Flight, October 1923

THE "MUMMERT" (U.S.A.) LIGHT 'PLANE

   NEARLY two years ago Harvey C. Mummert, aeronautical engineer for the Curtiss Aeroplane and Motor Company, produced a successful miniature biplane, known as the "Baby Vamp," fitted with a 25 h.p. Lawrence ДальшеMore>>> engine (see FLIGHT, January 19, 1922). The advent of the "aerial motor-cycle" (i.e., light 'plane or "motor glider"), together with the results obtained with the "Baby Vamp," have apparently been the cause of Mr. Mummert's latest efforts, for, according to our American contemporary Aviation, he has designed and built a tiny monoplane fitted with a stock-model Harley-Davidson motor-cycle engine.
   This new machine is a single-seater, cantilever monoplane, designed to meet the present demand for a low-powered, inexpensive aeroplane, having a comparatively large cruising radius and capable of being operated at a very low cost. These requirements, it would seem, are fulfilled by this little "Mummert" light 'plane, which weighs only 300 lbs. empty, and has a fuel capacity for about 12 hours' sustained flight at 75 m.p.h., with a consumption of approximately 50 miles per gallon.
   From a constructional point of view this machine has several interesting details. The fuselage is constructed of three-ply maple veneer, nailed and glued to laminated spruce diaphragms, or bulkheads, which encircle the three longerons. It has a very roomy and comfortable cockpit, and the vision ahead is extremely good. For vision in a downward direction a window is provided on each side by covering a portion of the wings with transparent celluloid at the wing roots.
   The main wing spars are continuous across the fuselage, and are fastened to the top longeron fittings with small pins, which are easily removed, and the wings quickly detached. These spars are of the box-girder type, and the ribs consist of two cap strips glued to a solid web of 1/28-in. veneer. Doped fabric is used for the wing covering, but the ailerons arc veneer covered.
   The vertical and horizontal tail surfaces are faired into the fuselage, and, owing to the amount of side area aft provided by the latter, it has been possible to keep down the size of the vertical tail surfaces to a minimum without interfering with the stability and control of the machine.
   A special type of variable gearing between the stick and the control surfaces prevents the machine from being too sensitive on the controls at high speeds, and ensures ample movement of the control surfaces for small stick displacements at low speeds.
   The landing gear is of tubular construction, and the shock absorbers are located within the fuselage.
   The engine is a stock model Harley-Davidson, mounted on a light pressed-steel frame, which is bolted to the fire-proof bulkhead on the front end of the fuselage. The petrol and oil tanks are located between the pilot's cockpit and the engine, and are readily accessible for filling. A Reed-type duralumin airscrew is fitted, having a diameter of 4 ft. 4 ins. and a maximum r.p.m. of 2,800.
   The overall span of the "Mummert" monoplane is 20 ft. and the o.a. length 14 ft. 1 in.