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.

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Avro 503

  THE Avro company produced their first seaplane type in May, 1913. It was a large tractor biplane, powered by a 100 h.p. Gnome fourteen-cylinder engine, and was originally known as the Avro Type H. Later, the type number 503 was bestowed upon the aircraft.
  A. V. Roe & Co. were not without some experience in the construction of seaplanes, for an Avro tractor biplane had been used in 1911 by Commander Oliver Schwann m his experiments, aimed at producing a seaplane, which were conducted at Barrow-in-Furness. The company also built the airframe of the Waterbird Curtiss-type biplane for the Lakes Flying Co.
  The Avro 503 bore a certain resemblance to the Avro 500, particularly in the shape of its fuselage and tail unit. The upper wing was of slightly greater span than the lower, and was fitted with inversely-tapered ailerons. The main floats were single-step pontoon-type structures, covered with rubber-proofed cloth and sprung internally by rubber cord. The tail float was attached to the bottom of the rudder and moved bodily with it - an interesting analogy to the use of the base of the Avro 500’s rudder as a tail-skid.
  The test-flying of the Avro 503 was carried out at Shoreham by F. P. Raynham, assisted by John Alcock.
  A few examples of the type were built, and one was sold to Germany. Piloted by Leutnant Langfeld, this aircraft was the first to fly from the German mainland to Heligoland; the flight, with a passenger, was accomplished on September 6th, 1913.
  The Germans must have thought highly of the Avro 503, for the Gotha WD.1 seaplane which first appeared in February, 1914, was an unashamed copy of the Avro. In a German description published in June, 1919, the Gotha WD.1’s sprung floats and tail-high floating attitude were hailed as innovations, but no mention was made of their British origin. Whereas the Avro company built few other seaplanes, the Gotha concern developed a long series of successful floatplanes from the WD.1.
  The Avro 503 was also supplied in small numbers to the R.N.A.S. At least one was sent to the Isle of Grain for assembly; there it was test-flown and handed over to Commander J. W. Seddon. It is believed that this seaplane later participated in a bombing attack on Zeebrugge.
  The ultimate fate of that Avro 503 is unknown, and it is uncertain how many aeroplanes of the type were supplied to the R.N.A.S. At Eastchurch an Avro 503 was flown with a wheel undercarriage, and was used there for training purposes. This aircraft had bracing struts on the overhanging portions of the upper wings, and was fitted with enlarged ailerons.


SPECIFICATION
  Manufacturers: A. V. Roe & Co., Brownsfield Mills, Manchester.
  Power: 100 h.p. Gnome.
  Dimensions: Span: upper 50 ft, lower 47 ft. Length: 33 ft 6 in. Chord: 6 ft.
  Areas: Wings: 567 sq ft.
  Weights: Loaded: about 2,200 lb.
  Service Use: R.N.A.S., Eastchurch. Serial Numbers'. 16.

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.

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.