Flight, April 1926
THE BUHL-VERVILLE CW-3
An American Commercial Biplane
THE new American commercial aeroplane described below is the latest product of the Buhl-Verville Aircraft Co., of Detroit, Mich., and it has been designed by Mr. Verville, who is one
of the pioneer aeroplane designers of America and has been responsible for several successful machines built in that country during the past ten years or so. Until recently Mr. Verville has been in charge of the racing and pursuit design section of the Air Service Engineering Division at McCook Field, where he directed the design of the U.S. Verville-Sperry messenger 'plane, the D.9, the Verville-Packard racer, the Verville-Sperry racer, the U.S. D.4 ambulance 'plane, the V.C.P.I and the P.W.I pursuit 'planes.
The CW-3 is a strong, serviceable and efficient tractor fuselage biplane, combining design features which facilitate its adaptability to the following types of service – passenger carrying, light freight carrying, aerial photography, crop-dusting, and training. Furthermore, it is designed with a degree of ruggedness and strength compatible with the classes of work for which it is intended. Provision is made whereby almost any power plant between 100 and 200 h.p. may be installed, only simple changes being necessary since the engine mount is made detachable.
The wing cellule is of the biplane type without stagger or sweepback. Both upper and lower planes are interchangeable and are hinged to the upper centre section and lower wing buts respectively with fittings designed to allow the folding back of the wings in order to facilitate the storage of the machine within a restricted hangar space of approximately 9 ft. high by 13 ft. 6 in. by 25 ft. The operation of folding back the wings takes no longer than 15 minutes. This feature of folding the wings also possesses considerable advantage for storage on board ship should the machine be required for shipboard reconnaissance work.
One pair of steel tube N-inter-plane struts each side separate the top and bottom planes, whilst the top plane centre section is supported above the fuselage by six tubular struts with diagonal bracing struts for the front members. The lower plane wing buts are braced to the fuselage by tubular struts with streamline fairings. Ailerons are fitted to both upper and lower planes.
The tail unit consists of a horizontal stabilizer, vertical fin, rudder, and divided elevator, all of which are of welded steel tube construction, fabric covered. The two elevator sections, and the rudder are all identical with each other, and the stabilizer is made up of two triangular halves bolted and braced on each side of the fuselage, and provided with angle adjustment, effected while the machine is on the ground. Special adjustment is likewise provided for the fin for the purpose of counteracting the airscrew-torque reaction. The stabilizer is braced, on its under surface, to the bottom longerons of the fuselage by two streamline tubes, and, on its upper surface, to the upper extremity of the rudder post by two streamline wires. A large, quickly detachable metal inspection door is provided in the rear end of the fuselage for inspecting the tail skid, etc.
The fuselage is of steel tube construction, welded into an integral structure without any wire bracing of any kind, thus obviating the necessity of continual rigging and truing up. This construction adapts itself very well to repairs on the field, as any welding can be carried out with an oxy-acetylene outfit, and the steel tubing employed is of an ordinary commercial size and grade which is readily obtainable in the open market.
Two cockpits are provided, one beneath the wings for the passengers and the other behind, aft of the wings, for the pilot. Both have comfortably upholstered seats, the passengers' cockpit measuring 2 ft. 11 in. wide, allowing ample accommodation for two sitting side by side. Between the two cockpits is a small tool and luggage compartment. Access An end view of the Buhl-Verville CW-3, with wings folded - the overall width thus being 13 ft. 6 in. to the front cockpit is facilitated by a triangular hinged door on the port side of the fuselage. If the machine is required for freight or crop-dusting work, the seats in the front cockpit can be removed, providing a space of about 23 cub. ft.
An instrument board, provided with an air-speed indicator, clock, altimeter, oil pressure gauge, radiator thermometer' switch, carburettor adjustments, &c, is provided in the pilot's cockpit. A parachute seat is fitted for the pilot, and a parachute can be worn in the front cockpit if desired.
The controls are of the stick and rudder bar type, dual control being optional, depending upon whether or not the machine is required for training purposes. The control is carried out by means of wire cables extending, in the case of the elevator controls, from the control column back to a countershaft in the after end of the fuselage, from the extremities of which extend the radius rods to the elevator horns. Attached to the rudder bar are two sets of cables, one set extending back to the rudder, and the other set to the tail skid to facilitate ground steering while taxying.
A wide-track axleless under-carriage is fitted, which not only reduces the resistance present in the ordinary axle type when taking off in long grass - and also lessens the chance of accident when landing under similar conditions - but the wide track makes for much smoother and safer landing, with less risk of damaging the wing tips in a bad landing. The shock absorbers are of the Oleo-rubber disc type, and underload the rubber discs are in compression, while an internal perforated plunger piston simultaneously travels into a loaded oil chamber at the lower end of the chassis strut. This absorbs the impact energy and neutralises the effect of the rebound so prevalent in the ordinary rubber sprung shock absorbers. It thus cushions the landing shocks to the extent of saving the whole aeroplane structure from the deterioratory effects occasioned by shocks in bad landing over rough ground.
The CW-3 model described herewith is equipped with a 90 h.p. Curtiss OX5 engine, housed in a quickly detachable cowling, and driving a Reed duralumin airscrew. The radiator is of the underslung type, located immediately under the engine and provided with shutters manually operated by the pilot during flight. A 40-gallon petrol tank, sufficient for 5 hours' flight, is located in the fuselage, immediately behind the engine, and the oil is carried in the bottom half of the engine crankcase. The petrol system is of the gravity feed type.
The main characteristics of the CW-3 are as follows :-
Span 35 ft.
Overall length 25 ft.
Width with wings folded 13 ft. 6 in.
Height 9 ft.
Wing area 300 sq. ft.
Area of ailerons 28 sq. ft.
Area of stabilizer 21 sq. ft.
Area of elevators 165 sq. ft.
Area of fin 5-75 sq. ft.
Area of rudder 8-5 sq.ft.
Weight empty 1,380 lb.
Weight laden 2,150 1b.
Speed range 40-95 m.p.h.
Range of action (full throttle) 5 hrs.
With 200 h.p. Wright "Whirlwind" -
Weight empty 1,415 lb.
Weight laden 2,300 lb.
Speed range 45-133 m.p.h..
Range of action (full throttle) 3-5 hrs.
Climb (ground level) 900 ft./min.