Flight, February 1927

THE HUFF-DALAND "PEGASUS”
A Successful American High-Powered Single-Engined Bomber

   ALTHOUGH the Huff-Daland "Pegasus" made its first public appearance at the National Air Races held at Mitchell Field, New York, in 1925, it was only a few months ago that any information regarding this machine was allowed to be published. At the races in question the "Pegasus" won the Air Transport Race.
   The "Pegasus" or XLB-1 is a tractor fuselage biplane light bomber designed by C. T. Porter, chief engineer of Huff, Daland Airplanes, Inc., of New York, and is one of the largest single-engined machines of its class; fitted with the Packard 2A-2500 800 h.p. water-cooled engine, it has remarkable speed and load-carrying qualities. As with other types of Huff-Daland aeroplanes, such as the "Petrel," "Pelican," "Panther," etc., the "Pegasus" has an all-metal fuselage of welded steel tube, constructed in one unit from the nose to the tail, in which the employment of wire bracing has been entirely eliminated. The mounting for the 800 h.p. Packard engine is readily detachable, together with the engine, by the removal of only four bolts, and an interchange of engines in service is thus rendered easily possible.
   The structure of the fuselage is of the Warren type, there being four main longerons, tapering to a vertical knife-edge at the rear; the maximum depth is at the trailing edges of the main planes, fore and aft of which the fuselage tapers slightly. The covering of the fuselage is fabric, except for the engine section.
   The undercarriage is of the split-axle - or, to be exact, non-axle - type, consisting of two wheels with a very wide track (14 it.), each hinged to the fuselage by an "axle-strut" extending from the stub axles up to the fuselage, and a “radius-strut" running back from the stub-axles to the fuselage. This undercarriage is also particularly interesting on account of the shock absorbing principle employed. The use of rubber is eliminated in both the undercarriage and the tail skid in favour of units of three oil and spring oleo shock-absorbing cylinders for each wheel, and a single cylinder for the tail skid. The wheel absorber units are mounted above and alongside each wheel, being attached to the lower plane centre section (front spar). The tail skid is steerable.
   The main planes, which are of standard Huft-Daland hollow box spar construction, arc of equal span and chord, top and bottom, the wing section, U.S.A. 45 modified, being fairly thick at the centre and tapering towards the tips. The wing cellule is of the single-bay type, the top and bottom planes being made up of three panels - a two outer and one centre. The lower centre panel is divided by the fuselage, into which it is built. The outer panels, which are set at a dihedral angle of 2 deg. taper in chord from 10 ft. 6 ins. at the root to 7 ft. at the tip.
   The upper centre panel is supported above the fuselage by two sets of N struts, whilst the lower panel is braced by two struts each side, all struts being attached to the top longerons of the fuselage. The fuel tanks are located in the top centre panel, between the spars, so that the petrol feed is of the simplest gravity type. Ailerons are fitted to both top and bottom planes, and are unbalanced, while the divided elevators and the rudder are balanced.
   As previously stated, the engine fitted is the Packard 2A-2500, 800 h.p. geared type, driving a 16-ft. airscrew; a tunnel type radiator is fitted.
   The "Pegasus" carries a service crew of three - pilot, located in line with the leading edges of the planes; bomber, located amidships; and gunner, located some way back of the main planes. The armament includes five machine guns, in addition to the bombs. It is stated that with larger wheels fitted, a 4,000-lb. bomb can be carried.
   Twelve of these machines were ordered by the U.S. Army Air Service, in addition to one heavy bomber of another type, known as the "Cyclops." The latter is also a single-engined machine of metal construction, but no details of are available other than it weighs approximately 17,000 lbs will carry a useful load of 9,000 lbs., is equipped with six machine guns, one 4,000 lb. or two 2,000 lb. or four 1,000 lb. bombs.
   The principal characteristics of the "Pegasus," together with certain performance details reported by the Engineering Division, are as follows :-
   Span 66 ft. 6 in.
   Overall length 46 ft. 2 in.
   Overall height 15 ft. 4 in.
   Chord 10 ft. 6 in. - 7 ft.
   Gap 9 ft. 4 in.
   Area of main planes 1,150 sq. ft.
   Angle of incidence 1 3/4 deg.
   Dihedral angle 2 deg.
   Weight, empty 5,323 lb.
   Disposable load 4,817 lb.
   Gross weight 10,140 lb.
   Weight per sq. ft. 8-82 lb.
   Weight per h.p. 12-63 lb.
   Speed range (loaded) 55 - 130 m.p.h.
   Climb to 1,000 ft. (loaded) 24 mins.
   Service ceiling (loaded) 16,000 ft.