Water based capsules

I was reading Jeff Foust's Bigelow article in this weeks Space Review, and near the end, Jeff tells how they are prefering to shy away from water landings. My suspcion is that this is based on the perception that when water landings are happening, you need an area the size of an ocean for safety margins - Im wondering if that is infact the case. For example, could a company plan water landings for a capsule in one of the Great Lakes, and still maintain a high level of safety? What about the Finger lakes? Or a smaller lake, like Houghton Lake, in Michigan? Or something even smaller?

To me water landing means parachute landing, and parachute landing means less accurate. How much less? It depends on how accurate reentry is. The shuttle can come in high on purpose and circle or extend downwind if needed to loose altitude, but a parachute equipped capsule can't really do that.

I think that there are also issues with the cost of recovery at sea, special vessels etc and possibly water ingress into the vehicle or damage to its heatshield. All of which is likely to increase the turn-around time for the vehicle.

Also there is always the chance that your craft will sink which makes it IMO more safe to choose a solid landing site.

I think that it is more likely that the vehicles servicing Bigelow stations will be lifting-body type designs for these reasons rather than a capsule.

With most of the current vertical launch vehicles, there will inherently be some level of specialized vehicles inherently. And damage can be had by run-way crafts as well. As for capsule crafts that land on land, well, don't tell me there aren't safety issues there. And we've seen that winged crafts can be expensive (although I don't think the shuttle is necassarily a good measure of the technology)

And the Dragon is being designed for a water landing.


He's said he's in discussion with Kistler, and SpaceX (or at least, I'd be surprized if they weren't), both of which use capsules, and the Dragon is water landing.

Finally, as I said someplace else, he didn't mention safety or cost when he specifically mentioned ocean landing - he mentioned the experince - I read that as more of a time kind of thing.

Has the recovery of water-landed capsules been ship-based up to now? Ships aren't as fast as airplanes - so what about basing the recovery on airplanes?

I am thinking about airplanes like White Knight 2 or t/Space's VLA that are enabled to land on water. They might be able to get to the capsule quickly in comparison to ships, recover them and return then. This also would avoid helicopters.

What about such ideas?



Dipl.-Volkswirt (bdvb) Augustin (POlitical Economist)

With a modern parafoil, landings cound be much more accurate - wasnt the X36 (or something - the space station escape craft) a lifting body with steerable parafoil for landing?

James

Gemini was originally designed to land on dry ground using a parafoil, but that capability was never used in operational flights. If it is really feasible, then why has nothing been done with it in all those years? Anyway, the parafoil only gives you control in the last 10 or 20 thousand feet to landing. The Shuttle can maneuver all the way through reentry to landing. It was a military requirement to have enough cross range maneuverability to abort to launch site after one orbit.

Is corrosion and erosion by water a problem at water-based capsules?

If yes then an article under www.wissenschaft.de might be of interest perhaps - in particular if contact to oil etc. is problematic as well.

The article says that americam scientists have developed a new material that behaves to oil like some known materials behave to water: hydrophobe.

Might that be of interest? In particular if reusability is intended?

The article refers to Gareth McKinley (Massachusetts Institute of Technology, Cambrige) et al.: PNAS ( www.pnas.org/ ), Online-Pre-Publication, DOI: 10.1073/pnas.0804872105



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)