Cessna Helicopters?

When the name Cessna is mentioned today, several images come to mind; the single engine range of aircraft that are the basis of private flying around the world, the workhorse single turboprop Caravan, and finally the up market business jet Citation range. Incorporated in 1927, Cessna has produced more aircraft than all the other general aviation manufacturers combined, and in July 2004 delivered its 150,000th single engine piston aircraft, a 172S Skyhawk SP. The total number of aircraft produced is in excess of 184,000 and the company likes to boast that more than half of the general aviation aircraft flying in the world today are Cessnas.

But they have not just been producing civil aircraft either. During World War II Cessna built more than 750 gliders and over 5,400 twin engined trainers among numerous other types for the US Armed Forces. Jet trainers followed in the fifties, and during the Vietnam War, the US Army and Air Force operated Cessna aircraft in the observation, forward air control and light attack roles. The famous Bird Dog was a welcome sight to ground troops under fire because it meant that close air support was near at hand. The Australian Army operated Cessna 180s for many years, including service in Vietnam and Papua New Guinea. 161 (Indep) Recce Flt also operated two O-1 Bird Dogs for a short period in Vietnam in 1967-68. The OC at the time, MAJ George Constable was shot down and killed while flying one of them on a convoy support mission on 23 May 68.

With all this heritage and production behind them, you would think that Cessna would trumpet the achievement of a world aviation record, but a search of the company website draws a blank. Yet in December 1957 the company did set two world altitude records that still stand. So why the reluctance to acknowledge it?

Well, if you are the world’s largest producer of general aviation fixed wing aircraft, you are not going to generate more sales by telling the world that you once set an altitude record for helicopters. Yes, helicopters! A Cessna helicopter set the world altitude record for two classes of helicopters in 1957, and the achievement is quite a story.

From a Cessna perspective it started in the early fifties when the company gained control of Siebel Helicopter Company located at Witchita in Kansas, but its real genesis was several years before that. Charles Siebel had been experimenting with building helicopters in the 1940’s and had a number of flying prototypes. Among these was one with a novel solution to controlling the helicopter; make the center of gravity adjustably by splitting the cockpit and moving it fore and aft to climb and descend. It flew in this configuration but needless to say it didn’t get beyond prototype!

Seibel produced a fairly agricultural looking side-by-side cockpit helicopter to compete for a US Army contract but was unsuccessful in the venture. When Cessna acquired his company and took control of the design and development their influence was readily apparent. In fact, early drawings of what was to become known as the CH-1 show what looks remarkably like a Cessna 150 fuselage without the wings but with a rotor system sitting on the roof of the cabin. Early evaluation of the prototype revealed a performance in excess of that predicted, particularly at altitude, with a maximum gross weight hover ceiling of 11,000 feet. Not bad for a helicopter powered by a 265 horsepower piston engine with a belt driven supercharger.

Shortly after the CH-1 was certified it became the first helicopter to land and take off from Pikes Peak (14,110 feet) in Colorado, with two and then three people aboard. Bell Helicopter, incidentally, got wind of the Cessna plans to land on Pikes Peak and attempted to beat them to the punch with a Model 47, failing to do so by only a matter of hours.

The helicopter first appeared in a civil guise, but Cessna always had their eye on the military market, and in 1955 the YH-41 was born. With a bigger engine, gear driven supercharger, increased rotor speed and better flight control configuration, Cessna gained a US Army evaluation contract to produce ten aircraft. Again the helicopter featured excellent high altitude performance, and, as a way of impressing the military evaluators an attempt on the world altitude record for all helicopters (500-1000kg) was mooted. At the time the three post World War II record holders had all been turbine engine helicopters and the then current holder was the Alouette II with an achievement of 27,830 feet. To consider that a piston engine helicopter could beat that was bold thinking to say the least.

Initial trials were conducted with a standard aircraft that had been modified by the removal of as much superfluous equipment (passenger seating, dual controls, engine cowls) as was safely possible. This helicopter reached an altitude of some 23,000 feet, and when the calculations were done to extrapolate the data, an altitude attempt was deemed feasible.

While it was actually designed to impress the military, in fact a civil version of the YH-41 was used for the attempt. And it was very heavily modified. The electrical system was totally removed, and two small batteries were used to power the instruments. The landing gear was removed and substituted by scuff tubes on the belly of the aircraft, and a dolly system to land on. The starter relay, vibrator and starter itself were redesigned to enable removal after start; and the auxiliary fuel pump, transmission oil cooler, engine filter and exhaust system were all removed. There were no engine cowls and vinyl sheeting was used to cover the door spaces. In all some 266 pounds of gear were removed, but the addition of an oxygen system and ballast to address the center of gravity movement returned 27 pounds. The oxygen system, incidentally, was fitted to the tailskid to assist resolving the cg problem. Also of interest, is that one of the engineers working on this project was none other than a young Frank Robinson, of R22 fame.

Two days after Christmas 1957, on a chilly Kansas morning, the attempts were made. The pilot was a US Army Aviation officer, Captain James E. Bowman, who was also the evaluation pilot for the YH-41. (No conflict of interest there!) Two flights were to be conducted, at different weights, to qualify for different categories of helicopter. With all the modifications completed and supercharger pressure increased, and having been officially weighed, the helicopter departed on a profile of best climb speed that was constantly constrained by compressibility problems and retreating blade stall at the high angles of attack required.

The flight went off without a hitch, and after reaching an indicated altitude of 30,755 feet, Captain Bowman returned to the aircraft to the Wichita airfield. Additional fuel was added and the aircraft reweighed to ensure it qualified for the heavier category, and again it was off on the climb. This time an altitude of 28,200 was achieved, and the helicopter generated a contrail across the Kansas sky! Unfortunately, it also picked up the jetstream, and by the time it got down it had to land at El Dorado some thirty miles to the east of Wichita.

Not that this bothered Cessna too much. While they were happy at the time for the publicity a world record garnered, they wanted to give the impression that it was achieved in a standard YH-41, and not a skeletal look-alike. No photos of the attempt aircraft were taken while it was in the air, and those taken of it on the ground were marked “not for release” by the company. Instead, a smiling Captain Bowman was photographed in full uniform in front of standard YH-41, and that photo gained wide circulation. Captain Bowman, incidentally, was awarded a Distinguished Flying Cross by the Chief of Staff of the US Army, General Maxwell Taylor, one week after the flight.

Both records are still current and recognized by the FAI, albeit in the piston engine sub-category. The Cessna held the absolute record for about a year before another Alouette II eclipsed it. The current altitude record for the 500-1000kg class of helicopter is 40,822 feet set in France in 1972 by a SA 315 Lama.

But in the end, it was all for naught. Cessna didn’t get a further contract with the US military, despite developing the first helicopter to be certified by the FAA for instrument flight, and competing, along with eleven other manufacturers, for the Army LOH program. Civil helicopter production sputtered on for a few more years, but it was clear that it was not Cessna’s focus, and on 26 th December 1962, one day before the fifth anniversary of the setting of world records, the decision was taken to cease all helicopter activity at Cessna. Existing civil models were bought back by the company and destroyed, and all mention of helicopters in any company documents was deleted. Cessna still held the world altitude record for piston engined helicopters, but as far as the company was concerned then and apparently still so today, they were never really in the chopper business.

The sealed barograph carried for the attempt recorded an altitude of 29,777 feet and this was the figure adopted by FAI for the record.

 

 

Author's note: This article has been drawn largely from information provided by Steve Remington on the Cessna helicopter page of the CollectAir website at:

www.commercemarketplace.com/home/CollectAir/cessna.html.

Mr Remington worked at Cessna as an engineer, and then a flight test engineer throughout the Cessna helicopter program. His article provides considerably more information on this little known area of helicopter history, including many photos, and is well worth visiting.)