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How it works

A specially modified aircraft

The A300 Zero-g looks very much like a conventional aircraft, with a few special modifications.
Cockpit of the A300-0G. Crédits : CNES/C. Bardou

Cockpit of the A300-0G. Crédits : CNES/C. Bardou

The cockpit has been fitted out to meet the needs of parabolic flight, with the addition of accelerometers and repositioning of certain controls to make them more accessible during the weightless phases. The plane is flown by a crew of experienced test pilots.

The cabin was totally redesigned. The number of seats was reduced to 40, located in the forward and aft of the cabin. The floor and bulkheads were covered with foam padding to protect passengers and the experimental modules which are attached to the floor over a 100m² surface area. Electric panels, handrails, and modified lighting were installed to optimize the A300 Zero-g for scientific work.

The aircraft’s electrical power system and inertial navigation units have been modified to withstand successive periods of microgravity.

Since 2003, the Airbus A300 Zero-g has also been used by ESA and CNES under the ARTA research programme to keep track of main cryogenic propulsion stages falling backing to Earth during Ariane 5 launches. A radar system was installed on the front cargo door for this purpose.

Illustration of section of Airbus Zero-G on the ground ; credits : CNES/ill.D.Ducros, 1999

The parabolic principle

During the 1st phase of the flight, the aircraft travels horizontally. The pilot prepares for the parabolic manoeuvre by gradually increasing the speed to around 810 kph, the maximum authorized speed for this type of aircraft. The plane then begins to climb until it reaches an angle of 45°. This increases the acceleration forces, causing the passengers to weigh 1.8 times as much as they do on Earth.

While the aircraft is in maximum climb, the flight engineer throttles back, cutting most of the power to the engines. The aircraft then goes into the parabolic trajectory, resulting in “free fall” conditions for the passengers and cargo and producing nearly weightless conditions.

Twenty seconds later, gravity conditions quickly return. When the aircraft reaches a 45° angle nose-down, the flight engineer throttles up to gain speed, enabling the pilot to gradually level off. The passengers again weigh 1.8 times their normal weight for 20 seconds. The A300 returns to level flight for 2 minutes, before again performing the parabolic manoeuvre.

These manoeuvres are repeated 30 times during each flight.
Imagined by Jean-Pierre Penot (CNES) and Bernard Nicolas, illustrated by Bernard Nicolas

Imagined by Jean-Pierre Penot (CNES) and Bernard Nicolas, illustrated by Bernard Nicolas

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