Bell XV-3
| XV-3 | |
|---|---|
 |
|
| The second Bell XV-3, 54-148, during flight testing (c.1959) | |
| Role | Experimental VTOL aircraft |
| Manufacturer | Bell Helicopter |
| First flight | 11 August 1955 |
| Status | Display |
| Number built | 2 |
The Bell XV-3 (Bell 200) was a tiltrotor aircraft developed by Bell Helicopter for a joint research program between the United States Air Force and the United States Army in order to explore convertiplane technologies. The XV-3 featured an engine mounted in the fuselage with driveshafts transferring power to two-bladed rotor assemblies mounted on the wingtips. The wingtip rotor assemblies were mounted to tilt 90 degrees from vertical to horizontal, designed to allow the XV-3 to take off and land like a helicopter but fly at faster airspeeds, similar to a conventional fixed-wing aircraft.
The XV-3 was first flown on 11 August 1955. Although it was limited in performance, the aircraft successfully demonstrated the tiltrotor concept, accomplishing 110 transitions from helicopter to airplane mode between December 1958 and July 1962. The XV-3 program ended when the remaining aircraft was severely damaged in a wind tunnel accident on 20 May 1966. The data and experience from the XV-3 program were key elements used to successfully develop the Bell XV-15, which later paved the way for the V-22 Osprey.
In 1951, the Army and Air Force announced the Convertible Aircraft Program and released the Request for Proposals (RFP) to solicit designs from the aircraft industry. In October 1953, Bell Helicopter was awarded a development contract to produce two aircraft for testing purposes. The original military designation was XH-33, classifying it as a helicopter, but its designation was changed to XV-3 in the convertiplane series. The designation was changed once again in 1962 to XV-3A when the V-prefix was changed to mean VTOL. The leading designers were Bob Lichten and Kenneth Wernicke.
The first XV-3 (serial number 54-147) flew on 11 August 1955 with Bell Chief Test Pilot Floyd Carlson at the controls. On 18 August 1955, the aircraft experienced a hard landing when the rotor developed dynamic instability. Bell attempted to remedy the situation, and flight testing resumed on 29 March 1956 after additional ground runs. Bell continued to expand the flight envelope of the XV-3, but on 25 July 1956, the same rotor instability occurred again. Flight testing of the XV-3 resumed in late September 1956. Then, on 25 October 1956, the aircraft crashed when the test pilot blacked out due to extremely high cockpit vibrations. The vibrations resulted when the rotor shafts were moved 17 degrees forward from vertical. The test pilot, Dick Stansbury, was seriously injured, and the aircraft was damaged beyond repair.
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