Note: The Avro Avian name is attached to a number of different aircraft and at times the history and specification can be rather confusing. For the purposes of this web page, we concentrate on the prototype aircraft under the designation Avro 581.
The Avro Type 581 Avian was a light-weight biplane designed after the end of World War I, in an attempt to find sales in the private and flying school market which led to the enormous success of the De Havilland Moth.
Initially, it was built to gain publicity through participation in the Lympne Light Aircraft Trials, held by the Daily Mail in September 1926. The prototype was built as part of a requirement issued by the Air Ministry for the development of two machines, under the Autogyro contract. Avro at Hamble, (on the South Coast) were already engaged in building fuselage sections for the experimental fixed-wing rotary aircraft, now better known as the Cierva C.6 or Avro 576, and so they were an obvious choice to fulfil the requirement.
Although built with a wooden fuselage, centred around a reduced size Avro 504 design, the second of the pair (designated the Avro 581) was a remarkably robust aircraft. The design produced by Roy Chadwick and his team was for an orthodox biplane configuration, powered by an Armstrong Siddeley Genet 70 hp engine.
For competition purposes, the Avro 581 Avian had a generous wing area of 295 Sq ft and was of a remarkably simple, easily repairable construction. The centre-section was mounted on four tall wooden struts and gave an exaggerated mainplane gap of 5 ft 3 in whilst ailerons were only fitted to the lower wings.
Competition class regulations required folding wings and quick release bolts fitted at the wing roots and jury struts were required to support the front corners of the wing bay. The main undercarriage legs were sprung by rubber blocks with large wheels. A tail skid was fitted, to which small wheels could be attached for ease of handling and stowage.
Despite its early promise at the September trials where it was flown by Bert Hinkler (a well-known Test and Display Pilot of the day seen left), the Avro 581 was eliminated on day 3 of the trials due to an unfortunate engine failure.
By way of compensation however, during the earlier part of the trials Hinkler had actually won the Society of Motor Manufacturers and Traders (SMMT) Association Race and was awarded the £200 prize for averaging 90 mph over the 6-lap duration at Lympne.
Before the engine failure, such was the competitive enthusiasm amongst aviators of the day, there was a serious proposal to remove the upper wing and then enter the aircraft in the Grosvenor Trophy Race for monoplanes (being entered as the Avro 588) although this never took place.
The machine was returned to Hamble where it was immediately fitted with a more powerful ADC Cirrus II 85 hp powerplant, re-designated as the Avro 581A and sold to Bert Hinkler. Hinkler intended to use the aircraft for a series of long-distance flights and after modifications to wings and undercarriage it was further re-designated as the Avro 581E.
In mid-April 1927, Hinkler competed at the Bournemouth Easter Meeting, winning the eloquently titled ‘Kill Joy Stakes’ at an average of 89 mph along with the Hotels Handicap Race at 90 mph and the Holiday Handicap Race at 93 mph.
Given Hinkler’s success, limited production began at Hamble originally intended to be designated Avro 581B although after considering the large number of changes it was decided that it would be known as the Avro 594 Avian I.
In 1927, Hinkler’s aircraft received its civil registration (G-EBOV) and after a 1,200 mile non-stop flight to Riga, Latvia, he became convinced that the aircraft was capable of a flight to his Australian homeland. The proving flights to Latvia had additional purposes as not only were they record breaking point-to-point journeys, but they also convinced the Latvian Air Force to place an order for Avian trainers.
In 1928, and after departing Croydon on 7th February, Hinkler found even greater celebrity by arriving in Darwin some 15½-days later following an 11,050-mile solo flight.
The ‘prototype’ was never registered in Australia and so it currently resides in Brisbane Museum resplendent in its G-EBOV markings.
Variants & Numbers
|1||Produced as Avro 581a, converted to Avro 581b before becoming Avro 581e|
|Powerplant||One 85 hp ADC Cirrus II|
|Span||28ft 0 in|
|Maximum Weight||816 lb|
|Capacity||Single pilot only|
|Maximum Speed||93 mph|
|Cruising Speed||70 mph|
|Range (normal)||200 miles (Additional tanks extended range during record attempts)|
|Aircraft||Location / Website|
Hinkler Hall of Aviation, Bundaberg, Queensland, Australia