It was with some interest that I read your comment about the Rolls Royce Viper engine, which was designed and initially developed by Armstrong-Siddeley Aircraft Gas Turbines, of Parkside Coventry.
As a young graduate engineer in the design and evelopment department of Armstrong-Siddeley's from 1949 to 1951 I had been engaged in the development of the Armstrong-Siddeley Mamba turbo-jet and its sister engine the Armstrong-Siddeley Adder pure-jet engine. Both of those were excellent engines with a small frontal area profile and individual combustion cans. However they both suffered to some extent from problems of matching the turbines to the axial compressors.
The Viper was a new design to a Ministry specification for an expendable jet engine to power the Jindivik target towing aircraft being developed for use at the target range at Woomera in Australia. Having had the experience of working on the Adder, it fell to me to arrange and carry out the very first-ever test on the first prototype Viper, which, if I can recall correctly was in April 1951. John Marlow was the Chief Development Engineer and he was present during that test. The main functions initially being recorded were thrust and fuel consumption. After going through the preliminary run-up procedures, we put some power on to the engine and on calculating the specific fuel consumption, Johnnie Marlow thought I'd got something wrong, so would I do it again. I repeated the calculations with Johnnie looking over my shoulder and, agreeing with what I did, He was totally astounded at the result and performance and was immediately and joyously telling all around that at last Siddeley's had matched a turbine and a compressor.
The prototype was quite remarkable. The first few rows of the axial compressor had plastic blades, the oil pumps for the shaft bearings were simple plunger pumps which were bought from the local motor cycle makers. However, part of the real success was annular combustion chamber with its inherent simplicity. Siddeley's had already had extensive experience of annular combustion chambers with their Sapphire engine, which in fact was used by the US Army to power their fleet of Canberra bombers which they built under licence, although I believe that the original annular combustion chambers were inherited from Metrovickers whose designs had been sold to Rover cars before being transferred to Siddeley's.
Eventually Siddeley's were merged with Bristol Engines to form Bristol Siddeley, which eventually was absorbed by Rolls Royce who continued and advanced the Viper design to what is indeed the longest production aircraft engine in the business. I believe it is from that merger that most Rolls engines have the pre-fix RB.
Shortly after running the Viper test, I left Coventry to take up an academic lecturing post in Aberdeen, where I eventually became Associate Head of the School of Mechanical and Offshore Engineering in what is now the Robert Gordon University. But I look back on those days at Parkside and the testing bays at Ansty with fond memories and some pride.
Regards,
Bert Hosie, BSc,CEng, FIMechE, Fellow of RGU, Inverurie, Aberdeenshire.