Flight, December 1927

THE CURTISS "CONDOR”
A Recent American Night Bomber

   IN a recent issue of FLIGHT, reference was made to the tests that had been carried out with a new bombing machine, known as the "Condor," constructed by the Curtiss Company. We are now able to give some illustrations and brief particulars of this machine.
   The "Condor," which is claimed to be the largest all-metal bomber in the world, is a twin-engined fuselage biplane, being a development of the Curtiss NBS-4 bomber built by the Curtiss company in 1924 which proved to be a very successful machine in service. Several of the NBS-4 features have been retained in the "Condor," which together with various improvements and increased power should go to make the new bomber one of the best of its class.
   In spite of its size - it has a span of 90 ft. and weighs, empty, 9,020 lbs. - it has an excellent performance, accomplishing in its preliminary tests a speed of 128 m.p.h. and attaining a service ceiling of IS,000 ft. Fully loaded it took off in 18 seconds, climbed well, was easy and sensitive on the controls, and flew well on one engine. It carries a useful load of about 7,300 lbs., or 45 per cent, of its gross weight.
   Perhaps the most interesting feature of the "Condor" is the location of its crew of five, comprising pilot, bomber and three gunners. One of the latter is stationed in the nose of the fuselage when with his double Lewis gun he commands an uninterrupted range of fire forward, above and below. The second and third gunners are located in cockpits at the rear of each of the engine nacelles, which project beyond the trailing edges of the lower planes, from which position an unrestricted range of fire to the rear is obtained.
   This placing of the gunners, therefore, is such that it permits intersection of fire at any given point by at least two of the three gunners. The "Condor" should thus prove to be a formidable customer for any attacking aircraft.
   The pilot's cockpit is located, as usual, in the forward part of the fuselage, in line with the leading edge of the main planes; it is provided with two seats side by side, and a "single-dual" control. That is, it is a conventional wheel-type control column which is, however, pivoted so as to swing from side to side and thus be operated from either seat. The rudder pedals and seats are adjustable to suit the pilot. Auxiliary pedals are provided for operating hydraulic brakes fitted on the landing wheels, which can be applied either in unison or independently. The bomber's compartment is located forward below the pilot, and sliding metal floors provide communication between the bomber's compartment and the pilot's cockpit; the forward gunner can also obtain access to the bomber's compartment. The starboard gun station, it may be added, is provided with wireless apparatus while the port gun station is equipped with photographic gear, so that the two rear gunners also act as wireless operator and photographer.
   As regards the construction of the "Condor," several interesting features arc to be found. The structure is entirely of metal, in which duralumin plays a greater part, this material being employed for the fuselage, tail and wing ribs, while alloy steel is used for the wing spars, engine mounting, bomb-bay and other highly-stressed parts.
   The high-aspect wings, which are of equal span and chord without sweep back but with a dihedral angle of 3 degs. For the lower plane, are of conventional design, having the C-72 wing section developed in the Curtiss wind tunnel. The upper wings comprise a centre section and two outer panels (each two-bay), and the lower wings have two "sidewalk" panels between engine nacelles and fuselage and two outer panels corresponding to the upper ones.
   Balanced ailerons of the Frieze type are fitted to both top and bottom planes, providing exceptionally easy and effective lateral control. The operating cables are in the lower wings, a strut connecting upper and lower ailerons.
   The main wing spars - of welded heat-treated chrome-molybdenum steel - are built up of two elliptical tubes with welded interbracing forming a Warren truss ; the ribs are built up of riveted Duralumin. The only non-metal material of the wings is the fabric covering. Numerous inspection windows (celluloid) are provided at various points. Interplane bracing is of the usual streamlined wires and steel-tube struts, with all attaching fittings concealed.
   It is stated that the entire wing structure comes out lighter than one of wood construction - the average weight of the wing panels of the "Condor" being 1-30 lbs. per square foot as compared with 1-34 lbs. per square foot for the wood and fabric wings of the NBS-4 - in spite of the fact that the "Condor" has a greater wing loading.
   The tail is of the biplane type - similar to that used on the NBS-4 - of Duralumin construction, fabric covered. The stabilisers are adjustable in flight, and the twin rudders are provided with an automatic compensating device which can be set by the pilot to hold the rudders in an offset position when flying on one engine.
   The fuselage is a Warren truss structure of Duralumin tubing, except in the highly-stressed parts, where steel is employed. Fittings are of steel tubing or sheet steel fastened into the tubing with hollow steel tubular rivets.
   A standard Army G-5 bomb rack is fitted in the fuselage, just aft of the pilot's cockpit, and non-shatterable glass windows are provided in the nose and floor for bomb sighting.
   The two Curtiss V-1500 engines arc carried in outboard nacelles on the lower plane, each engine being located at the forward end and driving a tractor airscrew. The nacelles are of steel tubing and the engine mounting is detachable. In each nacelle, just aft of the engine, is a 192-gal. petrol tank, while a third, 60-gal., tank is carried in the upper wing. Either engine can draw fuel from any one of these three tanks, while in the event of failure of the fuel pump on either engine, the other pump will supply fuel to both engines.
   Cartridge core type radiators, of fan streamline section, are employed for cooling, one radiator, with vane shutters, being mounted above the nacelle behind the engine.
   The engines are neatly cowled, new flush type fasteners being used, which facilitate quick removal and replacement. Each engine drives a 14-ft. Curtiss-Reed airscrew at 1,200 r.p.m. (engine speed - 2,400 r.p.m.). The pitch of the blades can be adjusted on the ground.
   The landing gear is of the non-axle type, and the shock-absorbing unit is a combination of oleo and the compression rubber disc unit employed successfully on other Curtiss machines.
   It may be of interest to note, in conclusion, that the "Condor" when completed weighed within 10 lbs. of the original calculated weight!
   The principal characteristics of the "Condor" are :-
   Span 90 ft. 0 in.
   O.A. length 47 ft. 5 1/2 in.
   Height 16 ft. 6In.
   Chord 9 ft. 0 in.
   Gap (max.) 13 ft. 6 in.
   Wing area 1,498 sq.ft.
   Weight, empty 9,020 lbs.
   Weight, laden 16,300 lbs.
   Wing loading 10-9 lbs./sq. ft.
   Power loading 13-6 lbs./h.p.
   Speed range 56-116m.p.h.
   Climb (ground level) 860 ft./min.
   Ceiling 14,000ft.
   Range (cruising) 800 miles.