“Shoe,” Retriever, “Hupmobile” or Army Mule – a HUP by any other name is still a HUP: The Piasecki HUP Retriever and H-25 Army Mule helicopters, and the HUP of the Canada Aviation and Space Museum

The first production example of the Piasecki HUP Retriever helicopter. Anon., “News Picture Highlights.” Aviation Week, 15 January 1951, 9

Do you like helicopters, my reading friend? As a reader of our ode to science, technology and innovation, you must have some thoughts on the matter. Yes, yes, you must. Personally, while yours truly cannot say that I like helicopters, I must admit they are pretty amazing machines, which explains why this article of our blog / bulletin / thingee will go over the history of one of the types of helicopters on display at the Canada Aviation and Space Museum in Ottawa, Ontario.

And yes, I forgot to indicate how wonderful this national museum is. Sorry.

Once upon a time, and yes, that is the cliché to end all clichés, but bear with me. Once upon a time, say I, there was a firm called P-V Engineering Forum Incorporated, which became Piasecki Helicopter Corporation in 1946.

It so happened that, in 1945, the Bureau of Aeronautics of the United States Navy (USN) issued a requirement for a helicopter able to operate from aircraft carriers, as well as battleships and cruisers. Said jane / jack of all trade chopper was to be used for ship to shore / shore to ship communication, rescue work, passenger / very important people transportation and observation.

And yes, Piasecki Helicopter was mentioned in October and November 2017 issues of our blog / bulletin / thingee.

The USN and P-V Engineering Forum signed a development contract in February 1946. The first Piasecki HJP, one of the first helicopters specifically designed for use by the USN if you must know, flew in March 1948.

This rugged and compact design had overlapping tandem rotors which rotated in opposite direction. The blades of said rotors could be folded to save space aboard warships.

The HJP had an all metal structure, a feature which greatly reduced the level of vibration which had affected its earlier and larger stablemate, the Piasecki HRP Rescuer, a tandem rotor transport or rescue helicopter operated by the USN, the United States Marine Corps (USMC) and the United States Coast Guard. And yes, my lighthearted reading friend, the Rescuer was also known as the “Harp” and the “Flying Banana.”

Incidentally, a banana is technically a berry, and not a fruit, but I digress.

As you may imagine, the HJP was the not the only machine designed to fulfil the USN’s 1945 requirement. It was, however, superior to the other design submitted for the competition. As a result, Piasecki Helicopter was duly informed that the HJP would be put in production, as the Piasecki HUP Retriever, a designation / name which was seemingly adopted in July 1949. Incidentally, the firm got the first of several production orders in September of that year.

As of the fall of 1950, the relatively small facilities of Piasecki Helicopter were so utterly busy that it had to subcontract the fabrication of the HUP’s fuselage to Goodyear Aircraft Corporation, a subsidiary of a giant in the American automobile industry, Goodyear Tire and Rubber Company, and the Aircraft Division of Twin Coach Company, a well-known American vehicle manufacturer. Ford Instrument Company Incorporated, a subsidiary of, no, no, not of Ford Motor Company. It was a subsidiary of Sperry Corporation. Ford Instrument, say I, on the other hand, fabricated the HUP’s forward transmission assembly which linked the engine’s driveshaft to the forward rotor head.

For a time, in 1949 (and 1950?), the HUPs were assembled in a hangar at Philadelphia International Airport. And yes, Piasecki Helicopter’s facilities were located near “Philly,” in Morton, Pennsylvania.

Before I forget, I should probably provide you with the caption of the photograph from the 15 January 1951 issue of the American weekly magazine Aviation Week at the heart of this article. Here goes…

HUP-1 Enters Service – First production Piasecki HUP-1 utility copter to enter operational service leaves Morton, [Pennsylvania], for Lakehurst, [New Jersey], for use in pilot familiarization program before joining a Navy vessel. Powered by a 525-hp Continental, the all-metal HUP-1 can do over [209 kilometres/hour] 130 mph., seats five plus a crew of two. The inclined stabilisers are a recent addition.

The speed mentioned in this caption was / is worthy of note. Would you believe, my gullible, sorry, sorry, my faithful reading friend, that one of the 2 HJP prototypes reached a speed of 211 or so kilometres/hour (131 miles/hour) in February or March 1949?

Sadly enough, this unofficial world speed record for helicopters was not made official in later days or weeks. In any event, a helicopter designed by Bell Aircraft Corporation, a world famous firm mentioned several times in our blog / bulletin / thingee since August 2018, unofficially reached a speed of more than 215 kilometres/hour (almost 134 miles/hour) in March 1949.

Incidentally, the HUP was commonly known as the “Shoe,” a moniker derived from its appearance. It was also nicknamed the “Hupmobile,” the name used by an American automobile manufacturer active until 1940 or so, Hupp Motor Car Company, to designate its vehicles.

Would you believe that one of the HJP prototypes was the first helicopter to loop the loop, in late 1948 or early 1949? And no, the test pilot was not actually trying to do so at the time. James “Jim” Ryan was performing some pretty steep dives and found himself in the middle of a loop before he realised what was happening.

In late 1950, one of the HJP prototypes was used to test an autopilot developed by a world renowned specialist in the field mentioned in a September 2018 issue of out yadda yadda, Sperry Gyroscope Company Incorporated, a subsidiary of the aforementioned Sperry. The device in question was standard equipment aboard the second production version of the Retriever – a first for a production helicopter. The inward canted vertical fins mounted on the nearly horizontal stabilisers of the Retriever thus became unnecessary, and were removed.

Indeed, at some later date, the nearly horizontal stabilisers themselves were deemed unnecessary, and were also removed, but we are getting ahead of our story. Sorry.

It is worth noting that the HUP became, in the early 1950s, one of the first helicopters fitted with all metal rotor blades. That particular idea had been under consideration since early 1949.

In 1952, Piasecki Helicopter looked into the possibility of developing a twin-engined version of the HUP. This idea did not proceed beyond the design (and model?) stage.

In turn, no civilian version of the HUP was produced either, and this despite the fact that firm founder Frank Nicholas “Pi” Piasecki, a gentleman mentioned in a November 2017 of our blog / bulletin / thingee, very much wanted to do business with flying taxi and feeder liner operators.

Did you know that, from, late 1950 onward, one or both HJPs were used as flying scale models and flying component test beds for the Piasecki H-16 Transporter, a ginormous transport and / or rescue helicopter developed for the United States Air Force (USAF) and, later on, the aforementioned USMC and / or the United States Army, which could transport a large detachable passenger / cargo / troop container underneath its capacious fuselage.

Interestingly, it has been suggested that the USAF initiated the development of the Transporter in order to take under its wing the development of large transport helicopters, thus forcing the United States Army to use only relatively small observation and utility machines – a development that the latter was strongly opposed to.

The first of the pair of prototypes of the Transporter flew in late October 1953. This helicopter, possibly the largest rotary wing aircraft of the world at the time, was not put in production for a variety of reasons, a crucial one being the crash of the second prototype in early January 1956. Both crew members died in the accident.

Yours truly remembers playing with a small soft plastic Transporter back in the early 1960s. It might have been yellow, I think, or was it red?

In any event, I also remember, I think, playing with a much larger soft plastic Army Mule, also in the early 1960s. I believe it was green, and…

Why is your head spinning uncontrollably, my reading friend? Oh, apologies. I forgot to bring up the Army Mule, and complete the history of the Retriever.

The aforementioned second production version of the Retriever was the main production version of this helicopter. Like its predecessor, it served with distinction with USN units, as well as with the USMC and the Aéronautique navale of the French Marine nationale. The 20 or so machines of the latter were delivered in 1953 under the guise of the United States’ Mutual Defense Assistance Programme.

It is worth noting that at least one Retriever was used to see if was possible to operate a new type of lightweight submarine detection device, or sonar, from a helicopter. Said device could be lowered in the water while the helicopter was in the hover. The trials also included test flights with one or more specially equipped HRPs and Sikorsky HO4Ss. Indeed, the first test flight was seemingly made in 1951 and involved an HO4S – a type of chopper found in the wonderful collection of the Canada Aviation and Space Museum and one mentioned in August and November 2017 issues of our you know what.

In any event, a small number of specially-equipped Retrievers were used as anti-submarine helicopters. Indeed, it looks as if the USN had planned to use most of the HUPs on order for that type of work. Sadly, the anti-submarine HUPs did not prove very effective and were soon replaced by HO4Ss.

And no, it looks as if the USN’s HO4Ss did not have a name. Those of the United States army (and USAF?), on the other hand, were known as Chickasaws. And yes, for a great many years, and still in 2021, the United States Army gave to its transport and attack helicopters the names of First Nations tribes, from the Hughes / Boeing AH-64 Apache to the Sikorsky CH-54 Tarhe.

And yes, the Royal Canadian Navy (RCN) also conducted anti-submarine trials of its own, using at least one of its HO4Ss. The main anti-submarine helicopter of the Canadian military (RCN and later Canadian Armed Forces / Canadian Forces / Royal Canadian Air Force) was, however, the Sikorsky CHSS / CH-124 Sea King – another type of chopper found in the wonderful collection of the Canada Aviation and Space Museum, and one mentioned in February and July 2019 issues of our you still know what.

At some point in the 1950s, presumably in answer to a request from the USN, EDO Aircraft Corporation, one of the most famous maker of aircraft floats of the 20th century, fitted a Retriever with a watertight fibreglass hull and a pair of lateral floats. This helicopter was used for tests on water.

I hear (read?) that, in early 1954, the USN, or a firm working for it, seemingly equipped a Retriever with a ground-based and radio-based aircraft positioning device. Raydist, as it was called, was said to be surprisingly accurate for the time. Flown without a crew, the HUP could be directed by radio to fly within 1.5 metre (5 feet) of a precise location by an operator on the ground and, once there, hover in position.

Raydist was allegedly able to measure the position of an aircraft within 19 centimetres for every kilometre (12 inches for every mile) it was from the ground station, which meant about 52 metres at almost 275 kilometres (170 feet at 170 miles), the maximum range of the device in early 1951. I don’t know about you, but I find such results pretty astonishing given the technology of the time.

A large console developed by Raydist’s maker, Hastings Instrument Company, later Hastings-Raydist Incorporated, could automatically plot the position of several aircraft in traffic areas. The USAF acquired at least one such console in 1951, for the precision bombing range used by the crews of its new Boeing B-47 Stratojet jet powered bomber. It also used Raydist to test the accuracy of other position and plotting systems.

By 1956, a team from the Massachusetts Institute of Technology (MIT) was using a Raydist system to evaluate the radar systems and computer networks under development for use with the Semi-Automatic Ground Environment (SAGE), a very complex computer system which, when it became operational from 1958 onward, directed and control the USAF’s squadrons of surface to air missiles and all-weather bomber interceptors which would intercept and destroy, it was hoped, the fleet of long range bombers of the Dal’naya Aviatsiya Voruzhonnykh Syl, the long range aviation force of the armed forces of the Union of Soviet Socialist Republics, if a third, and last, world war began.

And yes, SAGE also directed and controlled the squadrons of surface to air missiles and all-weather bomber interceptors of the Royal Canadian Air Force / Canadian Armed Forces / Canadian Forces, and this until the early to mid-1980s.

And yes again, the globally known organisation which MIT was / is was mentioned in several issues of our yadda yadda, and this since July 2019.

Did you know that the USN used Raydist to calibrate the navigation systems of its nuclear-powered (thermo)nuclear missile launching submarines?

Would you believe that Raydist was one of the devices used to track the specially equipped Pratt Read TG-32 sailplane used, in March 1952, to set a world altitude record (13 488 metres (44 255 feet)) for 2-seat sailplanes? The TG-32 and its record, which remained in the books until August 2006 by the way, were mentioned in an October 2018 issue of our you know what. And that’s where you can go to obtain more info.

Interested as it was in producing large civilian transport helicopters, which might require such equipment to operate safely in crowded airspaces, Piasecki Helicopter followed the development of Raydist with a lot of attention.

The American oil industry followed the development of Raydist with a lot of attention. Indeed, the latter soon became one of the tools used in conjunction with oil rigs located in the Gulf of Mexico. Raydist stations could be found from Texas all the way to west coast of Florida.

A number of stations could also be found in Australia and Brazil. Yours truly cannot say (type?) who operated these stations or for what purpose.

What about the Army Mule, you ask, my reading friend? Apologies. We’re getting there.

At the beginning of the 1950s, the United States Army came to think that it could use a version of the Retriever, a utility / light transport / ambulance version to be more precise. Said helicopter was given the name / designation Piasecki H-25 Army Mule. Machines of this type, ordered in 1951, possibly thanks to the good offices of the USAF, were delivered in 1953-54. They were in fact the last of the 340 or so Retriever / Army Mule type helicopters delivered.

Sadly, the Army Mule proved unsuitable for frontline use. As a result, most of them were quickly turned into Retrievers and transferred to the USN – and to the aforementioned RCN, which received 3 of them in the spring of 1954.

The 3 HUPs, a designation I use because the RCN seemingly did not refer to these machines as Retrievers, were primarily acquired for use aboard the arctic patrol vessel / ice breaker HMCS Labrador, a powerful ship commissioned in July 1954.

A great deal of information on the career of the RCN’s HUPs and, more specifically, on the career of the HUP currently on display in the Canada Aviation and Space Museum can be found in a very well documented text written by Robert T. Murray, a fine gentleman and museum volunteer. (Hello, Sir.)

A (Piasecki Helicopter? USN?) proposal, seemingly made at some point in the 1950s, to install a more powerful engine on all USN Retrievers still in service was politely turned down.

Sadly, a serious conflict within Piasecki Helicopter led to the departure of Piasecki and some colleagues. His firm became Vertol Aircraft Corporation in March 1956. Piasecki had founded Piasecki Aircraft Corporation in 1955. These firms were mentioned in issues of our blog / bulletin / thingee: October 2017 and May 2019, and October 2017.

The French and Canadian-operated HUPs, as well as the USN’s Piasecki UH-25 Retrievers, a new designation adopted in 1962, soldiered on (sailored on?) until 1965 or so. The Canadian machines, for example, were put to pasture in 1964.

A number of Retrievers were soon acquired by American civilian operators and operated for a number of years. Would you believe that a (airworthy?) helicopter of this type was still in the American civil aircraft register as of early 2021?

I don’t know about you, but I feel like going out for a walk. So, if you don’t mind, I will sit down for a while, until that feeling goes away.

Profile picture for user rfortier
Rénald Fortier