Opensource MicroGravity Laboratory

Technology of the OMGL as presented to the IAC 2004 Congress

      You can also read our paper, published in the IAC congress CD, and use a java simulator to simulate the flight of the OMGL on your computer with different parameters.

Slide 16:  The first flight mode will probably be the easiest one to realize as the laboratory design is the least complicated one. Therefore, also construction and operating costs will be the lowest of the three possibilities. Additionally, the comparatively low release altitude, combined with the simple design, will probably allow multiple launches in a relatively short time interval. On the other hand, this flight mode restricts microgravity time to approximately 30 seconds, and will require multiple launches even for the repetition of identical experiments.

Slide 17: Considering the additional mass of the multiple parachutes and the additional propulsion fuel for the multiple drops, the laboratory's starting mass was increased to 1500 kg for this simulation. The 3.0 m parachute radius used for all parachute phases except the final landing parachute with a radius of 5.0 m. Propulsion mass output was assumed to be identical to flight mode 1 (0.5 kg/s). The different peak velocities are due to the speed of sound depending on temperature and air density, as the trigger condition for parachute deployment was the critical mach number rather than an absolute critical velocity.

Slide 18: Flight mode 2 still avoids the difficulties of supersonic flight, but now allows multiple repetitions of a single experiment to be conducted during a single launch. It has the disadvantage of short microgravity intervals just as in flight mode 1, while the multiple parachute system will probably prove to be more complicated to realize than a single landing system.

Slide 19: For flight mode 3, the laboratory's starting mass was also assumed at 1500 kg, but this time to account for the more powerful vertical propulsion unit and the larger quantity of propulsion fuel. For this reason, propulsion mass output was also doubled to 1.0 kg/s. While the landing parachute was kept at a radius of 5.0 m, the first stage was drastically reduced in size to a radius of 0.75 m because the velocity at parachute deployment reaches almost three times the speed of sound. For this simulation, the parachute drag was estimated by a turbulent airflow not considering supersonic effects, but even so, it shows a drastic deceleration which puts a great strain on both the laboratory structure as well as on the parachute system. Future calculations and experiments may even show that a non-parachute braking system will be necessary to pre-brake the laboratory to subsonic velocities where parachutes can be used safely.

Slide 20: The third flight mode promises by far the longest continuous microgravity time, but it also brings up a number of difficulties because of the supersonic velocities: First of all, a sufficiently powerful propulsion unit and, as mentioned above, a suitable braking system, but probably also sophisticated vibration damping and flight stabilization systems for the supersonic transition. This version would be the most interesting one, but certainly also the most difficult and expensive one to realize.