Aérospatiale Djinn
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The Sud-Ouest SO.1221 Djinn (alternatively written S.O.1221) is a French two-seat light
helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attribut ...
designed and manufactured by aircraft manufacturer Sud-Ouest (SNCASO), which was later merged into
Sud Aviation Sud Aviation (, ''Southern Aviation'') was a French state-owned aircraft manufacturer, originating from the merger of Sud-Est ( SNCASE, or ''Société nationale des constructions aéronautiques du sud-est'') and Sud-Ouest ( SNCASO or ''Sociét� ...
. It was the first production French helicopter, as well as being one of the first practical European helicopters to be produced. The Djinn was also the first rotorcraft to harness
tip-jet A tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor, much like a Catherine wheel firework. Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not re ...
propulsion to enter production. The Djinn was developed to function as a practical implementation of the earlier experimental Sud-Ouest Ariel rotorcraft. Atypically, the
rotor Rotor may refer to: Science and technology Engineering *Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator *Helicopter rotor, the rotary wing(s) of a rotorcraft ...
was driven by compressed-air jets at the end of each blade, which had the benefit of eliminating the need for an anti-torque tail rotor. On 2 January 1953, the proof-of-concept SO.1220 performed its
maiden flight The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets. The maiden flight of a new aircraft type is alwa ...
; it was followed by the first of the SO.1221 Djinn prototypes on 16 December 1953. During the subsequence test program, one of the prototypes was recorded as having achieved a world altitude record. Having been suitably impressed by the performance of the Djinn during testing, both the
French Army The French Army, officially known as the Land Army (french: Armée de Terre, ), is the land-based and largest component of the French Armed Forces. It is responsible to the Government of France, along with the other components of the Armed Force ...
and the German Army chose to procure the type, as well as a number of other customers. Operationally, the type was used for various purposes, including
liaison Liaison means communication between two or more groups, or co-operation or working together. Liaison or liaisons may refer to: General usage * Affair, an unfaithful sexual relationship * Collaboration * Co-operation Arts and entertainment * L ...
,
aerial observation Aerial reconnaissance is reconnaissance for a military or strategic purpose that is conducted using reconnaissance aircraft. The role of reconnaissance can fulfil a variety of requirements including artillery spotting, the collection of ima ...
,
training Training is teaching, or developing in oneself or others, any skills and knowledge or fitness that relate to specific useful competencies. Training has specific goals of improving one's capability, capacity, productivity and performance. I ...
, and
casualty evacuation Casualty evacuation, also known as CASEVAC or by the callsign Dustoff or colloquially Dust Off, is a military term for the emergency patient evacuation of casualties from a combat zone. Casevac can be done by both ground and air. "DUSTOFF" is ...
. The Djinn was phased out of production during the 1960s as a consequence of the greater success of the comparably more conventional
Aérospatiale Alouette II The Aérospatiale Alouette II (, "lark"; company designations SE 313 and SA 318) is a French light helicopter originally manufactured by Sud Aviation and later Aérospatiale. It was the first production helicopter powered by a gas turbine en ...
and
Aérospatiale Alouette III The Aérospatiale Alouette III (, ''Lark''; company designations SA 316 and SA 319) is a single-engine, light utility helicopter developed by French aircraft company Sud Aviation. During its production life, it proved to be a relatively popular ...
helicopters.


Development

Positive experiences that had gained from the earlier
Ariel Ariel may refer to: Film and television *Ariel Award, a Mexican Academy of Film award * ''Ariel'' (film), a 1988 Finnish film by Aki Kaurismäki * ''ARIEL Visual'' and ''ARIEL Deluxe'', 1989 and 1991 anime video series based on the novel series ...
experimental
tip jet A tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor, much like a Catherine wheel firework. Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not re ...
helicopter had given French aviation company Sud-Ouest a strong desire to pursue development of a practical light helicopter that would harness this technology. Out of their efforts towards this aim emerged the design of a light twin-seat rotorcraft, which was promptly designated as the ''SO.1221 Djinn''.Boyne 2011, p. 101. While this newer design did not share an identical tip jet system to the Ariel, the type did rely upon the same basic concept of feeding compressed air, which was generated by an onboard pump, to the tips of the vehicle's rotor blades to drive the movement of the blades. A single seat prototype, designated ''SO.1220'', was constructed to function as an aerial test bed for the rotorcraft's propulsion concept."Helicopter Runs On Air."
''Popular Science'', April 1953.
On 2 January 1953, the SO.1220, which was a simple uncovered structure with an exposed seat for the pilot, conducted its
maiden flight The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets. The maiden flight of a new aircraft type is alwa ...
; early test flights of the rotorcraft proved the viability of the propulsion system. Accordingly, it was decided to proceed with the production of five two-seat prototypes, designated as the ''SO.1221''; the first of these flew on 16 December 1953.McGowen 2005, p. 74. Within a few days, one of the prototypes had climbed to a recorded altitude of 4,789 m (15,712 ft) to establish a record in its class. During the late 1950s, an improved version of the Djinn, tentatively designated as the ''Djinn III'' or ''Super Djinn'', was being studied by Sud Aviation, who held the intention of pursuing further development of the type at one point. As envisioned, the modifications present upon the projected Super Djinn variant would have included the adoption of the newer Turbomeca Palouste IV engine; alongside other changes, it would have possessed both greater power and endurance than the original production model."Hew French Helicopters."
''Flight International'', 17 April 1959. p. 512.


Design

The Sud-Ouest Djinn was the first
tip-jet A tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor, much like a Catherine wheel firework. Tip jets replace the normal shaft drive and have the advantage of placing no torque on the airframe, thus not re ...
propelled rotorcraft to enter production. As such, the propulsion system involved a
Turbomeca Palouste The Turbomeca Palouste is a French gas turbine engine, first run in 1952. Designed purely as a compressed air generator, the Palouste was mainly used as a ground-based aircraft engine starter unit. Other uses included rotor tip propulsion for h ...
gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...
engine that drove a pump to produce compressed air, which was in turn fed into the aircraft's hollow
rotor blade A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) with a control system, that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerod ...
s to exit at their tips, causing the blades to rotate. The rotor hub assembly, which freely oscillated around a spherical thrust bearing, was mounted on a steel pylon by means of a
ball joint In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. They bionically resemble the ball-and-socket joints found in most tetrapod an ...
and rubber
shock absorber A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Mos ...
s. Unlike some of the experimental tip-jet designs of the era, a 'cold' tip-jet approach was used: that there was no
combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combust ...
activity present at the exhaust nozzles installed at the ends of the rotor blades. Consequently, the nozzles produced little noise in operation, and were claimed by Sud-Ouest to be "noiseless"."The World's Helicopters."
''Flight International'', 23 January 1953. p. 114.
The all-metal rotor blades, through which the compressed air travelled to be ejected at the blade tips, consist of a spar of tapering thickness, a
honeycomb A honeycomb is a mass of hexagonal prismatic wax cells built by honey bees in their nests to contain their larvae and stores of honey and pollen. Beekeepers may remove the entire honeycomb to harvest honey. Honey bees consume about of honey t ...
-filled
trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...
, and feature faired roots to the increase their lift coefficient. It was claimed that the blades possessed a highly homogenous structure, a highly finished surface and a constant profile, and could be easily dismantled to facilitate inspection of the main spar. The blade had no risk of icing owing to the internal current of warm air. The Djinn used relatively standard flight controls, such as the
collective pitch A helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor bl ...
control (upon which the throttle was positioned) and adjustable friction trims. Apart from its method of propulsion, the Djinn was a relatively conventional helicopter, featuring a two-seat side-by-side configuration in an enclosed cabin. The cockpit is provided with an array of
plexiglas Poly(methyl methacrylate) (PMMA) belongs to a group of materials called engineering plastics. It is a transparent thermoplastic. PMMA is also known as acrylic, acrylic glass, as well as by the trade names and brands Crylux, Plexiglas, Acryli ...
panels, which provide the occupants with a high level of all-round visibility."Helicopters of the World..."
''Flight International'', 21 March 1958. p. 376.
Directly to the rear of the cockpit was the rotorcraft's single Palouste engine. The engine lacked any electronics and had to be hand-started via a
crank Crank may refer to: Mechanisms * Crank (mechanism), in mechanical engineering, a bent portion of an axle or shaft, or an arm keyed at right angles to the end of a shaft, by which motion is imparted to or received from it * Crankset, the compone ...
handle located on the starboard side of the fuselage. The Djinn possessed the ability to fly at high overload weights for around 5 sec by correctly harnessing the accumulated
kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its a ...
of the rotor; this 'jump' technique was successfully used to achieve
certification Certification is the provision by an independent body of written assurance (a certificate) that the product, service or system in question meets specific requirements. It is the formal attestation or confirmation of certain characteristics of a ...
for it to be operated to carry heavy payloads, some of which could represent up to 54% of the rotorcraft's overall gross weight. The Djinn featured a two-seat cockpit as standard, which accommodated a pilot and passenger. A range of specialised equipment could be outfitted to suit mission roles, such as
stretcher A stretcher, gurney, litter, or pram is an apparatus used for moving patients who require medical care. A basic type (cot or litter) must be carried by two or more people. A wheeled stretcher (known as a gurney, trolley, bed or cart) is often ...
carriers, spray bars,
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300  gigahertz (GHz). They are generated by an electronic device called a transm ...
sets, electrical systems, additional fuel tanks, and a load-bearing
hook A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved or indented, such that it can be used to grab onto, connect, or otherwise attach itself onto another object. In a number of uses, one e ...
. Akin to the later
Aérospatiale Alouette II The Aérospatiale Alouette II (, "lark"; company designations SE 313 and SA 318) is a French light helicopter originally manufactured by Sud Aviation and later Aérospatiale. It was the first production helicopter powered by a gas turbine en ...
helicopter, the Djinn made considerable use of pneumatic systems. According to aerospace publication
Flight International ''Flight International'' is a monthly magazine focused on aerospace. Published in the United Kingdom and founded in 1909 as "A Journal devoted to the Interests, Practice, and Progress of Aerial Locomotion and Transport", it is the world's olde ...
, considerable weight savings had been on the rotorcraft via the use of
bleed air Bleed air is compressed air taken from the compressor stage of a gas turbine upstream of its fuel-burning sections. Automatic air supply and cabin pressure controller (ASCPCs) valves bleed air from high or low stage engine compressor sections. Lo ...
to operate various cockpit indicators and functions, including the blind-flying instruments,
fuel gauge In automotive and aerospace engineering, a fuel gauge is an instrument used to indicate the amount of fuel in a fuel tank. In electrical engineering, the term is used for ICs determining the current State of Charge of accumulators. Motor vehicl ...
s, cabin heaters, windshield demisters, trimmers, air/sea rescue
hoist Hoist may refer to: * Hoist (device), a machine for lifting loads * Hoist controller, a machine for raising and lowering goods or personnel by means of a cable * Hydraulic hooklift hoist, another machine * Hoist (mining), another machine * Hoist ( ...
s and crop-spraying equipment. The rotorcraft was equipped with an uncovered tail boom, fitted with twin
fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...
s and a
rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adverse yaw a ...
; both directional control and stability were provided by the controlled deflection of exhaust gases from the engine.Mutza 2010, p. 20. As a consequence of the torque-free method of rotor propulsion, the Djinn did not require the presence of an anti-torque
tail rotor The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. T ...
. A simplistic wheel-equipped twin-skid arrangement was also present; this was retractable by the same manually-operated crank handle used for engine start."SO. 1221S Djinn."
''Flight International'', 2 November 1956. p. 733.
The Djinn could also be deployed with multiple armaments. In the ground-attack role, it could be equipped with a single
machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifl ...
, which was manned from the second seat of the cockpit. For performing anti-tank warfare, the Djinn was able to carry a
guided missile In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocket ...
. When deployed in an effective manner against an adversary, the manufacturer claimed the combination to be extremely difficult for an opposing
tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and good battlefield mobility provided by tracks and a powerful e ...
to sight its adversary and to defend itself during the anticipated rapid speed of engagements.


Operational history

Having observed the development of the Djinn with considerable interest, the
French Army The French Army, officially known as the Land Army (french: Armée de Terre, ), is the land-based and largest component of the French Armed Forces. It is responsible to the Government of France, along with the other components of the Armed Force ...
encouraged the construction of a pre-production batch of 22 helicopters, which were used for evaluation purposes. The first of these pre-production aircraft flew on 23 September 1954. Three of the pre-production helicopters were subsequently acquired by the
United States Army The United States Army (USA) is the land warfare, land military branch, service branch of the United States Armed Forces. It is one of the eight Uniformed services of the United States, U.S. uniformed services, and is designated as the Army o ...
, designating it as the ''YHO-1'', for the purpose of participating in their own series of trials; according to aviation author Stanley S. McGowen, the US Army held little interest in the type. According to author Wayne Mutza, the US Army had found the YHO-1 to be an excellent weapons platform, but had been compelled to abandon interest in the programme by political opposition to the procurement of a rotorcraft that had non-American origins.Mutza 2010, p. 19. The French Army ordered a total of 100 helicopters. The Djinn was operated by the French Army in variety of mission roles, such as liaison, observation, training purposes; when flown with a single pilot, it could be outfitted with two external litters for the
casualty evacuation Casualty evacuation, also known as CASEVAC or by the callsign Dustoff or colloquially Dust Off, is a military term for the emergency patient evacuation of casualties from a combat zone. Casevac can be done by both ground and air. "DUSTOFF" is ...
mission. In addition to the French military, a further ten countries placed orders for the type; such as a batch of six rotorcraft which were procured by the German Army. Production of the Djinn came to an end during the mid-1960s, by which point a total of 178 Djinns had been constructed; the type had effectively been replaced by the more conventional and highly successful
Aérospatiale Alouette II The Aérospatiale Alouette II (, "lark"; company designations SE 313 and SA 318) is a French light helicopter originally manufactured by Sud Aviation and later Aérospatiale. It was the first production helicopter powered by a gas turbine en ...
. Some Djinns were sold on to civil operators; in this capacity, they were often equipped for
agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
purposes, fitted with chemical tanks and spray bars.


Operators

; *
Cameroon Air Force The Cameroon Air Force (french: Armée de l'Air du Cameroun, AdAC) is the air force of Cameroon. The Cameroon Air Force, along with the Cameroon Army, the Cameroon Navy (including the Naval Infantry), the National Gendarmerie, and the Presiden ...
; *
French Army The French Army, officially known as the Land Army (french: Armée de Terre, ), is the land-based and largest component of the French Armed Forces. It is responsible to the Government of France, along with the other components of the Armed Force ...


Specifications


See also


References


Citations


Bibliography

* Apostolo, Giorgio. ''The Illustrated Encyclopedia of Helicopters''. New York: Bonanza Books, 1984. . * Boyne, Walter. ''How the Helicopter Changed Modern Warfare''. Pelican Publishing Company, 2011. . * McGowen, Stanley S. ''Helicopters: An Illustrated History of Their Impact''. ABC-CLIO, 2005. . * Mutza, Wayne. ''Helicopter Gunships: Deadly Combat Weapon Systems''. Specialty Press, 2010. . * ''The Illustrated Encyclopedia of Aircraft (Part Work 1982–1985)''. London: Orbis Publishing, 1985.


External links


'' "Helicopter Runs On Air" '', April 1953, Popular Science, rare photo of the single seat SO.1220 that tested the power concept – i.e. bottom of page 128
{{US Army helicopters 1950s French military utility aircraft 1950s French helicopters
Djinn Jinn ( ar, , ') – also romanized as djinn or anglicized as genies (with the broader meaning of spirit or demon, depending on sources) – are invisible creatures in early pre-Islamic Arabian religious systems and later in Islamic my ...
Aircraft first flown in 1953 Single-turbine helicopters Tipjet-powered helicopters