J.Bruce British Aeroplanes 1914-1918 (Putnam)

Grain Griffin

  WHILE the P.V.9 was being constructed, a Sopwith B.1 single-seat bomber was delivered to Port Victoria. Instructions were issued that it was to be converted into a two-seat fleet reconnaissance machine, fitted with wireless and folding wings. The job was regarded as urgent, but in spite of that the Sopwith machine was delivered without a radiator and could not be flown for some time after its arrival at Grain.
  The Sopwith bomber was accompanied by its performance figures which, established at Martlesham Heath with a large load of bombs, were highly creditable. So good were the performance figures, in fact, that they gave rise to a good deal of conjecture as to why the aeroplane was not used for its designed purpose.
  The task of modifying the B.1 as required proved to be no easy matter. Its fuselage was comparatively slender and was not wide enough to accommodate the wireless installation, and the position of the outer interplane struts was such that they would foul the tailplane if the wings were folded. The Port Victoria design staff reported that it would be quicker and more satisfactory to design and build a new machine based on the Sopwith than to attempt to modify the original and produce a hybrid of doubtful value.
  Permission was granted for work on the new design, but the modification of the original machine was carried out at the same time.
  The modified aircraft was N.50. The pilot’s cockpit remained in its original position under the centresection, and a second cockpit for the observer was provided just behind the rear centre-section struts. The original narrow centre-section, borne on vertical struts, was retained; but the wing span had to be slightly reduced to enable the outer pair of interplane struts to clear the tailplane with the wings folded. The ailerons of N.50 were narrower than those of the original Sopwith B.1, and were hinged to an auxiliary spar some inches behind the rear spar. The engine was a 200 h.p. Hispano-Suiza; and a large hydrovane was fitted to the undercarriage forward of the wheels.
  These modifications were severely detrimental to the machine’s performance, and the ailerons proved to be virtually ineffective as control surfaces.
  By this time, design work was well advanced on the redesigned machine, which had been christened Griffin: six prototypes had been ordered. From the drawings for the new wings a set of mainplanes were made and fitted to the original fuselage. It is uncertain whether these wings included the wider centresection fitted to the Griffins proper, but the disposition of the bracing bays had been changed in such a way that the outer interplane struts cleared the tailplane when the wings were folded. The span was not reduced, however.
  The original universally-jointed control column was replaced by one with wheel control for the ailerons, and on test it was found that the machine had regained much of its lost performance.
  The true Griffins (that is, the machines built throughout to the revised design) had a wider fuselage and a considerably wider centre-section; consequently the span of the Griffin was 3 feet greater than that of the Sopwith B.1. In end elevation the centre-section struts were raked outwards, and the lower centre-section was braced by struts to the upper longerons of the fuselage.
  The first Griffin was N.100. This machine was powered by the 200 h.p. Sunbeam Arab, and had no hydrovane on the undercarriage. At first, plain ailerons were fitted, and were full-width surfaces hinged to the rear spar. Lateral control was still unsatisfactory, however, and horn-balanced ailerons were substituted: these cured the trouble. The engine installation also underwent detail modification at about this time.
  The original Sopwith-designed rudder was fitted to N.50 and, at first, to N.100. A horn-balanced surface of increased area was later introduced. The second true Griffin, N.101, was fitted with the 230 h.p. Bentley B.R.2 rotary engine in place of the Arab: the use of the alternative engine may have been prompted by trouble with the Arab.
  The Griffins were flown a good deal, but none saw operational service and the type was abandoned late in 1918. It was the last aeroplane to be produced by the Experimental Construction Depot.


SPECIFICATION
  Manufacturers: R.N.A.S. Experimental Construction Depot, Port Victoria, Isle of Grain.
  Power: N.50: 200 h.p. Hispano-Suiza. Grain Griffin: 200 h.p. Sunbeam Arab; 230 h.p. Bentley B.R.2.
  Dimensions: Span: 42 ft 6 in. Length: Arab, 27 ft 3 in.; B.R.2, 27 ft 6 in. Height: Arab, 10 ft 6 in.; B.R.2, 10 ft. Chord: 6 ft 3 in.
  Areas: Wings: 506 sq ft.
  Tankage: Petrol: 50 gallons. Oil: 5 gallons.
  Armament: One Lewis machine-gun on movable mounting behind rear cockpit.
  Serial Numbers: N.50; N.100-N.106.

  Weights (lb) and Performance:
Engine Arab B.R.2
No. of Trial Report N.M. 195 M.209
Date of Trial Report June 29th, 1918 June, 1918
Type of airscrew used on trial A.B.8212 Lang 4040
Weight empty 1,911 1,675
Military load 178 346
Grew 360 360
Fuel and oil 409 477
Weight loaded 2,858 2,858
Maximum speed (m.p.h.) at
5,000 ft 115 -
6,500 ft 113 112-5
10,000 ft 108-5 108
15,000 ft 101 99
m. s. m. s.
Climb to
6,500 ft 7 05 9 00
10,000 ft 12 00 15 55
15,000 ft 23 30 33 40
Service ceiling (feet) 19,000 16,500
Endurance (hours) 3 5 1/2

O.Thetford British Naval Aircraft since 1912 (Putnam)

GRAIN GRIFFIN

   Produced by the Port Victoria design staff at the Isle of Grain, the Griffin reconnaissance aircraft was based closely on the concept represented by the Sopwith B.1 single-seat bomber prototype of 1917. The Griffin introduced a second cockpit for an observer and folding wings for carrier operations. Prototype (N50) was followed by seven production aircraft (N 100-106). The type saw very little service but one (N 100) was reportedly embarked in HMS Vindictive during 1919. One 200 hp Sunbeam Arab or 230 hp Bentley B.R.2 engine. Span, 42 ft 6 in. Length. 27 ft 3 in. Maximum speed, 115 mph at 5.000 ft. Climb, 12 min to 10,000 ft. Endurance, 3 hr. Service ceiling, 19.000 ft.

H.King Armament of British Aircraft (Putnam)

Grain Griffin. This 1918 conversion of a Sopwith Bomber as a two-seater fleet reconnaissance aircraft had a Lewis gun on a pillar-mounted swiveling bracket behind the rear cockpit.