Aviation News — September 2017

experimentally with a two-pounder Davis Gun

above its cabin, but that modification went

no further. Further aircraft were 9061-9064

and N2140-N2159, though the final four were

probably not completed. Twenty additional

aircraft were ordered but later cancelled. All

from 9061 onwards received the 200hp geared

Hispano-Suiza and were known as the N.T.4A;

deliveries ran between March 1917 and

May 1918. Other modifications included an

increase in cockpit glazing and relocation of the

gravity tank above the upper wing, the ailerons

were reduced in chord and the lower rudder

given a protective plywood covering. N.T.4s

and N.T.4As flew from Calshot, Cattewater,

Torquay, Killingholme Seaplane School, Grain,

Dover, and Felixstowe Seaplane School, in

the roles of maritime patrol and later training.

Post-war, N2155 became G-EAOY but the

registration was cancelled in October 1920.

TRAINERS

Though the N.T.4/4A was of itself

successful, as a maritime patrol ’boat it was

eclipsed by the Felixstowe types, ironically

masterminded by Porte. But during the

winter and spring of 1917 the company also

built 20 FBA Type Bs (N1040-N1059), small

training flying boats, which became known

as N.T.5s. Norman Thompson also secured

success with a training ’boat of its own: the

N.T.2B.

The need for a small trainer for initial

instruction emerged as operational flying boats

grew bigger and more complicated. The N.T.2B

proposal found favour with the Admiralty and

in November 1916 ten were ordered, N1180

to N1189. The first arrived at Calshot Flying

School on June 8, 1917 and many subsequent

examples were based there, though N1181 and

N1189 spent time at Lee-on-Solent, Hampshire.

Deliveries were completed by October 1917.

The N.T.2B was a two-bay, unequal span

biplane, again with long-chord ailerons and

equipped with faired bracing kingposts above

the outermost struts. At first, power came

from an uncowled pusher 160hp Beardmore.

Side-by-side dual-control was fitted, the cockpit

enclosed with extensive glazing – a lesson

from the N.T.4. The hull bottom employed a

single step, the afterbody again supporting

a lengthy fin and the tailplane being suitably

high-mounted. The N.T.2B became the

standard RNAS flying boat trainer. A second

batch followed, N2555-N2579, delivered

between December 1917 and May 1918 and

powered mostly by the 200hp Hispano-Suiza.

N2760-N2784 appeared between April and

August 1918, again using the Hispano-Suiza

and built by Pemberton-Billing Ltd at Woolston.

N2400-N2429 were delivered from July to

November 1918 and were powered by the

Sunbeam Arab engine.

Deliveries of further batches, N2260-N2359

and N2500-N2523, began in November 1918,

but the war’s end served to cancel many.

Only N2260-N2295 and N2500-N2514 were

built, the latter by S E Saunders. Of the final

allocation, N3300-N3374, the first 14 may

have been constructed by Supermarine during

1919, although there’s no evidence of delivery.

The N.T.2B series was notable for its engine

changes, partly a product of Hispano shortages

but also intended to improve performance. Of

the first 50, most used the 160hp Beardmore,

though several received the 150hp Hispano-

Suiza. With the aim of providing more power, a

200hp Sunbeam Arab was tested in N2294, but

longitudinal control became difficult because

of the Arab’s greater torque, overcome by

mounting it slightly starboard of centre. When

the Arab proved temperamental another

change was made, this time to the 200hp

Hispano-Suiza; again, torque proved a problem,

cured by slewing the engine mounting.

After the war, many N.T.2Bs were stored

at Aeroplane Acceptance Parks and Marine

Aircraft Depots, while others travelled far and

wide: N2266 was purchased by a Norwegian

owner, N2275 joined the Royal Norwegian Air

Force, becoming N-12 and later N-27, while

N2288 became N-13. In May 1919, N2286

and N2287 were bought by the Estonian Air

Force. The Japanese Government acquired

N2283, while N2284 and N2293 joined the

Peruvian Air Force. N2290 became G-EAQO,

before travelling to Canada where it assumed

G-CACG.

Norman Thompson produced several other

designs during the war years. A pusher 150hp

Hispano-Suiza-powered flying boat serialled

N26 was ordered early in 1917, arriving at

Calshot during April. A two-seater, it bore a

marked similarity to the No 3 Flying Boat. A

second project, to Admiralty Specification

N.1B, was a tandem fighter flying boat, again

a pusher, employing the 200hp Hispano-Suiza

between equal-span two-bay wings designed

to fold. The N.1B discarded Thompson’s

favoured lengthy fin for a more conventional,

higher aspect-ratio arrangement. Serialled

N37, it was completed in December 1917 and

travelled to Grain for assessment, but crash-

landed during January 1918. Trials revealed

http://www.aviation-news.co.uk 81

Employing an early, very limited form of cockpit glazing, N.T.4 8343 comprised a boat-built hull

form with broad-chord ailerons. This photo was taken at Killingholme Seaplane School in 1917.

Norman Thompson N.T.5 prototype N1040, a modified FBA Type B flying-boat. This was the

only example to feature a triangular-section rear hull with a flat top.

The private venture pusher 150hp Hispano-Suiza-powered two-seat flying boat N26 was

purchased by the Admiralty for trials.

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