LZ-5 gimballed-rotor system transport helicopter
From my dear Jemiba,
two unknow Doman projects.
Why do I feel like these have been posted somewhere already? Nothing comes up in a search except this topic.
Also see at the main site:
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.Specifications and performance (estimated):
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!)
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.
Main sources:- R.Simpson "Airlife's Helicopter and Rotorcraft", 1998- New England Air Museum website
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.Source: Flight, 26 Jan 1950
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.
Doman LZ-5/YH-31 from USAAM archives.
Doman LZ-5 carrying a 1,800 pound Volkswagen. From Popular Science Jun 1956.
Army YH-31 from here and here, and the civilian LZ-5 from here and here.
Hi,the Doman D-10 was a project for small two-seat helicopter,poweredby one Allison 250 turbine engine,the D-10B was only built.
No, D-10B was simply the commercial designation for the production civilian version of the LZ-5 and YH-31.
Platt-LePage wrote:I've only seen one photo of the kit back in the 1970s, good luck finding one outside of Japan.
I've only seen one photo of the kit back in the 1970s, good luck finding one outside of Japan.
Thanks to your information and my little knowledge of Japanese I was able to retrieve the following picture of said model, released in 1962:
Stargazer2006 wrote:No, D-10B was simply the commercial designation for the production civilian version of the LZ-5 and YH-31.
From a brochure from Mark Nankivil: