A.Jackson Avro Aircraft since 1908 (Putnam)

Avro 501 and Avro 503 (Type H)

   The choice of Shoreham as the Avro company's new flying ground when it moved from Brooklands in the autumn of 1912 was largely the result of Cdr. Schwann's successful waterborne experiments and Avro's awakening interest in seaplanes. It was an ideal site with Shoreham Harbour close at hand and it was from the adjacent River Adur that the Avro Type H seaplane made its first take-off. Construction of this machine followed tests on Windermere by H. Stanley-Adams in January 1913 with the Avro 501 which, apart from a considerable strut-braced top wing overhang, was similar to an enlarged float-equipped Avro 500. Built at Brownsfield Mills in November 1912 and powered by a 100 h.p. Gnome, the Avro 501 first flew as an amphibian with a sprung central float designed by O. T. Gnosspelius, 15 ft. long and 7 ft. wide from which projected three small wheels, two in the rear and one forward. With so narrow a float an aircraft with a wing span of 47 ft. 6 in. could be expected to heel over when steerage way was lost, and for this reason small wing tip floats were fitted and inclined to sit squarely in the water. This arrangement proved unsatisfactory and Gnosspelius replaced it with a twin float unit without wheels which made the aircraft sufficiently seaworthy to interest the Admiralty, to whom it was eventually delivered in the Isle of Grain. In the light of experience at Barrow, the airscrew leading edges were sheathed with brass to prevent damage from flying spray and the tail float was bolted directly to the old-style sprung rudder for steering on the water.
   Also powered by a 100 h.p. Gnome, the Type H (later known as the Avro 503), was a slightly larger version of the Avro 501 but with less mainplane overhang and no inclined struts. Following standard Avro practice, the new seaplane was built with an eye to quick dismantling and was constructed round a 9 ft. centre section to which were bolted fuselage, undercarriage and outer wing panels. The upper mainplane, 3 ft. greater in span than the lower, was fitted with large inversely tapered ailerons but none was fitted to the lower wing. Two-step, internally sprung floats, 14 ft. long and 2 ft. 6 in. wide, set at a track of 6 ft. 6 in., were covered with rubberised material and attached to the aircraft by 14 tubular steel struts bound with varnished fabric.
   Such was his confidence in the Type H that F. P. Raynham made the first take-off from the Adur in sea mist on May 28, 1913 carrying passenger John Alcock, two hours' fuel and an anchor. The aircraft became airborne after a run of only 60 yards and cleared the adjacent railway bridge by 100 ft. Next day, again carrying the future conqueror of the Atlantic, Raynham made a first landing on the open sea outside Volk's seaplane hangar opposite Paston Place, Brighton. A float was damaged on take-off so a landing was made in Shoreham Harbour where the aircraft was hastily beached. After some local strengthening of the nose of each float the machine was out again on June 12 and two days later Raynham made an hour's demonstration flight over Brighton carrying Lt. J. W. Seddon R.N., Inspector of Naval Aircraft. Despite the weight and drag of the floats, the Type H climbed to 1,300 ft. in 5 minutes.
   The Avro 503 was then flown by Capt. Schultz, a German naval officer who had made several visits to the works while it was under construction, and before the month was out the machine was purchased by the German Government, dismantled and packed for shipment. Flown by Lt. W. Langfeld it became on September 3, 1913 the first aircraft to cross the 40 miles of North Sea from Wilhelmshaven to the Island of Heligoland, a successful return trip to Cuxhaven being made on September 15. An Avro 503 seaplane was also ordered by the Peruvian Government but the outbreak of the First World War prevented delivery and it is believed to have been turned over to the British Admiralty.
   At least-three other 100 h.p. Gnome-powered Avro 503s were built - all to Admiralty order for use by the Royal Naval Air Service. The float undercarriage of the old Avro 501 having proved far too heavy, the Admiralty agreed to accept it as a landplane. A. V. Roe thereupon devised a two-wheel, twin skid undercarriage but the track was still too narrow to support the aircraft vertically at rest and stout wing tip skids were necessary. In landplane form, with large inversely tapered ailerons replacing the constant chord units, the Avro 501 was so quaint a structure that it soon earned the name "Rickety Ann". After delivery to Eastchurch it had to be lightened and several airscrews tried before F. P. Raynham could complete the acceptance tests. Bearing naval serial 16 it was flown to Shoreham on June 2, 1913 by Raynham with Lt. Seddon as passenger.
   In the course of R.N. A. S. trials by F. P. Raynham at Eastchurch on August 28, 1913 a second landplane climbed to 3,000 ft. in 19 minutes with 36 gallons of petrol, 10 gallons of oil and 182 lb. of ballast. In the speed test 65.1 m.p.h. was reached and this aircraft, last of those ordered from A. V. Roe before the firm became a limited company, was followed by a float-equipped example which arrived at Sheerness in crates on September 8, 1913. On October 15 it was handed over to the R.N.A.S. in the Isle of Grain where it was joined eventually by an improved version built in the following December. One of these machines was damaged in a hangar fire at Eastchurch and sent to Brooklands for repair in July 1914.

SPECIFICATION AND DATA
   Manufacturers: A. V. Roe and Company (reconstituted as A. V. Roe, and Co. Ltd. 11.1.13), Brownsfield Mills, Great Ancoats Street, Manchester (moved to Clifton Street, Miles Platting, Manchester 4.13); and Shoreham Aerodrome, Sussex
   Power Plant: One 100 h.p. Gnome
   Dimensions, Weights and Performances:
   Avro 503 seaplane
   Span (upper) 50ft. 6 in.
   Span (lower) 47ft. 0 in.
   Length 33ft. 6 in.
   Height 12ft. 9 in.
   Wing area 567 sq. ft.
   All-up weight 2,200 lb.
   Maximum speed 50 m.p.h.
   Initial climb 225 ft./min

   Production:
   Avro 503 prototype first flown at Shoreham 28.5.13, to the German Navy 6.13 with serial D12
   At least one other landplane to R.N.A.S. Eastchurch and two seaplanes to R.N.A.S. Isle of Grain

H.King Armament of British Aircraft (Putnam)

503 (Type H). There is reason to suppose that a seaplane of this type, which appeared in 1913, made a bombing attack on Zeebrugge early in the war, but the load is not known.

M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)

P.Lewis British Aircraft 1809-1914 (Putnam)

Avro H 503

   In May, 1913, the prototype of the first Avro production seaplane appeared at Shoreham for testing by Jack Alcock and F. P. Raynham. The new machine was based on the successful 500, but was fitted with greater power for water operations in the form of the 100 h.p. Gnome. Wings of 50 ft. span and 567 sq. ft. area were fitted to provide sufficient lift to overcome the drag of the water when taking-off; the stubs of the lower wings were built as an integral part of the fuselage for a distance of 9 ft. out, the outer panels being readily detachable. Inversely-tapered ailerons were hinged to the upper wings. The two main floats were of Avro design with a single step each and were 14 ft. long and 2 ft. 6 ins. wide, being set with a 6 ft. 6 ins. gap between them. The unstepped tail float was mounted on the underside of the rudder.
   The 503 was very successful in its trials on the South Coast, taking off in 180 ft. in a calm. Raynham was accompanied by an anonymous German officer, Capt "X", during the test flights, at the end of which the prototype was bought by Germany. The machine was dismantled in June, 1913, and sent to its new owners. Two months later, on 6th September, Leutnant Langfeld flew the 503 from the German coast to Heligoland. One machine was supplied to a British private owner and a few went to the R.N.A.S. One of these seaplanes was converted to a landplane for training at Eastchurch Naval Air Station, flying there as No. 16, and was given extra strut bracing to the upper wing-tip extensions.

SPECIFICATION

   Description: Two-seat tractor hydro-biplane. Wooden structure, fabric covered.
   Manufacturers: A. V. Roe & Co. Ltd., Brownsfield Mills, Manchester.
   Power Plant: 100 h.p. Gnome.
   Dimensions: Span, 50 ft. Length, 33 ft. 6 ins. Height, 12 ft. 6 ins. Wing area, 567 sq. ft.
   Weights: Loaded 2,200 lb.
   Performance: Cruising speed, 48 m.p.h.

Журнал Flight

Flight, July 12, 1913.

THE AVRO WATERPLANE.

   THE new Avro 100 h.p. waterplane, which has been flying so well at Shoreham in the hands of Mr. Raynham, is the first machine to have floats designed by A. V. Roe and Co., their earlier hydroplanes having been built to customers' designs. The result appears to have justified the enterprise, for the machine gets off the water within 60 yards in calm weather, and requires but little more space in a moderate swell.
   In general, the Avro waterplane has a close resemblance to the usual Avro type, which is already so well known in the R.F.C. It is, of course, considerably larger throughout, as is rendered necessary by the larger engine power, and by the comparative difficulty of arising from water, as compared with getting off land. Furthermore, there are certain alterations in construction which have been rendered necessary by the altered conditions, as, for example, the substitution of flaps for warping.
   The main planes measure 50 ft. in span, as compared with the standard span of 36 ft., and contain five panels instead of three, as in the standard Army type. They have a chord of 6 ft., and the gap between planes is 6 ft. 9 ins. The upper plane only is provided with flaps of 12 ft. 9 ins. span each, increasing in chord towards the tips. These are balanced to pull up as well as down.
   The body is supported from the wings in the usual Avro style, with the exception that the planes, instead of detaching from the body itself, detach from a fixed inner cellule having a span of 9 ft., so that the struts at its extremities are immediately above the floats.
   These latter are of the pure hydroplane type with 2 steps, and are 14 ft. long x 2 ft. 6 ins. wide, with their inner edges 6 ft. 6 ins. apart. The total buoyancy when submerged is 4,400 lbs., or twice the weight of the machine. The chassis struts are all of steel bound with varnished fabric, and are 14 in number, 7 each side, of which 6 support the cellule from the float, whilst the 7th is carried direct to the engine bearers on the fuselage.
   The body itself is rectangular in cross-section with a horizontal top and curved bottom. It tapers at the rear to a vertical rudder post which carries the rudder, and with it a small tail float, which moves with the rudder for steering purposes. The elevators and empennage are of the standard Avro size. The pilot's seat is behind the passenger's, the latter being placed on the centre of gravity of the machine. The engine is enclosed in the usual housing, with a wind-shield for the pilot.
   The tractor-screw is an Avro with brass-capped leading edge at the tips, having a diameter of 8.9 ins. and a pitch of 6 ft. The control is by wheel and rudder bar, and is of the usual type.
   The weight of the whole machine with full allowance of fuel is just under one ton, and the surface of the main planes being 567 sq. ft. gives a loading of rather under 4 lbs. per sq. ft., and 22 lbs. per h.p. This means, of course, that the machine is not a very high speed one, its estimated velocity being about 48 to 50 miles per hour. This slow speed was adopted as being more likely to be successful, considering the experimental state of our present-day knowledge of hydroplane floats.
   It is interesting to know that this machine is already purchased by a private owner, and that several are already on order for the Admiralty.