Turning to the individual types John described their configurations and outlined their histories and achievements. First of the shaft driven tilt-rotor types was the twin-rotor Transcendental 1-G which completed its first transition in December 1954. It was lost due to rotor control failure. The later Model 2 was unable to compete with the twin rotor Bell XV-3 of 1955, built for US Army but also flown for 15 years by NASA and the USAF on research.
    Tilting propellers were employed by Curtiss-Wright on their twin-propeller X-100 flown with some success in 1960 and on its successor, the four-propeller (at the tips of a pair of tandem wings) X-200 or X-19. Hovered and flown conventionally in 1963, it never completed transition and crashed in 1965. Tilting duct types were the 'successful' (ie VTO-double transition-VL) twin-duct Doak 16 and the four-duct Bell X-22A (1966), and the twin-duct Nord 500 which achieved tethered hover only (1968).
    Moving on to tilt-wings John covered the 'successful' twin-prop Vertol 76/VZ-2 (1957), the twin-prop Hiller X-18 (1959) which never hovered and was scrapped, and the four-prop LTV-Hiller-Ryan XC-142 (1964). Five were built and evaluated by the US services but handling and mechanical problems caused a number of accidents. The four twin-prop Canadair CL-84s (1965) were also subjected to lengthy service evaluation but came to nought.
    The Bell XV-15 (1977) was a tilt-rotor type with twin tilting engines at the tips of a fixed wing. Two examples were flown very successfully and led to the Bell Boeing Vertol V-22 Osprey (1989) which, after a long and troubled development programme, and a number of accidents, is about to enter service with the USMC.
    The tilt-jets were represented by the Bell Model 65 ATV (Air Test Vehicle) of 1954 which carried two tilting J-44s on the sides of a Schweizer sailplane fuselage beneath a Cessna 170 wing. It did well everything a VTOL should do apart from a full transition, precluded by lack of power.
    Deflected slipstream was tested by the Robertson Aircraft Corporation in a VTOL,  four-seat, twin Lycoming, high wing machine with a sliding flap system. It flew tethered in 1957 but was not pursued. The twin propeller Ryan VZ-3 was underpowered and could hover only in a light wind. Ryan's VZ-5 Fledgling with four propellers flew tethered only, in 1959.
    In 1957 the Bell X-14 successfully pioneered vectored thrust. Built for the USAF it flew on for many years with NASA on research programmes. Hugh Merewether flew the X-14 in preparation for the P.1127 test programme. We all know the P.1127 story which started in 1960 and led to the Harrier series of in-service fighters with one engine, the Bristol Pegasus, and four nozzles.
    In 1963 the twin engined, two nozzle Soviet Yak-36 flew, demonstrated complete transitions and high speed flight and led to the Yak-36M/Yak-38. The latest manifestation of vectored thrust was the Boeing X-32B JSF contender. This two nozzle design with straight through flow for conventional flight was defeated in a 'fly-off' by Lockheed-Martin's X-35B, its main problem being hot gas reingestion in spite of an intake jet screen provided by fan bleed air.
    Tail-sitting VTOL proved to be a fascinating dead-end. The USN-funded turboprop Lockheed XFV-1 and the Convair XFY-1 flew in 1954 but only the latter completed the transition sequence. The Avon powered Ryan X-13 for the USAF was launched from and retrieved by a cable stretched between two arms on the flat bed of a tipping truck, by means of a hook under the nose. Flown in 1951 complete transitions and high speed flight were demonstrated. In France the annular wing, Atar powered  SNECMA C-450 Coleoptere of 1959 hovered but crashed on its ninth flight.    
    To some extent utilising data from the Rolls-Royce 'Flying Bedstead' of 1953, the RAE's Short SC-1 aircraft had four R-R RB-108 lift engines plus one for cruise. Fully autostabilised, the two built carried out much valuable research flying from 1957.
    This multi-engined concept promoted by Rolls-Royce led to the experimental Dassault Balzac, a converted Mirage III prototype, with eight RB-108 lift engines and a Bristol Orpheus for cruise. Flown in 1962 it accomplished transitions and high speed flight, but achieved the distinction of fatally crashing twice. Its successor, the bigger and heavier Mirage IIIV, with eight RB-163 lift engines and a SNECMA TF-104/106 or P&W TF-30 for cruise. Although the IIIV fully demonstrated VTOL and Mach 2 capabilities, the concept's complexity and weight led to another dead-end.  
    Lift plus lift/cruise engined hybrids included the German VJ-101 of 1963 with six R-R RB.145 engines, two in a swivelling pod at each wing tip for lift and cruise, and two in the forward fuselage for lift only. The second aircraft had reheated wing tip engines. VTOL  and Mach 1+ were demonstrated but the project faded away.
    Dornier's Do-31 was a V/STOL transport with two underwing Pegasus for lift and cruise and wing-tip pods each containing four R-R RB.162 lift engines. Two hovering rigs preceded the Do.31 which flew in 1967. Although V/STOL and conventional flight were fully demonstrated and a research programme was flown by NASA this project also faded away.
    In the USA Ryan converted their XV-4A to take four J-85s in the fuselage for lift and two beside the fuselage for cruise to become the XV-4B Hummingbird II. Flown in 1969 it crashed in less than a year.
    Germany's last attempt was the VFW-Fokker VAK-191B. This had a centrally mounted, four nozzle, R-R RB.193 vectored thrust lift/cruise engine with a R-R RB.162 lift engine in the front and rear fuselages. It was one of the most complex V/STOL aircraft ever built. Flown from 1971, three prototypes were built but the German Government abandoned their VTOL fighter requirement.
    In the Soviet Union the Yak-38 Forger naval fighter of 1971 had a two nozzle vectored thrust Tumansky R-27V-300 in the centre fuselage and two Rybinski RD36-35 lift engines in the forward
 fuselage. As an engine failure would cause catastrophic pitching an automatic ejection system fired the pilot's seat if pitch attitude changed by more than 10 degrees. John showed an impressive film of such an ejection off the bow of an aircraft carrier. 231 aircraft were built and served for 15 years paving the way for what was to be its supersonic successor, the Yak 41/141.
    This aircraft had a similar layout to the -38 except that the reheated Soyuz/Kobchenko R-79V-300  lift/cruise engine exhausted through a single vectoring nozzle between two tail booms. The lift engines were Rybinski/Novikov RD-41s. Sadly the project fell victim to drastic cuts in the Russian defence budget. This successful Mach 1.8 ASTOVL fighter appeared at Farnborough and was the subject of a teaming agreement with Lockheed-Martin for the JAST/JSF programme.
    Another form of hybrid had tip jet driven rotors which were unloaded and autorotated at cruising speeds, with propeller propulsion. The USAF's McDonnell XV-1 of 1955 had a rotor driven by tip mounted pressure jets and a pusher propeller. A Continental piston engine drove a compressor for VTOL and the propeller for cruise. VTOL and conversion to horizontal flight were successfully demonstrated but the principle was not pursued.
    However, in England Fairey's Rotodyne VTOL airliner was intended to carry 48 passengers from and to city centres. It had a 90 ft diameter rotor and low aspect ratio wings mounting two Napier Eland turboprops. These drove tractor propellers and compressors delivering compressed air to the rotor tip jet units. Its performance was entirely satisfactory but its tremendous noise during take-off made it quite unsuitable for its intended use. During question time the Fairey Gyrodyne and Jet Gyrodyne, Rotodyne predecessors, were discussed.
    Several attempts were made to augment VTO/hover thrust by means of ejector nozzles or fans. The US Army's Ryan XV- 4A Hummingbird had a P&W JT12A turbojet each side of the fuselage exhausting rearwards for cruise. For VTOL/hover the exhausts were diverted downwards via complex cross-connected ducting to ejector nozzles in the fuselage. It flew in 1962, with transitions in 1963 and a fatal crash in 1964. The expected augmentation ratio was not achieved and the lift system took up a large percentage of the fuselage volume.
    The 1977 Rockwell XFV-12A canard fighter with ejector slots in the foreplane and wings was a complete failure, this supersonic design never achieving its planned augmentation ratio or even a VTO.
    The fan-in-wing configuration was pioneered by the Vanguard 2C Omniplane which had a fan in each wing and a tail mounted propulsive ducted fan. The Ryan XV-5A's twin J-85 exhausts could be diverted to two large wing mounted tip turbine driven fans and a smaller similar unit in the nose for vertical thrust, or could exit through normal tailpipes for wingborne flight when shutters covered the fans. First flown in 1964 the complete transition sequence was demonstrated satisfactorily before the first aircraft was lost. A second flew on until 1966 when it too crashed but was rebuilt as a research aircraft for NASA, the XV-5B
    The contemporary manifestation of the fan concept is the Lockheed-Martin X-35B Joint Strike Fighter prototype. Here a nose mounted, shaft driven fan is clutched-in for vertical flight and the single vectoring engine nozzle, using Yak-141 technology, is articulated downwards. In this configuration the hot engine exhaust is far removed from the intakes minimising hot gas reingestion, and the Rolls-Royce fan is very efficient; for a weight penalty of 6,000 lb, 16,000 lb of vertical thrust is gained. Modern fly-by-wire and autostabilisation techniques make flying the aircraft straightforward and although the design is complicated compared with the Harrier modern technology renders it practical.
    Finally John touched on some rotor types. The 1960 Kamov Ka-22 was a large transport compound or winged helicopter in which wing tip mounted turboshaft engines drove propellers for propulsion and rotors which were powered for take-off  but autorotated in the cruise. It achieved 221 mph and lifted 36,000 lb to 8,500 ft. Piasecki's 16-H1 of 1962 was an early research compound helicopter but the Lockheed  AH-56 Cheyenne was a successful winged tandem two-seat attack compound helicopter for the US Army. Flown in 1967 budget cuts led to its demise after ten had been built.
    In conclusion John remarked that out of all this effort had emerged just two in-service types: the Harrier series and the Yak-38, intended to be the precursor of the supersonic Yak-141. However, the V-22 Osprey will enter service shortly and the F-35B Lightning II, developed from the X-35B, is expected to enter service with the USMC and Royal Navy in 2015.