K.Wixey Parnall Aircraft Since 1914 (Putnam)
Parnall and Sons Limited
Aircraft Built under Contract 1914-1918
Parnall Scout / Zepp Chaser
On the evening of 19 January, 1915, the German Zeppelin airships L3 and L4 made the first air attack on Britain, when they bombed Great Yarmouth and King's Lynn killing four people, injuring 16 others, and causing damage to a number of houses and a power station.
As a result the government began organising home-defence units on a more effective basis, a move which necessarily involved the deployment of forces in Britain that would otherwise have proved strategically more valuable elsewhere. The possibility of the demoralisation of the civil population, which had never before been subjected to such terror from the skies, was another factor the authorities had to take into consideration.
It was decided that the most effective deterrent against the large airships was the aeroplane, and as a consequence B.E.2c and D.H.4 biplanes of the RNAS were sent up on anti-Zeppelin patrols, at times meeting with some success.
The Admiralty, having assumed the role of defender of Britain's coastline against air attacks, soon wished to procure an aircraft type of naval concept that would be capable of quickly intercepting any raiding German airships. As a result Parnall was invited to submit plans for such a type. The requirements were for a single-seat scouting aeroplane for service with the RNAS which would have the ability to rapidly attain the height of marauding Zeppelins and attack them.
The response from Parnall was the Scout, or Zepp-Chaser as it was more popularly known, and it was the company's first aircraft design.
The Parnall Scout's creation was accredited to Adolf Camden Pratt (later to become head of Vickers Aviation stress section), but the idea for the aircraft was attributed to Keith Davies, who was a test pilot with the Parnall company at that time. Davies was born in London during 1885, trained as an engineer and became interested in aviation. He held RAC Aviator's Certificate No. 22, and flew with the early pioneers at Brooklands, where he was employed by Messrs Humber in connection with the Humber three-cylinder engine installed in a Bleriot monoplane. Davies later went to India with Capt Windham and gave flying demonstrations in the Central Provinces Exhibition at Allahabad, thus becoming in 1910 the first man to make an official flight in India. In 1912, Keith Davies was the second officer to be gazetted to the RFC reserve, and later was attached to the Royal Aircraft Factory as an experimental pilot. He was one of the first pilots to undertake night-flying tests, and after being a member of the AID at Farnborough, Davies transferred to Parnall & Sons where it was intended that he should take on the duties of a test pilot flying both landplanes and seaplanes. Keith Davies joined Parnall in 1916, and after his work with the Zepp-Chaser, he eventually left the company's services to take over an aircraft factory in London until the end of the war.
Davies's ideas and Camden Pratt's interpretation of them in designing the Parnall Scout - sometimes referred to as the 'night flyer' - resulted in a large aeroplane incorporating a two-bay biplane layout with unequal span wings and considerable stagger. In order to provide the pilot with a good field of view, the upper mainplane was quite close to the top of the fuselage, the lower mainplane being set well below it and attached by N struts, the forward sections of which were symmetrical with the rear undercarriage legs.
The undercarriage was a cumbersome affair of the cross-axle type with thick front supporting members attached to the corners of the blunt nose. The 250 hp Sunbeam Maori II was cooled by a large square-shaped radiator slung between the undercarriage legs. The Zepp-Chaser's nose-heavy appearance was accentuated by the fitting of a large diameter two-bladed wooden propeller. The upper mainplane trailing-edge contained a large cut-out to enhance the pilot's upward field of view. Ailerons were fitted to all four wings while the relatively short fuselage necessitated a large tailplane.
The Parnall Scout was completed in an all-black factory finish in readiness for its role of Zeppelin interception at night.
Meanwhile a nocturnal attack system against enemy airships had already been tried out at Orfordness and applied with some success to a number of Home-Defence aircraft types. The idea was to fit a machine-gun at an angle to the side of the aircraft's cockpit, and when the pilot dived his machine at a predetermined attitude at the target, the machine-gun fired on a horizontal trajectory. As a consequence the Parnall Zepp-Chaser was fitted with a .303-in Lewis gun mounted on the starboard side of the cockpit at an angle of forty-five degrees.
The Parnall Scout was destined never to fire its gun in anger however, if it ever fired it at all! When the machine was sent to Upavon for its trials, the stress calculations proved the Zepp-Chaser to be excessively heavy and the aircraft's safety factor was declared as very low. Indeed after further ground tests had been made the machine was proclaimed as unsafe, and as far as is known, it was never flown.
Two Parnall Scouts were originally ordered (N505-N506), but only N505 was built.
The second Zepp-Chaser was to have been powered by a 190 hp Rolls-Royce Falcon engine, but work on this aircraft was never started. Parnall are believed to have scrapped the sole example of the Zepp-Chaser in 1917.
The following information was gleaned from the official Aeronautical Inspection Directorate (Preliminary Experiment Report) of 1916.
Parnall Scout (Zepp-Chaser)
Two-seat scout for defence against German airships. 250 hp Sunbeam Maori II twelve-cylinder vee water-cooled engine.
Span 44 ft upper, 40 ft lower; chord 7 ft upper, 5 ft 6 in lower; incidence 2 deg; dihedral 4 deg; stagger 4 ft; gap 5 ft 6 in; wing area 516 sq ft; aileron area 36 sq ft; tailplane span 18 ft; tailplane area 74 sq ft; elevator area 38 sq ft; fin area 6.5 sq ft; rudder area 12.75 sq ft.
Estimated maximum speed 113.5 mph at sea level, 101.5 mph at 10,000 ft.
Fuel 36 Imp Gal.
One .303-in Lewis machine-gun at 45 deg elevation.
Two ordered, only one completed.
H.King Armament of British Aircraft (Putnam)
Zeppelin Scout. Built in 1916 for 'Zeppelin strafing at night', this large single-seater had a gun mounted in the starboard side of the cockpit and firing forward and upward at 45 degrees. This gun appears to have been, or to have been intended to be, a Crayford rocket gun, as installed in the Vickers F.B.25 and the N.E.I built by the Royal Aircraft Factory. The makers stated in June 1916 that, in order to provide maximum field of vision, the upper wing was placed substantially in the line of forward horizontal vision of the pilot, and the lower wing was arranged substantially symmetrically below his seat. Mention was made of a cut-out in the upper trailing edge to allow downward vision, and the scat could be adjusted up and down.
F.Mason The British Fighter since 1912 (Putnam)
The Parnall Scout of 1916 was one of those aircraft which themselves came to naught yet, being somewhat adventurous in approach, contributed more than a modicum to the growing fund of knowledge about design parameters. Parnall & Sons of Bristol, an established firm formerly engaged in general woodworking, had for some time been manufacturing Avro 504s and Fairey Hamble Babies, and the high quality of workmanship evident in those aircraft had prompted the Admiralty to encourage the company to embark on designs of its own.
Designed by A Camden Pratt, the company’s first aircraft was a relatively big, single-engine biplane intended for the RNAS as a night fighter which, in 1916, would have been a euphemism for an ‘anti-Zeppelin’ aircraft. However, unlike other such aircraft, it was intended to possess high performance and great strength. To these ends a water-cooled 250hp Sunbeam in-line engine was selected as powerplant and an extremely strong structure designed. The two-bay wings of unequal span were rigged with considerable stagger, the upper wing being located fairly close to the fuselage to afford the pilot a good upward field of vision; the lower wing was also a continuous structure, located below the fuselage. The sturdy undercarriage, comprising twin V-struts, was positioned well forward to cater for the big engine.
Whether the Scout ever flew is not known. It was delivered to Upavon for its official tests - and such tests occasionally included an aircraft’s maiden flight - but on measurement of its weight and c.g. range it was immediately decided that the safety factor was dangerously deficient. As far as is known, all work on the aircraft stopped forthwith. It was subsequently burned to make space available for other work at the factory.
Type: Single-engine, single-seat, two-bay biplane night fighter.
Manufacturer: Parnall & Son, Eastville, Bristol.
Powerplant: One 250hp Sunbeam water-cooled in-line engine driving two-blade propeller.
Dimensions: Span, 44ft 0in.
Performance: Design max speed, 113.5 mph at sea level.
Armament: Intended to fit a two-pounder Davis recoilless gun, inclined to fire upwards at about 45 degrees immediately forward of the cockpit.
Prototype: One, N505 (probably completed in July 1916, but it is not known whether it was flown). No production.
W.Green, G.Swanborough The Complete Book of Fighters
PARNALL SCOUT UK
Parnall and Sons of Bristol initiated work on the company’s first original aircraft, a single-seat anti-airship fighter to the designs of A Camden Pratt, in 1916. Intended to meet a requirement formulated by the Admiralty, this aircraft, unofficially known as the Zeppelin Chaser, was a large, two-bay staggered biplane of wooden construction. It was powered by a 260 hp Sunbeam Maori 12-cylinder water-cooled engine and armed with a single 0.303-in (7,7-mm) gun offset to starboard and firing upward at an angle of 45 deg. Two prototypes were ordered, but the first of these proved appreciably overweight. Although the Scout reportedly flew twice, it was considered to possess unacceptably low safety factors and was returned to the manufacturer, development being abandoned. The following data are manufacturer’s estimates.
Max speed, 113 mph (182 km/h) at sea level.
Span, 44 ft 0 in (13,41 m).
Wing area, 516 sq ft (47,94 m2).