The Hawker Siddeley HS.141 was a 1970s design study and submission for a British V/STOL airliner requirement. Designed by Hawker Siddeley Aviation and tested in wind tunnels neither prototypes nor production aircraft were produced. Design and development Outline Requirement In 1969 the British Transport Aircraft Requirements Committee (TARC) issued a design study "Outline Requirement" (OR) for a 100-seat VTOL airliner capable of a range of 450 miles (725 km). Emphasis was to be on noise reduction by using steep approach and departure profiles, much like those used today at London City Airport. It was thought at the time that money would be better invested on designing new aircraft types than building a third London airport. Hawker Siddeley investigated various configurations of aircraft, powerplant and control systems including an early proposal using ogival delta wings and twin fins, before submitting their draft design proposal to the TARC in January 1970. At the March 1970 German Aviation Show in Hanover, the first official details were released of the newly named HS.141 project. Design The HS.141 design was a jet airliner of all-metal construction with a T-tail and a low-mounted swept wing with a quarter-chord sweepback of 28 degrees. The design featured two wing-mounted "cruise" engines and 16 lift jet engines mounted in sponsons either side of the fuselage (eight per side). The engines under main consideration were the Rolls-Royce RB.220 turbofan for forward propulsion and the Rolls-Royce RB.202, a high bypass ratio lift turbofan engine using technology developed for the Rolls-Royce RB.162 lift jet. Both engines were themselves design studies by Rolls-Royce and it was feared that there would be delays in their development due to the company's problems at the time. One new engine type also considered for main propulsion was the 'SNECMA M.56', which became the CFM International CFM56. Variations using fewer lift jet engines for STOL operations only were also studied as it was realised that the engines could account for 15% of the total weight of the aircraft and 35% of the final cost. During the design stage many solutions involving high-lift devices were explored including flaps blown by the "cruise" engines. The flight control system proved the greatest challenge to the design team, systems had to be devised to control the aircraft in slow or hovering flight. This was to be achieved by swivelling the lift engines in their mounts combined with varying the thrust of each