The Bell XV-15 is an American tiltrotor VTOL aircraft. It was the second successful experimental tiltrotor aircraft and the first to demonstrate the concept's high speed performance relative to conventional helicopters.
The Aerotécnica AC-12Pepo is a Spanish two-seat light helicopter manufactured in 1956 by Aerotécnica.
The Aerotécnica AC-14 was a Spanish five-seat light helicopter of the 1950s, designed by Jean Cantinieau, based on enlarging his Nord Norelfe design.
The Agusta A.115 was a prototype helicopter flown in 1961 in Italy. It was essentially a Bell 47J-3 with an unclad, tubular tail boom, and powered by a Turbomeca Astazou II turboshaft engine. No production ensued.
The Agusta A.101 was a large prototype transport helicopter developed in Italy during the 1960s. Despite prospective orders from the Italian armed forces, no buyers emerged and the project was abandoned in 1971.
The Agusta A.103 was an Italian prototype single-seat light helicopter flown in October 1959. The pilot was enclosed by a perspex bubble with the engine at the rear and the tail rotor carried on an enclosed boom.
The Agusta A.104 Helicar was an Italian prototype light commercial helicopter first flown in December 1960.
The Agusta A.106 was a single-seat light helicopter designed to provide an anti-submarine warfare (ASW) platform for the Impavido-class destroyers of the Italian Navy. The aircraft was provided with a sophisticated electronics suite by Ferranti for autostabilisation and contact identification. Two torpedoes could be slung under the fuselage. The tail and two-bladed main rotor could be folded for shipboard stowage, and the skid undercarriage had fittings for flotation bags.
The Bell HSL was an American 1950s anti-submarine warfare (ASW) helicopter built by the Bell Helicopter company, the only tandem rotor type designed by Bell.
The Bölkow Bo 103 was an ultralight experimental helicopter flown in West Germany in 1961. It was designed for reconnaissance and command-control purposes and constructed by Bölkow Entwicklungen KG as part of a research order by the German Federal Ministry of Defense.
The Cierva CR Twin was a five-seat utility helicopter that first flew in the UK in 1969. It was a joint development between Cierva Autogiro Company and Rotorcraft now a subsidiary of Cierva, based on the dynamic systems of the latter company's Grasshopper design. A new, highly streamlined pod-and-boom fuselage was married to the Grasshopper's coaxial rotor system, and the new aircraft registered G-AWRP first flew on 18 August 1969.
The Boeing Model 360 is an American experimental medium-lift tandem rotor cargo helicopter developed privately by Boeing to demonstrate advanced helicopter technology. The aircraft was intended as a technology demonstrator, with no plans to put the type into production, and many of its design features were carried onto other programs including the RAH-66 Comanche and V-22 Osprey. The sole prototype has been preserved and is a static exhibit at the American Helicopter Museum in West Chester, Pennsylvania.
The Vulcanair SF.600 Canguro was a feederliner developed in Italy in the late 1970s. Despite a number of attempts to put the aircraft into series production, only a small number were ever built. The Canguro was a high-wing cantilever monoplane of conventional configuration with a fuselage of rectangular cross-section and a high-set tail. The tricycle undercarriage was not retractable, and its main units were carried on sponsons on the fuselage sides. SIAI Marchetti provided funding towards the construction of the prototype, and constructed this aircraft at the former Aviamilano plant. After flight testing proved positive, the type was put on sale, but failed to attract buyers in any number, even when the original piston engines were exchanged for turboprops and retractable undercarriage was offered as an option.
The Gyrodyne RON Rotorcycle was a tiny, single-seat helicopter designed under contract for the United States Navy. in the mid-1950s. It later was redesigned for a U.S. Marine Corps requirement for a small personal helicopter that would fulfill a number of roles, including observation, liaison, small unit tactical maneuvers, and which could be dropped to downed airmen behind enemy lines to facilitate their escape.
The American Aircraft Penetrator, now referred as the Aerocraft Stealth Star 204 SS, was a gunship helicopter modified from the Bell UH-1B Iroquois with tandem seating for the pilots and a troop-carrying compartment.
The Kawasaki KH-4 was a light utility helicopter produced in Japan in the 1960s as a development of the Bell 47 that Kawasaki had been building under licence since 1952. The most visible difference between the KH-4 and its forerunner was its new and enlarged cabin. This was fully enclosed and provided seating for three passengers side-by-side on a bench seat behind the pilot's seat. The helicopter was provided with a new control system, revised instrumentation, and larger fuel tank.
The Kellett XR-8 was a helicopter built in the United States during World War II. It was a two-seat machine intended to demonstrate the feasibility of a twin-rotor system and, while it accomplished this, it also demonstrated a number of problems that prevented further development of this particular design.
The Kellett XR-10 was a military transport helicopter developed in the United States in the 1940s that only flew in prototype form. It was designed in response to a USAAF Technical Instruction issued for the development of a helicopter to transport passengers, cargo, or wounded personnel within an enclosed fuselage. Kellett's proposal followed the general layout that the company was developing in the XR-8, with twin intermeshing rotors, and was accepted by the Air Force on 16 October over proposals by Sikorsky, Bell, and Platt-LePage.
The Meridionali/Agusta EMA 124 was a light utility helicopter flown in prototype form in Italy in 1970. The design was undertaken by Agusta for production in a joint venture with Elicotteri Meridionali, based on the Bell 47 that Agusta was building under licence at the time.
The Agusta A.105 was an Italian rotorcraft designed by Agusta. It was never developed beyond the prototype stage.
