O.Thetford British Naval Aircraft since 1912 (Putnam)
Norman Thompson N.T.4
The Norman Thompson N.T.4 is perhaps the least known of all the large flying-boats employed on coastal patrol by the RNAS in the First World War. It never enjoyed the fame that attended the American Curtiss boats, or the Felixstowe series, but nevertheless was responsible for a good deal of routine anti-submarine reconnaissance from a string of bases between Calshot and Scapa Flow.
The N.T.4 was the first new design to appear after the old White and Thompson Company changed its name to the Norman Thompson Flight Company in October 1915, and its emergence coincided with the Curtiss H.4. For this reason, in the somewhat haphazard custom of those days, it was known by the name of 'America', and later changed to 'Small America', in the same way as the Curtiss. This may account for the obscurity in which its operational record is shrouded, as there may have been some confusion between the two types in official archives.
A feature of the N.T.4 was the completely enclosed accommodation for the crew. In the earlier version the view was poor and the cabin was progressively improved, so that in the late production models the cabin-top was glazed as well as the sides.
The first batch of aircraft (Nos.8338 to 8343) were fitted with two 150 hp Hispano-Suiza engines. Subsequent machines had 200 hp geared Hispanos, were designated N.T.4A and were allotted the serial numbers 9061 to 9064 and N2140 to 2159. Production ceased in the summer of 1918 after 30 had been built.
One of the N.T.4 flying-boats (No.8338) was the subject of an interesting experiment in armament. It was fitted with a Davis two-pounder recoilless gun mounted above the cabin. The installation was never embodied in production aircraft.
RNAS coastal air stations at Calshot, Cattewater. Dundee, Felixstowe, Invergordon, Killingholme and Scapa Flow.
TECHNICAL DATA (N.T.4A)
Description: Anti-submarine reconnaissance flying-boat with a crew of four. Wooden structure, with wood and fabric covering.
Manufacturers: Norman Thompson Flight Co Ltd, Bognor Regis, Sussex.
Power Plant: Two 200 hp Hispano-Suiza.
Dimensions: Span, 78 ft 7 in. Length, 41 ft 6 in. Height, 14 ft 10 in. Wing area, 936 sq ft.
Weights: Empty, 4,572 lb. Loaded, 6,469 lb.
Performance: Maximum speed, 95 mph at 2,000 ft; 91 mph at 10,000 ft. Climb, 3 min 50 sec to 2,000 ft; 31 min 5 sec to 10,000 ft. Service ceiling, 11,700 ft.
Armament: Possibly provision for free-mounted Lewis gun firing through a side window and racks for bombs beneath lower wings.
H.King Armament of British Aircraft (Putnam)
N.T.4 and 4a. The first N.T.4 twin-engined pusher flying-boat (1917) had a 2-pdr Davis recoilless gun mounted above the enclosed cockpit in the nose. The mounting was braced by lateral struts running downward through the cockpit. Later a Lewis gun may have been carried by aircraft of this type. For anti-submarine work a maximum load of two 100-lb bombs appears likely.
N.1B. A two-seater, this fighter flying-boat was probably intended to carry a Lewis gun for the observer's use.
N.2C. Developed in 1918 primarily for patrol, this flying-boat probably carried a Lewis gun, and perhaps bombs also.