Bell XV-15

VTOL Technology Demonstrator [ 1977 ]

The Bell XV-15 tilt-rotor technology demonstrator was the forerunner to the in-service V-22 Osprey of the American military.

Authored By: Staff Writer | Last Edited: 03/04/2020 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

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Since the dawn of vertical-to-horizontal flight offered by helicopters (the first operational models were had during World War 2), aeronautical engineers have strived for ways to incorporate even better straight-line performance. This led to a myriad of experiments seen throughout the Cold War period as companies attempted to find a proper solution. For a time, "pusher" propellers seemed the future while other designs relied on complex turbojet arrangements coupled to traditional helicopter blade arrangements. In time, the technology behind "tilting" nacelles was refined, leading to the concept of the "tilt-rotor" aircraft - an air vehicle that was part helicopter, part airplane.

In time, Bell worked on bringing its XV-3 prototype to life which followed the Transcendental "Model 1-G" and "Model 2" forms. The Model 1-G was the first tilt-rotor in aviation history to fly and was powered by reciprocating engines buried in the fuselage driving power, via shafts, to wingtip rotors that could tilt. The subsequent XV-3, a more evolved form of the Model 1-G and Model 2, reached the skies in 1955 using similar concepts and this aircraft went on to hold the distinction of becoming the first tilt-rotor aircraft to convert from vertical-to-horizontal flight, paving the way for the refined XV-15 development that followed.

The XV-15 was a radical redesign of the same tilt-rotor approach but relocated its engines to tilting nacelles placed at the wingtips. Between the two engines was a shared driveshaft to be relied upon should one engine fail - the other could keep up the workload. The XV-15 project was formally launched in 1971.

The basic arrangement of the XV-15, which is mimicked today by the in-service V-22 of the American military, was set: the fuselage held a helicopter-like form with side-by-side seating at the cockpit for two crewmen while the aft-section was tapered. Over the roof of the vehicle was seated the shared wing component to which the tilting engine nacelles were seated at the tips, these driving large, thick rotor blades about an oversized spinner. The fuselage was braced on the ground by a retractable tricycle arrangement and the tail incorporated a twin-fin rudder configuration set on a shared horizontal plane.

The XV-15 was flown for the first time on May 3rd, 1977 and, itself, was the progenitor to the Boeing V-22 "Osprey" line detailed elsewhere on this site. The Boeing V-22 became the first tilt-rotor aircraft to formally enter operational service n 2007.

The U.S. government contracted for a pair of flyable prototypes to continue the program and competition was had from Boeing, Grumman, and Sikorsky joining Bell. For NASA, the Bell submission ultimately won out with its Model 301 when going head-to-head against Boeing (which supplied its Model 222). Bell then produced two prototypes, N702NA and N703NA. These went on to be extensively tested at the Ames Research Center in Mountain View, California and then to Dryden (NASA, Edwards AFB) for their time in the air. It made its public debut at Paris Air Show 1981 and proved itself a hit with onlookers.

N702NA later crashed on a test flight (no loss of life) with its remains reconstituted for the simulator role. N703NA survived its flying days to become a display, first, at the National Museum of the United States Air Force in Dayton, Ohio and then, later, a display at the Udvar-Hazy Center aviation museum near Washington, D.C.

With its usefulness over, the XV-15 series was retired in full in 2003.

Bell teamed with Boeing to bring about the V-22 series, a larger version of the XV-15 with greater power and capabilities.©MilitaryFactory.com

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Specifications

Service Year

1977

Origin

United States

Status

RETIRED
Not in Service.

Crew

2

Production

2
UNITS

Bell Helicopter Textron - USA

(View other Aviaton-Related Manufacturers)

United States (retired)

(OPERATORS list includes past, present, and future operators when applicable)

✓ X-Plane (Developmental, Prototype, Technology Demonstrator)
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.

Length

42.2 ft
(12.85 m)

Width/Span

57.3 ft
(17.45 m)

Height

12.6 ft
(3.85 m)

Empty Wgt

10,086 lb
(4,575 kg)

MTOW

13,228 lb
(6,000 kg)

Wgt Diff

+3,142 lb
(+1,425 kg)

(Showcased structural values pertain to the base Bell XV-15 production variant)

Installed: 2 x Avco Lycoming LTC1K-4K (T53-L-13B) turboshaft engines developing 1,550 horsepower each driving three-bladed propeller units in tilting nacelles.

Max Speed

348 mph
(560 kph | 302 kts)

Ceiling

29,035 ft
(8,850 m | 5 mi)

Range

513 mi
(825 km | 1,528 nm)

♦ MACH Regime (Sonic)

Sub

Trans

Super

Hyper

HiHyper

ReEntry

♦

(Showcased performance specifications pertain to the base Bell XV-15 production variant. Performance specifications showcased above are subject to environmental factors as well as aircraft configuration. Estimates are made when Real Data not available. Compare this aircraft entry against any other in our database or View aircraft by powerplant type)

Hardpoint Mountings:

XV-15 - Base Project Designation; two flyable forms completed.

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