N-3PB Patrol Bomber

With delivery in February of the first Northrop N-3PB patrol bomber seaplane, Northrop Aircraft, Inc, set a unique production record by designing, tooling, building, testing, and delivering a military airplane in just eight months. This record was estaishehed in spite of the fact that Northrop Aircraft did not even have a factory building completed when the order was taken.

A three-place single-engine, low-wing full cantilever monoplane seaplane equipped with two Edo floats, the N-3 patrol bomber incorporates novel features of design and construction. In addition to a load of 2,000 lb of bombs, each plane is equipped with six machine guns. Four .50-caliber guns are mounted in the wings, and two .30-caliber guns on flexible mounts are carried in the fuselage to fire aft, top and bottom.

Of general design and construction made familiar by earlier Northrop planes, the N-3 incorporates stressed-skin aluminum alloy covering over fuselage, wings, and fixed tail members. The fuselage is fabricated in two sections, divided along the horizontal centerline, the lower half being built integral with the center wing section. Generous use of extruded aluminum alloy stringers is made in fuselage and wings. Accommodations for the crew are provided in tandem cockpits, with a transparent enclosure of streamlined form extending over the three cockpits. As in earlier Northrop designs, the split trailing edge wing flap is incorporated. Power is supplied by a Wright Cyclone GR-1820-G200 engine of 1,200 hp.

The two Edo floats are mounted to the center wing section by streamlined full cantilever pedestals, eliminating all struts and brace wires. The airplane may also be equipped with wheel landing gear for operation from land.

A measure of the excellence of this a rplane is given by comparison of test results with the performances originally guaranteed to the Norwegian gov't:

Performances
Guarantees
(Estimated)
(Actual test
results)
Maximum speed at 16 400 ft    
  Military rating  228 mph  260 mph
  Normal power  224 mph  
Cruising speed at 16,400 ft    
  65% normal power  184 mph  215 mph
Landing speed at sea level  72 mph  65 mph
Takeoff to clear obstacle of
50 ft at sea level
  2,100 ft  Cleared 75 ft from 2,100 ft run
starting from lake surface
1,500 ft above sea level.
Service ceiling  24,000 ft  29,000 ft

Specifications and performance data on the Cyclone-powered N-3PB are:
Wing span…  48' 11"
Overall length…  38'
Overall height…  12'
Wing area…  376.8 sq ft
Wing loading…  24.4 lb/sq ft
Power loading…  7.65 lb/hp
Gross weight…  10,600 lb
Fuel capacity…  320 gal
Oil capacity…  23 gal
Maximum speed…  260 mph
Cruising speed…  215 mph
Service ceiling…  28,400 ft
Cruising range…  1,400 miles

This article was originally published in the "Flying Equipment" column of the April, 1941, issue of Aviation magazine, vol 40, no 4, p 77.
The original article includes 1 photo.
Photo is not credited.