Bell Tiltrotor Aircraft
Bell Helicopter Textron
Bell D326 Clipper

The following aircraft display the progression of designs following the XV-3 project to the beginning of the XV-15 project.


D-207
Description
Project Engineer
Date
Cargo convertiplane Graham 2-26-1953
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D-220
Description
Project Engineer
Date
Observation-reconnaissance version of XV-3 with T58 turbine (General Electric) Graham 4-27-1955
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D-222
Description
Project Engineer
Date
Air rescue convertiplane with multi-engines Graham 11-21-1955
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D-223
Description
Project Engineer
Date
Vertical takeoff transport with 4 General Electric XT58 turbines Sawicki 5-18-1956
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D-224
Description
Project Engineer
Date
Air rescue convertiplane with 3 General Electric ST-112 turbines Sawicki 5-18-1956
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D-225
Description
Project Engineer
Date
Air rescue convertiplane with 2 Allison T56 turbines Sawicki 6-4-1956
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D-232
Description
Project Engineer
Date
Tilt wing rotor feasibility study Haig 5-28-1957
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D-242
Description
Project Engineer
Date
Target activation convertiplane Graham 3-31-1959
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D-243
Description
Project Engineer
Date
One to two ton cargo convertiplane Graham 3-31-1959
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D-244
Description
Project Engineer
Date
Utility command convertiplane Graham 3-31-1959
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D-246
Description Project Engineer Date
Medium transport convertiplane powered by 4 Lycoming T55-L-5 turbines Graham 1-13-1960
Bell D-246A. Bell Helicopter
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D-252
Description
Project Engineer
Date
VTOL transport aircraft with 2 T64 turbines. Entered into Tri-Service competition and designed to meet these requirements:
  • Weight: 35,000 lbs.
  • Payload: 4 tons
  • Operating Radius: 200-300 miles
  • Ferry Range: 2,200-2,600 miles
  • Cruising Speed: 250-300 knots
  • Maximum Speed: 300-400 knots
Graham 2-21-1960
Bell D-252
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D-252A
Description
Project Engineer
Date
NATO version of D-252 Graham 10-18-1961
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T-37 Trailrotor
Description
Project Engineer
Date
Trailrotor concept full scale testbed project Unknown Unknown
Early folding rotor testbed proposal from Bell files was this modified Cessna T-37. Rotors are shown in partial nacelle conversion toward pusher configuration. Rotor blades would fold once horizontal speed was attained. Bell Helicopter Textron 244231 Early folding tilt rotor concept aircraft dates from mid-1960's. Transport configuration is shown. Bell Helicopter Textron 004738 Wind tunnel full-scale folding rotor test device is shown during instrumentation testing at Bell Helicopter. Bell Helicopter Textron Picture circa 1965
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D-266
Description
Project Engineer
Date
Proprotor VTOL research aircraft composite pre-design study proposal. Developed in response to Army's Composite Aircraft Program. Project ended early 1969 due to lack of funding. Also contributing to the project was Bob Lichten.
  • Power: Two General Electric T64-GE-16 turbine engines
  • Maximum Cruise Speed: 350 knots (determined via wind tunnel models)
  • Design Gross Weight: 28,000 lbs.
  • Overload Gross Weight: 35,000 lbs.
  • Rotor Diameter: 38 feet, 6 inches
Ken Wernicke 6-28-1965
The D-266 was a serious tilt rotor proposal from Bell that was initially evolved as a testbed aircraft. In this particular variant, the engines are mounted at the wing root, driving the prop rotors via shafting. Bell Helicopter Textron

Click here to see models of D-266 in three modes of flight.

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(Model Number) 266
Description
Project Engineer
Date
V/STOL Transport. Project funded in 1966 & 1967 via US Army Composite Aircraft Program.
  • Power: Two General Electric T-64's which power three-bladed proprotors.
  • Speed: 370 knots (686 km/h)
  • Weight: 35,000 lbs. (15,875 kg.)
  • Capacity: 25 seats
Unknown Circa 1966
The Model 266 Commercial was a civil design evolved from an earlier military proposal. Note that the Model 266 and the D-266 are two totally different designs. Bell Helicopter Textron
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D-267
Description
Project Engineer
Date
First design study for a full-scale tilt rotor demonstrator. Significantly smaller than the D266, and oriented toward commercial rather than military operation. Ken Wernicke 4-26-1968
First major step toward the development of the XV-15 was the D267. This design eventually gave birth to the Model 300. Bell Helicopter Textron 006111
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D-270
Description
Project Engineer
Date
Design study for a 60,000-lbs. proprotor Jack DeTore 6-5-1969
The D270A design study was for a large rescue aircraft. Version shown, in wind tunnel model form, was the D270B transport. Gross weight was to have been 66,000 lbs. Bell Helicopter Textron 007801
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D-271
Description
Project Engineer
Date
Proprotor proof of concept aircraft design Jack DeTore 7-15-1969
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D-272
Description
Project Engineer
Date
Folding proprotor proof of concept aircraft design Jack DeTore 7-15-1969
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D-300
Description
Project Engineer
Date
CARA (Combat Air Rescue) +64. This model evolved into the Model 301, otherwise known as the built XV-15 . Graham 5-9-1967
Full-scale mock-up of Model 300. This configuration was modified substantially before giving birth to the Model 301. Bell Helicopter Textron 269141 This mock-up was a forerunner of the XV-15. It was designated the Model 300 and had a conventional tail. It was never built as a flying aircraft. Bell Helicopter Textron

Click here to see Model 300 drawing used for competition

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    Sources:
  • Ahnstrom. The Complete Book of Helicopters. 156.
  • "Bell XV-15" Aerophile. October 1979: 2-21.
  • Brown, David A. The Bell Helicopter Textron Story. Arlington, TX: Aerofax, Inc., 1995.
  • Campbell, John P. Vertical TakeOff & Landing Aircraft. New York: The Macmillan Company, 1962.
  • Der Flieger. May 1965: 111.
  • "Straight Up and Away" Flying Review. May 1969: 52.
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