Parabolic flight
A parabolic flight is a special flight maneuver in which the aircraft describes a trajectory parabola that is open to the surface of the earth . The purpose of this maneuver is to achieve weightlessness or to simulate reduced gravity, e.g. B. the moon or Mars gravity. In practice 5 to 30 parabolas are flown in a row.
When initiating the climb as well as catching the dive, there is almost double the gravity in the aircraft , composed of gravity and the force of inertia , which is about as strong . This is also known as hypergravity. The concept of parabolic flight was developed in 1950 in the USA by Fritz Haber and Heinz Haber .
procedure
To get used to it, flatter parabolas can be flown that simulate the force of gravity on the surface of Mars (0.38 g) or the moon (0.16 g) before weightlessness is made possible in several wave-like flights.
- The machine first flies horizontally at maximum speed, around 800 km / h or 220 m / s. In a first phase, it then goes into a climb until an angle of inclination of 47 ° is reached. During this phase there is roughly twice the acceleration due to gravity in the machine . The horizontal component of the speed is, similar to the vertical, around 550 km / h or 150 m / s.
- In the second phase, a transition phase, which usually lasts about 5 seconds, the engines are throttled so that the thrust only compensates for the air resistance and the aircraft slows down. In this phase you can feel a significant decrease in gravity, similar to when the landing approach is initiated in a normal flight.
- The third phase is the actual parabolic flight. The pilot pushes the control stick slightly forward so that the machine follows a trajectory parabola . The passengers inside are now largely weightless ( microgravity ). The machine initially continues to rise with decreasing vertical speed and decreasing angle until it reaches the maximum altitude, depending on the type of aircraft, about 7000 to 8500 m (23,000-28,000 ft). Then the machine sinks again with increasing vertical speed. The vertical movement in connection with the airspeed is like a free fall in the entire 3rd phase . The duration of weightlessness is on average around 22 seconds, which corresponds to a vertical start and end speed of around 108 m / s or 390 km / h and a difference in altitude of almost 600 m in each case.
- In the 4th phase (a further transition phase) the pilot exerts weightlessness evenly at an orbit inclination angle of around −45 ° so that everyone in the cabin can gently return to the ground.
- In the 5th phase, the dive is now intercepted by pulling the elevator and the engines are started up again. Again, there is about 2 g. This process takes 20 seconds.
After a pause of about two minutes in level flight, the next parabola begins.
Medical impact
By the acceleration and the steep flights Send eyes and balance organs information to the brain, the contents do not match. Some people respond to the rapid change of gravity during a parabolic flight with nausea or vomiting . Therefore, antiemetics , usually scopolamine , are administered before such a flight . Because of the unpleasant symptoms for many participants, the aircraft with which such flights are carried out are sometimes nicknamed "Kotzbomber". The US space agency NASA calls their KC-135 , which is used for parabolic flights, “Vomit Comet”.
Most participants find the weightlessness pleasant, which is why such flights are very popular.
Applications
- Testing of devices that are supposed to work in space under weightlessness. Flames, liquids, gases, sand and other materials sometimes behave completely differently under weightless conditions than on the ground.
- Scientific experiments on fluid dynamics , materials science or chemistry under weightlessness.
- Biological experiments on gravitaxis .
- Simulation of reduced gravity, such as that found on the moon or on Mars.
- Some space scenes from the film Apollo 13 were filmed during parabolic flights to mimic the weightlessness that prevails in space.
- A parabolic flight can cause an aircraft to reach an altitude at which it cannot maintain itself permanently due to insufficient air pressure. In this way, the world altitude record for jet aircraft was set in 1977 by a Soviet MiG-25 . The aircraft reached an altitude of 37.65 km.
Suitable aircraft types
In principle, parabolas can be flown with any aircraft. However, mostly slightly modified large jet aircraft are used. It is advantageous to have a large interior space that offers enough space for experiments and floating freely. Examples are an Il-76 at the Russian space agency, a KC-135 , a C9-B at NASA and an A300 ZERO-G at ESA .
Parabolic flights can also be carried out with small planes and even gliders. But free floating is only possible to a limited extent due to the lack of space. The maximum time in weightlessness is determined by the maximum permissible speed of the aircraft.
literature
- Hans-Erhard Lessing: Mannheim Pioneers , Wellhöfer-Verlag, Mannheim 2007
- Novespace, Parabolic Flights and Microgravity, User´s manual July 7, 2004
- Novespace, Parabolic Flight Campaign with A300 ZERO-G, User's Manual July 5, 1999
Web links
- Parabolic flight: information from DLR
- About the NASA C9-B
- Purdue University Team Page with pictures, video and flight information
- Operating company of the A300 Zero-G
Individual evidence
- ^ Fritz Haber, Heinz Haber: Possible methods of producing the gravity-free state for medical research . In: Journal of Aviation Medicine . 21 (5), 1950, pp. 395-400. PMID 14778792 . Summary and historical classification in: Mark R. Campbell: Classics in space medicine. Possible methods of producing the gravity-free state for medical research . In: Aviation, Space, and Environmental Medicine . 80 (12), 2009, p. 1077. doi : 10.3357 / ASEM.26010.2009 . PMID 20027862 .