Bell XV-15: Tilt Rotor Technology Realized
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Bell XV-15: Tilt Rotor Technology Realized

Bell XV-15: Tilt Rotor Technology Realized

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            Breakthroughs in design engineering had been brought by necessity so goes the famous saying “necessity is the mother of invention”. This was true with the case of enduring experiments in aviation that brought forth new and interesting aircraft designs which defy our average imagination.

            Before the successful Bell-Boeing V-22 Osprey came into service with the US Marine Corps, a technology demonstrator was needed to prove the feasibility of tilt rotor technology. The Bell XV-15 was conceptualized in order to fill up this need when the US Army and NASA sought Bell to come up with a prototype. In general perspective, the XV-15 is a VTOL (Vertical Take-Off and Landing) aircraft that takes off and lands like a helicopter and flies like any fixed wing aircraft making short runways and confined landing areas with average clearance for it to land and take-off functional as its temporary airport. The first prototype had its maiden flight on 3 May 1977 on the hovering mode followed by its first transition from vertical to forward flight on 24 July 1979. 

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            Equipped with two 7.62 m (25 ft) diameter rotor blades (called a prop-rotor when it is applied to V-22s) this aircraft has a span of 17.73 m (58 ft) when on hovering mode measuring from the tips of the rotors on rotation at both sides of the wings (contrary to measuring a wingspan from wing tip to wingtip on conventional airplanes). Transition from take-off to cruising takes 12 seconds and from hovering the XV-15 could attain 445 km/h (276 mph) in 30 seconds. Power is generated from two AVCO Lycoming turboshaft engines rated at 1156-kW (1,550 hp) each. Despite its impressive performance, it was simply confined to carry 9 passengers as a test vehicle a capacity which the Bell-Boeing Osprey could carry more than twice when it was put to service. A range of 825 km (510 miles) with maximum fuel had been certified with a maximum attainable cruising speed of 615 km/h (381 mph). It could operate at a service ceiling of 8,840 m (29,000 ft) with a maximum climb rate of 960 m/min (3,150 fpm) at sea level.

            The Bell XV-15 may have been a less known type of experimental aircraft as only two were built and one was lost in a crash halfway to the end of the program but its significance was realized years later when the Bell Boeing V-22 Osprey took off on its maiden flight 19 March 1989 employing the refinements based on the research data gained from the Bell XV-15 experiments. Tilt rotor technology was realized and eventually changed the way of flying forever.


Concept Aircraft: Prototypes, X-Planes and Experimental Aircraft by Jim Winchester

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Comments (7)

Another great aircraft article here Will.

excellent. I love aviation and other heavy things that fly

This is one of the aircraft that I would love to take for a test flight. Great job as always.

Great article! You always entertain and I thank you.

Comprehensive and interesting article.

Very well discussed, Will. Fascinating aircraft too :)

Very useful invention appropriate to small islands.