|
|
|
|
PRECISIONWhen it comes to precision, accuracy and specialized instrumentation, and all you present-day chaps with your quartz-crystal timers and silicon chip technology, let me tell you “YOU DON’T KNOW NOTHIN’”. In 1935, when I was working in the Planning Department for Frank Verrier’s father, I approached Micky Dunn for a job in the Drawing Office. He said “Well, not exactly, but you can start in the Aft Wind Tunnel, which was then run by L.D. (Whistle) Whistler and Ray Westaway. The Chief Designer at the time was Captain Barnwell (we didn't have Technical Directors in those days) and he used to visit the tunnel about twice a week. |
|
In addition to the everyday work of tunnel testing, there was the occasional additional task of evaluating the sea-level straight and level performance of new types of aircraft, and aircraft being sold to overseas customers. Where better than the Wind Tunnel to find experts with that advanced technical knowledge and experience neces-sary to operate the sophisticated equipment required for the job? The “SPEED COURSE” consisted of a 2 mile long straight section of railway line at Winterbourne; along which the aircraft was to fly at some 200 or 300 feet altitude. At either end of the course was a viewing hut. Each hut had a removable roof panel exposing a pair of sighting wires. The huts were connected by electric cables and each hut had a Morse tapper key. In addition, the Master hut had a timer consisting of a pendulum, whose bottom contact swung through a pool of mercury – at a frequency of once per second. It also had a motorised paper roll (I’m sure there must be a name for this?) which passed the paper at “constant-speed” between 3 pairs of contacts. One pair of contact was connected to the pendulum so that a small burn mark was made on the paper at one second intervals. On receiving a telephone warning from Filton that the aircraft would be approaching shortly, the pendulum would be started up. Whistle in the “entry” hut and Ray Westaway in the “exit” hut would both fix their eyes firmly on the sight wires and at the same time, hold down their Morse keys, each of which would burn a separate, continuous line on the record paper. As the nose of the aircraft passed each sight wire, the corresponding key would be released. There you have it. A roll of paper with a couple of continuous burn lines whose ends could be related to the one second interval burn marks made by the pendulum. Now I ask you “You can’t get more accurate than that – can you?” We sometimes had to perform an additional, slightly more devious function. On one occasion, when the Company was selling Bulldogs to Finland, the Finish representatives wished to attend the “speed tests” to see for themselves that all was being conducted in a proper manner. We were instructed to delay them at the site for as long as possible after the tests, to give time for the Flight-Shed people to change the propeller to one of finer pitch. The ensuing test would be to establish rate of climb performance. “Tut, tut – such goings on.” Tom Boucher |