Long before Grand Master Flash and Melle Mel sang about “survival,” NASA was singing the same song when developing manned space systems. The entire trip from launch to splashdown was one big survival game and it’s no difference from ours.
In this early development phase of Tycho Deep Space (TDS), one must keep in mind all subsystems to ensure correct allocated space and co-operation between them. The top part of TDS contains all parachutes but must also hold inflatable bags to ensure a correct flotation attitude of the capsule after splashdown. If failed to do so, it could pose a danger to the recovery and survival of the astronaut if hatch and personal are facing downward. In Apollo NASA terms, a correct orientated capsule is called “stable-1” or else “stable-2,” which you really want to avoid.
Apollo CM had three bags inflated using a small compressor making use of the surrounding atmosphere. Since Apollo CM had an off-center mass point, they knew it would never tumble to one side, thus only needed three bags.
But Peter Madsen has asked me to keep a perfect center aligned mass point for launch stability reasons. In this case I cannot predict to which side TDS will tumble, leaving me with no other options than using four inflatable bags.
They will be placed in the top cone of the capsule behind small aluminum doors which will be “jettisoned” from the capsule when our bags are inflated. The inflated bags must be attached to the capsule as closely as possible for maximum effect. Preliminary studies seem to suggest a maximum diameter of 700 mm in order for them not to conflict with each other.
Our system with four inflatable bags has three main functions (shown in order of importance):
- Providing positive buoyancy preventing capsule to sink
- Providing stable-1 condition
- Looking cool
In the last days I have been doing studies on the buoyancy of the capsule itself in various attitudes to learn more about its capabilities to tumble based on suggested water line and mass center. The studies are simply based on the 500 kg TSD mass and displaced water. It doesn’t not tell me directly how the capsule will tumble, but its does provide me with some hints based on my knowledge of the capsule mass distribution.
I will keep making these studies to animate possible tumbling events in my brain and do studies with models. Eventually I aim to dump Tycho Deep Space in the harbor of Copenhagen to see it actually work.
But dear Wired reader — maybe you want to help!?
One of the Copenhagen Suborbitals guys suggested that a model of the capsule could be added a game engine where you are able to push and tilt the capsule to see how it would actually behave (with or without inflatable bags). We may do this study ourselves but if you or someone you know would like to help us out and play with this, do not hesitate to download the study package (below) containing 3-D files of Tycho Deep Space in various formats and additional info to perform the study. You are also welcome to e-mail me (see header) if you want to get more info and files/formats for the study.
This study should be based on the following:
- The 3-D shape of the capsule TSD
- Capsule mass 500 kg
- Mass center 480 mm from capsule bottom and center aligned
- Creating four inflatable bags 700 mm diameters each with 1+ atm air density
- Correct water density for sea simulation
- User interaction such as pushing and tilting the capsule to validate behavior.
If you are able to simulate bags which are slowly inflated separately it would be an extra winning feature. If this can be presented either as animation or a stand-alone plug-in I would like to show it here on a wired blog post.
Download study pack here. (667 Kb, Zip)
That’s all for now, folks.
I will leave my apartment and head off to the space factory. Have a great day!
Ad Astra
Kristian von Bengtson
