The Bell 47G, produced by the Bell Aircraft Corporation of Buffalo, New York, in the 1950s, is an improved version of the D-1 model, the first aircraft of the 47 series capable of carrying two passengers in addition to the pilot instead of just one.
The Bell 47D-1 saw widespread use in both the civilian and military sectors. The military versions, known as the H-13D (USAF) and respectively the HTL-4 and HTL-5 (US Navy), were used extensively during the Korean War as an aerial ambulance to transport the wounded to the Mobile Army Surgical Hospitals (MASH) units.
The Bell 47G received FAA civil certification on June 19, 1953, and the first deliveries began at the same time. That year Bell sold its 1'000th Bell 47. In 1953 the sale price of a Bell 47G equipped with skid-type landing gear and base equipment was of about 38'000 US dollars (the equivalent of approximately 185'000 Sfr.).
The G version differs from the D-1 in having two interconnected fuel tanks, each with a capacity of 81 liters, instead of a single tank. Mounted on either side of the mast, these tanks increase range by more than 35%. A selector allows the quantity in each tank to be read separately.
Thanks to a horizontal stabilizer directly linked to the cyclic control, it is no longer necessary on this helicopter to shift the position of the battery to restore proper center of gravity. During translational flight, the stabilizer provides greater stability. Owing to center-of-gravity limits that are approximately 40% wider, the cabin can carry a payload of up to 250 kg, regardless of the amount of fuel carried.
The 47G was the first helicopter to be mass-produced under Bell license by the Italian company then known as “Costruzioni Aeronautiche Giovanni Agusta” in Cascina Costa di Samarate. Between 1954 and 1959, a total of 108 AB 47Gs were manufactured here. The first 47G made its test flight in the hands of test pilot Ottorino Lancia (1915–1977) on May 22, 1954. For the occasion, Bell Aircraft’s grand patron Larry Bell was invited to witness the event. It was the beginning of a long history for the Lombard company, which today is a world leader in the helicopter industry.
This model became the star of the American television series “Whirlybirds” produced by Desilu studios in the late 1950s.

A new electrical system with a higher-capacity battery makes engine starting easier.
Another important innovation is the introduction of metal blades for the tail rotor. The aircraft is also equipped with a new fixed vertical fin made of aluminum, which is stronger and lighter than the previous one.
Further improvements include: relocation of the static pressure line of the airspeed indicator, allowing more accurate speed readings; new, lighter cabin cushions; improved mast lubrication; new engine silent blocks; a new mounting for the engine cooling fan; a revised air filter installation; new dust protection for certain rotating mechanical parts; modification of the routing of the tail rotor control cables; increased effectiveness of tail rotor control (with reduced operating costs); new wiring; a new position for the rear position light with improved illumination of the tail rotor (and therefore increased safety during night operations); and new landing skids reinforced with steel.
In 1953 (the year in which Bell sold its thousandth Bell 47), the selling price of the Bell 47G was approximately 38,000 US dollars, corresponding to about 185,000 Swiss francs.
The Bell 47G became very popular thanks to the American television series Whirlybirds (known in Italy as Avventure in elicottero), produced by Desilu Studios between 1957 and 1960.

Civil employ

In the civilian field, the Bell 47G was mainly used for the transport of passengers and cargo, aerial crop treatment flights, mail transport, observation flights, advertising and photographic flights, and flight training. 

Main Technical Characteristics

The Bell 47G is a three-seat helicopter with side-by-side seating (the pilot sits on the left), equipped with a two-blade main rotor (with wooden blades) fitted with a stabilizer bar, and a two-blade tail rotor with metal blades.
The fuselage consists of three main elements: the cabin, the central section, and the tail boom.
The cabin, which distinguishes this helicopter and made it famous worldwide, is protected by a heated Plexiglas sheet that is “blown” like a soap bubble. On each side there is an access door that can be removed if required. The cabin is built of light alloy and Plexiglas. Pilot and passengers enjoy excellent all-round visibility.
The central section consists of a welded tubular steel structure. The engine compartment is separated from the cabin by a firewall made of stainless steel. Installed in the central section are the engine with its accessories, the supports for the two dorsal fuel tanks, and the landing gear cross members.
In its original version, the helicopter is equipped with a vertically mounted six-cylinder Franklin 6V4-200-C32 engine (military designation O-335-5), developing a maximum power of 149/200 kW/hp at 3,100 rpm. Average fuel consumption is approximately 55–60 liters per hour. Cooling is provided by a fan mounted at the front. The reduction ratio between engine speed and rotor speed is 9:1.
The 28-volt electrical system incorporates a 50-amp generator and a standard aviation battery. An external socket for auxiliary starter-assisted starting is also provided if required.
The triangular-section tail boom consists of a structure built from welded steel tubes and is bolted to the central section. The horizontal stabilizer (synchronized with the cyclic pitch control) and the fixed vertical fin are attached to the tail boom. An extension made of tubular steel supports the tail rotor and its protective arch. On the upper part of the tail boom are the supports for the tail rotor drive shaft.
The Bell 47G2 was normally supplied with landing gear fitted with skids made of light-alloy tubes connected by transverse tubes, which are in turn attached to the fuselage structure. The lower surface of the skids is covered with stainless steel strips. A maneuvering wheel that can be raised by means of a lever can be fitted to each skid.

Performance

Under standard atmospheric conditions, at the maximum authorized takeoff weight of 2,350 lb (1,065 kg), the helicopter has a maximum cruise speed of 78 knots (144 km/h) and a standard cruise speed of 65 knots (123 km/h). The maximum authorized speed is 87 knots (161 km/h) up to an altitude of 1,410 feet (430 m above sea level), above which it must be reduced by 1 knot (1.85 km/h) for every additional 305 feet (100 meters) of altitude.
The maximum rate of climb at a speed of 40 knots (74 km/h) is 800 feet per minute (244 m/min). The helicopter takes approximately 8 minutes to reach an altitude of 5,000 feet (1,525 m above sea level). At full load, it can reach a maximum operating altitude of 12,500 feet (3,810 m above sea level), while hovering in ground effect (IGE) can theoretically be performed up to about 3,600 feet (1,100 m above sea level). Maximum range is 345 km. The stated data refer to performance measured in calm wind and standard atmospheric conditions.

Limitations

Rotor speed must be maintained between 294 and 360 rpm, while engine speed in flight must be kept between 2,900 and 3,100 rpm (oil pressure 40–60 psi, cylinder head temperature 100–224°C).

Dimensions and Weights

The Bell 47G has a main rotor diameter of 10.72 m, while the tail rotor diameter is 1.72 m. The fuselage, of triangular section built as a truss from welded steel tubes, has a length of 8.33 m. Maximum height is 2.79 m.
The empty weight of the helicopter equipped with skid-type landing gear is approximately 645 kg, while the maximum takeoff weight in the original version is 1,065 kg.
After deducting the standard pilot weight (77 kg) and fuel and oil reserves for one hour of flight (36 kg), the useful load of the aircraft is approximately 300 kg.

Autorotation

In the event of an engine or tail rotor failure, the pilot must immediately perform an autorotation, maintaining a speed of at least 35 knots (64 km/h). At an altitude of about 15 meters, the pilot should begin a steady deceleration toward the ground. At approximately three meters above the ground, sufficient collective pitch must be applied to arrest the rate of descent while touching down.

Equipment

The helicopter may be equipped with dual controls, night flying lights, floats for amphibious operations, installations for the external transport of two injured persons on stretchers, systems for aerial treatment of crops and forests, a hook for suspended load operations, snow skis, hydraulic servo control with irreversible valves for cyclic control, external containers, radio equipment, cabin heating, rotor brake, fire extinguisher, emergency medical kit, and four-point safety harnesses.

The Bell 47G in Switzerland

The first Bell 47G to be registered in Switzerland was HB-XAG (c/n 668, built in 1953, ex F-BGXS), purchased by Schweizerische Helikopter AG (later Heliswiss) in September 1953. This aircraft arrived by air from Paris on October 8, but was unfortunately destroyed a few week later in a tragic accident occurred on October 26.

It was replaced by HB-XAE (c/n 689, built in 1954), purchased directly from Forrer-Fenwick of Zurich, the company that at the time acted as the Swiss representative for Bell helicopters. This helicopter, equipped with dual controls and a night-flying kit, cost 38,762 US dollars. To this amount were added shipping and customs clearance costs, bringing the final total price to approximately 210,000 Swiss francs.
HB-XAE arrived in Zurich by air on February 27, 1954, and was transported by truck to Belp, Canton of Bern, where it was assembled. On March 25, the renowned French Fenwick pilot Jean Moine carried out test flights, as no Swiss pilot yet held the required qualification.
During a demonstration, Moine took off with five people on board, four of whom were seated on the landing gear cross tubes. In the following days, Heliswiss pilot Leonard Kunz traveled to Issy-les-Moulineaux, France, where he obtained his type rating for this model.

HB-XAK (s/n 1305, built in 1954) was also shipped by air and arrived in Switzerland on December 6, 1954, but officially entered service only on February 25, 1955. These two helicopters were used for passenger and advertising flights, demonstrations, flight training, aerial photography, aerial crop treatment, and the first material transport operations in mountainous areas.

In 1954, the Italian company Costruzioni Aeronautiche Giovanni Agusta S.p.A. of Cascina Costa began manufacturing this model under license from Bell. Heliswiss established close ties with the Italian manufacturer and placed numerous orders to meet its growing demand for aircraft. Among these was the Agusta-Bell 47G (s/n 101, b/y 1957), registered HB-XAV—the last aircraft of this version—purchased in 1957.