text: B.Mk1 (Special) in flight In March, Lancaster wheels and tyres were replaced by those of the heavier Avro Lincoln and the maximum weight of the Special was set at  with a maximum landing weight of  excepting emergencies. The commander of 617 Squadron, John "Johnny" Fauquier, ordered that if returning with a bomb, the Special would divert from Woodhall Spa and use the longer runway at RAF Carnaby near the coast at Bridlington in East Yorkshire. The centre of gravity when loaded with a Tallboy or Grand Slam was within the aircraft design limits, provided the rear turret was retained. Merlin 24 engines [ at 3,000 rpm,  at 3,000 rpm, + boost at ] were to equip the Special, fitted with paddle-bladed propellers. Particular attention was to be paid to the skin of the wings and rear fuselage when checking the airframe and the Special would take off only from smooth runways and always with experienced pilots. Fuel was to be used from inboard tanks to outboard ones to relieve the stresses on the wings,
  The Specials were to have day bomber camouflage, the black underside being painted in Sky a pale green shade with the upper surfaces keeping the usual dark green and dark earth. To discriminate between Tallboy and Grand Slam Lancasters, the Tallboy aircraft kept the code letters KC and the Specials were coded YZ.