The Avro 706 Ashton was devolped from the one-off Tudor 8 (VX195) which was in turn a modified Tudor 1, fitted with four Nene jet engines mounted in podded pairs under each wing.
The Tudor 8 had made its first flight in September 1948 and retained the original tail wheel layout of the Tudor 1 which brought the jet engine nacelle tailpipes rather close to the ground. The Ministry of Supply ordered six further experimental jet-powered derivatives of the Tudor, fitted with a tricycle undercarriage and although designated Tudor 9 although these were renamed the Avro 706 Ashton.
The first of these was the Ashton Mk.1 (WB490) was built at Woodford and was flown for the first time on 1st September 1950.
Unlike the Tudor 8, the Avro Ashton made use of a Tudor 2 fuselage with thicker skins, which was reduced in length to that of the Tudor 1. This was a low risk approach, as the aircraft handling and performance had, in effect, been already proven on the Tudor 8.
The initial production order comprised one Ashton Mk. 1 WB490; one Ashton Mk. 2 WB491; three Ashton Mk. 3 WB492, WB493, WE670; and one Ashton Mk. 4 WB494 and were used for a wide variety of trials.
Despite being one of the first jet-engined transport aircraft, the Avro 706 Ashton was never intended for commercial use and its potential was hugelyover-shadowed by the De Havilland Comet. It remained as primarily a research aircraft.
Ashton 1 (WB490): initial handling tests from late 1951 followed by high altitude engine research at Boscombe Down. Trials continued until around 1956. Maximum operating Mach number 0.65. Underwing tanks installed to increase endurance.
Ashton 2 WB491: First flown August 1951 and used for cabin conditioning trials. Converted for engine test bed work by D Napier & Son at Luton and tested with Rolls-Royce Avon and Conway and Armstrong Siddeley Sapphire. The Conway and Sapphire were tested with an icing rig. The forward fuselage of WB491 is displayed at the Newark Air Museum.
Ashton 3 (WB492): Flown in July 1952 and used for radar bombing research and bomb sight development. Fitted with outboard underwing bomb containers and a ventral mapping / target locating radar antenna aft of the wing trailing edge.
Ashton 3 (WB493): Flown in December 1951. Initially used for instrumentation development, followed in 1955 by engine test bed work for Bristol Siddeley with two afterburning Olympus engines fitted in outboard underwing nacelles. Subsequently used for testing of the Bristol Orpheus engine.
Ashton 3 (WE670): Flown in April 1952 and equipped with underwing pods for bomb carriage (up to 1,000 lb in each). Cleared for 82,000 lb maximum weight and operation up to Mach 0.64. Modified for engine test work in 1955 and used for R-R Avon intake icing trials with a water spray test rig.
(Ashton 4 WB494): Flown in November 1952 and used for visual bombing research. Underwing bomb containers and a ventral bomb aiming position.
Avro 706 Ashton Specification
|Powerplants||Four 5,000 lbst Rolls-Royce Nene 5 and 6 jet engines|
|Span||120 ft 0 in|
|Maximum Weight||Ashton 1 72,000 lb; Ashton 3 82,000 lb|
|Capacity||Five crew and test equipment|
|Maximum Speed||Ashton 1: 439 mph at 35,000 ft|
|Cruising Speed||Ashton 1: 406 mph at 35,000 ft|
|Endurance / Range||Endurance 2hr 15 min at 40,000 ft; Range 1,725 miles|
Variants & Numbers
|Ashton 1||One aircraft WB490|
|Ashton 2||One aircraft WB491|
|Ashton 3||Three aircraft WB492, WB493, WE670|
|Ashton 4||One aircraft WB494|
|Ashton 2 (WB491)||Forward fuselage displayed at Newark Air Museum|