F.Mason The British Fighter since 1912 (Putnam)

Port Victoria P.V.7 and P.V.8

   Early in 1916 the Admiralty directed the Experimental Construction Depot at Port Victoria and the Experimental Flight at Eastchurch to examine the feasibility of producing a small scout capable of taking off from a very short platform aboard a Torpedo-Boat Destroyer, specifying the use of a geared 45hp ABC Gnat engine.
   Both agencies produced independent designs, Capt W H Sayers rfc producing the P.V.7 at Port Victoria; at Eastchurch, Lieut G H Millar rnvr devised a rather different sort of aircraft. However, when Sqn Cdr H R Busteed moved from Eastchurch to assume command of Port Victoria, he took with him both Millar and his design, which was then designated the P.V.8. To differentiate between their design origins, the P.V.7 came to be called the Grain Kitten, and the P.V.8 the Eastchurch Kitten.
   The P.V.7 was unquestionably the more attractive of the two, with sesquiplane wings, outward canted and paired interplane struts, gracefully tapering fuselage in plan and low aspect ratio ailerons on the top wing only. There was a spigot-mounted Lewis gun above the wing. However, tested first on 22 June 1917, the P.V.7 proved difficult to handle on the ground, and tail-heavy in the air; moreover the sesquiplane layout, with high-lift wings, was shown to be unsuitable for the tiny aeroplane.
   By contrast, the aesthetically less-pleasing Eastchurch Kitten was much more successful. It featured heavily staggered single-bay wings of equal span employing I-form interplane and cabane struts from a crashed Sopwith Triplane, and when first flown on 7 September, it featured a balanced elevator without fixed tailplane. The pilot, Harry Busteed himself, reported severe longitudinal instability, with the result that a fixed tailplane was added, and much of the elevator horn balance was removed. To provide some shock absorption during landing, very big landing wheels with large-section tyres were fitted.
   As with almost all Port Victoria’s aircraft, the engines promised for the two Kittens never materialised, and both aircraft had to be modified to take the direct-drive 35hp version of the ABC Gnat. This engine, designed by Granville Bradshaw, was an ingenious horizontally-opposed twin-cylinder aircooled engine weighing 115lb dry. Yet, despite the obvious success of the P.V.8, and the ease with which it could be flown, interest in the idea was shortlived.


   Type: Single-engine, single-seat, single-bay lightweight biplane scout.
   Manufacturer: RNAS Experimental Construction Depot, Port Victoria, Isle of Grain.
   Powerplant: One direct-drive 35hp ABC Gnat horizontally-opposed two-cylinder aircooled engine.
   Dimensions: P.V.7. Span, 18ft 0in; length, 14ft 11in; height, 5ft 3in; wing area, 85 sq ft. P.V.8. Span, 18ft Oin; length, 15ft 7 1/2 in; height, 5ft 5in; wing area, 106 sq ft.
   Armament: Both aircraft equipped to carry one 0.303in Lewis gun above wing centre section.
   Prototypes: P.V.7, N539 (first flown by H R Busteed on 22 June 1917). P.V.8, 540 (first flown by Busteed on 7 September 1917). No production.

W.Green, G.Swanborough The Complete Book of Fighters

PORT VICTORIA P.V.7 (GRAIN KITTEN) UK

   To meet a requirement for a diminutive lightweight single-seat airship interceptor suitable for operation from platforms on relatively small seagoing vessels, the Depot produced the P.V.7 to the designs of W H Sayers. To become known as the Grain Kitten to distinguish it from a competitive design created by the RNAS Experimental Flight at Eastchurch (which accordingly became known as the Eastchurch Kitten), the P.V.7 was an extremely small sesquiplane intended to be powered by a 45 hp geared ABC Gnat two-cylinder air-cooled engine. Armament consisted of a single 0.303-in (7,7-mm) machine gun mounted above the wing centre section. Unavailability of the geared Gnat engine led to installation of a 35 hp direct-drive Gnat with which the P.V.7 was completed in the summer of 1917. Difficulties were experienced with the engine from the start of flight testing in June, the aircraft being tail-heavy and performance disappointing. A series of modifications was introduced, but the P.V.7 was not flown subsequently.

Max speed, 89 mph (143 km/h) at 2,000 ft (610 m).
Time to 6,500 ft (1980 m), 10.8 min.
Empty weight, 272 lb (123 kg).
Loaded weight, 491 lb (223 kg).
Span, 18 ft 0 in (5,49 m).
Length, 14 ft 11 in (4,55 m).
Height, 5 ft 3 in (1,60 m).
Wing area, 85 sq ft (7,90 m2).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Port Victoria P.V.7, the Grain Kitten, and P.V.8, the Eastchurch Kitten

  WHILE the P.V.5 and P.V.5a were under construction, an official request was made for the investigation of the possibility of building a small single-seat aeroplane of reasonable performance, powered by the 45 h.p. A.B.C. Gnat horizontally-opposed two-cylinder engine. The aim was to produce a machine which would be small enough to be carried by Torpedo-Boat Destroyers and similar small craft. Obviously, therefore, it had to be able to take off from a very small flying-off platform.
  Both the Experimental Construction Depot, Port Victoria, and the Experimental Flight at Eastchurch were asked to tackle this problem, and both ultimately produced designs. When the work began, the Experimental Flight was commanded by Squadron Commander H. R. Busteed, who had as his Chief Technical Officer Lieutenant G. H. Millar, R.N.V.R. Lieutenant Millar was the designer of the Eastchurch machine. When Squadron Commander Busteed took over the command of Port Victoria, Lieutenant Millar accompanied him, and the partly-built Eastchurch, machine was taken to Port Victoria for completion in the workshops there.
  The designation P.V.6 had been given to the design of a projected high-speed landplane scout which did not proceed beyond the preliminary layout. The little biplane designed by the Experimental Construction Depot was therefore designated P.V.7, and the Eastchurch machine was given the type number P.V.8 despite the fact that it was not a true P.V. design. Their diminutive size earned both machines the name Kitten, and for distinguishing purposes the P.V.7 was known as the Grain Kitten and the P.V.8 as the Eastchurch Kitten. Not unnaturally, the two Kittens differed markedly from each other. Like its predecessors, the Grain Kitten was a sesquiplane with wings of high-lift section and the characteristic elliptical vertical tail surfaces, but was otherwise of conventional appearance. The P.V.8, on the other hand, had rather severe lines with heavily staggered wings of equal span connected by a single broad interplane strut.
  Construction of the P.V.7 was entirely conventional - in fact, novel and unusual features were deliberately avoided in its design - and it was intended that the all-up weight should not exceed 520 lb. In point of fact the completed machine, fully loaded, weighed rather less than that.
  As with the P.V.4, P.V.5 and P.V.5a, so with the P.V.7 and P.V.8 the promised engines were not forthcoming. For want of the 45 h.p. geared Gnats each machine had to be considerably modified to take the 35 h.p. direct-drive Gnat instead. In both cases the engine had to be installed about six inches higher to bring the thrust line into its proper place. Both machines were completed in the summer of 1917.
  The Grain Kitten was completed first. On test, it proved to be tail-heavy, the performance did not come up to expectations, and it was very difficult to handle on the ground. Unfortunately, the original aerofoil section was by no means a success and ultimately new wings of more conventional form were fitted. At the same time the tail-unit was modified to overcome the tail-heaviness and the wheels were moved forward to improve ground-handling characteristics. Whether these attempted remedies proved effective is not known, because there is no record of any subsequent flights by the Grain Kitten.
  The P.V.8 design was based on a greater loaded weight than that of P.V.7, but larger wing area gave a lower wing-loading. The undercarriage had no springing: the large diameter tyres were relied upon to provide shock absorption. The lower ends of the main flying wires were anchored to the ends of the undercarriage axle, presumably to provide them with the most favourable angle possible. Ailerons were fitted to both wings, but only the upper mainplane was rigged with dihedral.
  As originally built, the P.V.8 had no fixed tailplane, but was provided with a balanced elevator similar to that which was a characteristic of the earlier Morane-Saulnier monoplanes and biplanes. On its first flight, however, the machine was found to be seriously unstable longitudinally. Most of the elevator balance area was removed, leaving only a small horn balance at the tip, and a small fixed tailplane was fitted. The effect of this modification was at once beneficial, and seemed to point to overbalancing of the original elevators as the cause of the instability.
  With its new tail unit, the Eastchurch Kitten proved to be remarkably successful. It was extremely easy to fly, and ultimately proved to be a much better aeroplane than the P.V.7 Grain Kitten.
  The P.V.8 became quite widely but erroneously known as the “Sopwith Kitten”, and was so described even in some official publications. The misnomer is usually attributed to the plank interplane struts, which resembled those of several types of Sopwith Triplane and the tapered-wing version of the Camel. Another possibility which cannot be completely disregarded is that the Sopwith company’s practice of naming most of their products after animals may have led to the belief that the Eastchurch Kitten was another addition to the Sopwith “Zoo”.


SPECIFICATION
  Manufacturers: R.N.A.S. Experimental Construction Depot, Port Victoria, Isle of Grain.
  Power: 35 h.p. A.B.C. Gnat.
  Dimensions: P.V.7: Span: upper 18 ft, lower 12 ft 7 in. Length: 14 ft 11 in. Height: 5 ft 3 in. Chord: upper 3ft 6 in., lower 2 ft 6 in. Gap: 3 ft. P.V.8: Span: 19ft. Length: 15 ft 7 1/2 in. Height: 5 ft 5 in. Chord: 3 ft. Gap: 3 ft.
  Areas: Wings: P.V.7, 85 sq ft; P.V.8, 106 sq ft.
  Armament: One Lewis machine-gun mounted above the centre-section.
  Serial Numbers: P.V.7: N.539. P.V.8: N.540.

  Weights (lb) and Performance:
Aircraft P.V.7 P.V.8
Date of Trial Report October 6th, 1917 October 11th, 1917
Type of airscrew used on trial Lang 2340 Lang 2340
Weight empty 284 340
Military load 30-5 30-5
Pilot 138-5 138-5
Fuel and oil 38 77
Weight loaded 491 586
Maximum speed (m.p.h.) at
2,000 ft 89 94-5
6,500 ft 85 87-5
10,000 ft 74 84
15,000 ft - 78
m. s. m. s.
Climb to
6,500 ft 10 50 11 00
10,000 ft 22 00 20 10
12,000 ft 35 00 - -
15,000 ft - - 47 00
Service ceiling (feet) 11,900 14,900
Tankage (gallons): Petrol 4 9
Oil 1 1

H.King Armament of British Aircraft (Putnam)

Port Victoria

P.V.7 (Grain Kitten). Designed specially for anti-Zeppelin operations from small naval craft, this tiny single-seat biplane of 1917 had a single Lewis gun above the centre-section, the trailing edge of which was cut away for elevation. Three drums of ammunition were specified.