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McCulloch MC-4 / YH-30 / HUM-1
Jovair Sedan 4A / Sedan 4E




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.



The design was offered to the U.S. Army as the XH-30 (MC-4C, serials 52-5837 through -5839) and to the Navy as the XHUM-1 (MC-4A) by McCulloch Motors Corporation. Three were built for the Army and two for the Navy in 1953. Neither service had a use for them and they were returned to McCulloch.

The YH-30 was a craft of relatively simple construction, consisting of a steel tube framework to which was attached a light metal skin. The helicopter's single 200hp Franklin engine was mounted horizontally amidships and drove the two inter-meshing tandem rotors through a single horizontal drive shaft and two right-angled reduction units. Two small endplate rudders were fixed to the rear fuselage to provide additional lateral stability, and the aircraft was equipped with wheeled tricycle landing gear. The craft's two crew members enjoyed better than average visibility to the front and sides, though the view upward was blocked by the overhanging front rotor housing.

The Army's evaluation of the YH-30 showed the helicopter to be somewhat underpowered and its drive system to be overly complex. The type was therefore not procured in quantity, and the three evaluation machines were declared surplus in mid-1953 and disposed of.


McCulloch MC-4


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.


Jovair 4E


The Jovair E4 features independently removable components for ease of maintenance, including heavy-duty vibrationless control system, interchangeable rotor balades and ground resonanceless design. Landing gear is fixed type tri-gear. The Jovair Sedan has skinned, steel tube fuselage structure. Rotor blades are all metal using bonded, wrap-around skin construction, factory balanced. A hinged type rotor system is utilised. Vibrationless flexible Vee-belt drive transmits power to the shafts and gears (2 sets of bevel gears used) and one-size flex-spline type coupling replaces universal joints.


Jovair Sedan


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.




McCulloch MC-4
Prototype with a 165 hp Franklin engine, two built, one for evaluation by the United States Navy.
McCulloch MC-4A
Variant for evaluation by the United States Navy as the XHUM-1, two built.
McCulloch MC-4C
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
I was one of the engineers on the project. There were only 23 people on the project including engineers, welders, mechanics and a test pilot. A real fun project that didn't go anywhere because the Korean war ended and so did the market for helicopters.


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
Height: 2.77m
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
Crew: 2


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
Crew: 2
Powerplant: 1 × Franklin O-335-6 (6A4-200-C6), 200 hp (147.1 kW)
Crew: two
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)


Jovair 4E
Rotor blade diameter: 23 ft
Rotor blades chord: 6.76in
Overall width: 18 ft
Height: 9 ft
Overall length: 33 ft 2 in
Fuselage length: 18 ft
Empty weight: 1463 lb
Useful load: 837 lb
Gross weight: 2300 lb
Cruise speed: 90+ mph
Endurance: 2 hr
Service ceiling: 12,500 ft
Hover ceiling IGE: 6000 ft
Hover ceiling OGE: 3000 ft
Undercarriage tread: 6 ft 6.75 in
Undercarriage track: 7 ft
Basic price: $48,500






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