On the 13th April 2017, the Royal Aeronautical Society Heathrow Branch successfully concluded the final lecture of the 2016/2017 season at the British Airways Waterside Theatre. The lecture, presented by John Thorpe, a former BAC Flight Test Engineer and was entitled ‘BAC1-11 Initial Flight Trials‘. Mr Thorpe, a man with a great story to share, took the audiences back in time for the evening.
Mr Thorpe was part of the flight test team at Filton, he was initially involved with the Bristol 188 supersonic research aircraft. However after a 5 year long apprenticeship he joined the team of flight test observers at Wisley to work on the BAC1-11. A challenging role at first, as most of the training he received was on the job. After this he returned to Filton before build up to Concorde.
Mr Thorpe initiated his presentation by engaging the audience with some questions, to his delight the response from the audience was very positive. This was followed by a detailed background of the BAC1-11 aircraft. Back in the days it was a popular choice for holiday destinations, 30-seat Hunting 107 set the foundation for the initial designs, over the years 244 aircrafts were produced across three different production sites. Hurn produced 222 aircrafts while Weybridge (13) and Romania (9) accumulated the rest. It was a revolutionary design, one of the only few in that era to feature an auxiliary power unit (APU). Time from project initiation to the first prototype was just over two years, first prototype G-ASHG rolled out of Hurn assembly line on 28th July 1963. British United Airways was the first airline to place orders for the aircraft. The BAC1-11 had two integral air stairs, one in the rear under the tail and one at the front. It was a twin engine aircraft with two rear mounted engines. First commercial service of the aircraft was on 9th April 1965.
Wisley was the centre of flight testing for Vickers aircraft, VC10’s were also tested at Wisley. After the crash of the first prototype on 26th October 1963, it was vital that some design changes were made to prevent this occurrence. A thorough investigation revealed deep stall as the sole reason behind the crash, the aircraft was unable to recover from deep stall due to insufficient airflow for the servo tab to operate, it floated freely and had no effect on the elevator. This locked the aircraft in to high incidence descent at a very high rate of descent. There was no explosive hatch on this aircraft, the only way out was the rear emergency exit. Air outflow valves on the pressurisation system were unable to depressurise the cabin at a fast rate, this prevented the door from opening. All 7 onboard did not survive. AIB report at the time concluded, stalling should have been more cautiously approached, more closely controlled and carefully correlated with wind tunnel and flight recorded data. This phenomenon was explained to all American manufacturers by BAC working party, it was not to be taken lightly. A powered elevator was the devised solution.
As the evening progressed, Mr Thorpe compared pictures from 1964 to what remains of Wisley Airfield today, only commonality being the concrete on the ground. Adventures on the G-ASJD aircraft were one of the many moments he cherishes while working at Wisley. It had an Anti-Deep Stall chute attached to the rear of the aircraft, deploying the chute at high incidence will lower the nose and prevent aircraft from entering deep stall again. His experience with one of the apprentices remains a highlight, a moment many could relate to in the audience.
Mr Thorpe was also involved in noise testing certification, his experience of carrying out those tests in the early hours of the morning whilst the air is still. This provided proper readings as the wind dissipates noise therefore it gives false readings. During the testing stage he was given a flutter demonstration, servo tabs on elevators had a limitation of 280 knots. Anything above this exposed elevator flutter problems. Calibration of equipment was very important for accurate readings for flight tests. Some of the other tests that were carried out involved flutter clearance, water testing for wet runway landings, negative g work and pushover manoeuvres.
Being part of the team for demo flights for prospective customers is an experience he enjoyed, selling to KLM and TAP (Portuguese Airline) were the highlights. Route proving flights were intensive as 200 hours were clocked over the course of three weeks. Production testing at Hurn involved full checks of all systems, flap and gear lowering times, single engine climb performance, cruise performance, engine relights, never to exceed speed, depressurisation tests to check oxygen masks dropout, stick shaker and stick pushers and checking auto-pilot.
Mr Thorpe’s passion towards the BAC1-11 was evident, he shared with the audience the exact dates of his penultimate flights on the aircraft. The last of which was on May 1999 on route to Nice for the Monaco Grand Prix to celebrate his retirement after 30 years with CAA. He gave a brief comparison with McDonnell Douglas DC-9 and insight in to losses compare with similar twin jets, concluding that Americans were superior in their flight testing, delivery and production stages.
The evening concluded with Mr Thorpe sharing pictures of the Gatwick Airport from 1970’s, signed postcards from the penultimate flights and outlining noise restrictions being the fundamental reason that brought BAC1-11 out of service, last civil service in Europe was on the 31st August 2003. A brief summary of the differences between the variants alongside outlining 50 different UK operators had flown the aircraft. Last two flyable BAC1-11s are in the hands of Northrop Grumman for radar research for developing equipment for fighter aircraft. Mr Thorpe also shared some of the locations where BAC1-11 is on display, Brooklands Museum, Imperial War Museum Duxford, National Museum of flight Scotland and Classic Air Force Museum Newquay Cornwall.
Mr Thorpe has been actively involved in reunions amongst other professionals that worked on the aircraft, 2013 Brooklands Museum and 2003 celebrating the 40th anniversary of the 1st flight of BAC1-11. Some of the people from the reunions were present at the lecture. The lecture ended with other members sharing their experiences of the BAC1-11.
Karanvir Uppal, 16 April 2017