An Airplane Swing for the Back Yard (Sep, 1930)
An Airplane Swing for the Back Yard
by Dick Cole
Children will get endless hours of fun out of this airplane swing, run by pedal-driven propellers. Any handy man can build one out of inexpensive junked auto parts and a few lengths of pipe.
OF ALL the sensational “rides” at an up-to-date amusement park, perhaps none is more thrilling than an airplane swing. It affords many of the sensations of actually flying, but without any danger. There is no case on record where a passenger has been seriously injured in an airplane swing. So, while it may look spectacular to see the cars of the swing whirling over people’s heads, the hazardous element is lacking in a strongly constructed swing.
A home-made airplane swing can be made at a small cost by any handy man. The drawing shows the general appearance of the finished swing. Six carsâ€”or gondolasâ€” are suspended from the overhead revolving frame. Only three gondolas are fitted with propellers; the others are “trailers.” Unlike the usual amusement park swing, in which the overhead frame is turned mechanically and the propellers are only dummies for effect, this home-made swing is rotated by the direct action of the propellers. These can be operated with pedals.
The most important part of the device is the overhead revolving frame. It is built up on the wheel of a half section of a full-floating type rear axle assembly from a junked automobile. Many old-time cars used this style, and they can be bought for a dollar or two from any auto junk yard. Six pieces of selected wood â€” preferably hardwood â€” 2″x4″x72″ are bolted radially to the side of the wheel. Usually there are six bolts securing the driving axle flange to the wheel, and six rim lug bolts. These can be driven out and be replaced with longer bolts for bolting the radial pieces, making it unnecessary to drill additional holes.
The radial pieces should be strengthened with stay-rods as shown. In the drawing, a length of pipe is used to support the stay-rods at the middle, but in many cases the driving axle itself can be reversed and will serve the purpose even better.
At the end of each radial piece is a substantial eyebolt to which the swing cables are attached. Quarter-inch steel cable is recommended, but heavy fencing wire will serve. The cable or wire should pass around cable thimbles to prevent chafing. It is obvious that the thimbles will have to be spread open slightly to be placed within the eyebolts. Afterward they are closed again, and the cable or wire put in the thimble groove and twisted a few times. The free ends of the cable should be left about 11 feet long for attaching to the swing gondolas.
After the overhead assembly is complete, it is rigidly attached to one end of a 15-ft. length of 2-1/2-inch iron pipe. The method of doing this depends upon the axle housing design. Sometimes the pipe can be inserted into the housing and be bolted or brazed. Whatever method is employed, it must be absolutely solid. The other end of the pipe is now set firmly in the ground. It is suggested that a floor plate be used on the end of the pipe to prevent it settling. Stay-rods are also necessary. It is well to set the pipe and the rods in concrete, but if sunk deeply in firm soil, and tamped with rocks, sufficient solidity can be had.
Next come the swing cars, or gondolas. The drawing suggests a design which will prove satisfactory. Of course the builder can make gondolas that more closely resemble airplanes if he desires to, but the one illustrated offers the all-essential factorâ€” safety. The sketch makes the construction obvious. The most important point is the bearing for the propeller shaft. The shaft must be oiled freely.
The propeller shaft is of 1/2-inch cold-rolled steel threaded at one end to receive the propeller, and at the other end to receive a small, grooved pulley.
The pedaling gear is not shown in detail in the drawing. Its construction depends upon the material and facilities one has at hand. Two wooden disks about 18 inches in diameter can be beveled on one edge and then be bolted together to form a satisfactory pulley. Or a bicycle or velocipede wheel, with tires removed, can be used for the driving pulley. The gear ratio should be such that the propeller can be turned about 750 r.p.m. with comfortable pedaling. Leather belting 2-1/2 inch round, is used for transmission. The sketch shows how this passes around the pulleys.
The construction of a suitable propeller may seem like a rather difficult job to many. Yet an efficient propeller can be made very simply as shown. Instead of being cut from a solid block, this prop is built up of slats â€”laminated, as it were. Not only does this method result in a very strong propeller, but it also has inherent balance and uniform pitch. The center holes of the slats should be so small that the propeller shaft must be screwed into them, and afterward be locked between two nuts and large washers. Glue on the threads will make the attachment even more rigid.
The propeller illustrated is intended to be foot operated at 750 r.p.m.
We now have an airplane swing. If built according to directions, there is no danger of its collapsing.