A Scandinavian manned space program like ours, with a non-heated facility, is completely at the mercy of the weather. During the summer you are dying from welding in the heat, and during the winter season, everything freezes up. At the moment, one must work wearing many layers of clothing and time tests accordingly to the temperature.
Yes, this is Denmark and we are in the “North” -- but contrary to what many people believe there are no polar bears here, and not that many crazy winters. Last year we had only two weeks of snow. But you never know if you suddenly get two months covered in snow. Of course it does get below freezing, and this is a challenge because many chemical processes rapidly change over a ± 40 °C temperature span.
At the moment I am working on the last major puzzle on space capsule Tycho Deep Space II. Most of the subsystems and their mutual relationships make sense now, but I need to get the uprighting sequence and system working with -- not against -- the rest of the systems.
Uprighting makes sure that the capsule maintains a correct attitude in water, post splashdown. It is important to get the hatch above water and the astronaut in a correct position. It might take hours for the recovery crew to find the capsule and you need to be in a safe position, even for a solo emergency egress at sea.
To do this we created a 1/3 scaled model of the capsule before Xmas, and Tuesday I introduced the highly advanced and fancy Buoyancy Test Facility (see image below, right) used to simulate capsule behavior at sea. Prior to this we did some basic buoyancy testing in the harbor, but it is very time consuming and you always need to get back to the facility for tools or materials.
New guy Rene Olsen has joined Copenhagen Suborbitals and is currently helping with these tests. He will also be a vital part of the capsule crew during the development and production since he is a skilled metal worker.
The current geometry of the capsule has led me to place the seat in an upright position in order to fit hatch, seat and avionics inside the pressure hull. However, this upright seating position requires the capsule to be angled in water unless you want to wait for recovery head-down or sideways. No, this is not a mission-critical issue, but why ignore the problem if we can fix it in time?
Getting a correct attitude in water is normally fixed by deploying uprighting bags only. But Rene also came up with the idea of flooding parts of the interior pressure hull, changing the center of mass, when landed. I like this idea and there is nothing particularly crazy or kinky about this. Just a couple of manually operated valves, letting in water and exhaling the air.
The flooding chamber will be placed behind the astronaut seat, opposite the hatch, forcing the capsule to tilt the heaving flooded volume below water and the hatch towards the sky.
After many considerations, sketches and tests we have come up with the following uprighting sequence for Tycho Deep Space II. The sequence is equally important if you want to go from landing to final attitude without getting stuck in weird positions.
Image explanation:
1: Splashdown with app 10 m/s
2: Capsule will place itself on the side with random 360 degree roll.
3: Deploying bag-1 locking random roll to only 180 degrees and forcing the flooding valves to face down
4: Flooding engaged using just passive opened valves or active pumps.
5: Deploying bags 2&3 lifting the capsule to its final correct attitude.
We talked about flying with vacuum in the flooding chamber for passive water suction, post splashdown. But personally I don’t like the idea of only having one change, if you end up sucking in air and not water. Also, the internal flooding chamber suddenly requires major construction to withstand the vacuum.
We will continue these tests (before the water freezes up) and keep searching for ideas hoping for some kind of simplification to emerge (might not happen). Soon, we will begin the construction of a full size boiler plate and leave for Space Center Lindoe to perform drop and buoyancy tests in full scale and full mass.
I will go battle capsule uprighting and imagine polar bears ... plenty of stuff to do here.
Ad Astra
Kristian von Bengtson
