Piasecki HUP Retriever explained

The Piasecki HUP Retriever or H-25 Army Mule, later UH-25, is a compact single radial engine, twin overlapping tandem rotor utility helicopter developed by the Piasecki Helicopter Corporation of Morton, Pennsylvania. Designed to a United States Navy specification, the helicopter was produced from 1949 to 1954, and was also used by the United States Army and foreign navies. The HUP/H-25 was the first helicopter to be produced with an autopilot and also the first to perform a loop.

Design and development

The design was a product of a competition by the U.S. Navy in 1945 for a compact utility/rescue helicopter to operate from ships including aircraft carriers, battleships, and cruisers. Either 2 or 3^[1] prototypes—designated PV-14 by the factory and XHJP-1 by the Navy—were built and subjected to a side-by-side flight evaluation against the 3 prototypes of the Sikorsky XHJS-1; however, the XHJS was fundamentally a scaled-up version of the Sikorsky H-5, and the increased weight and size magnified the design's problems with maintaining proper weight and balance under varying loading conditions.^[2] The Piasecki won the competition,^[2] and with the introduction of the aircraft configuration letter "U" for Utility in the 1950s,^[3] the aircraft was ordered for production as the HUP-1.

The design featured two three-bladed, 35adj=midNaNadj=mid rotors in tandem in which blades could be folded for storage; the relatively small rotor diameter allowed the aircraft to use aircraft carrier elevators with its blades fully extended. The tandem overlapping rotor configuration was a development by Piasecki and was used in future helicopter designs by the company and successors including the H-21, HRB-1/CH-46, and CH-47. The original HUP-1 was powered by a single Continental R-975-34 radial engine, with a take-off rating of 5250NaN0, while later versions used the uprated R-975-42 or R-975-46A with 5500NaN0. To aid search and rescue (SAR) operations, the aircraft was equipped with an overhead winch capable of lifting 400 lb (181 kg), which could lower a rescue sling through an electrically-operated door available after the copilot's seat was folded forward.^[4]

During a flight demonstration of its capability to withstand high g-force, the type became the first helicopter to perform a loop, albeit unintentionally.^[4]

Operational history

The aircraft first entered service in February 1949 with the delivery of the first of 32 HUP-1 aircraft to the US Navy. The improved HUP-2 (Piasecki designation PV-18) was soon introduced with a more powerful engine, deletion of the inward-canted horizontal stabilizer endplate fins, and various minor changes in equipment; a sub-variant equipped with dunking sonar for anti-submarine warfare was given the designation HUP-2S.^[4] The HUP-2 was the first production helicopter equipped with an autopilot.^[4] The US Navy also tested a radio navigation system called Raydist that allowed an unmanned HUP-2 to be directed from a ground station and by radio ordered to hover within 5feet of the desired point.^[5] Edo tested a HUP-2 with a fiberglass hull and outrigger floats for amphibious operations.^[6]

An upgraded version of the HUP-2 was built for the US Army and designated as the H-25A Army Mule, but most were quickly withdrawn from Army service and converted for naval use under the designation HUP-3.^[4] In 1954, the Royal Canadian Navy received three former US Army H-25A aircraft, which were modified and redesignated on delivery to conform to US Navy HUP-3 standards.^{[7] [8]} The aircraft were used aboard HMCS Labrador for search and rescue and varied utility duties, and were later used to support construction at Distant Early Warning Line radar sites.^[8] The helicopters were subsequently posted to NAF Patricia Bay and naval air station HMCS Shearwater; after the last two were stricken from inventory on 18 January 1964, one aircraft was donated to a technical school and the other two were sold as surplus.^[8]

The US Army H-25 designation was adopted by the US Navy in 1962 on introduction of the 1962 United States Tri-Service aircraft designation system. The final units were withdrawn from US service in 1964. It also served with French Naval Aviation (Aeronavale) from 1953 to 1965.^[4]

A total of 339 aircraft were delivered during the 6-year production run.^[4] A large number of surplus US Navy aircraft later appeared on the US civil registry, and at least seven were transferred to the French Navy.

On 7 November 2009, former US Navy HUP-1, BuNo 124925, civil registration number N183YP, collided with high-voltage power lines in Adelanto, California; the subsequent crash and post-crash fire killed all 3 occupants and substantially damaged the aircraft.^[9] Operated in association with Classic Rotors, the accident aircraft was the only airworthy example in the world.^[10] The National Transportation Safety Board attributed the crash to "The pilot’s failure to maintain clearance from powerlines during en route flight."^[9]

Variants

XHJP-1

Prototype, powered by a 5250NaN0 Continental R-975-34 piston engine, equipped with large sloping endplate fins on the horizontal stabilizers. Piasecki-Vertol designation was PV-14. 2 or 3^{[2] [1]} produced.

HUP-1

Utility transport and search and rescue helicopter for the US Navy, largely similar to XHJP-1, Piasecki designation was PV-18. 32 built.^[4]

HUP-2

Improved version, 5500NaN0 Continental R-975-42 piston engine, horizontal stabilizer endplate fins eliminated.^[4] 165 built for the US Navy, 15 for French Aeronavale. Redesignated UH-25B in 1962.

HUP-2S

Anti-submarine warfare version of HUP-2 fitted with dunking sonar. 12 built.^[4]

HUP-3

Naval utility conversion of H-25A aircraft transferred from US Army: 50 to US Navy, 3 to Royal Canadian Navy.^[11]

H-25A Army Mule

Utility transport helicopter for US Army, similar to HUP-2 but powered by a 5500NaN0 Continental R-975-46A piston engine, and fitted with large doors, power-boosted controls, and strengthened floors.^[4] 70 were delivered from 1953, but they were unsuitable for front-line use, with 53 transferred to the Royal Canadian and US Navies in 1954–1955,^[11] and the remaining helicopters used for training, being withdrawn from army service by 1958.^[12]

UH-25B

HUP-2 redesignated after 1962.

UH-25C

HUP-3 redesignated after 1962.

Operators

Canada

• Royal Canadian Navy^[13]

• French Navy^[14]

:

• United States Army
• United States Navy

Surviving aircraft

For surviving aircraft, hyphenated numbers are original US Army Serial Numbers; six-digit numbers are original US Navy Bureau of Aeronautics (BuAer) Bureau Numbers (BuNo). All 50 H-25A/HUP-3 aircraft transferred from the US Army to the US Navy were given new bureau numbers; 3 aircraft transferred to the Royal Canadian Navy were redesignated, but retained their original US Army serial numbers.^[11]

Canada

On display

• UH-25B (HUP-2) 128529 at Shearwater Aviation Museum in Shearwater, Nova Scotia.^[15] This aircraft has been restored to the appearance of 51-16621, the first Royal Canadian Navy HUP-3.^[8]
• UH-25C (HUP-3), 51-16623 - Canada Aviation and Space Museum in Ottawa, Ontario.^{[16] [17]}

Netherlands

• UH-25B (HUP-2), 130076 (construction number 253) – Baris Business Park roadway roundabout in Rotterdam. This aircraft was originally used by the US Navy and was later transferred to the French Navy.^[18]

United Kingdom

• UH-25C (HUP-3), 51-16622 – displayed at The Helicopter Museum in Weston-super-Mare, England, wearing Canadian markings.^{[11] [19]}

United States

On display

H-25A Army Mule

• 51-16616 – United States Army Aviation Museum in Fort Rucker, Alabama.^[20]

HUP-1

• 124915 – USS Hornet Museum in Alameda, California.^[21]

UH-25B (HUP-2)

• 128479 – American Helicopter Museum in West Chester, Pennsylvania.^[22]
• 128517 – Wings of Freedom Aviation Museum in Horsham, Pennsylvania.^[23]
• 128519 – Intrepid Sea, Air & Space Museum in New York City, New York.^[24]
• 128596 – Flying Leatherneck Aviation Museum in San Diego, California.^[25]

• 130059 – USS Midway Museum in San Diego, California.^[26]
• 130082 – on the deck of the USS Iowa Museum in San Pedro, California.^{[27] [28]}

UH-25C (HUP-3)

• 147595 – Pima Air & Space Museum in Tucson, Arizona.^[29]
• 147600 – Air Zoo in Kalamazoo, Michigan.^[30]
• 147607 – National Naval Aviation Museum in Pensacola, Florida.^[31]
• 147628 – Mid-America Air Museum in Liberal, Kansas.^[32]
• 51-16621 – Classic Rotors in Ramona, California.^[33] As of December 2019, this is the only Piasecki Helicopter-manufactured aircraft with valid FAA aircraft registration.^[34] This former Royal Canadian Navy aircraft is reportedly the last HUP/H-25 capable of being restored to airworthy condition; it was exchanged in 2000 by the Canadian Museum of Flight for unflyable HUP-2 128529, which was subsequently traded again in 2002 to the Shearwater Aviation Museum and repainted as 51-16621.^{[8] [15]}

Under restoration or in storage

UH-25B (HUP-2)

• 128598 - Stored at New England Air Museum in Windsor Locks, Connecticut.^[35]
• 130053 – Stored at Quartzsite, Arizona.^[36]
• 130063 - Stored at New England Air Museum in Windsor Locks, Connecticut.^[35]

UH-25C (HUP-3)

• 147610 – Yanks Air Museum in Chino, California, in storage.^[37]

References

Notes

Bibliography

• Bridgman, Leonard. Jane's All The World's Aircraft 1956–57. New York: The McGraw-Hill Book Company, 1956.
• Harding, Stephen. U.S. Army Aircraft Since 1947. Shrewsbury, UK:Airlife, 1990. .
• Book: Swanborough . Gordon . Bowers . Peter M. . 1976 . United States Navy Aircraft since 1911 . 2nd . Annapolis, Maryland . Naval Institute Press . 0-87021-968-5. .

External links

• H-25 US Army Aviation history fact sheet
• HUP Retriever warbird at the 2002 Chino Air Show

Notes and References

1. Web site: Piasecki PV-14 XHJP-1 US Navy. 1000aircraftphotos.com . 26 January 2014.
2. Web site: S-53 (U.S.Navy (XHJS-1) . Devine . Vinny . 10 April 2013 . Sikorsky Product History . Igor Sikorsky Historical Archives . 1 November 2018.
3. Swanborough and Bowers 1976, pp.8–9.
4. Web site: . HUP-1 Retriever/H-25 Army Mule Helicopter . dead . https://web.archive.org/web/20230609042841/https://www.boeing.com/history/products/hup-h-25-army-mule.page . 9 June 2023 . 1 November 2018 . boeing.com . Boeing.
5. Popular Mechanics. Hearst Magazines. Radio Waves Hold Helicopter In Fixed Hovering Position. May 1954. Hearst Magazines. 122.
6. Picture News: Watertight hull makes helicopter amphibious. Popular Science. February 1958. 172. 2. 149.
7. Web site: Piasecki HUP-3 . ingeniumcanada.org . Ingenium Canada - Canada Air and Space Museum . 31 October 2018 .
8. Web site: Piasecki HUP-3 . www.shearwateraviationmuseum.ns.ca . Shearwater Aviation Museum . 1 November 2018 . 4 May 2018 . https://web.archive.org/web/20180504131807/http://www.shearwateraviationmuseum.ns.ca/exhibits/hup.htm . dead .
9. NTSB Aviation Investigation Final Report. WPR10LA048 . 18 July 2011 . National Transportation Safety Board. 25 February 2023.
10. News: Allnutt . Richard Mallory . 25 December 2009 . Piasecki crash claims three lives . Aircraft Illustrated . Stamford, Lincolnshire, UK . Key Publishing Ltd. . 0002-2675.
11. Web site: Royal Canadian Navy – HUP detailed list . Walker . R.W.R. . Canadian Military Aircraft Serial Numbers . 31 October 2018 .
12. Harding 1990, pp. 197–198.
13. Web site: Piasecki H-25 History. Boeing. 2013-02-02. dead. https://web.archive.org/web/20121029172611/http://www.boeing.com/history/boeing/hup.html. 2012-10-29.
14. Web site: Piasecki PV-18 (HUP/H-25/UH-25) (Photo) . pictaero.com . 2 February 2013.
15. Book: Skaarup, Howard . 2009 . Canadian Warplanes . Bloomington, Indiana . iUniverse . 520 . 978-1-4401-6758-4 .
16. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=9090 "Piasecki HUP Retriever/51-16623."
17. Web site: Piasecki HUP-3. Canada Aviation and Space Museum. Canada Aviation and Space Museum. techno-science.ca. 5 May 2016. 7 February 2017. https://web.archive.org/web/20170207022704/http://casmuseum.techno-science.ca/en/collection-research/artifact-piasecki-hup-3.php. dead.
18. Web site: De helikopter . www.baris.nl . 11 November 2013 . Baris Groep . 1 November 2018 . nl . The helicopter .
19. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=11752 "Piasecki HUP Retriever/622 RCN."
20. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=17233 "Piasecki HUP Retriever/51-16616."
21. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=10923 "Piasecki HUP Retriever/124915."
22. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=63563 "Piasecki HUP Retriever/128479."
23. Web site: Piasecki HUP-2 "Retriever". Wings of Freedom Aviation Museum. 26 August 2016.
24. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=35971 "Piasecki HUP Retriever/128519."
25. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=419 "Piasecki HUP Retriever/128596."
26. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=29266 "Piasecki HUP Retriever/130059."
27. http://www.dailybreeze.com/general-news/20161018/historic-wartime-helicopter-to-be-pieced-together-for-san-pedros-battleship-iowa "Piasecki HUP Retriever/130082."
28. Web site: New Exhibits. 20 February 2022. Pacific Battleship Center. USS Iowa Museum. pacificbattleship.com. 2019 . https://web.archive.org/web/20200424002946/https://www.pacificbattleship.com/visit-us/special-exhibits/. 24 April 2020. dead.
29. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=34520 "Piasecki HUP Retriever/147595."
30. Web site: Piasecki HUP Retriever/147600. www.aerialvisuals.ca. 2016-06-08.
31. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=26108 "Piasecki HUP Retriever/147607."
32. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=75028 "Piasecki HUP Retriever/147628."
33. Web site: N-Number Inquiry Results N7089F. 1 November 2018. Federal Aviation Administration. Federal Aviation Administration. 1 November 2018. 6 November 2018. https://web.archive.org/web/20181106005032/https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=7089F. dead.
34. Web site: Manufacturer Inquiry Results Piasecki. 16 December 2019. Federal Aviation Administration. Federal Aviation Administration. 16 December 2019. 4 January 2020. https://web.archive.org/web/20200104033145/https://registry.faa.gov/aircraftinquiry/AcftRef_Results.aspx?Mfrtxt=PIASECKI&Modeltxt=&PageNo=1. dead.
35. Web site: Bradley - Museum, Connecticut. 20 September 2023.
36. https://www.aerialvisuals.ca/AirframeDossier.php?Serial=33423 "Piasecki HUP Retriever/130053."
37. http://www.aerialvisuals.ca/AirframeDossier.php?Serial=161310 "Piasecki HUP Retriever/147610."

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