McCulloch MC-4 / YH-30 / HUM-1
The HUM-1 is a small two passenger utility helicopter originally designed by the Helicopter Engineering Research Corporation in 1948. In 1949 Helicopter Division of McCulloch Motors Corporation appointed as chief designer D. K. Jovanovich, formerly of Helicopter Engineering and Research Corporation, who developed his JOV-3 as McCulloch MC-4 tandem rotor two-seat helicopter.
Constructed of a steel tube fuselage and light aluminum skin, the engine is mounted amid ship. The main drive shaft is driven through a 12-unit vee-belt system.
This was the first tandem-rotor helicopter to be certificated by the U.S. Civil Aeronautics Administration for commercial use, and is also one of the smallest helicopters to be built with a tandem layout. Its development began in 1946 with the Helicopter Engineering and Research Corporation headed by D.K. Jovanovich and F. Kozloski, where a small 2-seat prototype (N9000H) was built with the designation JOV-3. This aircraft, powered by a 125hp Lycoming O-290, was flown successfully in 1948.
Jovanovich and Kozloski transferred in 1949 to the newly-formed helicopter division of the McCulloch Motors Corporation, where an enlarged development of the JOV-3 was built as the MC-4 with 6.71m rotors and a 165hp Franklin 6V4-165-832 engine. The main drive shaft is driven through a 12-unit vee-belt system. This prototype (N4070K) flew for the first time on March 20, 1951 at Los Angeles, and soon afterwards McCulloch began the construction of a prototype MC-4C (N4071K) and three generally similar YH-30's (52-5837 to '39) for evaluation by the U.S. Army. These were slightly larger than the MC-4, having 200hp Franklins and egg-shaped tail fins mounted on outriggers below the rear rotor head. The YH-30's trials programme yielded no military orders, and no civilian customers were immediately forthcoming for the MC-4C, which was certificated by the CAA on 17 February 1953.
Jovanovich and Kozloski left McCulloch when the Airplane Division was closed, and formed Jovair Corp in 1957 to continue their work on helicopters. They resumed the design rights and purchased one of the MC-4A’s (N4071K) which had been produced for evaluation by the USN (as the HUM-1).
Four-seat 4E Sedan with the 1962-built Jovair 4A, a stripped-down two-seat agricultural and training aircraft
Jovair modified the MC-4C as a prototype for a four-seat private helicopter designated the Sedan 4E. The Sedan 4E was powered by 210 hp Franklin 6A-335 engine and received certification in March 1963. A version with a turbocharged engine was designed as the Sedan 4ES and a more basic Sedan 4A for agricultural use. By 1965 a small number of Sedan helicopters were built. In 1969 McCulloch regained the rights to the helicopter designs who continued development of the Jovair 4E Sedan as the McCulloch MC-4E.
An MC-4C was used in the 1954 science fiction production Gog.
The civil version, the slightly larger MC-4, was unable to generate any sales and McCulloch lost interest in the project and turned it back over to the original designer D. K. Jovanovich.
Jovair Corporation produced N4071K in developed form as the prototype for a new 4-seat private or executive helicopter known as the Sedan 4E. The Franklin 6A-335 of 210hp was now installed and the fuselage offered comfortable accommodation and easy 4-door access to 3 passengers in addition to the pilot. A supercharged version, the Sedan 4ES, was offered with a 225hp Franklin 6AS-335. The Sedan 4E received type approval from the FAA in March 1963, and some two years later small-scale production of this version was begun; a version, with a 235hp 6A-350 engine, is slightly heavier. In mid-1963 Jovair offered the stripped-fuselage Sedan 4A as an agricultural, training or utility cargo version, with provision for some 450kg of cargo or crop spraying equipment in place of the rear passenger compartment.
In 2008 two MC-4Cs were still registered in the United States. The Pima Air and Space Museum has a HUM-1, registration N4072K (Serial Number: 133817). The Yanks American Air Museum at Chino are restoring a MC-4C to flying condition although they have no plans to fly it. It may be N4071K or N4091K. One of the three YH-30 miitary prototypes is preserved by the US Army Aviation Museum at Fort Rucker, Alabama. It is c/n 001 and has the military serial 52-5837. As of April 2013 it remains in a storage building and is not on public display.
Prototype with a 165 hp Franklin engine, two built, one for evaluation by the United States Navy.
Variant for evaluation by the United States Navy as the XHUM-1, two built.
Prototype with a 200 hp Franklin engine, one built and an additional three for United States Army evaluation as the YH-30.
Jovair Sedan 4E
Production civil four-seat version powered by a 210 hp Franklin 6A-335 engine.
Jovair Sedan 4ES
Sedan with a turbocharged 225 hp Franklin engine.
Jovair Sedan 4A
Simplified agricultural version.
Military version of the MC-4C, three built.
Two MC-4As for evaluation by the United States Navy, later redesignated HUM-1.
Jim Trego 02.09.2011
Engine: 1 x Franklin 6A4-200-C6, 149kW / 200 hp
Rotors: 2 x 3-blade tandem inter-meshing
Rotor diameter: 7.01m / 23 ft
Fuselage length: 9.88m
Max take-off weight: 1043kg / 2,300 lb
Empty weight: 726kg
Max speed: 169km/h / 120 mph
Cruising speed: 137km/h
Ceiling: 3048m / 10,000 ft
Range: 322km / 200 miles at 85 mph with full load
Engines: 1 Franklin 6A4-200-C6 200 hp
Rotor diameter: 23 ft
Length: 32 ft 5 in
Height: 9 ft 3 in
Weight: 2,300 lbs
Max. Speed: 105 mph
Service Ceiling: 8,000 ft
Range: 200 miles
Powerplant: 1 × Franklin O-335-6 (6A4-200-C6), 200 hp (147.1 kW)
Length: 32 ft 0 in
Main rotor diameter: 2× 22 ft 0 in
Height: 9 ft 2 in
Empty weight: 1200 lb (544 kg)
Gross weight: 2000 lb (907 kg)
Maximum speed: 105 mph (168.98 km/h)
Range: 200 miles (321.86 km)