Wire strike protection system
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The wire strike protection system (WSPS) is a mechanical wire cutter designed to mitigate the risk of wire strikes whilst flying
History
During the six-year period covering calendar years 1974 through 1979, wire strike accidents accounted for a significant share of
Because the Bristol testing did not determine the effectiveness of the lower fuselage-mounted cutter, and was a ground-based test that did not evaluate how a wire strike with the cutter would affect aircraft attitude during flight, the
During the Langley tests, an OH-58 was attached to the end of a 196-foot (60 m) long cable, pulled back, and released to swing through wires mounted horizontally at a height of approximately 22 feet (6.7 m).
All small to medium [a] United States Army helicopters were fitted with WSPS in a retrofit programme that was completed in 1992.[7] Between 1996 and 2002 the US Army had no fatal wire strike accidents.[7] In civil helicopter operations, wire cutters were thought to be most effective for agricultural flights.[2]: 37–38 Of the 208 wire strike accidents in the 1970s, almost half could have been avoided with wire cutters and other recommended mechanical upgrades.[2]: 45
Description
The system is typically mounted around the front of American military helicopters,[6] rescue helicopters and of civilian helicopters involved in agricultural work. It is effective when the helicopter strikes the wires at angle of less than 90 degrees and at speeds more than 30 knots (35 mph; 56 km/h).[7] The system is designed to cut a 3⁄8-inch (9.5 mm) steel cable with a breaking strength of 12,000 lb (5,400 kg).[7]
The WSPS developed by Bristol, which is typical of most cable cutters today, consists of a roof-mounted cutter, a lower cutter fitted to the fuselage,[b] and a deflector fitted to the middle of the windshield to guide the cable into the cutters.[1]: 9 [7] Sometimes a windshield wiper protector frame is used to stop the cables from catching on wiper motor shafts.[8][unreliable source?] As installed, the OH-58 WSPS developed by Bristol weighs 16.3 lb (7.4 kg) and requires 40 man-hours to install.[1]: 15
Wire Strike Protection System is a registered trademark of
See also
- Wire cutter (jeep)
Notes
References
- ^ a b c d e f g h i Burrows, LeRoy T. (June 1980). Investigation of Helicopter Wire Strike Protection Concepts (PDF) (Report). US Army AVRADCOM. Archived (PDF) from the original on June 4, 2021. Retrieved 2 April 2020.
- ^ a b c d Tuomela, Clyde H.; Brennan, Mark F. (October 1980). Civil Helicopter Wire Strike Assessment Study (PDF) (Report). Vol. 1. National Aeronautics and Space Administration. Retrieved 2 April 2020.
- ^ CA patent 1079182, Nelson Chan, "Cable-cutting device", published 10 June 1980, assigned to Canada Minister of National Defence
- ^ US patent 4215833, Nelson Chan, "Cable-cutting device", published 5 August 1980, assigned to Canada Minister of National Defence
- ^ a b Burrows, LeRoy T. (November 1982). Verification Testing of a UH-1 Wire Strike Protection System (WSPS) (PDF) (Report). US Army AVRADCOM. Archived (PDF) from the original on June 7, 2021. Retrieved 2 April 2020.
- ^ a b c Burrows, LeRoy T. (December 1982). Verification Testing of an AH-1S Wire Strike Protection System (WSPS) (PDF) (Report). US Army Aviation Research and Development Command (AVRADCOM). Archived (PDF) from the original on June 7, 2021. Retrieved 2 April 2020.
- ^ a b c d e Nagaraj, Vengalattore T.; Chopra, Inderjit (September 2018). Safety Study of Wire Strike Devices Installed on Civil and Military Helicopters (PDF) (Report). Air Traffic Organization, Operations Planning Office of Aviation Research and Development, Federal Aviation Administration, United States Department of Transportation. Retrieved 2 April 2020.
- ^ WSPS
- ^ "Wire Strike Protection System™" (PDF). Magellan Aerospace. Retrieved 2 April 2020.
- ^ "Cable Cutters". DART Aerospace. Retrieved 2 April 2020.
- ^ US patent 4407467, Charles F. Emigh & Morris Goldin, "Tactical wire-cutter system for helicopters", published 4 October 1983, assigned to McDonnell Douglas Helicopter Co
- ^ US patent 4826103, James M. McKown, "Active cable-cutting assembly for aircraft", published 2 May 1989, assigned to Custom Air Inc.
- ^ FR patent 2935956, Gerald Claeys, "Dispositif sectionneur de cables", published 2 May 1989, assigned to Airbus Helicopters SAS
- ^ FR patent 2982844, Marc Denante & Lacroix Pierre Prudhomme, "Dispositif sectionneur de cables, et aeronef", published 14 March 2014, assigned to Airbus Helicopters SAS
- ^ US patennt 9725165, Michael Smith; Chen-Ho Tho & Anand Kumar Marimuthu, "Cable cutter system", published 8 August 2017, assigned to Bell Helicopter Textron Inc.
- ^ US patent 5286170, William W. Brannon, "Helicopter wire strike cutter", published 15 February 1994
External links
- www.helicopterpage.com - WSPS (How Helicopters Work) [unreliable source?]
- Wire Strike Accidents in General Aviation: Data Analysis 1994 to 2004 – Page 33
- Wire Strike Protection System, MDHS 500 Maintenance Manual
- Magellan Aerospace Announces New Bell Helicopter Wire Strike Protection System Development
- Wire Strike Protection System (WSPS) - The Cutting Edge of Helicopter Safety on YouTube. Marketing video from Magellan/Bristol that includes development of WSPS. Clips from flatbed and pendulum testing are shown.
- Un hélicoptère percute des lignes de haute tension on YouTube. Video of a helicopter wire strike that occurred during a rescue exercise. The helicopter was equipped with a WSPS.
- Prior art
- DK patent 38811C, Jacob Christian Hansen-Ellehammer, "Flyvemaskine", published 29 May 1928 =, assigned to Fabrikant af Motorer og Motorkøretøjer
- DE Grant 739409C, Georg Baierle & Gustav Leutner, "An einem Flugzeug angebrachte Vorrichtung zum Zerstoeren von Sperrdraehten", published 24 September 1943
- US Grant 2335952A, James Martin, "Cable cutting device for use on aircraft", published 7 December 1943
- AU Grant 6573374A, William Ronald Smith & Sydney Langford Howlett, "Improvements in and relating to cable specification or other line cutting devices", published 21 August 1975, assigned to Commonwealth of Australia