PV. 704
In April 1956, Avro began detail design work on what it now called the PV. 704 (PV standing for "Private Venture"), a somewhat less ambitious attempt to develop an air vehicle resembling the six-Viper configuration of the Y2 design. PV.704 had two aims: construction of a full-scale ground test rig of the six-Viper design, and production of proof-of-concept components that could lead to an eventual flying vehicle. While PV. 704 was technically a fully Avro-supported project again, USAF's Air Research and Development Command maintained its interest in its progress, as shown in ARDC's Command history from mid-1957.
By October 1957, about the time the Avro CF-105 Arrow fighter was being rolled out, a full-scale engine test rig had been constructed in a small, unobtrusive facility behind the Avro plant. Engine testing, including dynamic tests of the massive, crucial compressor rotors of the radial flow turbine, started at the end of January 1958 and continued for the next several months.
The illustrations below detail the main components of the PV. 704 vehicle.
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(USAF/WS 606A file)
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(USAF/WS 606A file)
The engine rig was designed to use up to six small Armstrong Siddeley Viper 8 turbojets (above) to drive the giant impellers.
The "six-Viper test rig" was a self-contained enclosed outdoor stand which consisted of the central section of the saucer vehicle, a control room, fuel supply and exhaust ducting.
(USAF/WS 606A file)
Links to selected portions of Avro reports on the development of the PV. 704 design:
TR 91: "Estimated Engine Performance, Project PV. 704" (11 pages)
TR 137: "Report on Air Intake Pressure Recovery Tests on a 1/12 Scale Model ... At Mach Numbers Of 2.0, 2.5 and 3.0," February 1958 (10 pages)
TR 150: "Tests on a Radial Flow Compressor Powered by Six A.S.M. Viper Engines," May 1958 (10 pages)
TR 160: "Supersonic Speed and Range Performance of the P.V. 704 Aircraft," June 1958 (3 pages)
