A forgotten project is the Doman Whippet, which was mentioned a few times in Flight magazine in 1959 and 1960, but was apparently never built.
The Whippet was a four-seater with a Lycoming VO-360 engine of 180 h.p., driving a three-blade rotor. It was supposed to be marketed in 1961 for a pricetag of $18,500 per unit, but that never materialized.
The Doman-Frasier LZ-1 Little Zipper was never built.
However, the Doman LZ-1A prototype was a Sikorsky R-6 (lent by the USAF) converted to a Doman rotor and control system. The rotor had four blades, and though their length was increased from 11.58 to 12.2 metres, this resulted in improved hovering ability and, curiously enough, did not lower the top speed.
The first ground tests took place in 1947, with first flight early in 1950, and it should be noted that during one experimental flight this rotorcraft flew for forty minutes without the pilot needing even once to touch the cyclic pitch control.
Specifications and performance (European units, sorry!)
Length: 10.34 m
Rotor diameter: 12.2 m
Height: 3.35 m
Empty weight: 871 kg
Maximum weight: 1350 kg
Crew: 1+1
Power plant: 1 x 245 hp Franklin 0-405-9
Load: 350 kg
Maximum speed: 150 kph
Ceiling: 1500 m
Range: 640 km
Fuel type: AVG
Fuel capacity: 150
Fuel consumption: 124/31
-- Edited by Stargazer2006 on Wednesday 14th of December 2011 11:22:15 PM
The LZ-1A was followed by the larger LZ-2A Pelican, of which I haven't been able to find any picture so far (despite years of searching!)
Doman's system was then designed into a larger helicopter that was seen as a viable commercial production machine. During 1948 and 1949 there were various proposals to license the use of the rotor on helicopters then in development, usually where vibration was a problem. Curtiss-Wright Corporation bought a limited-term patent license and, under an engineering service agreement, financed the construction of the Doman LZ-4, a quickly built 400-horsepower prototype intended for research and development.
The LZ-4 (sometimes called LZ-4A) had a capacious fuselage with three rows of double seats in the main cabin and a two-crew flight deck in front. Large folding doors provided access for loading bulky cargo into the main compartment. The tail boom was conventional with a cranked-up rear section mounting a tail rotor, and the LZ-4 sat on a four-leg undercarriage with trailing link dampers. A 400hp Lycoming SO-590-B engine was positioned in the lower nose, driving the four-blade rotor via a flexible transmission.
On November 7, 1950, the LZ-4 (registration N74147) made its first flight and was re-designated the CW-40. It appears in some records as the Arctic Rescue Helicopter, probably indicating some cold-weather tests aimed at an Army proposal.
The Army did fly the CW-40, and proposed to purchase a cleaned up version under Civil Aeronautics Authority (CAA) certification, thus avoiding Air Force handbook engineering. However, Curtiss-Wright was then closing its Airplane Division and declined to make a proposal. Curtiss took the CW-40 to New Jersey and, despite preservation efforts by the New England Air Museum, eventually scrapped it. Undeterred, Doman contracted to develop a successor, the LZ-5, which was evaluated as the YH-31 and met with very limited success.
One more Doman project that never left the drawing board:
Another noteworthy American project is the Doman HC-3, transportable bodily by a Fairchild C-120 Packet and designed to carry a 6,600-lb load for no miles, or 1,300 lb for 1,400 miles. As a flying crane it could lift a 12,000-lb object for a short distance; troop capacity would be 33.
A little note for the model collectors. It's very, very, hard to find...back in the 1960s the Japanese model kit company Otaki made a 1/50th scale plastic kit of the Doman YH-31.
I've only seen one photo of the kit back in the 1970s, good luck finding one outside of Japan.