SNCASO (abbreviated from Société Nationale des Constructions Aéronautiques du Sud-Ouest, or commonly, Sud-Ouest) was formed in 1936 from the merger of several French aircraft manufacturers. (SNCASO merged with SNCASE in 1957 to form Sud Aviation, which became part of Aérospatiale in 1970, and is today part of the Airbus legacy.)

The Sud-Ouest SO.1120 Ariel III tip-jet helicopter flew for the first time on April 18, 1951. It was powered by a 260 hp (195 kW) Turbomeca Artouste turbocompressor, which provided compressed air for the tip jets at the tips of its 35.4 ft (10.8 m) diameter 3-bladed rotor. The helicopter had a conventional layout; but instead of a tail rotor, it used the exhaust from the turbine as a source of high-pressure air for directional control-in effect.
The Ariel series of helicopters represented a new approach to power a rotorcraft. Up to that time, helicopters were powered by relatively heavy piston engines and associated cooling systems. Helicopter designers were desperate for ways to improve the power-to-weight ratio of their machines. Tip jets seemed to provide the answer they were looking for; but even though tip jets negated the need for heavy gearboxes and complicated anti-torque systems, it was not without compromises. The long-sought breakthrough by SNCASO creative engineers did not arrive until a turbine engine was married to a helicopter as the source of compressed air for the tip jets. As its name implies, the Ariel III was not the first Ariel in the series; and the Ariel I and Ariel II differed in design and powerplant. Only the Ariel III used a turbine engine for the compressor. The Ariel III was the first turbine engine powered helicopter to fly (albeit it was not a “direct drive” turbine-powered machine as nearly all other turbine-powered helicopters have been — see note below).

Two prototypes of the Ariel III were built, both capable of carrying 3 persons side by side. The two prototypes (registered as F-WFUY and F-WBBL) flew very successfully for quite some time. In the end, the Ariel series of tip jet helicopters’ greatest contribution was that they paved the way for SNCASO to develop and produce the most successful of the tip jet helicopters, the SO.1221 Djinn. The Ariel III also pointed the way for future rotorcraft designers to use turbine powerplants as the engine of choice for helicopters.

Note: The media sometimes erroneously state that the Kaman K-225 turbine-powered demonstrator was the first turbine-powered helicopter to take flight. It was, however, the first turboshaft-driven helicopter to fly; first flight was in Dec. 1951, 8 months after the Ariel III.


Source: "Sud-Ouest SO.1120 Ariel III | First gas turbine-powered helicopter", Erasmo Piñero, Jr., 2019 VTOL History Calendar


Data on design, manufacture and status

Design authority: Société Nationale de Constructions Aéronautiques du Sud-Ouest

Primary manufacturer: Société Nationale de Constructions Aéronautiques du Sud-Ouest

Parent type: No type defined

Aircraft status: No longer flying


Primary flight and mechanical characteristics

VTOL type: Helicopter

Lift configuration: Single main rotor

Dedicated control device: Thruster

Crew required: 1

Crew seating: Side-by-side

Landing gear: Wheels (non-retractable)

Layout and Dimensions

Data on aircraft size

Overall Dimensions
Overall Height:  
Overall Length:  
Overall Width:  
Airframe Dimensions
Airframe Length:  
Airframe Width:  
Airframe Height:  
Landing Gear Dimensions
Landing Gear Base:  
Landing Gear Track:  
Cabin Dimensions
Cabin Internal Height:  
Cabin Internal Length:  
Cabin Internal Width:  

Weights and Performance

Data on aircraft weight and flight characteristics

Max Gross Weight (ground):  
Max Gross Weight (airborne):  
Max Take-off Weight:  
Empty Weight:  
Useful Load:  
Empty Weight Fraction:  
Climb Performance
Max Rate of Climb:  
Hover Performance
Hover Ceiling IGE:  
Hover Ceiling OGE:  
Max Level Flight Speed:  
Never Exceed Speed:  
Service Ceiling:  
Range and Endurance
Max Range:  
Max Endurance:  

Engine Details

Aircraft powerplant (lift and/or propulsion)

Provided powerplant data is for uninstalled, sea level, static operations.

Number of engines: 1
Normal Ratings
Max continuous:  
Take-off / rated:  
OEI Ratings
OEI contingency:  
OEI continuous:  
OEI 30-second:  
OEI intermediate:  

Primary Lift Device

Data on primary lift devices such as main rotors

Main Rotor Characteristics
Direction of Rotation: Unknown
Hub Type:  
Main Rotor Blade Characteristics
Blade Construction:  
Blade Chord:  
Blade Tip Geometry:  
Blade Twist:  
Number of Blades:  
Main Rotor Derived Characteristics
Disc Area:  
Disc Loading:  
Main Rotor Blade Derived Characteristics
Blade area per blade:  
Tip Speed:  

Primary Control Device

Data on primary control devices such as tail rotors

Tail Rotor Characteristics
Configuration: Unknown
Direction of Rotation: Unknown
Tail Rotor Blade Characteristics
Number of Blades:  
Blade Construction: N/A
Blade Chord:  
Blade Twist:  
Tail Rotor Derived Characteristics
Disc Area:  
Tail Rotor Blade Derived Characteristics
Tip Speed:  
Blade Area (per blade):  

Related VFS Resources

Resources related to the SO.1120 Ariel III, provided by the Vertical Flight Society.
Forum Proceedings
Vertiflite articles
Enter a search term in the box above.
Web files from
Enter a search term in the box above.
Webpages from
Enter a search term in the box above.

Related Public Resources

Resources related to the SO.1120 Ariel III, provided by public sources across the internet.