Parabolic Flights



Parabolic Flights1



Description of a flight

Phase 1 :

From an horizontal flight at an average height of 8000 to 9000 meters, the aeroplane starts climbing to until it has an inclination of 50 degrees, accelerating by 1,8 to 2 g during about 20 minutes.

Phase 2 :

The plane highly reduces the thrust of its engines during about 20 seconds but keeps just enough to counterbalance the atmosphere drag ; at that moment , the global force , except for the gravity, acting on the flying plane is equal to zero, so that it is in free fall and follows a balistic trajectory of parabolic type.Thanks to its initial velocity which was directed upwards, the plane continues to go up passing by the climax of its parabolic trajectory at an average altitude of 11000 to 12000 meters , then flies straight downstairs.

Phase 3 :

Once the angle of flight reaches an inclination of 50 degrees, the pilot turns the engines at full power and the plane speeds up by 1,8 to 2 g again for about 20 sec. to come back to horizontal flight.

These operations follows one another, separated by normal flight periods during 2 minutes at most . Each flight takes approximately 2 hours and a half and offers about thirty paraboles.

Qualilty of microgravity during parabolic flights

The remaining accelerations that are mesured during a parabolic flight are of 10 to 2 g for an equipment bound to the floor of the plane and of 10 to 3 g for a free flight in the cabin. these remaining accelerations, that are to be lessened at most are mainly brought about by climatic conditions ( wind among others) , by the hability of the pilot to follow the exact parabolic trajectory , by mechanical vibration of the plane because of the structure, by aerodynamic forces and by board system of the plane. In order to reduce the effect of these parasitic accelerations so to make the microgravity better in free flight, the pilot follows the movement of the equipment in free flight in the cabin through camera and control screen, instead of folling the accelerometer to achieve the best flight, he drives the plane "around" the equipment in free fall.

Types of experimental activities during parabolic flights

Qalitative experiments

These experiments are based on simple ideas and realized with laboratory equipment ; they consist in doing sheer research thanks to pretty short tests, that allow the observation of phenomena. This way, you can observe how drops of fuel burn in microgravity, which is a phenomena that is difficult to study in a station where people live for security reasons.

Our experimental measure of "driven-induction" Marangoni effect is part of this category of experiments : indeed, a part of our work will consist in observing whether the theoritically predicted force will act so . The action of that force will mean a certain observable speed of the melted metal at the surface . These observations will be a first check of the theoritical model.

The quantitative experiments

These experiments aim to measure the phenomena that are happening on microgravity and that give exploitable results.

Secondly, our experiment will enter this category too. Indeed, we will film the surface of a melted metal with a specialized camera that will allow to deduct the numerical value of the velocity of the metal at its surface . These quantitive measures will be compared to the theoritical model.

Working trials for experimental equipment for space

These trials are supposed to check the process during the experiment, to define a scale of value in which scientists can discover in orbit ; the point is to obtain indications about the possible progresses and about the effects of adjustments in real time of operational parameters.

Experiments completing those made in orbit

These experiments are meant to complete those made with devices in orbit ; the allow to confirm or to infirm hypothesis made upon results and to verify an event that may have influenced the process in space.

Advantages and drawbacks of parabolic flights

 

Parabolic flights are more economic and less contraining than missions in orbit . A laboratory shuttle flight costs more than 400 millions $.

The development of a device means an investment of several millions $ . It must be patented before being launded into space.

A campaign of 3 parabolic flights ( with about 30 par. in each one ) costs not less than 100000 euros.

The advantage of the flight through space is that it allows to obtain constant microgravity during several days or weeks , where a parabolic flight only allows 20 to 25 seconds.



1. Ces notes sont en partie inspirées par la revue "Space Connection". Revue éditée par les Services fédéraux des affaires scientifiques, techniques et culturelles www.belspo.be