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Aerotecnica AC-12

Aerotecnica S.A. entered the helicopter field by engaging the services of the French engineer Jean Cantinieau and at the same time acquiring the Matra-Cantinieau MC-101 light helicopter which was built by the French Societe Matra in 1952. This helicopter was given the designation AC-11 (Aerotecnica-Cantinieau-11).

From the AC-11 have been developed the AC-12 and AC-13, the former powered by a 150hp Lycoming O-320 engine and the latter by a Turbomeca Artouste I gas turbine.

Two prototypes of the AC-12 were built in Madrid by the AISA company and ENHASA, the national airscrew company. A production order for 12 more has been received from the Spanish Government. Two prototypes of the AC-13 were built in France by the Societe Nationale de Constructions Aeronautiques du Nord (S.N.C.A.N.), which had acquired a licence to build the AC-13 and by whom it was known as the Nord 1750 Norelfe. This licence has now lapsed and the two prototypes have been acquired by the Spanish Government.

An improved version of the AC-13, known as the AC-14, has been designed and an initial series of six is being completed in Madrid by ENHASA. In addition, Aerotecnica is working on the design of the AC-15 helicopter, powered by a 245-260hp Lycoming O-435-V engine.

A further development is the AC-21, a projected 10-12 passenger helicopter powered by two Turbomeca Turmo III turbines.



Like the original Matra-Cantinieau MC-101, the AC-12 has its engine mounted above the cabin. Two prototypes were built by the AISA company, with a transmission and reduction gear designed on motor-car principles and built by the ENHASA airscrew company. The first of these flew on July 20, 1956. The Spanish Government has ordered a production series of twelve of these aircraft.

TYPE: Two-seat single-rotor Helicopter.

ROTOR: Three-blade rotor with double-articulated blades. Each blade has a solid machined duralumin spar which forms the leading-edge, duralumin ribs and trailing-edge. Space between ribs is filled with a plastic foamed resin compound named Klogecell, with a final overall covering of Fiberglas. Floating hub, with cyclic and collective-pitch changes made through a "spider." Rotor blade area each 0.71m2. Rotor disc area 57m2. Three-blade anti-torque rotor of similar construction to main rotor. Anti-torque rotor blade area 0.0927m2. Anti-torque rotor disc area 2.26m2.

ROTOR DRIVE: The main rotor is driven direct from the engine gear-box (7.28 : 1 ratio) and clutch through a universal joint. The anti-torque rotor is driven through a gear-box (1.4 : 1 ratio) and cardan shaft.

FUSELAGE: Light alloy structure.

LANDING GEAR: Skid type. Track of skids 2.0m

POWER PLANT: One 168hp Lycoming O-360-B2A fan-cooled engine mounted above the cabin with direct drive through the gear-box to the main rotor. Fuel tank under seats with capacity of 60 litres. Oil capacity 9 litres.

ACCOMODATION: Enclosed cabin seating two side-by-side with dual controls. Entrance door on each side of cabin.

Jane's All the World's Aircraft, 1959-60

Aerotecnica AC-12

The story of the Aerotecnica helicopters goes back to the original research carried out in the early 1950s by Jean Cantinieau in France. Cantinieau, an engineer with Sud Ouest (SNCASO), designed his C.100 in cooperation with M. Decroze. It was an open frame single-seat machine with a triangulated tube structure surrounding the pilot and carrying the engine and rotor installation at its apex above the pilot's head. The engine was mounted just forward of the rotorhead so as to reduce the extent of mechanical linkages and the C.100 had a three-wheel undercarriage and high-set tubular tailboom structure carrying a small tail rotor. The C.100 made its first of a total of three flights on 10 Novembers-1951 at St. Cyr and performed reasonably well.

Cantinieau quickly moved on to a two-seater, the MC.101, which retained the general layout of the first machine but with a much cleaned-up structure and a 105hp Hirth engine. Two examples of the MC.101 were built by Matra (F-WGIX and F-WGIY), the first of which was flown by Gerard Henry at Buc on 11 November 1952. It was shortly after this that Cantinieau gained the interest of the Marquis del Merito, a Spanish industrialist, who had established Aerotecnica SA as an aerial photography and crop spraying business based at Cuatro Vientos near Madrid.

In 1953, Cantinieau took his designs to Spain where the C.101 became the Aerotecnica AC.11. It soon became evident that the aircraft was underpowered in Madrid's hot and high conditions and a 150hp Lycoming was installed - in which form it became the Model AC.12. With Spanish Government funding, two AC.12 prototypes were built. These differed from the AC.11 in having a full all-metal monocoque fuselage with a large overhead 'spine' encompassing the boom and engine installation. The powerplant, which was upgraded to a 170hp O-320-B2A, was attached in front of the three-blade rotor head and the AC.12 had a fully enclosed two-seat cabin and small skid undercarriage.

Cantinieau had also been working on another project for a three-seat turbine-powered helicopter, the designs for which he had sold to SNCAN. The layout of this machine was very close to that of the AC.12. SNCAN built two prototypes of this helicopter as the Nord N.1750 "Norelfe" which was a rather futuristic all-metal machine with a large bubble canopy and a Turbomeca Artouste I turbine mounted above and behind the cockpit. The three-blade rotor was positioned directly over the engine and had a rotorhead enclosed in a large spherical fairing. The tail rotor was replaced by a ducted exhaust gas arrangement similar to that employed forty years later on the McDonnell Douglas NOTAR designs. This was controlled by the pilot through pedals.

The three-seat Noreife prototype, F-WGVZ, was flown on 28 December 1954 but SNCAN was occupied with other projects and sold both the aircraft and the rights to Aerotecnica who designated them AC.13A. After further testing in Spain, Aerotecnica moved to a larger five-seat version known as the AC.14. The prototype AC.14 used part of the structure of one of the AC.13s but had a lengthened cabin section with a rear seating area and a larger 400shp Turbomeca Artouste IIB turboshaft engine.

Having funded much of the Aerotecnica helicopter project, the Spanish Government placed orders for twelve examples of the piston engined AC.12 and ten of the AC.14. These were delivered to the Spanish Air Force, with the designations EC-XZ-2 and EC-XZ-4 respectively, where they served for a relatively short period before being retired. Aerotecnica also started construction of a prototype of the much larger AC.21 which was a 12/14 passenger machine with twin Turbomeca Turmo III turbines and a massive ducted-air tailboom. A turbine version of the AC.12 was planned and they also started working on the AC.15 development of the AC.14 with a 260hp Lycoming O-435-V engine. Unfortunately, in 1962 the Spanish Government withdrew further financial support and Aerotecnica went into liquidation.

Following the collapse of Aerotecnica, Jean Cantinieau returned to France where he joined Matra. There, he designed and completed a single example of the "Bamby". This single-seat machine closely resembled the Aerotecnica machines but embodied a triangular end to the tailboom which provided a better direction and control of exhaust gas. After brief testing in 1963 the "Bamby" suffered a power train failure and was abandoned.

R.Simpson "Airlife's Helicopter and Rotorcraft", 1998

Technical data for Aerotecnica AC-12

Main rotor diameter: 8.50m, overall length: 8.30m, fuselage length: 7.35m, height to top of rotor pylon: 2.75m, fuselage width: 1.22m, weight empty: 490kg, weight loaded: 770kg, max speed: 140km/h, cruising speed: 110km/h, rate of climb at sea level: 258m/min, hovering ceiling IGE: 1650m, hovering ceiling OGE: 800m, service ceiling: 3100m, still air cruising range: 170km

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