Parabolic flight using what is sometimes referred to as Vomit Comets, as a way of simulating weightlessness, was first proposed by the German aerospace engineer Fritz Haber and the German physicist Heinz Haber in 1950. Both had been brought to the U.S. after World War II as part of “Operation Paperclip”. The primary purpose for Operation Paperclip was U.S. military advantage during the Cold War, and the Space Race.
The “Vomit Comet” refers to a NASA program that introduced astronauts to the feeling of zero-gravity spaceflight. Recruits climbed aboard a specially fitted aircraft that dipped and climbed through the air to simulate the feeling of weightlessness, in twenty to twenty-five second intervals.
The Vomit Comets
According to NASA, its “reduced gravity” research program started in 1959. NASA has flown several types of aircraft over the years, perhaps most famously the KC-135A aircraft that is now retired. The agency currently offers flight opportunities on the Boeing 727-200F operated by Zero G Corp. In late 2004, the Zero Gravity Corporation became the first company in the United States of America to offer zero-g flights to the general public, using Boeing 727 jets. Each flight consists of around fifteen parabolas, including simulations of the gravity levels of the Moon and Mars, as well as complete weightlessness. This profile allows ZERO-G’s clients to enjoy weightlessness with minimal motion discomfort.
In 2014, Integrated Spaceflight Services, the research and education partner of Swiss Space Systems (S3) in the United States of America, began offering comprehensive reduced-gravity services on S3’s Airbus A340 aircraft, as well as FAA certification of science and engineering payloads. This project has been unsuccessful and Swiss Space Systems has bankrupted and ceased all operations.
Aurora Aerospace in Oldsmar, Florida, offers zero-g flights using a Fuji/Rockwell Commander 700. It is also used to simulate the gravity of the Moon and Mars. The Canadian Space Agency and the National Research Council have a Falcon 20 used for microgravity research. The small plane is normally not used for people to float freely and experience weightlessness.
The first zero-g plane to enter service in Latin America was a T-39 Sabreliner nicknamed CONDOR, operated for the Ecuadorian Civilian Space Agency and the Ecuadorian Air Force since May 2008. On June 19, 2008, this plane carried a seven-year-old boy, setting the Guinness World Record for the youngest person to fly in microgravity.
Europeans, meanwhile, did the first parabolic flights to carry out experiments in microgravity since 1989 aboard a Sud Aviation SE 210 Caravelle. This program was initiated at the time by the French astronauts Jean-François Clervoy and Jean-Pierre Haigneré, to be independent of the United States of America or Soviet planes, which realized this type of flights after the Second World War. It was the French DGA which was operator at the time of the plane.
In Russia, commercial flights are offered on the Ilyushin Il-78 jet. Several U.S. companies book flights on these jets. OK Go, an American alternative rock band, made a music video for their song “Upside Down & Inside Out” while moving about in microgravity. The music video was shot on an Ilyushin Il-76 jet as part of an advertising campaign for Russian S7 Airlines.
What are they used for?
An airplane flies with its engines and wings mainly. The engines provide the acceleration necessary to counteract the drag force due to friction of the air. The wings provide the lift, a force that counteracts gravity. During a parabolic flight, the aircraft is brought into an angle that allows the suppression of lift and fall into free fall, like satellites.
For this, in a first step, the plane flying at twenty thousand feet (about six thousand meters altitude) is pitched between forty-seven and fifty degrees. The pilot then decreases the thrust of the reactors so as to compensate for the friction of the air and the aircraft enters the phase of free fall. Its content then returns to microgravity. The momentum of the aircraft allows it to reach twenty-eight thousand feet (about eight thousand meters) then it falls (descending phase of the parabola) with an angle of about forty-two degrees. Then, the plane resumes its horizontal flight at twenty thousand feet. The operation lasts about one minute to obtain twenty to twenty-five seconds of weightlessness sandwiched between two periods. During the phases of ascent, people on the plane can weigh up to almost twice their weight.
A typical flight will see two to three hours of plunging arcs, giving astronauts about thirty or forty chances to experience weightlessness when the airplane drops to a lower altitude. Some researchers also use the flights as a chance to run experiments in weightlessness.
At the beginning these flights were useful for science research, indeed many scientists work all day on theories related to space or lack of gravity, and that sometimes these same scientists need to go through experiments, their theories. These practical cases could be done in outer space, but for budget and practical reasons, the zero-g flight is an excellent compromise. The thing that is great with the zero-g flight, it is that the experiment can embark with the scientist, which is priceless and what is not really feasible during a space flight. The zero-g aircraft can board up to fifteen experiments at the same time. Some student research projects (and the students themselves) can also come on board. Nearly eighty percent of scientific experiments are satisfied with one or more parabolic flights, and do not need a space flight afterwards.
Also with Vomit Comets, before going into space, astronauts must train. They must know how to move in a state of weightlessness and these flights allow them to do this, as well as training in the pool to complete their training to go on missions aboard the ISS. Microgravity flights are used for a variety of purposes, especially in the film industry. For instance, the actors of the movie “Apollo 13” (Tom Hanks, Kevin Bacon and Bill Paxton) were probably the most famous visitors on the KC-135A parabola flights in the 1990s. Set designers created a spacecraft interior adapted to the inside of the airplane, then the cameras captured shots on film, in less than thirty seconds of acting at a time. Director Ron Howard leased the aircraft over six months to achieve the weightless shots. This is what can be said concerning Vomit Comets.