The use of helicopters in the U.S. Air Force predates the Air Force as a separate service.
In World War II, limited numbers of Sikorsky R-4s flew for the Army Air Forces. But with the separation of the Air Force from the Army in 1947, both branches of the military coveted helicopters to do certain jobs better than fixed-wing aircraft.
The new Air Force, and the Army, reviewed and tested a number of helicopter types at Wright Field, which became Wright-Patterson Air Force Base in 1948.
It was a promising era, when futurists fondly predicted we’d all be commuting in our personal helicopters by the year 2000.
Meanwhile, the Air Force and Army looked at the advancing helicopter state of the art and made choices that affected the future of rotorcraft.
One such choice was the non-selection of the Seibel YH-24 for production.
The Seibel YH-24s featured a fabric and plastic enclosure for the pilot and one passenger. Of the two built for Army evaluation, one was said to have been modified later to allow side-by-side seating and the use of skids instead of the original wheeled landing gear.
In the photos accompanying this article, YH-24 serial 51-5113 shows its tricycle wheel configuration and rudimentary cabin enclosure. That’s a 125-horsepower Lycoming O-290-D riding in the open behind the main rotor. The YH-24 cruised at 58 mph and had a top speed of 65 mph.
The YH-24s were returned to Seibel in 1952 without a production order from the military.
But that was not the end for Charles Seibel’s helicopter design forays. Cessna obtained control of the Seibel company and employed him as Cessna’s helicopter division chief engineer in 1952.
Cessna’s only foray into rotary-wing aircraft was the Seibel-designed CH-1, with a front-mounted six-cylinder Continental engine and a streamlined aluminum fuselage reminiscent of traditional Cessna aircraft, and influenced by company industrial designer Richard Ten Eyck.
The Cessna helicopter set a world altitude record for piston-engine helicopters variously measured at above 29,000′ or 30,000′ in December 1957.
The Army evaluated the CH-1 as the YH-41 Seneca. Ten YH-41As were used by the U.S. Army. Fifteen UH-41As were purchased as military assistance for allied countries. Perhaps 50 CH-1s and H-41s were built in total before construction ended late in 1962.
The Sikorsky H-18 (civilian model S-52) evaluated by the Army was the first American helicopter to feature all-metal rotor blades. Its 245-horsepower Franklin engine gave the H-18 a cruise speed of 96 mph.
The H-18, not a major Army or Air Force buy, was used in some quantity by the U.S. Navy, Marine Corps, and Coast Guard as the HO5S, which incorporated some design changes over the YH-18As, including downward canted stabilizers on the tailboom.
Only four YH-18As were made; total production of this basic design has been tallied at 93 helicopters.
The Bell Model 47 helicopter evolved as the archetypal whirlybird of the late 1950s, with many still in civilian service today.
Before the Model 47 acquired its signature uncovered tube truss tailboom structure and landing skids instead of wheeled landing gear, a military version arrived at Wright-Patterson Air Force Base in 1947 as the YR-13, subsequently redesignated H-13 in 1948.
The YR-13 was powered by a 175-horsepower Franklin O-335-1 engine. Its skinned tailboom and aft fuselage, plus landing gear that looks like it would be at home on a large grocery shopping cart, gave the YR-13 an appearance far removed from latter-day Model 47s and H-13s.
If the Seibel YH-24 and Sikorsky YH-18 failed to get career status with the U.S. Army, the developed H-13 was a big winner, with more than 2,000 built.
Sikorsky’s all-metal R-5, later H-5, saw service during the Korean War. Before that conflict, some H-5s were fitted with amphibious pontoons and unique transverse litter pods in the fuselage that extended beyond the original fuselage lines, as seen in the accompanying Air Force photo.
These vintage military helicopter photographs from Wright-Patterson AFB all tell a tale of ever-advancing state-of-the-art.
Note: General Aviation News reader Jack Handy recently sent a batch of U.S. Air Force photos that were gathered by Wilber Clouser, an Air Force Systems Command technical editor of handbooks after World War II. With thanks to both Handy and Clouser, photos from this group will illustrate columns over time.