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Post Info TOPIC: Weir rotorcraft designations


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Date: Aug 5, 2015
Weir rotorcraft designations

J&G Weir Company, 1932-1943

Weir W-1 - Autogyro with two-blade rotor measuring 8.53m in diameter plus a 40hp Douglas Dryad HO-2 engine. First flight May 1933.

Weir W-2 - Derivative of the W-1 as a "jump-start" autogyro with 50hp Weir O-92 flat twin-cylinder engine (according to Apophenia, the engine was also referred to as "Dryad II" in other sources). Used a modified W-1 rotor utilizing the first auto-dynamic rotor head. First flight March 1934. To solve some stability issues, it was later fitted with tail surfaces of the W-3. Planned for production but did not come to fruition.

  • Designation also used for a licence-built version of the Cierva C.28.

Weir W-3 - Single-seat experimental "direct take-off" autogyro with inverted 50hp Weir Pixie I 4-cylinder inline engine and clutched two-blade auto-dynamic rotor measuring 5.66m in diameter. First flight July 1936.

Weir W-4 - Refined W-3 design with inverted 68hp Weir Pixie II 4-cylinder inline engine. Built in 1937 but was destroyed during a test when the jump-start caused the aircraft to roll onto its side. The last of Weir autogyro designs.

  • Designation also used for an unbuilt project for a twin-rotor helicopter, which led to the development of the W-5.
  • Weir Jaberwock helicopter - Project derived from the remains of the W.4 by C.G.Pullin. Mockup only. (Possible alternate name for the above mentioned "unbuilt" project?)

Weir W-5 - Single-seat twin-rotor helicopter based on the Cierva-licensed Focke-Achgelis Fa 61 design with fan-cooled 50hp Weir Pixie II engine. Thrust was controlled by rotor speed. First flight June 7, 1938.

Weir W-6 - Larger two-seat derivative of the W-5 with fan-cooled 200hp DH Gipsy Six II engine driving twin 3-blade rotors on welded steel tube outriggers. First flight October 27, 1939, but work stopped in mid-1940 due to the outbreak of WWII.

Weir W-7 - Project for a three-seat "gyrodyne" helicopter with 3-blade main rotor and offset torque-countering rotor mounted on the shock-strut of the starboard wheel undercarriage. Unbuilt. Was offered to the Royal Navy as a "Fleet Shadower" ASW aircraft.

Weir W-8 - Project for a single-seat experimental helicopter with blown single-rotor system which Weir called "The Reaction System", comprising of a compressor fitted to either a de Havilland Gipsy Six or Rolls-Royce Kestrel engine. Unsuccessful.


Cierva-Weir (with Cierva Autogiro Company), 1943-1951

The following also fit respectively into Cierva's designation system, however the "W"-prefix was retained.

Weir W-9 - Two-seat single-rotor helicopter with fan thrust countered rotor torque. Based on the Sikorsky R-4/R-5 with the 200hp DH Gipsy Six II of the W-6 (other sources say it was a 205hp DH Gipsy Queen 31). First flight 1946.

Weir W-10 - Project for a four/six-seat helicopter similar to the W-9's basic layout powered by a 510hp Armstrong-Siddeley Cheetah engine.

Weir W-11 "Air-Horse" - Tri-rotor helicopter designed to carry 24 passengers.

  • "Spraying Mantis" - Crop-spraying version designed in 1946 for Pest Control Ltd. with two front rotors and one at the rear.
  • E.19/46 - Design specification in which two rotors are outrigged at the rear and one mounted at the front, opposite of the first crop-spraying layout. Contracted to Weir in July 1946 to develop a working prototype. A second was ordered in early 1947. Cunliffe-Owen Aircraft Ltd. was contracted to build both at Southampton/Eastleigh Airport under the technical and financial control of Cierva.
  • First prototype - Resulting from above specification. Powered by 1,620hp Rolls-Royce Merlin 24 engine driving three 3-blade rotors each measuring 14.32m in diameter. First flight December 1948. Crashed in June 13, 1950, after being displayed at the Farnborough air show. The three flight test crew members were killed, resulting in termination of the program until Cierva was taken over by Saunders Roe.
  • Second prototype - Same as above. Not flown. Scrapped upon project termination due to the crash of the first prototype.
  • W-11T - Project for a larger twin-engine derivative powered by RR Merlin 502 engines. An alternate layout consisted of turboshafts. Proposed in 1948. Unbuilt.

Weir W-12 - Project for a smaller derivative of the W.11 powered by RR Dart turbines. Unbuilt.

  • First variant - Designed to carry 12 passengers.
  • Second variant - Cargo-specific layout with rear clamshell doors. Designed to carry a 1.5-ton payload.

Weir W-13 - Not used.

Weir/Saunders-Roe W.14 "Skeeter" - Two-seat helicopter. Originally a Cierva-Weir development but was later taken over by Saro per acquisition of the company in January 1951. Production ended in 1960 after Saro became part of Westland. 77 total variants were built.

  • Experimental helicopter - Built in mid-1948 and developed into the W.14 program.
  • Skeeter 1 - First prototype (G-AJCJ) powered by a 106hp Jameson FF-1 HO-4 engine. First flight October 8, 1948.
  • Skeeter 2 - Second prototype (G-ALUF) with 145hp DH Gipsy Major X (10) engine. Rotor diameter increased plus had a slightly longer tailboom with circular cross-section instead of triangular. First flight 1949.
  • Skeeter 3 - Two prototypes built by Weir/Cierva, later acquired by Saro.
  • Skeeter 3B - The two previous prototypes redesignated after being fitted with 180hp Blackburn Bombardier 702 engines.
  • Skeeter 4 - Another prototype based on the previous two.
  • Skeeter 5 - Two prototypes built to reduce ground resonance problems found with all of the previous prototypes. Later fitted with 200hp Gipsy Major 201 engines in 1956.
  • Skeeter 6 - Three government-sponsored prototypes with 183hp Gipsy Major 30 engines.
  • ? - Skeeter 6 ambulance variant equipped with Napier NRE.19 boost system. Includes rocket-fuel tank above the rotor hub.
  • Skeeter 6A / AOP Mk.10 - Production variant for the Army Air Corps.
  • Skeeter 6B / T Mk.11 - Production variant for the Royal Air Force.
  • Skeeter 7 - Basic production standard for follow-on production orders which included the use of 215hp Gipsy Major 215 engines.
  • Skeeter 7A / AOP Mk.12 - AAC variant with above engine standard.
  • Skeeter 7B / T Mk.13 - RAF variant with above engine standard.
  • Skeeter 7(?) Mk.50 - 11 production variants for the Federal German Army.
  • Skeeter 7(?) Mk.51 - 4 production variants for the Federal German Navy.
  • Skeeter 8 - Derivative of the Skeeter 7 for civil use. Three were built but no civil production orders came.


lllll   As of 2019 I have transitioned; My name is now Rei. Please don't deadname or misgender me, thank you. <3   lllll

Global Moderator

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Posts: 1563
Date: Aug 7, 2015

Great list as usual but the chronology is questionable. :/


Airplanes are beautiful dreams. Engineers turn dreams into reality.


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Posts: 3528
Date: Aug 8, 2015

See my reply in the Cierva thread.


lllll   As of 2019 I have transitioned; My name is now Rei. Please don't deadname or misgender me, thank you. <3   lllll

Veteran Member - Level 2

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Posts: 246
Date: Aug 9, 2015

Excellent list.

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