Combustion engines ... - ... on Titan and Mars

karov · 2004-06-14 14:19:03

On Titan: The atmosphere contains several percents of carbohydrates - methan, ethan, etc. The combustion engine -- turbine, scram-jet, Otto or Diesel or Stirling one -- sucks in the atmosphere and combusts it`s fuel content with O2 stored in onboard tanks. The reverse way as on Earth. On Titan could be flyed helicopters, driven off-road cars, boats and ships on the seas/rivers/oceans/lakes...
===========================================
On Mars: In the CO2 atmosphere could be used chemical engines as well. Compress the CO2. Feed in alluminium or magnesium in form of thin wire, band... powdered or jellied. Ignite it with electric sparc or by pressure ... the more active metals take the O2 from the carbon in exotermic reaction. Use directly the gass expansion, or by steam-engine the heat to drive a ground vehicle. The atmosphere is too thin for real airplanes or copters with combustion engines to fly. But a ind of CO2/Al or Mg rocket hoppers could be usefull.

GCNRevenger · 2004-06-14 16:31:10

Mmmm I don't know if the Martian atmosphere is thick enough or metal combustion practical, especially with its solid reaction products. Liquid fueled jet and rocket engines are efficent with how finely mixed a sprayed liquid is, and that dealing with solid fuels is a pain. The only flying machines that will be practical most likly will LOX/Methane hoppers or a NTR-CO2 hopper and juuust maybe balloons filled with hydrogen.

Smaller ground vehicles will be powerd by LOX/Methane fuel cells almost certainly with its high energy density, or possibly operate heavy equipment directly from a nuclear power source by cable.

For long-range trips when colonization begins to heat up, trains will be the obvious choice unlike here on Earth, powerd by nuclear energy from the tracks plus solar auxillary, could reach speeds as high or greater than airliners do on Earth because the air is much thinner.

karov · 2004-06-18 11:21:05

I agree about the trains -- they could also be used on Moon or on other bodies, could be deployed vast rail-way nets, for havy weight mass surface transportation. Indeed the solar power coulds be the major source for train energy supply. Every rail-line could be paralleled with solar power panels -- between and out of the rails. If we have a net with total lenght of the rails, enough, than even on the Mars solar distance this grid vcould capture and supply all the necessary electricity, for the whole economy, not just the rail-way transport.

About the internal combustion engines with solid outcomes -- think about the vacuum cleaners. Or CO2+Al fuel cells.

karov · 2004-06-18 11:22:39

BTW, what`s your oppinion about the Titan`s up-side-down combustion engines and airplain tirbines, scramjeting, etc.

GCNRevenger · 2004-06-18 13:19:36

Having the traintracks double as electric transmission lines... saaay thats a prett good idea, wished I had thought of it.

I dunno if solar power will be all that useful on Mars though, its got quite a few things running against it...:
-Further from the Sun than Earth, 50% efficency cut off the top
-Must operate in extreme cold
-Must keep them clean, the dust is very fine and will stick since its so dry
-Dust storms would cause planetary blackouts for months
-Must store the power during the night somehow
-Must generate enough power to run the place in the day, and the night, and to make up for storage inefficency, all during the day
-Lack of hydrogen on Mars will make the creation of polymeric solar cells difficult

Well, you get the idea. Nuclear energy, being there is no ecosystem to harm and generates lots and lots of heat needed to survive, will obviously be ideal... I bet that bulldozers and other diggers will even be operated directly from a nuclear plant, supplied by a tether wire to the motors.

Hmmm jet engines on Titan sound interesting, and the atmosphere is thick enough, but its EXTREMELY cold... might be possbile though.

Solid reaction products + jet/rocket engines = baaad news on Mars too.

Josh Cryer · 2004-06-18 18:49:03

The necessary land area for solar panels on Mars would be roughly twice that of Earth, building them would be prohibitive unless a system of replicating robots could go out and use regolith to create these panels. Fortunately Mars' regolith compisition doesn't make this too difficult from a resource prespective, someone just needs to make magical tech that would do it.

karov · 2004-06-24 05:48:37

Having the traintracks double as electric transmission lines... saaay thats a prett good idea, wished I had thought of it.
I dunno if solar power will be all that useful on Mars though, its got quite a few things running against it...:
-Further from the Sun than Earth, 50% efficency cut off the top
-Must operate in extreme cold
-Must keep them clean, the dust is very fine and will stick since its so dry
-Dust storms would cause planetary blackouts for months
-Must store the power during the night somehow
-Must generate enough power to run the place in the day, and the night, and to make up for storage inefficency, all during the day
-Lack of hydrogen on Mars will make the creation of polymeric solar cells difficult
Well, you get the idea. Nuclear energy, being there is no ecosystem to harm and generates lots and lots of heat needed to survive, will obviously be ideal... I bet that bulldozers and other diggers will even be operated directly from a nuclear plant, supplied by a tether wire to the motors.
Hmmm jet engines on Titan sound interesting, and the atmosphere is thick enough, but its EXTREMELY cold... might be possbile though.
Solid reaction products + jet/rocket engines = baaad news on Mars too.

1.The traintracks not only electric transmission but also PRODUCTION LINES. Visualize them as wide (20 metters?) bands of photovoltaic pannels, as glass-covered massive highway.

2. About your points:
- On earth 10 000 sq.km. of silicon pannels within the existing efficiency are enough for the total nowaday consumption. On Mars - 20 000 sq.km. means earth level of overall power. 20 000 sq.km. on Mars means 1 000 000 km total lenght of the rail-way network. It is built incrementaly by mashines riding the trucks and powered by already biult panels. The trucks could be superconductors biult-in the pannels, so the trains or other vehicles to hover cantimeters over the glass with jet-plain speed. The same could be applied on Moon too -- physically integrate the ways and solarpower pannels networks. On minor bodies the railways could be used to communicate the corgoes with escape velocity or directly to link the roads/pannels with the beanstalk-elevator`s rails.
- The cold is not so extreme, BTW it helps to the superconductor version.
- The energy to power dust-cleaning machines or the vehicles themselves to have this function is more than enough. That will be no more different as the sand or snow cleaning of the roads or train trucks here on Earth.
- During the dust storms will use stored energy - in chemical way.
- The night is not a problem if the grid encompases the globe.
- We use silicon photovoltaics.

Nuclear power is inevitable. There should be uranium close to the martian surface cause it`s geological history resembling earths but quite faster frozen.

Titan jets -- the cold is not a problem for combustion. The compresion heats up the mixture.

GCNRevenger · 2004-06-24 08:23:27

I don't think that superconducting transmission lines or traintracks will be practical on that kin dof scale, they would still need a little cryogenic coolant... and hence if you are limited by the conductivity of conventional power lines, then stretching out a million kilometers of solar cells becomes 1,250,000-1,500,000km for transmission inefficency plus precludes day-side from powering night-side.

And "storing energy the chemical way" is a much, much bigger problem than it sounds, storing billions and billions and billions of watt hours for the night-time or dust-storm operation plus the inefficency of the chemical system, it gets out of hand quickly. That 1.25-1.50Mkm figure could roughly tripple.

Solar power on Mars is a losing proposition on a major scale for primary power.

Martian Republic · 2004-07-04 15:03:25

On Titan: The atmosphere contains several percents of carbohydrates - methan, ethan, etc. The combustion engine -- turbine, scram-jet, Otto or Diesel or Stirling one -- sucks in the atmosphere and combusts it`s fuel content with O2 stored in onboard tanks. The reverse way as on Earth. On Titan could be flyed helicopters, driven off-road cars, boats and ships on the seas/rivers/oceans/lakes...
===========================================
On Mars: In the CO2 atmosphere could be used chemical engines as well. Compress the CO2. Feed in alluminium or magnesium in form of thin wire, band... powdered or jellied. Ignite it with electric sparc or by pressure ... the more active metals take the O2 from the carbon in exotermic reaction. Use directly the gass expansion, or by steam-engine the heat to drive a ground vehicle. The atmosphere is too thin for real airplanes or copters with combustion engines to fly. But a ind of CO2/Al or Mg rocket hoppers could be usefull.

Actually, I think we should forget about gas powered cars and go all electric or electromagnetic super trains system and/or cars. I would even skip putting wheel on trains and/or cars. That way you would neither have to generate Grease and rubber tires for the wheels or have to generate pollution to create it. It would be a much cleaner process to use in those self-contained colonies. You will solve three or four problems if we choose to develop and build this techonogy and we could also use it down here to deal with polution down here too.

Larry,

RobS · 2004-07-07 12:29:35

If it rains methane on Titan, all one needs to "fill up" would be a nearby "river" or "lake"!

It occurs to me, also, that any sort of engine that ran on coal (which produces solid residue) could be adapted to silane (which produces SiO2 as a byproduct). I wonder whether a Martian "steam engine" could be made that burned silane in Martian air and transferred the heat to liquid carbon dioxide, which boiled and turned a turbine, cooled, condensed back to liquid carbon dioxide, then was sent back to the cooling jacket of the boiler to be heated again. Such a system would never "run dry" of working fluid.

-- RobS

Dook · 2004-08-05 22:30:22

I'm not seeing combustion engines as a very efficient way to travel on mars.

Take a 1 liter engine that produces 67 hp at 5,700 rpm. It has a four stroke cycle, intake (1 liter=61 cu in), compression (1 rpm), combustion, exhaust (2 rpm's).

So at full power-5,700 rpm, half of the revolutions require fuel. So 2,850 rpm multiplied by the 61 cu in engine size equals 173,850 cu in of fuel used per minute. A typical cylinder has 435 cu ft or 751,680 cu in of fuel. Eight of these would give you 34.5 minutes of engine time.

How are you going to carry enough fuel to get anywhere?

SpaceNut · 2004-08-06 10:49:12

Only problem with the train track conducting electricity from solar cells is the fact that Mars is made of Iron... which conducts electricity granted not as good as copper or gold or other metals. One would need to insulate the tracks from the planet to make it work.

karov · 2004-08-09 10:37:08

I don't think that superconducting transmission lines or traintracks will be practical on that kin dof scale, they would still need a little cryogenic coolant... and hence if you are limited by the conductivity of conventional power lines, then stretching out a million kilometers of solar cells becomes 1,250,000-1,500,000km for transmission inefficency plus precludes day-side from powering night-side.
And "storing energy the chemical way" is a much, much bigger problem than it sounds, storing billions and billions and billions of watt hours for the night-time or dust-storm operation plus the inefficency of the chemical system, it gets out of hand quickly. That 1.25-1.50Mkm figure could roughly tripple.
Solar power on Mars is a losing proposition on a major scale for primary power.

The case is not much different now on Earth. I don`t know what`s the total lenght of the earth`s power lines network - but I suppose that it is far greater than the several millions of km discussed. On Earth now the grid consists of thousands and thousands parts with lenght no more than several thousands of km each. There are ampifying the voltage stations along the electric highways.

What I mean is to combine: the roads ( respectivelly the rail-ways), the power lines and the solar power receivers. The volatiles pipeliners could also be burried under the 'glass highways'. The superconductivity was just an 'improvement' of the scheme, because is the power lines within the trucks than could serve also as giant power storage device. The electric grid would be like a enormous electrical condenser...
If ( and most probably) in the time when such production/supply/storage/transport-line would be constructable we have not the necessary room-temperature ( or +/- 20-30 K ) superconductors, than other ways of power storage and redistribution could be applicated. Such at least so effective as the nowaday terrestrial ones.

karov · 2004-08-09 11:04:08

On Titan: The atmosphere contains several percents of carbohydrates - methan, ethan, etc. The combustion engine -- turbine, scram-jet, Otto or Diesel or Stirling one -- sucks in the atmosphere and combusts it`s fuel content with O2 stored in onboard tanks. The reverse way as on Earth. On Titan could be flyed helicopters, driven off-road cars, boats and ships on the seas/rivers/oceans/lakes...
===========================================
On Mars: In the CO2 atmosphere could be used chemical engines as well. Compress the CO2. Feed in alluminium or magnesium in form of thin wire, band... powdered or jellied. Ignite it with electric sparc or by pressure ... the more active metals take the O2 from the carbon in exotermic reaction. Use directly the gass expansion, or by steam-engine the heat to drive a ground vehicle. The atmosphere is too thin for real airplanes or copters with combustion engines to fly. But a ind of CO2/Al or Mg rocket hoppers could be usefull.
Actually, I think we should forget about gas powered cars and go all electric or electromagnetic super trains system and/or cars. I would even skip putting wheel on trains and/or cars. That way you would neither have to generate Grease and rubber tires for the wheels or have to generate pollution to create it. It would be a much cleaner process to use in those self-contained colonies. You will solve three or four problems if we choose to develop and build this techonogy and we could also use it down here to deal with polution down here too.

Larry,

Within the self-contained habitats which in principle would be with little surface area and overall linear dimensions, I agree that maglev elevators, electric trains, individual transport 3D capsules, etc. no wheels -- will be far more effective and enclosed-environmental friendly, than the modern earth`s gas cars...

But outside in the non-terraformed Titan`s or Mars or else`s 'outback' we deffinitelly will need wheeled vehicles. The local atmospheric conditions allow local aerial gases to be combusted. On Titan almost non-changed car, helicopter, jet- or propeller plane, hovercraft... would suck the local air and burn its methan ~6% content with on-board oxigen. The experiments show that classical engines work quite well in such cold untill the fluid is in liquid/gaseous form. In "Terraforming Titan" thread you could see that in 100 K these plain machines achieve 80-90% efficiency... Deep heat sink!!! On Mars we have abundant CO2. The ambient pressure is far too low, but the modern compressors achieve easily pressures of hundreds of bars. The aluminium or other very chemically active reducent ( metal ) could be sprayed in nano-particle doses in the cilinders, turbines or Stirling engine`s torches...

Whatever exact reagents are chosen, you have to agree that the chemical-to-mechanical engines are quite well tested here. See the numerous rallyes and other automotive off-road competitions. The cars carry many tonnes on thousands of km.s long jorneys through absolutelly terrible lands.

For the future Zubrin`s Mars-Direct-type missions the crews will have waiting them on place stockpiles of fuel + oxidizer. I think that a couple of off-road motorbykes or "Hummers" will be much more usefull than some non-well tested electromobiles.

karov · 2004-08-09 11:10:28

If it rains methane on Titan, all one needs to "fill up" would be a nearby "river" or "lake"!
It occurs to me, also, that any sort of engine that ran on coal (which produces solid residue) could be adapted to silane (which produces SiO2 as a byproduct). I wonder whether a Martian "steam engine" could be made that burned silane in Martian air and transferred the heat to liquid carbon dioxide, which boiled and turned a turbine, cooled, condensed back to liquid carbon dioxide, then was sent back to the cooling jacket of the boiler to be heated again. Such a system would never "run dry" of working fluid.
-- RobS

That`s exactly what I mean. Off-road cars and bykes with the old plain combustion engines, adapted for local combination of oxidizing/reducent chemicals. To store aluminium, oxigen, some acid, or methane you need only tanks. To store electricity you need non-secure bateries... Of course one of the components would be artificially produced ( oxigen on Titan, aluminium on Mars -- depends on which exactly is more easily extractable from the local chemicals) , as on earth - the cars suck natural air, but the petrol should be pumped out and processed. On Titan you will have oxigen- instead of gas-stations, on Mars - aluminim fills...

karov · 2004-08-09 12:09:01

I'm not seeing combustion engines as a very efficient way to travel on mars.
Take a 1 liter engine that produces 67 hp at 5,700 rpm. It has a four stroke cycle, intake (1 liter=61 cu in), compression (1 rpm), combustion, exhaust (2 rpm's).
So at full power-5,700 rpm, half of the revolutions require fuel. So 2,850 rpm multiplied by the 61 cu in engine size equals 173,850 cu in of fuel used per minute. A typical cylinder has 435 cu ft or 751,680 cu in of fuel. Eight of these would give you 34.5 minutes of engine time.
How are you going to carry enough fuel to get anywhere?

Why?!

A typical EXISTING several tonnes carrying off-road vehicle with several-litters gasoline engine with , say a tonne of petrol-like fuel ( and respectingly ~1 tonne of O2) in the onboard tanks could travel thousands of kilometers on any terrain loaded with tens of tonnes cargo. These tens of tonnes: equipment, whole functional habitation modules for several member crew, folded greenhouse... Combine this with CO2 NTR Zubrin 'hoppers' for establishing bases on every roughly 1000-1500 km, and here you are your gass stations. If the refueling and consisting of various factories bases become permanent and growing -- than it occurs economical to build roads, power lines, etc. between them... rail-roads for multimegatonnes of cargo per annum if you decide it is necesarry ( here comes the road/power-line/solar-collector linear combination from the above posts of mine)...

Such transport network evolution occured everywhere down here, I think the same would be the situation innitially on Mars. BTW, the thin air on Mars promotes namely the ground vehicles transport, not the flying machines - ballons and planes, except the necessary nuclear 'hoppers' to outline the nodes-towns in the grid... On Titan its the opposite - the atmosphere is ~1.5 bars, ~3 times denser, 1/7th gees - there the helicopters, vertical take-off planes, dirigibles would be better than wheels, except for the extremelly slow shipping of extremelly heavy cargo. If on Titan indeed seas. lakes, rivers of Methan/ethan exist, than buoyant vehicles - enormous ships will traverse literal ocean of petrochemical fuel, rellying on onboard oxidizer reserves...

For such combustion engines` driven cars, bykes, lorries, trucks, copters, planes... you need refueling infrastructure - right, but as well on Earth in the beginig of the XXth century one could begin with very small infrastructure... A Mars-Direct-type of base having a fleet of off-road cars and motorcycles could 'control' several millions of km2 area.

karov · 2004-08-09 12:17:20

Only problem with the train track conducting electricity from solar cells is the fact that Mars is made of Iron... which conducts electricity granted not as good as copper or gold or other metals. One would need to insulate the tracks from the planet to make it work.

Insulation will be necesarry although I personally doubt that the natural conductivity of the Mars soil is so great to represent electricity leakage or short-cut problem. Mars soil has comperativelly big percent of iron oxides not pure iron. Regarding the direct maglev road-construction option and hence the need for superconductors, we could do the opposite: put the natural iron magnets as an armature in the glass-amorphic silicon road, include the superconductors with the criogenic equipment onboard the vehicles and power them by induction from the road...

The solution to integrate the electricity grid lines with the roads and railways and the bands of photovoltaic cells is just a way to arrange the hardware in spatial aspect.

Please, tell me exactly in what it differs to the way it is done the last hundred years here on earth?

Dook · 2004-08-11 20:15:06

Okay you say an engine size of several liters will go thousands of kilometers. I'd like to see the math that says you can do that.

Lets say you are using a 4 liter engine. That comes out to 244 cubic inches. At 2,500 rpm multiplied by the 244 we get 610,000 cubic inches of fuel/oxygen used per minute but this figure is deceiving because the engine is a four stroke cycle, meaning it uses fuel/oxygen every other rotation so we cut this number in half to 305,000 liters of fuel/oxygen used per minute.

A typical compressed gas cylinder holds 751, 680 cubic inches of gas so lets say you had 20 of these (at a weight of 148 lbs ea or 2,960 total), then you would have a fuel/oxygen supply of 15, 033, 600 cubic inches of gas. This number divided by the 305,000 gives you the total number of minutes that your engine will run which comes out to 49.2 minutes. Enough for you to go maybe 40 miles and then have to get out and walk home.

karov · 2004-08-13 03:44:21

Do the maths for your car assuming how much kilos of gasoline has it in its full tank and how much kilos of O2 it uses to burn the enture amount. Include the mass of the steel Dewar`s LOX tank containin enough O2 to burn all the kilos of gasoline, and I`m sure that such filled LOX tank will fit well in your trunk. Use the data for venting/evaporation rate of the existing LOX containers and you`ll see for how long after filling the oxidizer you have operational machine.

BTW, on Titan one can use simple non-pressurized bottle to store LOX. You know the ambient temperatures and atmosphere presures there. Compare with the O2 phase diagram.

Dook · 2004-08-13 15:38:52

Okay, a 50 gallon LOX tank would provide 43,100 gallons of oxygen gas which equals 11,948,624 cubic inches of oxygen gas.

A 1 liter (61 cubic inch) combustion engine at 2,500 rpm would use 76, 250 cubic inches of fuel/oxygen a minute. I don't remember the fuel/oxygen ratio but just guessing it's probably something like 1 part fuel to 10 parts oxygen. This means that at 2,500 rpm you need to supply 68,625 cubic inches of oxygen. Your 50 gallon supply of LOX would get you 174 minutes of operation. You could go maybe 100 miles total, 50 out, then turn around and come back.

Your LOX tank would vent oxygen unless you could keep it below -298 F

MarsDog · 2004-08-13 22:54:08

There is a weight penalty in carrying around http://www.airliquide.com/en/business/p … =78]Liquid O2 instead of the http://www.airliquide.com/en/business/p … 78]Methane.
-
One mole CH4 uses 2 moles Oxygen.
CH4 + 2(O2) = CO2+2(H2O)
16.043 g/mol 2*(31.9988 g/mol)
-
You need Oxygen 4 times the weight of CH4.
But Titan's gravity is only 1/7 and you might get similar to Earth mileage.

karov · 2004-08-14 10:03:24

There is a weight penalty in carrying around http://www.airliquide.com/en/business/p … =78]Liquid O2 instead of the http://www.airliquide.com/en/business/p … 78]Methane.
-
One mole CH4 uses 2 moles Oxygen.
CH4 + 2(O2) = CO2+2(H2O)
16.043 g/mol 2*(31.9988 g/mol)
-
You need Oxygen 4 times the weight of CH4.
But Titan's gravity is only 1/7 and you might get similar to Earth mileage.

Thank you, MarsDog. I know.

But the methane is already present there representing ~6% of the Titan`s ambient surface atmosphere pressure, according to the resent evaluations. The rest is alsmost entirelly N2. Perhubs the atmosphere hydrocarbon content is not too evenly distributed over the entire bulk of the atmosphere, due to 'hydrological' - equivalent cycle, but thus - in the worst case - one inly should collect the necesarry hydrocarbons from the surface and to provide the engines with 02 - electrolised from the crustal water ices. Both the methane and the oxigen will be liquid in the >100 K titan`s temperature, so they`ll need only to be bottled as water, alcohol or gasoline on Earth`s tanks, but not gryogenically stored.

The rest is as in the martian combustion-engine version. BTW, due to the low G - 1/7th earth`s and the higher presure and density of the atmosphere on Titan it would be far more easier the planetary transport vehicles to rather fly than run on wheels. Heavier than air flying vehicles will be ~10 times more promoted by the local conditions than on Earth.

On Titan we should expect the first manned expeditions to carry with them several helicopters with ten times smaller propelors in respect to the earth models + may be several big hydrogen dirigibles for heavy transport, both powered by, say gas-turbines combusting CH4/O2.

The best case is of course the turbines directly to suck in titanian atmosphere and to oxidize the CH4 content. Thus, say ~100 liters of LOX could be enough to ensure hours of operation.

karov · 2004-08-14 10:09:05

On Titan planes carrying only their LOX with methane-airbreathing jet engines instaled on could serve as shuttles to orbital stations on low titan orbit. To link the LTO-surface there we don`t need rockets. Such heavy-cargo cosmoplanes indeed can be designed to vertical take off and landing, thus making oblivious the building of air-fields.

SpaceNut · 2015-09-07 20:09:22

Repaired the topic for the shifting issue.

Tom Kalbfus · 2015-09-13 06:22:28

On Mars you need both the oxidizer and the fuel. Technically most rockets we use today are combustion engines. Mars' atmosphere lacks an oxidizer Zubrin talked about using combustion engines in rovers, the fact that the cars carry their own oxygen to burn methane with is somewhat compensated by Mars lower gravity.

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Re: Combustion engines ... - ... on Titan and Mars

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