April 28, 2022

Cessna’s only helicopter

Smoke On Go

The Cessna CH-1 Skyhook is the only helicopter ever built by the Cessna Aircraft Company.

It is not surprising to learn that Cessna tried its hand at building helicopters. After all, in the 50’s and 60’s, many aviation companies were trying to find their market niche.

Its semi-monocoque airframe greatly resembled its light aircraft siblings.

The CH-1 was named Skyhook for the civil market, similar to the marketing names used in the Cessna single engine airplane line, such as Skyhawk, Skylane and Skywagon.

The US Army designated the CH-1C as the YH-41 Seneca. The CH-1 had a single, two-bladed main rotor and a front-mounted reciprocating engine which gave the aircraft a stable (CG).

The CH-1 external design was created by Richard Ten Eyck, an industrial designer for Cessna. It was a low profile streamlined aircraft-style body, featuring the engine in front and cabin seating behind the powerplant. The forward engine location provided “ease of access, efficient cooling, and freed the centre of gravity behind the cockpit for use in disposable load. However the forward engine presented a problem for how to vent the exhaust which would prove to be a problem throughout the aircraft’s life.

Additionally, the tail boom size, resulting from the airplane-style fuselage, created aerodynamic problems in hover and forward flight that would have to be solved by later aerodynamic structural changes.

BACKGROUND

Cessna Aircraft Company acquired the Seibel Helicopter Company on 14 January 1952 through a stock swap with Seibel investors. All equipment from the Seibel Helicopter Company, including the Seibel S-4B, was moved to Cessna’s Pawnee Plant in Wichita and work began on the CH-1 design during the summer of 1952.

Charles Seibel, who became the new Helicopter Division’s chief engineer as part of the acquisition, believed that the S-4B with a Cessna body would make an excellent helicopter.

Cessna pilots test flew Seibel’s S-4B for several months to familiarize the engineers with helicopters, then they scrapped it.

Next, a quarter-size wind tunnel model of the CH-1 was created and tests were conducted at Wichita State University. The first full-size machine did not have an enclosed fuselage or cowling, or a horizontal stabilizer. This test bed skeleton, referred to as CH1-1, first hovered in July 1953, eventually making test flights as high as 10,000 feet (3,000 m).

The actual prototype CH-1 was built based on modifications made to the test bed aircraft and this second helicopter made its first flight in 1954, at the Prospect plant.

On 9 June 1955, the CH-1 received CAA type-certificate 3H10. Originally certified as a two-place helicopter, stability problems at higher gross weights required additional engineering solutions. A larger, free-floating horizontal stabilizer was introduced. During forward flight, the stabilizer pivoted to a variable mechanical stop, which was linked to the fore and aft cyclic control, thereby altering the stabilizer angle of incidence during flight.

Reworking the stabilizer permitted the addition of a second row of seating making the helicopter an actual four place helicopter.

This helicopter was certificated on 28 February 1956.

RECORDS

What better way to get the market to notice you…set records, and then the customers will come, or so it was believed.

Pike’s Peak

The CH-1 was the first helicopter to land on the summit of Pike’s Peak and the last piston-engined helicopter to set the helicopter altitude record at an altitude of 14,110 feet (4,300 m) on 15 September 1955

The previous record had been set by a turbine powered Aerospatiale Aloutte II and was later broken by another Alouette II, but the record set by the CH-1B remains the highest altitude ever achieved by a piston-powered helicopter.

Altitude

A CH-1B, modified with an FSO-526-2X engine, set an official FAI world altitude record for helicopters of 29,777 feet on December 28, 1957, while being piloted by Army Captain James E. Bowman.

IFR

The CH-1C was the first helicopter to receive IFR certification by the FAA.

MILITARY

In spring 1956, the Army awarded Cessna with a US$1.1 million contract for 10 test aircraft, designated as the YH-41 Seneca. For marketing purposes, the CH-1A prototype (N5156) was painted in an olive drab Army scheme.

The aircraft incorporated a unique L-section hinges to attach the main rotor blades to the hub in place of more conventional pitch change bearings.

While the CH-1 achieved several helicopter firsts and set world records, it never became a commercial or military success…….Only 50 where ever made!