Doman helicopters

Stingray · Administrator

Doman helicopters

Stingray · Administrator

RE: Doman LZ-5 gimballed-rotor system transport helicopter

hesham · Veteran Member - Level 3

From my dear Jemiba,

two unknow Doman projects.

Stingray · Administrator

Thanks Hesham.

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:

https://sites.google.com/site/stingrayslistofrotorcraft/doman-fleet-asw-helicopter

Stargazer2006 · Former Deputy Administrator

RE: Doman helicopters

Stargazer2006 · Former Deputy Administrator

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

Stargazer2006 · Former Deputy Administrator

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.

Length: 11.7 m
Height: 3.41 m
Rotor Span: 14.64 m
Empty Weight: 1,343 kg
Max Gross Weight: 2,165 kg
Range: 336 km
Top Speed: 125 km/h
Service Ceiling: 4880 m
Engines: 1 Lycoming SO-590-B rated at 400 hp
Accommodations: 2 pilots and 4 passengers

Main sources:
- R.Simpson "Airlife's Helicopter and Rotorcraft", 1998
- New England Air Museum website

Stargazer2006 · Former Deputy Administrator

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

hesham · Veteran Member - Level 3

Hi,

the BD-19

rotorwash · Veteran Member - Level 2

Doman LZ-5/YH-31 from USAAM archives.

Ray

-- Edited by rotorwash on Sunday 1st of January 2012 12:15:54 AM

SuperStallion · Veteran Member - Level 2

Doman LZ-5 carrying a 1,800 pound Volkswagen. From Popular Science Jun 1956.

SuperStallion · Veteran Member - Level 2

Army YH-31 from here and here, and the civilian LZ-5 from here and here.

hesham · Veteran Member - Level 3

Hi,

the Doman D-10 was a project for small two-seat helicopter,powered
by one Allison 250 turbine engine,the D-10B was only built.

Stargazer2006 · Former Deputy Administrator

No, D-10B was simply the commercial designation for the production civilian version of the LZ-5 and YH-31.

Platt-LePage · Member

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.