<hi style=afpcap>Kaman produced their model 600 helicopter for the US Navy as the HOK-1, with the Air Force showing interest in the type by placing an order for 18 H-43As in 1958. These were operated by Tactical Air Command but were somewhat short on performance. To rectify the lack of power, the Pratt and Whitney engine was replaced by a Lycoming T53 shaft turbine powerplant, with the Air Force ordering 116 H-43Bs, with a further 90 funded later, some of which were for export. The H-43 was the first helicopter purchased for an airborne fire fighting and crash rescue role, with small detachments located at flying stations across the United States as well as in Europe and the Pacific. These were operated by the Air Rescue Service of the Military Air Transport Service/Military Airlift Command. In 1962 the designation was changed to HH-43A and B, with the prefix being added to signify the Rescue role. <caption id=HV600001><title>Airborne shot of an XV-6 </title>Hawker Siddeley Aviation developed the worlds first truly operational vertical take off and landing combat aircraft, with the Royal Air Force and the US Marines placing orders for the Harrier and AV-8, as the two versions were known. Prior to these two aircraft types receiving firm orders, the company spent many years on development work, with the P.1127 Kestrel which was a proof of concept design. Six of these were supplied to the USA for a tri-service evaluation programme, initially receiving the designation VZ-12, but changing to the XV-6A. Nine were to have been transferred to the USA, although one was lost in an accident in the UK, and two more were retained by the RAF. The USAF aircraft were allocated serials in fiscal year 1964, with at least one of the survivors being transferred to NASA. </hi>
