طيار اختبار
L. E. Baynes designed the Youngman-Baynes High Lift Research Aircraft, an experimental flying test-bed for the system of slotted flaps invented by R.T. Youngman. It used components from the Percival Proctor, and was built by Heston Aircraft Company Ltd. Test pilot Flight Lieutenant Ralph S Munday piloted the first flight at Heston Aerodrome on 5 February 1948, carrying the military serial VT789.