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Atomic ramjet for exploring Titan



 
 
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  #11  
Old March 18th 09, 01:42 PM posted to sci.space.policy
Frogwatch
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Posts: 147
Default Atomic ramjet for exploring Titan

On Mar 18, 7:32 am, "Greg D. Moore \(Strider\)"
wrote:
"Frogwatch" wrote in message

...

In the late 50s and early 60s, the USA had "Project Pluto" a nuclear
reactor powered ramjet whereby a reactor directly heated incoming air
to provide thrust. It could be capable of flying for months but
emitted a lot of radiation, maybe even a lethal dose to anything
nearby.
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies around
for months sending back data. At the end of its life, we could simply
allow it to crash OR we could use onboard solid rockets to accelerate
it to escape velocity from Titan and allow it to either go in orbit
about Saturn or to drop into Saturns atmosphere.
Such a flying machine might be just what we need to explore Venus
too. The dense atmosphere would allow for fairly low speed flight
there.


I'm honestly trying to figure out if this is the most absurd idea I've heard
in awhile, or absolutely brilliant.

I suspect a bit of both.

--
Greg Moore
Ask me about lily, an RPI based CMC.


I suppose you could use the reactor to heat air to drive a Sterling
cycle engine to turn props but this is mechanically more complicated
than the ramjet. Neutrons are emitted regardless of whether if it is
a ramjet or prop driven. Pluto was tested on the ground in NV. Wings
are well known so how much testing do we need?
  #12  
Old March 18th 09, 09:13 PM posted to sci.space.policy
[email protected]
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Default Atomic ramjet for exploring Titan

This is a good idea - made even better by the fact that there is no
oxygen to ruin things in the Titan atmosphere. Also the temperatures
need not be as high as for Earth. That's because ambient temps are
higher and gravity is lower.

A counter-rotating prop - powered by an electric motor - supplied with
energy from a compact high temp nuclear reactor - using
thermophotovoltaic stack around a nuclear filament - would be
ideal. We'd get about 10 kW/kg of weight - so the nuclear lightbulb
generator would mass about 3.7 kg - and be capable of lifting 300 kg
or more - more weight than the Cypher in Titan's reduced atmosphere -
and denser atmosphere.

A mirv like bus would aerobrake into Titan orbit, and release an
orbiting communications satellite into a stable orbit. The bus would
then descend and aerobrake to a landing on Titan's surface, but not
before releasing two or three Cypher like nuclear aerial vehicles.
The aerosheild would descend to the surface and have the ability to
transmit data and images back to the hovering vehicles, which would
then communicate to the orbiting comsat which sends data back to Earth
and recieves commands from Earth.

Something like this;

http://en.wikipedia.org/wiki/Sikorsky_Cypher

General characteristics

* Crew: None
* Capacity: 50 lb (23 kg)
* Length: 6 ft 2 in (1.88 m)
* Rotor diameter: 4 ft 0 in (1.22 m)
* Height: 2 ft 0 in (0.61 m)
* Disc area: 25.2 ft² (2.4 m²)
* Loaded weight: 264 lb (120 kg)
* Max takeoff weight: 300-340 lb (136-154 kg)
* Powerplant: 1× UAV Engines AR801 Wankel rotary engine, 50 hp (37
kW)

Performance

* Maximum speed: 52 knots (60 mph, 97 km/h)
* Range: 49-67 nm (56-77 mi, 90-125 km) depending on model
* Service ceiling: 8,000 ft (2,440 m)
* Disc loading: 9.9 lb/ft² (47.5 kg/m²)
* Power/mass: 0.2 hp/lb (0.32 kW/kg)
* Endurance: 2-3 hours

Avionics

* EO, FLIR, small radars, chemical detectors and magnetometers,
radio relay, and non-lethal payloads

  #13  
Old March 18th 09, 09:16 PM posted to sci.space.policy
[email protected]
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Default Atomic ramjet for exploring Titan

Nuclear airplane and nuclear lightbulb (not gaseous core rocket, but a
nuclear core that operates in a vacuum like a lightbulb filament and
radiates away most of its energy in the form in light) can be combined
to create an electric airplane that is powered by a TPV stack around a
small nuclear filament. This power plant has a wide range of uses -
from ion rockets to driving fans for airplanes and helicopters on
Mars, Titan, gas giants and so forth.

  #14  
Old March 18th 09, 09:23 PM posted to sci.space.policy
[email protected]
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Default Atomic ramjet for exploring Titan

TPVs are capable of 30% and more -

http://www.appliancedesign.com/CDA/A...00f932a8c0____

Electric light bulb filaments are capable of 3,000K and more -
http://hypertextbook.com/facts/1999/AlexanderEng.shtml

Though not in the open literature, small self-heated nuclear filaments
that self regulate (neutron cross section changes with temperature)
and operate stably in a background - provide a means to create a tiny
very powerful very long lived very robust power plant - that with a
TPV stack turn into a very compact safe reliable etc., electrical
energy source with very high power to weight - to drive all manner of
electric engines.

http://en.wikipedia.org/wiki/File:Bo...trator_AB1.JPG

  #15  
Old March 18th 09, 09:26 PM posted to sci.space.policy
[email protected]
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Posts: 1,465
Default Atomic ramjet for exploring Titan

The radiation need not spew anywhere - much of that was mis-reported
to make the ideas contained in the project seem outlandish. That was
done to prevent folks from working on them when we decided not to.

Fact is, we can build nuclear filaments as easily as we now build
light bulb filaments and surround them with TPV stacks of tremendous
efficiency to create very powerful very lightweight very clean power
sources - to drive all manner of electric engines. The Navy is
already working on a miniature nuclear sub and adapting this
technology provides a means to power lots of different vehicles and
appliances without any central power or fuel supply - for periods of
decades or more.

  #16  
Old March 18th 09, 11:05 PM posted to sci.space.policy
hcobb
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Default Atomic ramjet for exploring Titan

On Mar 17, 2:14 pm, Frogwatch wrote:
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies around
for months sending back data.


Just use a hydrogen balloon and you can stop and sample the surface.

You may want a nuclear reactor along also, to crack the hydrogen from
the atmosphere and provide craft power under all that haze.

-HJC
  #17  
Old March 18th 09, 11:07 PM posted to sci.space.policy
Pat Flannery
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Default Atomic ramjet for exploring Titan



Frogwatch wrote:
So, say we want to explore Titan completely from the air, we drop a
Pluto style ramjet into the atmosphere of Titan where it flies around
for months sending back data. At the end of its life, we could simply
allow it to crash OR we could use onboard solid rockets to accelerate
it to escape velocity from Titan and allow it to either go in orbit
about Saturn or to drop into Saturns atmosphere.


You might run into a really unexpected problem with that...Titan has a
very thick atmosphere, which could generate a lot of drag and heating on
the ramjet if it tried to fly at multi-Mach velocities like SLAM/Pluto*
was supposed to.
On the other hand, Titan's high atmospheric density combined with its
low gravity might make a propeller driven aircraft using a electric
motor powered by a small reactor or RTG feasible. This could cruise
along at quite a low velocity giving its sensors time to examine the
surface under it. One other problem is that the atmosphere of Titan has
a lot of turbulence in it according to the latest findings, so anything
you fly around in it has to be pretty tough.

Such a flying machine might be just what we need to explore Venus
too. The dense atmosphere would allow for fairly low speed flight
there.


Can't get it too slow if you want a ramjet (nuclear or otherwise) to
work...start-up speed for one is around 300 mph, at least in Earth's
atmosphere.

* _S_upersonic _L_ow _A_ltitude _M_issile...SLAM was the missile proper,
Pluto was the code name for the project to develop it, TORY was the code
name for the reactor-driven ramjet engine:
http://www.designation-systems.net/dusrm/app4/slam.html

Pat
  #18  
Old March 18th 09, 11:23 PM posted to sci.space.policy
Pat Flannery
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Posts: 18,465
Default Atomic ramjet for exploring Titan



Martha Adams wrote:


I think that's an interesting idea and it sounds doable. However, is
a ramjet really the best vehicle for this? A slower, propellor driven
craft could feature less active and stressed machinery, better for a
long life. And in either case, you'd want to do (in my view) at least
three proof-of-principle machines to test out the engineering: where
would you fly those machines?


We must understand how it flies in a cold dense methane atmosphe
First we rent a wind tunnel.
Then we put huge air conditioner at the front end of the wind tunnel.
Then we put 1,000 cows inside of a building that's air output is fed
into the air conditioner's intake.
Then we feed the cows nothing but beans and wait for the Wonders Of
Biology to begin.
For testing the Venus one, we simply reverse the air conditioner's heat
exchanger, attach sparklers to the rear end of all the cows, and feed
them beans along with rotten eggs - creating a superheated carbon
dioxide and monoxide rich atmosphere including exotic sulfur compounds. ;-)

Pat
  #19  
Old March 18th 09, 11:38 PM posted to sci.space.policy
Pat Flannery
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Posts: 18,465
Default Atomic ramjet for exploring Titan



Matt wrote:
Project Pluto was dropped because, among other reasons, there was no
safe way to test the thing under actual flight conditions. Likewise,
you could not test this engine until it was well out in space, and
what if it didn't work?


They did test the TORY engine out on the ground, and it did work as
advertised.
There's a Discovery Wings episode about it, and when they show the view
up the back end of the reactor as it goes critical and starts glowing
yellow-white hot as the air is blown through it (the air was stored
under high pressure in a huge array of high-strentgh steel pipes) it's
really something to see. They photographed it by having the camera on
the far side of a radiation-proof wall and aimed at a mirror that faced
the exit nozzle of the engine.
If they did get around to tests, plans were to have the missile fly
around out over the ocean, and either crash into the ocean at the end of
the mission, or dive into a lake some ways inland for retrival.


You've shot your program budget. In any
event, emitting radiation into the atmosphere of another body is
bound to raise a storm of protest.


Titanic Titanian Methane Muskies are bad enough...exposure to radiation
could create Terrifiying Titanic Titanian Mutant Methane Muskies, and
that's the last thing our solar system needs.

Pat
  #20  
Old March 18th 09, 11:45 PM posted to sci.space.policy
Pat Flannery
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Posts: 18,465
Default Atomic ramjet for exploring Titan



Frogwatch wrote:
I suppose you could use the reactor to heat air to drive a Sterling
cycle engine to turn props but this is mechanically more complicated
than the ramjet. Neutrons are emitted regardless of whether if it is
a ramjet or prop driven.


Use a RTG, and you can seal the isotopes in ceramic and just use their
heat to drive some sort of power generator.
With its high atmospheric density and low gravity, Titan is the place
where you could literally float safely down to the ground under a
umbrella like in a cartoon, so the wings need not be very big in
comparison to the weight they can carry.

Pat
 




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