Reusable TPS in the Ocean?

(Henry Spencer) wrote in message ...
...
seawater, steel is better, aluminum is fine. Transpiration-cooling
systems would have to worry about clogging of orifices by waterborne
debris, and if they used a porous skin, about it taking up water.

If a reentry vehicle injects steam through a relatively large orifice
in the center of the heat shield, will it form a protective sheath and
have most of the effect of transpiration cooling without requiring
lots of little pores? The water would presumably be circulated through
the heat shield before being injected through the middle so this is a
combination of the two active cooling methods.

Oren

BllFs6 wrote:

Hi all..

Here is an idea for water landings...

Say the USA would really like to land near the USAs coast in the Atlantic,
Pacific, or Gulf of Mexico.....but landing in that salty water just doesnt
appeal to the engineers...

You make giant version of one of those inflatable kiddy pools...you know the
ones with the inflated rims that define and support the structure itself?...

Put it in the ocean and fill it full of nice, clean fresh water.....of course
you would like the rim to be high enough to keep out reasonable hieght
waves...and if you wanna really be anal about keeping out small amounts salt
water and salt spray cover the whole thing with an ulta thin plastic (like the
kind they make high altitude research ballons with) dome inflated to a few
psi....

Given active guidance upon decent I would think something on the order of
hundred feet across would be plenty....

And if things go bad you still have a whole ocean to land in without
catastrophe...probably just an extended refurb and inspection cycle....

Take care

Blll


I would think the Great Lakes and Lake Okeechobee (or artificial
lakes created near launch sites) would be adequate, much of the time....


--

You know what to remove, to reply....

In article ,
Oren Tirosh wrote:
...Transpiration-cooling
systems would have to worry about clogging of orifices by waterborne
debris, and if they used a porous skin, about it taking up water.

If a reentry vehicle injects steam through a relatively large orifice
in the center of the heat shield, will it form a protective sheath and
have most of the effect of transpiration cooling without requiring
lots of little pores?

In principle, yes. You might need multiple orifices, but there is some
evidence that they can at least be fairly far apart. The details are
poorly studied. In particular, the failure modes of such systems have not
been looked at very hard. This is the sort of thing NASA *ought* to be
spending research money on, and building flying demonstrators for.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Oren Tirosh) wrote in message . com...
(Henry Spencer) wrote in message ...
..
seawater, steel is better, aluminum is fine. Transpiration-cooling
systems would have to worry about clogging of orifices by waterborne
debris, and if they used a porous skin, about it taking up water.

If a reentry vehicle injects steam through a relatively large orifice
in the center of the heat shield, will it form a protective sheath and
have most of the effect of transpiration cooling without requiring
lots of little pores? The water would presumably be circulated through
the heat shield before being injected through the middle so this is a
combination of the two active cooling methods.

I remember a design, I think it was SASSTO or some other of Bono's work,
which used the engine exaust plume as a heat shield. How practical such
a thing would be however, I don't know.

wrote in message ...
Can someone think off the top of their head of suitable materials for
use as reentry shielding/ external shell material that are compatible
with either a fresh water or salt water environment after reentry?

You may also want to check into Titanium and its alloys. It's widely
used in sal****er industrial processes and the material of choice for
submergence.

The obvious problems of corrosion and sealing aside, how many TPS
materials can stand up to the shock of being immersed into the sea or a lake?


Re corrosion An excerpt from a Titanium spec sheet states the
following,

"Titanium is fully resistant to natural seawater regardless of
chemistry variations and pollution effects. Corrosion rates of well
below 0.01mpy have been measured in extended programs (exceeding 20
years) in subsea, splash, and tidal zones. The excellent corrosion
performance is attributable to a very thin, tenacious and highly
protective surface oxide film. If scratched or damaged, this surface
oxide will immediately reheal and restore itself in the presence of
air or seawater."

Note also that the worlds deep submergence submarines, namely the
Japanese Shinkai 6500 and the Russian/Finnish Mir1 and Mir2 utilise
titanium hulls.

If a suitable material might exist, how will it affect overall design of
a TSTO/SSTO?


I just keep thinking of some SSTO that lands and takes off in water,
bypassing the need for landing gear completely, as well as some safety
issues that get resolved by launching over water. Does this seem like a
crackpot idea or is there some merit to this?


That's my thinking as well for my concept so I hope it's not too
crackpot. Plus sea launching/recovery has the advantage of saving
millions in insurance costs and given the right circumstances can make
development of engines a simpler proposition, namely the use of
offshore facilities.


Junkboy

(SpaceSavant) wrote in message . com...
wrote in message ...
Can someone think off the top of their head of suitable materials for
use as reentry shielding/ external shell material that are compatible
with either a fresh water or salt water environment after reentry?

You may also want to check into Titanium and its alloys. It's widely
used in sal****er industrial processes and the material of choice for
submergence.

It does have excellent corrosion resistance, but titanium and its
alloys are only fit for "warm" applications, rarely being able to
handle the temperatures found in leading edge/belly re-entry
environments (or gas turbines).

For actively cooled TPS (transpirational cooling, for example),
titanium has an abysmal thermal conductivity (11-12 W/m*K vs 247 for
aluminum and 400 for copper) that'll make it hard to carry away heat.

Mike Miller, Materials Engineer

Henry Spencer wrote:

The most promising reentry protection approach for either of these is
active cooling, either transpiration or circulation, with heat-sink as a
runner-up. (Ablators are fine too, but I assume you want reusability.)
Heat sinks would be copper, beryllium, or beryllium-based composites.
Active cooling would quite likely be either copper or aluminum, with a
small possibility of steel. Copper and beryllium don't get along with
seawater, steel is better, aluminum is fine. Transpiration-cooling
systems would have to worry about clogging of orifices by waterborne
debris, and if they used a porous skin, about it taking up water.

Delft University in the Netherlands has a test vehicle that uses an
internal water cooling system, see
http://dutlsisa.lr.tudelft.nl/dart/introduction.html. As far as I
known, this design has been flown, but landed on land.

In article ,
Kees van Reeuwijk wrote:
Delft University in the Netherlands has a test vehicle that uses an
internal water cooling system, see
http://dutlsisa.lr.tudelft.nl/dart/introduction.html. As far as I
known, this design has been flown, but landed on land.

By the looks of the web site, it hasn't flown yet, but it's hard to be
sure...
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

(Henry Spencer) wrote in message ...
In article ,
Kees van Reeuwijk wrote:
Delft University in the Netherlands has a test vehicle that uses an
internal water cooling system, see
http://dutlsisa.lr.tudelft.nl/dart/introduction.html. As far as I
known, this design has been flown, but landed on land.

By the looks of the web site, it hasn't flown yet, but it's hard to be
sure...

The guys who made the X-33 tile system seemingly worked on active cooling
at a certain point. See:
http://www.aerostructures.goodrich.com/html/rd_tps.asp

Henry Spencer wrote:

In article ,
Kees van Reeuwijk wrote:
Delft University in the Netherlands has a test vehicle that uses an
internal water cooling system, see
http://dutlsisa.lr.tudelft.nl/dart/introduction.html. As far as I
known, this design has been flown, but landed on land.

By the looks of the web site, it hasn't flown yet, but it's hard to be
sure...

Sorry, you're right. They did have fairly concrete plans to launch it on
a Russian Volna, but even the article that I remembered doubts that this
will happen. See
http://www.delftoutlook.tudelft.nl/i...uk=Article&Art
ID=4242 for much better information than their own website.