seat, front framing, rudder are in place. Showing rotor blade, cables and control stick attached.
The next step is to saw a slot in the #3 side of the keel tube, as shown on plan, which will serve as a recess for the tail wheel. Drill 5/16-inch holes in the #2 and #4 sides of the keel tube for the tail wheel axle at the points indicated.
The two cluster plates (-4 on plan) should be cut to plan size and shape as the next step in construction. If you get the large-scale Bensen plans, the cluster plate template is shown full size, simplifying construction.
If you make them from the plan shown here, you’ll have to get a piece of 1/8x6x14½-inch aluminum sheet (5052-H-32 aircraft grade) and work out your own template. The bottom of the plates measure 6 inches. Note that the cluster plates have a 1/8-inch overhang when bolted (later) in position on the keel tube.
The mast tube is handled in the same manner as the keel tube. That is, the locations for the holes are marked off in the same way; proper size holes are drilled, etc., as was the case with the keel tube.
A 9-degree bevel is cut on the bottom of the mast tube (-3 on plan) on sides #2 and 4, as indicated. (This bevel is shown full scale on Bensen plans.) Lay the keel piece and mast on a flat surface.
Measure 46V6 inches along the keel from the left end on # 1 side and scribe a line with a pencil. When the #3 side of the beveled mast is placed against this line on the keel tube you will have the proper location of the mast on the keel tube and the angle between them will be 81 degrees.
Slide one cluster plate under the keel and mast junction, positioning it by the predrilled holes in plate and keel. Align with the bottom edge of the keel and clamp in position. Transfer-punch through the four pre-drilled mast holes and the two remaining keel holes.
Remove the plate and center-drill. Align on top of the other cluster plate by the use of one pre-drilled ¼-inch hole and drill the remaining six ¼-inch holes through both plates simultaneously. Bolt the cluster plates in position, forming a permanent junction with the keel.
It should be pointed out that every bolt, washer, nut, spacer, etc., used in constructing the Gyro-glider is indicated on the large-scale plans and also identified both in the material specifications sheets and manuals supplied with the kits.
Since there are literally several hundred different sizes of these items involved, it would be impossible to list them in the limited space accorded this article.
The axle tube (see plan) is prepared in the same manner as the keel and mast tubes. Proper-sized holes are drilled at the points indicated on the plans and the axle tube is bolted to the keel tube.
Details of the axle assembly, including the axle tube, axle proper, clamps, and necessary bolts, washers, etc., are shown in the accompanying plan. The head plates which are bolted to the top of the mast tube are made up in the same manner as the cluster plates.
In closing this article, I want to stress that the purpose is not to “plug” Bensen products. However, the facts are that Bensen has pioneered this “flying machine.” Consequently, they are the one—and only—authoritative source for plans, materials, and detailed instructions for building both the Gyro-copter and the basic Gyro-glider.
Some parts are available only from Bensen. Therefore, in an effort to assure maximum safety, low cost, and the utmost simplicity in the construction work, I most heartily suggest that you order the large-scale plans if you are sincere in your desire to build and fly a Gyro-glider and/or Gyro-copter.
The cost of the plans ($15) will be credited to your account if you decide to go ahead and build the craft from one of the firm’s kits. Another benefit of purchasing the kit is that the company’s experts will answer your inquiries if you should run into any problems while constructing your Gyro-glider.
Large-scale plans (6 sheets, 23½ x 36 in., scale 1:8) for the Gyro-glider are available. The large-scale Build It Yourself Gyrocopter plans and detailed instruction manuals, however, make it unlikely that even the amateur with the most basic skills will need further assistance in successfully constructing the machine.
In closing this first article, I’d like to state that, as an experienced commercial and military aircraft pilot with over 4600 flying hours, and an author of many home-built plane articles that have appeared in nationally circulated publications, I’m completely sold on the Bensen product. The thrill of flying the Gyro-glider was second only to my first solo plane flight.
And I, too, am now building a Gyro-glider from the Bensen kit!