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Avro 531 Spider

1918 WORLD WAR 1 X-PLANE

History of the Avro 531 Spider

The Avro 531 "Spider" was originally the company's private attempt to provide state-of-the-art biplanes for British service during the final stages of the First World War (1914-1918). Its design is attributed to Roy Chadwick and was heavily influenced by work related to the company's early 504 biplanes (detailed elsewhere on this site). During its maiden flight in April 1918, the Avro 531 was not accepted into service due to commitments made by British authorities about the future of the competing Sopwith Snipe (described in detail elsewhere on this website).

Only two spider prototypes remain.

The Type 531 was designed with the traditional two-wing layout of the time. However, the upper wing section remains close to the back of the fuselage, giving pilots better visibility over and around the aircraft. Also, the lower wing portion has a much smaller surface area than the larger (half wing). V-shaped (Warren truss) inter-aircraft struts are used to hold the wing components together, which gives the appearance of a spider web when the aircraft is viewed from the front - hence the aircraft's name "Spider".

The engine is housed in the front compartment, and the rear wing is very traditional. The landing gear is fixed, with a rear tug arrangement.

One sits in the open air cockpit and the suggested weapon is 1 x 7. A 7mm Vickers machine gun is located above the nose and fires simultaneously through the rotating propeller blades.

Power is provided by a 130 hp Clerget 9B air-cooled rotary engine of French and British production (by Gwynnes Ltd) that drives the twin-blade propeller on the nose. Top speed is 120 mph, range is up to 250 miles, and service is capped at 19,000 feet.

The climb rate was reported to be 1,250 feet per minute.

All in all, the Spider exhibits excellent control and is very agile, giving the pilot better situational awareness than its contemporaries. However, in the opinion of the War Department, it did not exceed the overall performance of the current Sopwith Camel fighter, and the Air Force switched to the Sopwith sniper fighter.

A 531A model (with modified struts) was also in development at the time, intended to be an improved version of the original. It appears that this variant was left unfinished and affected the related Type 538 dragster. The design was never completed, and the entire fuselage was scrapped in 1920.