Aviation Ancestry - February 2010
Still Earning Its Keep: The Bell UH-1
By Scott Schwartz
Painted as an Army Medevac helicopter, a privately owned Huey is still going strong at the Nellis AFB Air Show in 2007. Not the exhaust ripple from the Lycoming T-53 engine. (Scott Schwartz)Popular culture generally associates the Bell UH-1 Huey with the war in Viet Nam. The thumping of its rotor blades is familiar to a generation whose experience with that war was gleaned through movies such as Apocalypse Now. But, the origins of this aircraft date back to the early 1950’s, when the U.S. Army was looking for a new helicopter to meet its requirement for a battlefield “Medevac,” instrument training, and general utility aircraft. The reader should remember that jet-engine technology was in its adolescence at this point. Most “utility” aircraft – both fixed and rotary wing – were powered by piston engines. Given the power versus weight limitations that are inherent to piston engines, the helicopters that were in the Army’s inventory at the time tended to be underpowered and slow.
The year was 1953. During that year, numerous companies presented designs to the Army, in the hope of landing the contract. Among them were Bell, with its turbo-shaft model 204, and Kaman with a turbo-shaft version of its twin-rotor HH-43 (the earlier version having been powered by a nine cylinder radial piston engine).
By February of 1955, the Army had decided to purchase the Bell design. Perhaps this was because the Bell 204 was specifically designed to meets the Army’s requirements, and because it was not merely a gas-turbine version of a piston engine aircraft. Initially, the Army ordered three aircraft for test purposes, under the designation XH-40.
Apparently, the Army had great confidence in the XH-40, because the service wound up ordering six YH-40 service/test aircraft before the first XH-40 ever flew!
Given the power versus weight advantages of gas-turbine engines over piston engines, it is easy to understand why the Army was impressed with the YH-40’s performance. In that vein, a little perspective is in order.
Weighing more than 800 pounds, the Pratt &Whitney R-1340 nine-cylinder piston engine generates between 500 and 600 horsepower (depending upon the version of the engine in question). On the other hand, the Lycoming T-53-L-1A turbo-shaft engine that powered the YH-40, weighed in at 540 lbs., yet produced 770 shaft-horsepower. The YH-40’s first flight took place in 1956, and the other two helicopters that were part of the original order were delivered in 1957.
Three years later, the Army ordered the aircraft into production as the HU-1A Iroquois. The production contract called for 100 aircraft, and the official name, Iroquois, was hardly used in practice. Instead, the aircraft was usually referred to as the “Huey”, based on its HU-1 designation.
Despite the superior performance of the turbo-shaft helicopter over its piston-engine counterparts, the Army believed that the YH-40 was under-powered. In fact, concurrently with the delivery of the first HU-1’s (which were re-designated as “UH-1’s in 1962 – the “Huey” nick name stuck, though.), the Army was already requesting a more powerful version of the helicopter.
Bell’s response was the UH-1B, which had a 960 shaft-horsepower version of the Lycoming T-53 engine. The UH-1B’s fuselage was longer, enabling the aircraft to carry seven passengers (plus the pilots), or four stretchers and a medical attendant. Deliveries of the UH-1B began in 1961.
Combat experience indicated that there was a need for yet more improvements. One problem was the tendency of the rotor blade that was retreating in relation to the air stream, to stall – particularly during diving maneuvers. Another issue was the drag created by the variety of weapons that were being mounted on the helicopter. As a result, the new UH-1C was equipped with a new rotor blade system, a longer tail boom, and an 1100 shaft-horsepower version of the T-53 engine. This engine would eventually be installed in existing UH-1B helicopters, as well.
Other changes included an auxiliary hydraulic system and a better engine air-filtering system, which was a response to the dusty conditions in Viet Nam. Production of the UH-1C began in 1966.
As with many aircraft of both the fixed- and rotary-wing type, the design of the UH-1 evolved as more was demanded of it in combat.
In the case of the UH-1, the Army found that the ability to carry additional crewmen (in the form of door gunners) more troops, and/or more stretchers was necessary. Rising to the occasion, Bell introduced the Model 205, the fuselage of which was 41-inches longer than that of the UH-1B. This enabled the aircraft to carry 15 people, including the flight crew. The Model 205 was purchased by the Army as the UH-1D and this version featured the larger sliding doors with two windows each, as well as smaller hinged door near the flight deck. All of the doors were removable. Able to carry six stretchers, the UH-1D was a much more versatile medevac helicopter than its predecessors. Operational use of the UH-1D began in 1963.
A proper discussion of the “Huey’s” combat missions in Viet Nam would probably occupy several volumes. The reader should know that the UH-1 served in almost every role imaginable, during that conflict. Besides troop transport and medical evacuation, “Hueys” transported cargo, flew search and rescue missions, flew electronic warfare missions, were utilized as general transportation aircraft, and were flown on ground attack missions, and flew as armed escorts for troop-carrying helicopters.
For ground attack and escort missions, Hueys were fitted with grenade launchers, rocket launchers, and machine guns – in various combinations.
Other branches of the U.S. military operated the UH-1, and Bell practically tailored variants of the aircraft for each service.
The U.S. Marine Corps wound up buying the basic UH-1B; however more aluminum parts were used in its construction (to combat corrosion), Marine Corps compatible radio equipment was installed, and the aircraft was equipped with a rotor brake for quick wind-down during ship-board operations. These changes resulted in the aircraft being re-designated as the UH-1E. Navy training and utility versions of this aircraft were known as UH-1L’s and TH-1L’s, respectively.
Though not needing an assault helicopter, the USAF was in need of a helicopter for use in support operations at its missile bases. The Air Force also required the aircraft to make use of the General Electric T-58 turbo-shaft engine, which it had stock piled in connection with the HH-3 “Jolly Green Giant” fleet. This resulted in the UH-1F, and 27 of these aircraft were delivered to the Air Force in 1967.
More than 27 UH-1 variants have been built – and this number does not even include the civil 204/205/212 variants, and the same basic aircraft is in production to this day (if Bell’s web-site is any indication). The UH-1H version, however, was built in greater numbers than any other, with more than 5,700 of them coming off the production line. Powered by a 1400 shaft-horsepower version of the T-53 engine, the UH-1H is the “ultimate” of the two-bladed Huey design, and it retained the stabilizer bar mounted on the rotor head, which was originally found on the Bell 47. Deliveries of the UH-1H to the U.S. Army began in the early 1970’s, and the Air Force also purchased the type. Some of the Air Force variants were designated as HH-1H’s, and these were intended specifically for use as local base rescue helicopters.
Despite its versatility, the UH-1 is an old design, and the newer Sikorsky Blackhawk has replaced the UH-1 in U.S. military service in all but training and utility roles.
But, there is no need to become wistful about the sun setting on the Huey’s military service. Sixty years after it was designed, the distinctive “thump” of surplus two-bladed UH-1’s can still be heard in the skies, as these machines continue to earn their keep in the hands of fire departments and other civilian operators.
Specifications – UH-1C:
Maximum speed: 128 kts.
Service ceiling: 11,500 ft.
Maximum range: 331 nautical miles.
