WeRead Powered by ReaderPub
Model Aeroplanes and Their Engines: A Practical Book for Beginners cover

Model Aeroplanes and Their Engines: A Practical Book for Beginners

Chapter 26: THE MCMAHON COMPRESSED AIR DRIVEN BIPLANE
By George Anthony Cavanagh
Open in WeRead

Explore more books like this:

How To ...Sports/Hobbies

About This Book

This practical guide introduces model aeroplane hobbyists to the history, materials, and step-by-step construction techniques needed to build and fly models. It explains propeller design and carving, wing and frame construction, assembly, launching methods, chassis and pontoon fabrication, and includes measured diagrams and photographs. Sections survey powerplants and propulsion — rubber, compressed-air, gasoline, steam, and carbonic gas engines — and offer simple engine plans and performance data. The work also presents notable record models and flight examples, practical advice on forming clubs and competitions, and a concise dictionary of aeronautical terms for beginners.

THE MCMAHON COMPRESSED AIR DRIVEN BIPLANE

In the McMahon model we find a very satisfactory type of compressed air driven model. On several occasions this model has made flights of over 200 feet with a duration of between 10 and 15 seconds, and the indications are that by the use of a more powerful engine the model can be made to fly a greater distance, with a corresponding increase of duration. The engine used in connection with the model is of the two cylinder opposed type, such as described in the foregoing paragraphs. The tank, however, is somewhat different in design from that just described, it having been made of 28 gauge sheet bronze, riveted every one-half inch. The two long bolts that hold the steel caps on either end of the tank also serve as attachments for the spars that hold the tank to the engine bed, as shown in diagram 17. The tank has been satisfactorily charged to a pressure of 200 lbs. per square inch, but only a pressure of 150 lbs. is necessary to operate the engine. The tank measures 10″ in length by 3″ in diameter and weighs 7 ounces.

The wings of this machine are single surfaced and covered with fiber paper. The top wing measures 42″ in span by 6″ in chord. The lower wing is 24″ by 6″. The wings have a total surface of 396 square inches and are built up of two ³⁄₁₆″ dowel sticks, flattened to streamline shape. Only two sets of uprights separate the wings, thus adding to the streamline appearance of the machine.

Both tail and rudder are double surfaced and are built entirely of bamboo for lightness, the tail being made in the form of a half circle measuring 12″ by 8″. Steel wire is used on the construction of the landing chassis, the chassis being so designed as to render it capable of withstanding the most violent shock that it may possibly receive in landing. The propeller used in connection with the model is 14″ in diameter and has an approximate pitch of 18″.