Sunday, May 22, 2011

Britain - 1918 Avro 531 Spider

The Ill-Fated Avro 531 Spider

Avro 531 Spider - 1918
Avro 531 Spider - 1918
Avro 531 upper wing  Avro 531 lower wing
Avro 531 Upper and Lower Wing Paint Scheme

An unsponsored private-venture single-seat fighter designed by Roy Chadwick and flown for the first time in April 1918, the Spider made use of a number of Avro 504 components and had a fabric-covered wooden structure with a system of Warren-girder steel-tube interplane struts.

The upper wing was mounted close to the fuselage and directly above the cockpit. In its original form, the Spider was powered by a 110hp Le Rhone 9J nine-cylinder rotary engine, and proved to possess exceptional manoeuvrability, but overall performance was not sufficiently in advance of the contemporary Sopwith Camel to warrant quantity production. Armament comprised one fixed synchronized 7.7mm Vickers machine gun, and a 130hp Clerget 9B rotary was later fitted.

The Spider was a sesquiplane with a largely conventional configuration, but it used Warren truss-type interplane struts, hence the appellation "Spider". In tests, the aircraft demonstrated exceptional performance, handling, and pilot visibility. By the time it flew, the War Office had already selected the Sopwith Snipe for mass production.

A second, refined version, the 531A was apparently never completed, but some of its components seem to have been used to build a derivative design, the 538. This had standard interplane struts and was intended as a racing aircraft. It was never used for this purpose, however, since it was discovered that it had a faulty wing spar, so the Avro firm used it as a hack instead.


  1. Avro 531 Spider. (2010, September 15). In Wikipedia, The Free Encyclopedia. Retrieved 00:46, November 18, 2010, from
  2. Avro 531 Spider 1918 The Virtual Aircraft Museum
  3. Jackson, A.J. Avro Aircraft since 1908. London: Putnam Aeronautical Books, 1990. ISBN 0-85177-834-8.
  4. Taylor, Michael J. H. Jane's Encyclopedia of Aviation. London: Studio Editions, 1989, p. 93.
  5. World Aircraft Information Files. London: Bright Star Publishing, File 889, Sheet 94.


BigMike said...

This plane falls clearly into the "How did it stay in the air" category for me... some of these older planes BARELY hold onto the edges of aerodynamics.

W. I. Boucher said...

@ BigMike: The performance tests were good for the aircraft. Even today many fighters are on the edge of aerodynamics and can only fly because of advanced computer controlled avionics. There is a point when an aircraft is too stable for the quick maneuverability.