The Avro 504L Experiment

By 1913 the Royal Australian Navy realised the significance of naval aviation for reconnaissance and defence purposes, and a plan to form a Naval Air Service was under serious consideration. Kim Dunstan briefly outlines the early stages of naval aviation in the RAN and its first tentative steps post WW1.   

Left: An Avro 504 seaplane being hoisted aboard the heavy cruiser HMAS Australia in 1920 (ADF Serials)

The early days

In May 1917, HMAS Brisbane (1) used a Sopwith Baby floatplane to search for the German raider SMS ‘Wolf’ at large in the Indian Ocean (see ‘Brisbane’s Baby‘). In 1918, when operating with the Royal Navy in the North Sea, HMAS Australia (1), Sydney (1) and Melbourne (1) successfully launched Sopwith aircraft from platforms mounted on gun turrets to attack Zeppelins and enemy aircraft. All of which provided valuable experience for the RAN.

Captain Claude Cumberlege RN, following his experience in 1917 with the Sopwith Baby on Brisbane became an aviation enthusiast, making numerous recommendations urging the Australian Naval Board to acquire seaplanes for RAN ships. Captain John Dumaresq RN who took command of HMAS Sydney (1) in February 1917, also supported naval aviation and devised a rotating platform for launching aircraft from light cruisers. Later he used his influence with the Australian Naval Board to obtain aircraft for trials on RAN ships.

In March 1919 Dumaresq was promoted Commodore First Class, in charge of the RAN fleet, where he continued to advance the case for naval aviation. Aware of the benefits of aviation, both the RAN and the Australian Naval Board sought to capitalise on his experience with aircraft in order to establish a Naval Air Service. But this was frustrated as following the Armistice, the Sopwith aircraft on RAN ships were returned (to the Royal Flying Corps or RNAS) prior to the ships sailing for Australia in April 1919.  

In Australia the lack of suitable aircraft for use on RAN ships caused a delay. However, early in 1920 twenty Avro 504 aircraft, no longer needed in the UK, were shipped to Australia in crates ready to be assembled. These ‘Imperial Gift’ aircraft were taken on charge by the Australian Air Corps for the Central Flying School. Most of these aircraft were 504Ks, the wheeled version, but two were Avro 504L twin-seat seaplanes that Dumaresq requested for trials on RAN ships.

Above:  An Avro 504L being hoisted aboard HMAS Australia to be stowed on the upper deck.  The size of the aircraft and the fact it did not have folding wings made it very susceptible to damage (RAN Sea Power Centre).

The Avro 504L was similar to the Avro 504K except the landing wheels were replaced by floats. Early in WW1 the Avro 504s were front-line aircraft, but in 1915 they were moved to second-line employment. Like most biplanes of the time they had timber airframes covered with fabric and braced with wire. 

Despite the engine change the Avro 504L failed to lift of the water of Simpson Harbour at Rabaul and the Mioko Harbour survey was not done. HMAS Melbourne returned to Rabaul on 25th October for two days to embark the seaplane and for conferences with the local Administration about the problems experienced with receiving wireless signals and the difficulty of getting supplies of coal at Rabaul. However, Dumaresq said the visit to the ex-German Colonies “unquestionably did much good and supported the Administration considerably; but more good would have been done if the coal at Rabaul could have been used.”

Dumaresq was disappointed the Avro 504L did not fly at Rabaul saying: “The affect on the natives of the inability of the seaplane to fly was bad, as the German’s will put it about that a German machine would have done so”. [Note: the FF.30e on the German raider SMS Wolf was able to fly in the tropics – see the ‘Brisbane’s Baby’ story.] Dumaresq continued: “I endeavoured to initiate a propaganda that the machine was not a real seaplane, but a land machine experimentally converted with an unsuitable engine lacking in reserve power necessary for flying in damp tropical air,” he said, “I hope that if possible machines that will fly will be sent up next year.”

Above left: The Avro at Cairns, where successful flight trials were conducted. Note the wing-tip floats on the underside of the lower wing, a feature not seen in other 504Ls. (Sea Power Centre) Above right. Beached at Rabul, PNG, the Avro awaits an engine change in an attempt to gain more power (Australian War Memorial image).

Melbourne arrived at Port Moresby on 30 October. Again the Avro 504L did not fly owing to a stiff prevailing south-east wind and rough seas. Arriving at Cairns on 5 November, the seaplane took off from the water and obtained a height of about 2000 feet. But, according to Dumaresq, “The revolutions were not satisfactory and the flying tentatively arranged for the following day as a public display was cancelled.”

He said: “I do not consider the life of the pilot and observer should be risked by flying the machine without obtaining sufficient number of revolutions and all this was explained to the Mayor. Flight Lieutenant [sic] Fryer-Smith and his mechanics have worked unceasingly and the former in whom I have every confidence is naturally very keen not to disappoint the public.” At this point Dumaresq’s ‘Report of Proceedings’ ends.

The Cairns flight 

By contrast, an article in the ‘Cairns Post’ of 6 November 1920, page 8, headed “Up In The Air, Seaplane Flight Over Cairns” gives a glowing account of the flight which lasted just under one hour. It said: “The mechanic set the propeller spinning and the plane began gliding over the smooth waters of the inlet, gathering speed as it came along. About 8.30 the plane gracefully rose from the water like a big seagull and as the pilot raised the elevators, the plane rose higher and higher. The noise of the engine attracted a large number of people to the wharf and the excitement especially amongst the younger generation was intense”.

At Cairns, the pilot said the Avro skidded over a mud bank helping it to become airborne, but the engine overheated and lost power. A report in the ‘Sydney Morning Herald’ of 29 November 1920, says: “Whilst in the tropics Melbourne’s seaplane was unable to rise, and it was ascertained that due to the warmth of the climate, the engine did not develop the same number of revolutions as it did in cooler climes, and consequently was unable to raise sufficient power to lift itself from the water. The same effect of tropical heat was also experienced by Sir Ross Smith in his flight from England to Australia, but the Vickers-Vimy had powerful dual engines enabling it to overcome the difficulty”.  

The Avro problems

After leaving Cairns no further flights were made during the ship’s return to Sydney. The Avro 504 L trials on HMAS Melbourne identified a number of problems. The main issue was the dangerous lack of engine power in the tropics. Secondly, without folding wings the Avro was too big and unwieldy and easily damaged, striking the ship’s side when hoisted to or from the water; and it lacked tie-down points. Saltwater spray and tropical humidity degraded the wooden airframe and its canvas covering; and petrol tins stowed in the open rusted and leaked. Also, operating in all but calm conditions was impossible. Although the experiment proved the Avro 504 L was unsuitable, the idea of naval aviation was not diminished and the search for a better aircraft began.      

With the experience gained during the HMAS Melbourne cruise, Commodore Dumaresq advised the Naval Board that to cope with tropical conditions a purpose-built seaplane with a more powerful engine was necessary. The RAN subsequently ordered six Fairey 111D seaplanes with the 375 hp Rolls Royce Eagle V11 engine, the first of which arrived in August 1921. Unfortunately the idea of an RAN Air Service had been shelved by then, so the aircraft went to the newly formed RAAF, established on 31 March 1921.

The way ahead

This was not the end of aviation for the RAN’s aviation capability as Fairey 111D seaplanes, now flown by the RAAF Fleet Cooperation Unit, assisted HMAS Geranium to survey the Great Barrier Reef.  (See The Geranium Story).

Following the 1923 Imperial Conference, and growing defence concerns, the Australian government ordered two heavy cruisers, both capable of carrying a seaplane. Then, in June 1925, the government announced that a seaplane carrier, HMAS Albatross, would be built at Cockatoo Dock in Sydney; leading to the purchase of the Supermarine Seagull 111 & V amphibians. From this point onwards aircraft became an integral part of RAN operations.  

Graphic:  A copy of an excerpt from Petty Officer Joseph Kemp RAN, who kept a meticulous diary on events he observed during his time in service. He served on HMAS Sydney (1) in the North Sea, on which he commented on a Sopwith Pup launching to chase German aircraft; and in various other theatres.  In this entry he is aboard HMAS Melbourne (1) during the Mandate Island cruise, and he remarks on the inability of the Avro 504L to fly despite an engine change.  (Image courtesy of the Australian War Memorial).