Non-Airbreathing Aircraft Engine ?

[rust]

For my next setting, the "Martian" planet Samar, I will need a scout air-
craft and a transport aircraft with low technology non-airbreathing engi-
nes.

The aircraft will probably be designed along the lines of the Twin Otter
and the Caribou, comparatively small STOL aircraft able to land and to
take off "in the wilds", although I will try to give them a bit more range
than their real world counterparts have.

My problem are the engines, since the planet has a nitrogen - carbon di-
oxide atmosphere, so airbreathing engines do not work there, and a nu-
clear power plant or radiothermal generator would almost certainly be a
bit too heavy.

Any ideas for the engines or the power plant would be most welcome.

 

[Colin]

NASA had plans for a hydrazine-powered Mars Plane back in the 1970s:
http://beyondapollo.blogspot.com/2010/04/mars-airplane-1978.html

 

[rust]

NASA had plans for a hydrazine-powered Mars Plane back in the 1970s:
http://beyondapollo.blogspot.com/2010/04/mars-airplane-1978.html

Thank you very much, a very interesting idea.

 

[far-trader]

Just wondering, aside from the fuel burn issue, is your nitrogen - carbon dioxide atmosphere at standard pressure? There might be other issues if so...

Chemical corrosiveness leaps to mind for one but my chemistry knowledge is too largely forgotten to be sure.

Or if (as implied by the "Martian" reference) it is a thin atmosphere then you have the general reduced lift considerations for your aircraft. Nothing insurmountable, just a consideration, one you likely already figured on

 

[DFW]

For my next setting, the "Martian" planet Samar, I will need a scout air-
craft and a transport aircraft with low technology non-airbreathing engi-
nes.

Is the atmosphere going to be as thin as Mars?

 

[mattman]

Seems like a tall order for low tech. How about:

If there is abundant sunlight, a solar powered ornithopter complete with large flapping wings for the scout concept might work. Would be high endurance, low speed so it would need lots of time to cover ground.

For the transport, how about a steam-powered contraption that runs on the thermite reaction (aluminum dust and iron rust dust)? Probably short range but plenty of capacity.

These use no oxygen and could derive their energy from the environment around them (assuming some infrastructure). If you allow toxic chemicals, nitrogen tetroxide makes a spiffing oxidizer.

If you could bring yourself to go nuclear, they can be made light weight. A nuclear thermal engine can heat the surrounding air and direct it as thrust. Or power a steam system for rotors.

 

[rust]

Ah, yes, I should have mentioned some data ...

The planet has a surface gravity of 0.94 G and an atmospheric pressure
of 0.85 atm, so basically Earth-like conditions, except that hydrography
is 0 % (aquifers and polar ice caps, but no standing water) and the ter-
rain is mostly rock desert, sand desert and some mountain ranges and
shield volcanoes.

 

[rust]

If you could bring yourself to go nuclear, they can be made light weight. A nuclear thermal engine can heat the surrounding air and direct it as thrust. Or power a steam system for rotors.

Nuclear would be my preferred solution, especially since all ground ve-
hicles use radiothermal generators with a lifespan of 14 years to avoid
the fuel problem. Unfortunately all design systems I have describe all
nuclear power sources as too heavy for aircraft. Any idea for a light-
weight version would be most welcome.

 

[mattman]

Possibly "spin stabilized unobtanium shielding" that just needs to be painted on to the casing of a lightweight NT air turbine. Darned expensive stuff that has to be imported from offworld you know. Just as good as five feet of lead.

 

[SSWarlock]

I always like to share details of when "technology marches on" and makes Traveller come to life.

So, just for giggles, here's a link to NASA's comparative study of their Mars aircraft propulsion systems.

http://gltrs.grc.nasa.gov/reports/2003/CR-2003-212350.pdf

And here's some fun facts of the ARES aircraft itself.

http://marsairplane.larc.nasa.gov/platform.html

 

[atpollard]

As a thought, could the atmosphere contain a hydrocarbon - like methane?
Then your plane fuels up with LOX extracted from CO2 and off you go.

I think that Project Timberwind resulted in light Nuclear Reactiors.

 

[rust]

@ SS Warlock
Thank you very much for the links.

 

[rust]

Unfortunately no methane or other hydrocarbons in the atmosphere, or
at least only minimal traces of them.

I think that Project Timberwind resulted in light Nuclear Reactiors.

Thank you very much, I will look it up.

 

[atpollard]

Timberwind 45
Source: Encyclopedia Astronautica (http://www.astronautix.com/):'Timberwind 45'
DoE nuclear/lh2 rocket engine. 441.3 kN. Development ended 1992. Isp=1000s. Used on Timberwind Centaur launch vehicle.
Thrust (sl): 392.800 kN (88,305 lbf). Thrust (sl): 40,050 kgf. Engine: 1,500 kg (3,300 lb). Thrust to Weight Ratio: 30.

Status: Development ended 1992.
Diameter: 4.25 m (13.94 ft).
Thrust: 441.30 kN (99,208 lbf).
Specific impulse: 1,000 s.
Specific impulse sea level: 890 s.
Burn time: 449 s.


So 1500 kg engine with 40,050 kg thrust.

 

[rust]

So 1500 kg engine with 45,000 kg thrust.

Thank you very much indeed, this comes close to what I am looking for.

 

[DFW]

Here ya go rust. http://www.besslerwheel.com/wwwboard/messages/1149.html

Have fun!

 

[rust]

Here ya go rust. http://www.besslerwheel.com/wwwboard/messages/1149.html

Have fun!

Yep, thank you very much, this is perfect.

I have no idea whether the science is sound, but since the players will
also not know, this source is all I need. 8)

 

[DFW]

Here ya go rust. http://www.besslerwheel.com/wwwboard/messages/1149.html

Have fun!

Yep, thank you very much, this is perfect.

I have no idea whether the science is sound, but since the players will
also not know, this source is all I need. 8)

I don't know much about it but good stuff for Sci-Fi.

 

[Dave Chase]

What, no Stirling engines?




Dave Chase

 

[rust]

What, no Stirling engines?

Why not, with a nuclear power source like a radiothermal generator pro-
viding heat, a stirling engine could be used to drive a ground vehicle. As
for aircraft, it would probably not be a good method.