Origin of the Species

We want speed! We want vertical lift! The Bell XV-3 Tilt-rotor was the first to satisfy all aeronautical tastes.

  • By Jay Miller
  • Air & Space magazine, July 2004
 

(Page 2 of 2)

The restoration efforts will be shepherded by Charles Davis, one of the original XV-3 engineers. “Looking at it today, I realize just how basic it really was,” he says. “But the XV-3 was able to do what it was designed for: Prove tilt-rotors could work. The V-22 and [civilian] model 609 are the result.”

NEARLY A HALF-CENTURY AGO, A HYBRID AIRCRAFT with a stubby nose, truncated wings, and propeller rotors became the aeronautical headliner at the Bell Helicopter Company. Work on a combination helicopter and fixed-wing aircraft had begun in the late 1940s, when the industry accepted that the helicopter’s usefulness was limited by its comparatively low speed. The XV-3 was unveiled at Bell’s Hurst, Texas facility on February 10, 1955, and six months later, on August 11, it was flown in hover mode for the first time by Bell’s chief test pilot, Floyd Carlson. On December 18, 1958, in the hands of test pilot Bill Quinlan, it became the first tilt-rotor aircraft to transition from vertical to horizontal flight and back again. Over the next eight years the tilt-rotor underwent extensive flight testing, the last segments in May 1966 at the 40- by 80-foot full-scale wind tunnel at NASA’s Ames Research Center in California. The XV-3 logged 270 flights and tutored 11 Army, Air Force, NASA, and Bell pilots. (The first XV-3 was lost in October 1956 when a rotor instability problem led to an uncontrollable descent and hard landing. A second prototype, significantly modified, stepped in to replace it.)

Initially, Bell designated the convertible aircraft the model 200. As a joint Army and Air Force project, its given name—its military designation—was XH-33 (experimental helicopter), which eventually became XV-3 (experimental vertical) to better denote its capabilities. Like a helicopter, its lift came from rotor blades, but unlike most helicopters, it had two sets of rotors, one at each wingtip. The masts supporting the rotors were rotated by electric motors from vertical to horizontal to transition the craft from helicopter mode to fixed-wing-airplane mode.

Retired Bell engineer Ken Wernicke was a key player in the company’s post-XV-3 tilt-rotor development. “In 1964, I went to work for Bob Lichten, and we looked at all sorts of ways to combine the helicopter and the fixed-wing aircraft,” he recalls. “We looked at slowed rotors, stopped rotors, and folding rotors. To my mind, they were all garbage. We also looked at the variable-diameter rotor, which turned out to be too complex.” Basing his assessment on his experience with the XV-3 in its final years of flight testing, Wernicke says, “The tilt-rotor was the only feasible way to go.” Bell Helicopter Textron experimented with the twin-engine proof-of-concept XV-15 tilt-rotor in the 1970s, and in the 1980s teamed with Boeing to produce the V-22 Osprey. Today, the direct descendant of the XV-3 is in test and evaluation at U.S. Navy and Marine Corps bases in Maryland, North Carolina, and California.

After the wind tunnel tests, XV-3 no. 2 was turned over to the U.S. Air Force Museum at Wright-Patterson Air Force Base in Ohio, then was placed in outdoor storage at Davis-Monthan Air Force Base in Arizona. Several years later it was moved to the Army Aviation Museum at Fort Rucker, Alabama, cosmetically restored, and sent back outside for display, where it slowly deteriorated.

Last fall, a photo of the XV-3 in the Hurst office of Bell Helicopter’s new chief executive officer, Mike Redenbaugh, triggered a discussion. Retired Bell executive Dick Spivey noted the XV-3’s importance to the company’s unique tilt-rotor history, and lamented that “the aircraft is deteriorating and it’s only a matter of time before restoration efforts could prove futile.” Bell employees were aware of the aircraft’s condition, he told Redenbaugh, “but earlier attempts to save it received virtually no company support at a corporate level.”

In weeks, Spivey and Major General Charles Metcalf, director of the Air Force Museum, met in Fort Rucker, where it was agreed the XV-3 would be turned over to Bell for restoration. The aircraft’s wings, horizontal tail surfaces, and upper vertical tail panel were unbolted and packed alongside the fuselage in a flatbed truck. At Bell’s Plant 6 in Arlington, Texas, the various sub-assemblies were delicately off-loaded by forklift and moved into a hangar that was originally built to accommodate prototypes of the V-22. Bell plans a four-year refurbishment by a team of employees and retirees, then will deliver the grande dame of tilt-rotors to the Air Force Museum.

Originally concerned about corrosion, particularly of hard-to-replace parts, Bell has found little, and the company can buy or fabricate virtually everything necessary to reconstitute the aircraft back to near-original appearance. Areas of greatest concern, like the instrument panel, were essentially intact. Only two instruments were missing, but a check of old photos suggested they had never been installed.

The XV-3’s mid-fuselage-mounted, 450-horsepower Pratt & Whitney R-985 radial engine had been sufficiently preserved—the spark plugs had been replaced with desiccant-filled inserts to prevent moisture from accumulating in the cylinders. But the multi-piece canopy was declared unrestorable. The restoration team plans to hand-craft replacements for the broken or cracked panels.

The restoration efforts will be shepherded by Charles Davis, one of the original XV-3 engineers. “Looking at it today, I realize just how basic it really was,” he says. “But the XV-3 was able to do what it was designed for: Prove tilt-rotors could work. The V-22 and [civilian] model 609 are the result.”


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Comments (1)

Could I ask the question? Why does everybody rotate the rotating wing from the middle.It's much more efficiante turning it from the wing tips and eliminates the need for a tail rotor.I have a prototype built that runs on a 5h.p. generator 4 stroke.Contacts similar to a car horn allow the wing to rotate and tilt.Wing pitch still applical vertical control surfaces control axis Thanx Charlie I have pictures of this but am new at te computer can only send outlook express photo

Posted by Charles J Glazebrook on February 10,2009 | 09:00 AM

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