On this day 62 years ago - Bell XH-40 [Archive]

megan

22nd Oct 2018, 01:47

The Huey is our equivalent of the FW DC-3. Some info I picked up from somewhere on its designer, many of us owe a debt of gratitude to the work of Bartram Kelley.

The U.S. Army's UH-1 helicopter, better known as the "Huey," flew more than seven million flight hours between October 1966 and December 1975. Include the Huey Cobra model, and the Vietnam Helicopter Pilots Association estimates that the Huey had more combat flight time than any other aircraft in the history of warfare.

The UH-1 “sprang from the cold, muddy battlefields of the Korean War, where the original M*A*S*H helicopter, the Bell 47, recovered thousands of wounded soldiers and delivered them straight to critical care units,” writes David Hanselman in the National Air and Space Museum's collection notes for this fabled aircraft. In 1954, when the U.S. Army launched a design competition for a new medical evacuation helicopter, Bell Helicopter Company was expected to compete for the contract since their -47 had performed so well in Korea.

According to the diaries of Bell engineer Bartram Kelley, who designed the Huey, the Army wanted a helicopter that could carry a payload of 800 pounds, with a top speed of 131 knots and a maximum endurance of 2.7 hours. The requirements called for a pilot and medical attendant to be able to take off from an unprepared area, day or night, and land at a pre-determined destination on an unprepared area. There they would pick up two litter patients and return to the point of departure.

The Army was impressed enough with Bell’s XH-40 prototype to sign a contract for 200 medevac helicopters, plus an additional 100 to use as trainers to teach pilots to fly at night and in bad weather. And so began the saga of the Huey, which became a familiar sight in the sky for an entire generation of soldiers.

The 204, briefly labeled the H-40 before becoming the HU-1 (for Helicopter, Utility, Model 1), was designed by engineering genius Bartram Kelley, who joined Bell Aircraft Company in 1941, and became chief engineer of the helicopter division a few years later.

Kelley's diaries and engineering notebooks (nearly 50 in all) are part of the National Air and Space Museum's archives. When Kelley received the Alexander Klemin Award from the American Helicopter Society in 1955, he wrote in his diary: "Recently a group of us had the good fortune to be guests of the United States Navy aboard a small carrier at sea for 8 days. There were no airplanes, but there were 17 helicopters.... We were all of us constantly on deck throughout the 8 days to see the flight activities, and closely watched every take-off & landing, hour after hour. One of the sailors happened to notice my concentrated interest, and finally said to me: 'What's the matter? Haven't you ever seen helicopters before?' I could think of nothing better to answer than—'No, I haven't!' It would have been impossible to explain to him that after 15 years the novelty has not worn off, & that I will probably never tire of watching any helicopter take off at sea or on land.

"The first Bell UH-1s arrived in Vietnam in 1962, and were used as medevac helicopters to support the South Vietnamese Army. In October of that year, armed Hueys were used to escort Army and Marine Corps transport helicopters. By 1964, there were 300 -A and -B models in Vietnam.

In a 1964 end-of-year memo to all engineering personnel, Bart Kelley crowed: "We managed to keep the UH-1 series going with no more than the normal number of crises." That year Bell Helicopter Company delivered the first UH-1Fs.

As company commander of the 62nd Aviation Company "Outlaws" in Vietnam in 1964, Tom Anderson usually flew in the Command and Control (C&C) ship. The mission was supporting the South Vietnamese; Anderson would fly with the commander of the Vietnamese unit they were supporting and an American advisor. Each would have his own FM radio, used to communicate with ground troops. In addition, Anderson had two UHF radios, with one channel tuned to his slicks (troop transports) and the other to his gunships. He monitored a third channel that allowed him to call in Air Force or Navy close air support when needed.

“I got so I could monitor three different radio communications at one time,” he says. “When things got hot and busy, I’d have to decide which one I didn’t want to listen to, but I was almost always listening to two channels—my gunships and my slicks, because that’s how I would communicate with them.”

"We had Bs for both our 'slicks' [transport and medevac helicopters] and our 'gunships' [attack helicopters]," recalls Anderson. "The B was adequate for the time, but lacked both the power and the capacity to perform all of the tasks that came our way. We were always trying to come up with another mission it could do. We hung guns and rockets on the thing and called it a gunship."

Amid all the fighting, Anderson remembers a simple pleasure: Anderson’s Crew Chief stored a carton of C-rations under his seat in the back of the helicopter. During a mission, when the helicopter had to stop and refuel, the Crew Chief would call the pilot and copilot and ask what they’d like for lunch. As soon as the Huey landed, the Crew Chief would take two cans of pork-and-beans, pry the lid up halfway, and set the can on the exhaust stack of the helicopter. “Within a minute,” says Anderson, “that thing was so hot that you could eat it.

”The Huey's twin-blade rotors with their distinctive whop, whop, whop provided the soundtrack to the Vietnam War. But in January 1961, Bell engineer Bart Kelley was considering a 3-bladed version, as he wrote in his diary: "Thinking about 3-blade lack of collective response. Could it be that each blade hits downwash of its predecessor? Lower rpm might be better?" By March, he wrote: "We have been studying 3-bladed versions of the standard semi-rigid rotor system.... We have not yet found enough advantages in the three-bladed system to compensate for the somewhat greater weight and complexity, but are continuing to push the program as an insurance policy for the future."

Thomas Anderson, who flew 10 different aircraft (both fixed-wing and helicopter) in Vietnam, was trained on the UH-1A in Hawaii. "The thing that I remember most about learning to fly the Huey was that it was a turbine engine rather than a reciprocal engine. When you're flying a piston-engine helicopter, you have a gauge that shows both the rotor rpm and the engine rpm, and the needles have to be in sync—one needle has to sit on top of the other one. You can immediately tell if you've had an engine failure when the engine rpm needle starts to drop down quickly. On the Huey you didn't have those needles because the engine was always running at a constant speed; you didn't have to keep the needles joined. When you flew an H-13, you had both hands and both feet busy all the time. There was no way of holding a map and looking at it unless you wanted to put the control stick between your knees and fly with your knees while you're looking at a map." When asked if he ever flew that way, Anderson replied, "Oh, absolutely."

The UH-1B's short-wave radio system was used for long-range communications, but it was sometimes tricky to use, recalls Alfred Iller, who in 1964 was the 62nd Aviation Company's executive officer. Once, his unit was sent from the Mekong Delta region to support the 101st Airborne Division near Cam Rhan Bay. Required to check in on a daily basis, Iller attempted to do so, using the proper frequency and call signs. He was answered by a unit in Ft. Bragg. "I believe these types of occurrences cropped up from time to time due to some atmospheric phenomenon," recalls Iller. "It was otherwise a useful radio for long-range communications."

Iller was proficient in the -A, -B, -C, -D, and -H models of the Bell UH-1. Did he have a preference? "Well, the -B was the workhorse for us the whole time," he says. "But I liked flying the C-model because I was able to shoot back." The Vietnam Helicopter Pilots Association estimates that of the 696 UH-1Cs that served in Vietnam, 415 were destroyed, and 325 crew members were killed.The National Air and Space Museum acquired its UH-1H in 1995. The aircraft has had a long service life, starting with the U.S. Army's Company A in Vietnam in 1966. Nicknamed Smokey III, the helicopter served as a smoke ship: As slicks (troop transports) approached a landing zone, Smokey III would fly low, producing smoke between the landing zone and the enemy.

The aircraft remained in combat service until 1970, when it was damaged, and returned to the United States for repair. The aircraft, which began life as a D-model, was converted to an H-model and assigned to an Army National Guard unit. After more than 6,500 flight hours, the helicopter was donated to the Museum, where it is now on display at the Steven F. Udvar-Hazy Center in northern Virginia.

Bartram Kelley - Bart Kelley is one of the original and most outstanding pioneers of the helicopter industry. After joining Arthur Young and Bell in 1941, his engineering leadership was at the forefront of every new design at Bell Helicopters for the next 35 years.

In the course of Bart Kelley's tenure as senior engineer (Director of Engineering; Senior Vice President, Engineering) with Bell Helicopter Company, over 24,000 Bell helicopters were produced. By far the largest part were delivered to the U.S. Army as the H-13 Sioux, UH-1 Iroquois, AH-1G Cobra, OH-58 Kiowa, and XV-15. Mr. Kelley actively supervised the design, test, and development of all Bell experimental and production aircraft, and was accepted by his fellow engineers as clearly outstanding in his field.

A helicopter pilot himself, Bart Kelley was uncommonly sensitive to the flyability of aircraft from the pilot's point of view. Through extensive contact with the U.S. Army and its crewmen, he also became uniquely responsive to military needs with respect to reliability and maintainability.

Kelley's Model 209 Cobra attack helicopter, the first in the world, was designed and developed without government request or assistance during the Vietnam War. After acceptance, it emerged as the AH-1 and was used extensively in that war. In successive dash numbers, it is still used extensively by the U.S. Army and U.S. Marine Corps and in several allied foreign countries. Its basic configuration has been copied in later attack helicopter designs.

Bart Kelley also presided over the design of Bell's tilt-rotor aircraft, the first experimental model which flew successfully and often in the 1950s and early 60s, and which may well become the outstanding vertical take off and landing aircraft of the future.

Bart Kelley has designed aircraft which are flying in more than 70 countries, the world over.

Possessed not only of vast engineering expertise, Kelley has also exhibited an unusually perceptive instinct for the practical and (in a complex field of endeavor) the simple. In a word, he has exceptionally keen judgment as to what works well and reliably and what doesn't.

His distinguished service in the development of rotary wing aircraft led to his Honorary Fellowships in the American Helicopter Society and the Royal Aeronautical Society. After 35 years of service, Bart Kelley retired in 1975, but still serves as a consultant with Bell Helicopter Textron.