Page:Popular Science Monthly Volume 88.djvu/474

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��Popular Science Monthly

���Working drawing showing details of a simple aero ice-racer. This entire machine may be biiilt for less than twenty dollars, if good judgment is used in buying materials

��spring and a small wooden block, as can be seen by referring to the drawings. The bottom edge of the brake should present several rough teeth to the ice. This prevents any sudden catching due to lumps or ridges in the ice.

The small shields on the top of the body are intended to cut down the re- sistance caused by the bodies of the passengers, and can be constructed of metal or fiber. They are semi-conical in shape as shown, and afford consider- able protection from the cold.

A motorcycle motor is very well suited for use on a motor ice-racer. These motors can be bought second hand in running condition at most any price from $8.00 up, and ranging in horse power from 3 to 20. The smallest of these weigh only about 40 lbs. complete, and are capable of driving a small ice- racer at considerable speed.

The speeds possible with the aero- driven ice-boat range very high when the craft in question is properly designed and constructed, and if sufficient power is used. Even the smallest craft should be capable of a speed of a mile a minute when well made, and with a j)owerful

��motor a good machine should attain a speed of nearly 100 miles an hour ; a great deal, however, depends on how well the body is designed and con- structed, and how well the motor runs.

Having described the aero ice-racer in a general manner, it is next in order to furnish detailed instructions for the con- struction of a simple craft of this type which will give the most satisfactory service, and at the same time require the least eflFort in the making. A machine of this type is therefore described fol- lowing the design in Fig. 1.

To begin at the bottom and work up. Three wooden runners should be made of clear stock at least \" in thickness. One of these is represented by the lower portion of the rimner shown in Fig. 3. The other two should be similar in shape to the entire runner illustrated in the same figure. The dimensions for these are given in the drawing. The shape can be laid out from the sketch by mark- ing ofif the chief dimensions as indicated and drawing in the curves free hand.

A V-shaped groo\e •'>;" wide by 3/16" deep is cut along the middle of the bot- tom of these three runners with a miter-

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