| Light, though extremely rugged, this new Knight Twister is for a Pan American pilot down in South America. |
Several years ago, Vernon W. Payne designed and built a diminutive light biplane that was first described in the columes Of POPULAR AVIATION. So popular was this design and type of plane that we are still receiving inquiries from our readers on the subect.
POPULAR AVIATION has an unusual interest in this little biplane for the reason that many of the elements of its design were discussed with the staff of P. A. before Mr. Payne started on his noteworthy project and we have therefore watched its progress with a great deal of interest. This proves the affection lightplane fans still hold for a biplane construction that really looks like a small scale pursuit plane and we believe that such planes will always be popular.
But now, we have the pleasure of announcing a new Knight Twister, designed and built as before by Mr. Payne. This is the Model KTD-2, custom built for a sportsman pilot in Buenos Aires, Argentina, who plans to fly the little ship for sport in Argentina, Chile and Peru. It was given its flight tests recently at Curtiss-Reynolds Airport, Glenview, III., and showed a very fine performance.
The top speed is 160 m.p.h. with a cruising speed of 130 m.p.h., with a special Douglas 70 h.p. air-cooled Ford engine conversion. It lands at 45 m.p.h. and climbs 1,100 feet per minute at sea-level. The absolute ceiling is 19,000, an important factor in planes designed for the South American countries -- noted for their high mountain passes. The range is 550 miles at cruising speed with the present gasoline tank capacity of 18 gallons.
The wings are of the semi-cantilever type, completely covered with plywood. Wing spars are solid from tip to tip, with the wing tips solid from the last or outermost ribs, and are tapered to a knife edge. Running lights are built into the wings and the fins in the same way as the lights of a large ship.
The accompanying photographs clearly show the fine lines of the Knight Twister and the excellent job of cowling and streamlining. All parts in the air stream are thoroughly streamlined and the whole job is remarkably clean. It is America's answer to the Flying Flea of France, for both planes are approximately the same size.
| Though there are only 55 sq. ft. of them, the new Twister's wings are as rugged as a pursuit plane's. That's a 70 h.p. engine. |
The following specifications covering the general dimensions of the Knight will emphasize the extremely small dimensions and compactness of the new Knight Twister Model KTD-2:
| Span, upper wing || 15'-0" |
| Span, lower wing || 13'-0" |
| Wing area || 55 sq. ft. |
| Overall length || 13'-6" |
| Propeller diameter || 4'-10" |
| Horsepower || 70 h.p. |
While there are many arguments against the use of a biplane cell from a theoretical aerodynamic standpoint, yet they are highly practical in actual service. They are more compact for a given area and are far more rigid so that the loss of two or three per cent in aerodynamic efficiency is more than offset by the improved safety factors and the improved stability which comes with the proper adjustment of the wing cell.
As a further compensation for the loss of lift in a biplane cell, the wing structure is considerably lighter than the cantilever type and the arrangement makes it possible to employ thinner wing sections with higher L/D values.
The Douglas Ford conversion has been described before in P.A., but we will repeat that the Douglas system of aircooling the Ford marks a great advance in Ford conversion because it does away with the heavy and troublesome water-cooling system used in other conversions and therefore eliminates the dangers and troubles incident to water cooling.
The high speed and rate of climb made possible by the application of a full 70 h.p. will seem astounding to many lightplane enthusiasts who are accustomed to dealing with engines developing a feeble 15 to 40 horsepower.