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Technology
of the OMGL as presented to the IAC
2004 Congress
For a detailed explaination of the OMGL
technology, we publish here the slides presented at the International
Astronautics Congress 2004 in Vancouver,
Canada, with additional comments.
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
11: The probe is very simple. It has an octagonal pyramidal structure.
The OMGL is attached to the top and is kept by mechanical arms in
middle. The probe can contain small scientifc instruments but it cannot be used for high
resulution earth
observation by design. The
probe also contains a positioning
system and a satellite phone, a parachute and an inflatable floaters. 9
superpressure helium balloons are attached . After the release of the
OMGL and the completion of the scientifc mission of the probe, the
balloons are gradually deflated, and the probe slowly descent over the
sea. The probe then inflates its floaters and awaits the rescue ship.
Balloons are rescued with the probe and if possible reused.
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Slide
12: We want to investigate the capabilities of three different flight
modes for the laboratory (described above). As you will see, our first
simulations already show some of the major strengths and weaknesses of
each mode.
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Slide
13:
There are a few general safety and
security issues that have to be taken into account for any flight mode
to be realized: First of all, in order to prevent damage to the
laboratory as well as not to endanger
people, the OMGL system should be operated only over open sea, in a
safe
distance from the coastline and main ship traffic lines. This will, of
course, require a ship-based launch and service module. Also, because
of the
high kinetic energy reached by the laboratory during its descent, an
unbraked impact on the sea surface is to be prevented in any case. This
means
that the laboratory module will have to self-destruct if the parachutes
fail
to open before a critical minimum altitude is reached. This could be
done
by explosive charges placed in critical spots in the laboratory's
internal structure. Finally, it will not be possible to manipulate the
laboratory's flight path once it is released from the lifting system,
which by itself will also be fully automatic. This is to prevent abuse
for military
means or hijacking by terrorists.
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Slide
14: In the simulation whose results you will see in the following
slides, we took the atmospheric data from the U.S. Standard atmosphere
from
1976. As we do not yet have any concrete data on the propulsion
system's
efficiency, we assumed it to provide a vertical acceleration exactly
equal to the gravitational acceleration, thus completely compensating
air drag. When there is more data available on the propulsion system,
the simulation
will of course have to be updated. We also restricted the velocity
range to a maximum of 90% the speed of sound for the two subsonic
flightmodes to
take the effects of the transonic flight regime near sound barrier into
account. This value will probably also have to be updated when wind
channel data
on the laboratory's hull is available.
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Slide
15: For the simulation of the first flight mode we assumed the
laboratory to have a starting mass of 1000 kg (including propulsion
fuel and parachutes). This value is decreased during flight by an
(assumed) propulsion mass output of 0.5 kg per second. For the
parachutes, we put
in a two-stage system: A smaller parachute with a radius of 3.0 m to
pre-brake the laboratory from its near-sonic end velocity and a larger
parachute
of 5.0 m to slow it down to landing velocity.
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