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Avro 531 Spider

United Kingdom (1918)
Picture of Avro 531 Spider Single-Seat Biplane Fighter Prototype

The Avro 531 Spider failed to overtake the venerable Sopwith Camel in terms of performance - leaving just two prototypes completed.


Detailing the development and operational history of the Avro 531 Spider Single-Seat Biplane Fighter Prototype.  Entry last updated on 2/21/2018. Authored by Staff Writer. Content ©www.MilitaryFactory.com

The Avro 531 "Spider" began life as a private venture attempt by the company to provide an all-modern biplane fighter for British service during the latter stages of World War 1 (1914-1918). Its design was attributed to Roy Chadwick and was influenced heavily by work related to the company's earlier Type 504 biplane (detailed elsewhere on this site). With a first-flight held during April of 1918, the Avro 531 was not adopted for service as British authorities committed to the competing Sopwith Snipe (detailed elsewhere on this site) going forward. This left just two Spider prototypes completed.

In the Model 531 design, the traditional biplane arrangement of the period was featured. However, the upper wing section was held close to the dorsal surface of the fuselage thus affording the pilot with better vision over and around his aircraft. Additionally, the lower wing section was of much smaller surface area than the larger (sesquiplane). V-type (Warren truss-style) interplane struts were used for bracing the wing members to one another and this gave the appearance of a spider's web when viewing the aircraft from the front profile - hence the aircraft's name of "Spider". The engine was held in a forward compartment and the tail unit was wholly traditional. The undercarriage was fixed and of a tail-dragger arrangement. Seating was for one in an open-air cockpit and proposed armament being 1 x 7.7mm Vickers machine gun sat over the nose and synchronized to fire through the spinning propeller blades.
Power was from a French-originated, British-produced (by Gwynnes Ltd) Clerget 9B air-cooled rotary piston engine of 130 horsepower output driving a two-bladed propeller at the nose. Maximum speed became 120 miles per hour with an operational range out to 250 miles and a service ceiling of 19,000 feet. Rate-of-climb was listed at 1,250 feet per minute.

All told, the Spider exhibited excellent control and was highly agile in addition to providing better situational awareness for the pilot when compared to contemporaries. However, in the opinion of the War Office, it did not best the overall performance of the competing in-service Sopwith Camel fighter and the Air Service moved on the Sopwith Snipe instead.

The Model 531A (with revised strutworks) was also in development at the time and was to appear as a refined version of the original. It appears that this variant was not finished and went on to influence the related high-speed Model 538 racer. This design, too, failed to see completion and the whole airframe was scrapped by 1920.






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

Image of collection of graph types

Relative Maximum Speed Rating
Hi: 150mph
Lo: 75mph
    This entry's maximum listed speed (121mph).

    Graph average of 112.5 miles-per-hour.
Relative Operational Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Avro 531 Spider's operational range (on internal fuel) when compared to distances between major cities.
Aviation Era Impact
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
2
2


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
Small airplane graphic
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Supported Mission Types:
Air-to-Air
Interception
Unmanned
Ground Attack
Close-Air Support
Training
Anti-Submarine
Anti-Ship
Airborne Early Warning
MEDEVAC
Electronic Warfare
Maritime/Navy
Aerial Tanker
Utility/Transport
Passenger Industry
VIP Travel
Business Travel
Search/Rescue
Recon/Scouting
Special Forces
X-Plane/Development
National Flag Graphic
National Origin: United Kingdom
Service Year: 1918
Classification Type: Single-Seat Biplane Fighter Prototype
Manufacturer(s): A.V.Roe (Avro) - United Kingdom
Production Units: 2
Operational Status: Cancelled
Global Operators:
United Kingdom (cancelled)
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Avro 531 Spider model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
1


Dimension
LENGTH


Feet
20.51 ft


Meters
6.25 m


Dimension
WIDTH


Feet
28.54 ft


Meters
8.7 m


Dimension
HEIGHT


Feet
7.87 ft


Meters
2.4 m


Weight
EMPTY


Pounds
970 lb


Kilograms
440 kg


Weight
LOADED


Pounds
1,543 lb


Kilograms
700 kg

Installed Power - Standard Day Performance:
1 x Clerget (Gwynnes) 9B air-cooled rotary piston engine developing 130 horsepower and driving a two-bladed wooden propeller at the nose.

Performance
SPEED


Miles-per-Hour
121 mph


Kilometers-per-Hour
195 kph


Knots
105 kts


Performance
RANGE


Miles
249 mi


Kilometers
400 km


Nautical Miles
216 nm


Performance
CEILING


Feet
19,685 ft


Meters
6,000 m


Miles
3.73 mi


Performance
CLIMB RATE


Feet-per-Minute
1,250 ft/min


Meters-per-Minute
381 m/min

Armament - Hardpoints (0):

PROPOSED:
1 x 7.7mm Vickers machine gun over the nose synchronized to fire through the spinning propeller blades.
Visual Armory:

Graphical image of an aircraft medium machine gun
Variants: Series Model Variants
• Model 531 "Spider" - Base Series Name; two prototypes completed.
• Model 531A - Proposed refined variant; left incomplete.
• Model 538 - Proposed racer form built upon the Model 531 framework.