Author Topic: Internal Combustion Engines (ICEs) on the Moon  (Read 135248 times)

Offline A_M_Swallow

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #300 on: 02/20/2014 06:51 pm »
Aluminium and magnesium are both available on the Moon.

Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #301 on: 02/20/2014 08:34 pm »
Aluminium and magnesium are both available on the Moon.

So is oxygen from the regolith.

For those individuals who are unhappy with an H2O2/nano aluminum particle mono-propellant ICE powered Lunar Lander drill unit there is the possibility of carrying oxygen as LOX as part of an accessible mixture in a mono-propellant tank and running everything with Al–air batteries.


"Aluminium–air batteries or Al–air batteries produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of problems with high anode cost and byproduct removal when using traditional electrolytes and this has restricted their use to mainly military applications. However, an electric vehicle with aluminium batteries has the potential for up to eight times the range of a lithium-ion battery with a significantly lower total weight."

And, "The design battery energy density is 1300 Wh/kg (present) or 2000 Wh/kg (projected)."

From: Aluminium–air battery   Wikipedia
At: http://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery


The above noted energy density would be lowered on the Moon by the required need to carry LOX.


"As part of our research, we made a small rocket engine fueled by the LOX-aluminum monopropellant."

From: WSPC Develops Rocket Propellant Using Liquid Oxygen and Metal Powders From Lunar Soil
At: http://www.wickmanspacecraft.com/lsp.html


Since the LOX is in the residual mixture in the mono-propellant rocket engine tank, simply warming some of the mono-propellant so the oxygen evaporates, and maybe then also filtering the released oxygen gas, would remove the nano aluminum and make the oxygen, and the nano particles of aluminum, available for the Al–air batteries.

However, if we had LOX and aluminum ISRU production at a nearby Lander/station located in a polar area of almost perpetual sunlight, we could possibly do a 'hop' flight and then refuel both the Al–air batteries and the Lander's LOX/nano aluminum mono-propellant tank. This would allow us to do 'spoke and hub' type of 'hop' flights to investigate many PSR craters, and other areas of interest, in order to make extended and efficient use of the robotic Lander/drill ground truth exploration unit.

Lunar ISRU of LOX and aluminum offers many options for maximizing reuse and reducing both the risks and costs of extensive ground truth research and mining.

And the use of aluminum/LOX as a mono-propellant enables both quick rocket propulsion transportation and efficient Al–air batteries for those folks who don't like the idea of using an ICE, and it retains the option of having a mono-propellant that is useful for being burned as a mono-fuel/oxidizer for those folks who appreciate the virtues of ICEs. Win-win, right?

We don't always have to use hydrolox, or an H2O2/nano aluminum particle mono-propellant.

Maybe 'saving' some of the polar mined Lunar water for farms, parks, swimming pools, waterfalls, and lakes in dome habitats covered with two meters of GCR shielding regolith would be useful if we want to eventually have large numbers of scientists, engineers, politicians, tourists, NEO defense/astronomer folks, and settlers showing up on the Moon.



Edited.
« Last Edit: 02/20/2014 10:22 pm by HappyMartian »
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Offline Warren Platts

Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #302 on: 02/22/2014 09:04 pm »
The problem with aluminum is the exhaust product is the same stuff they make sandpaper out of. A good way to sabotage an internal combustion engine is to throw sand in it. I am skeptical. Pure H2O2 could be useful though.
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #303 on: 02/23/2014 03:20 pm »
The problem with aluminum is the exhaust product is the same stuff they make sandpaper out of. A good way to sabotage an internal combustion engine is to throw sand in it. I am skeptical. Pure H2O2 could be useful though.



Maybe a burning the aluminum nano particles would be a problem, or maybe burning them would not be a problem.



"Ultrafine particles, or nanoparticles, are between 1 and 100 nanometers in size."

And, "A bulk material should have constant physical properties regardless of its size, but at the nano-scale size-dependent properties are often observed. Thus, the properties of materials change as their size approaches the nanoscale and as the percentage of atoms at the surface of a material becomes significant."

And, "Gold nanoparticles melt at much lower temperatures (~300 °C for 2.5 nm size) than the gold slabs (1064 °C);.[30] Absorption of solar radiation is much higher in materials composed of nanoparticles than it is in thin films of continuous sheets of material."

And, "Suspensions of nanoparticles are possible since the interaction of the particle surface with the solvent is strong enough to overcome density differences, which otherwise usually result in a material either sinking or floating in a liquid."

And, "Nanoscale cerium oxide is used in electronics, biomedical supplies, energy, and fuel additives."

And, "While nano-scale iron is being investigated for many uses, including “smart fluids” for uses such as optics polishing and as a better-absorbed iron nutrient supplement, one of its more prominent current uses is to remove contamination from groundwater."

From: Nanoparticle    Wikipedia
At: http://en.wikipedia.org/wiki/Nanoparticle#Properties



"Silicon-based polishing pads or a diamond solution can be used in the polishing process."

From: Polishing (metalworking)   Wikipedia
At: wikipedia.org/wiki/Polishing_(metalworking)



Perhaps a "polishing" or buffing effect instead of a sandpaper effect is what we would actually note after burning an H2O2/aluminum nano particle mono-propellant in an ICE. Perhaps there wouldn't even be a polishing or buffing effect.


Edited.
« Last Edit: 02/23/2014 03:44 pm by HappyMartian »
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #304 on: 02/23/2014 03:36 pm »
Note also:

"Aerojet N2O4/Alumizine rocket engine. 1960's USAF development effort for a Titan storable engine using a metallized fuel (for greater impulse density) and gelled propellants (to facilitate in-space starts after a period of coasting)."

And, "This was the first time a liquid rocket booster engine had ever been run on aluminized propellant. Many years later Aerojet operated small thrusters on metallized storable propellants and achieved satisfactory results."

From: LR87 Alumizine    Encyclopedia Astronautica
At: http://www.astronautix.com/engines/lr8izine.htm
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Offline A_M_Swallow

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #305 on: 02/23/2014 07:16 pm »
Rockets can use aluminium as a fuel, aluminium-oxide is pushed out the back by the jet steam.  It is internal combustion engines that will have problems.
« Last Edit: 02/24/2014 12:02 am by A_M_Swallow »

Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #306 on: 02/23/2014 11:04 pm »
Rockets can use aluminium as a fuel, aluminium-oxide is pushed out the back by the jet steam.  It id internal combustion engines that will have problems.

Please cite some sources for your conclusion ICEs run on a H2O2/nano aluminum particle mono-propellant" will have problems".

Some types of rockets, including SRBs and ALICE types, depend on the internal combustion of aluminum. ICE's have internal combustion. Adding a piston and using the smallest possible nano particles of aluminum mixed with H2O2 shouldn't be a show stopper.
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Offline A_M_Swallow

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #307 on: 02/24/2014 12:10 am »
Rockets can use aluminium as a fuel, aluminium-oxide is pushed out the back by the jet steam.  It id internal combustion engines that will have problems.

Please cite some sources for your conclusion ICEs run on a H2O2/nano aluminum particle mono-propellant" will have problems".

Some types of rockets, including SRBs and ALICE types, depend on the internal combustion of aluminum. ICE's have internal combustion. Adding a piston and using the smallest possible nano particles of aluminum mixed with H2O2 shouldn't be a show stopper.

That is an extreme form of coking.
http://www.exxonmobil.com%2Flubes%2Fexxonmobil%2Femal%2Ffiles%2FTTopic6_OilCoking1.pdf

Few ICE are designed to handle solid and liquid products.

Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #308 on: 02/24/2014 02:42 pm »
Rockets can use aluminium as a fuel, aluminium-oxide is pushed out the back by the jet steam.  It id internal combustion engines that will have problems.

Please cite some sources for your conclusion ICEs run on a H2O2/nano aluminum particle mono-propellant" will have problems".

Some types of rockets, including SRBs and ALICE types, depend on the internal combustion of aluminum. ICE's have internal combustion. Adding a piston and using the smallest possible nano particles of aluminum mixed with H2O2 shouldn't be a show stopper.

That is an extreme form of coking.
http://www.exxonmobil.com%2Flubes%2Fexxonmobil%2Femal%2Ffiles%2FTTopic6_OilCoking1.pdf

Few ICE are designed to handle solid and liquid products.


Some ICEs are designed to handle solid propellants and some are designed to handle liquid propellants and some can handle various combinations of solid and liquid propellants.

"A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described."

And, "Most steel engines have a thermodynamic limit of 37%. Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18%-20%.[9] Rocket engine efficiencies are much better, up to 70%, because they operate at very high temperatures and pressures and can have very high expansion ratios."

From: Internal combustion engine    Wikipedia
At: http://en.wikipedia.org/wiki/Internal_combustion_engine



"Tip jet refers to the jet nozzles located at the tip of some helicopter rotor blades. The objective is to spin the rotor, much like a Catherine wheel firework."

And, "Some are rocket tip jets that run off stored propellant such as hydrogen peroxide."

From: Tip jet    Wikipedia
At: http://en.wikipedia.org/wiki/Tipjets



"In this case, thrusters based on the PulCheR concept are likely to be used also in all the missions for which continuous thrust is required (lift-off, landing), thus extending its intrinsic advantages (smaller weight, good performance even with 'green' propellants, components reduction) to these missions." 

From: "Pulsed Chemical Rocket With Green High Performance Propellants" By Pasini A., Torre L., Pace G., Valentini D., d'Agostino L.,  49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, San Jose, California, USA, July 2013.
At: http://www.alta-space.com/index.php?page=green_publications
[/quote]



If we put four small "tip" Pulsed Chemical Rocket engines evenly spaced along the rim of a lightweight wheel and intermittently fed them a dense monofuel/oxidizer mixture of H2O2 and nano powdered aluminum at a relatively low pressure, we would have a lightweight, high efficiency, and powerful spinning ICE type of engine without any 'sandpaper' worries. This ICE's rocket exhaust, consisting of particles and H2 would travel directly into the Lunar environment.

Liquid rocket engines normally use their propellant or propellants for cooling and they usually don't need radiators.

And the really useful part in this spinning rocket ICE is that the aluminum nano particles don't just burn with the released oxygen from the H2O2, they also burn with the remaining steam in a manner similar to what occurs in an ALICE rocket.

Are there any showstoppers with this concept?


Edited.
« Last Edit: 02/24/2014 02:54 pm by HappyMartian »
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Offline Warren Platts

Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #309 on: 02/24/2014 03:53 pm »
That is interesting: a Catherine Wheel generator. Could take advantage of the higher theoretical thermodynamic efficiency of rocket engines (that are technically a type of ICE). No air resistance on the Moon. Depending on the radius, you could generate amazing amounts of torque....

I like it! Good call Hap! Better slap a patent on that one!

As for AL/H2O2 engines, I see your point about the polishing effect. And in any case the engine would only need to last a couple hundred hours at most. However, density isn't the prime consideration: specific energy--how many Joules can be packed into a kilogram--is the main determinant for loiter time of an ICESIP prospecting rover. Density does help in that your tankage requirements are less. I'd be curious to know the Al/H2O2 specific energy.
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #310 on: 02/25/2014 01:47 pm »
That is interesting: a Catherine Wheel generator. Could take advantage of the higher theoretical thermodynamic efficiency of rocket engines (that are technically a type of ICE). No air resistance on the Moon. Depending on the radius, you could generate amazing amounts of torque....

I like it! Good call Hap! Better slap a patent on that one!

As for AL/H2O2 engines, I see your point about the polishing effect. And in any case the engine would only need to last a couple hundred hours at most. However, density isn't the prime consideration: specific energy--how many Joules can be packed into a kilogram--is the main determinant for loiter time of an ICESIP prospecting rover. Density does help in that your tankage requirements are less. I'd be curious to know the Al/H2O2 specific energy.


Pulsed Chemical Rocket Power Wheels using green high performance propellants might also make sense for generating clean peak power here on Earth.

Why?

High temperatures involved with a rocket engine enable very high thermal power production efficiency.

No need for the costly, complex, heavy, and wear prone high pressure turbines involved with the fuel and oxidizer injection systems used with the liquid rocket engines on current launchers. 

Kerosene is widely available and it could be used with H2O2 or liquid oxygen.

H2O2 or Liquid oxygen produced in bulk might not be too expensive.

Aluminum for an H2O2, or liquid oxygen, aluminum nano particle mono-propellant is also widely available and relatively easy to scavenge from the exhaust and then be recycled.

Minimal environmental issues.

No worries about needing large amounts of water to cool the system.

No need for a radiator.

Compactness means no need for a large and expensive power plant system.

Minimization of system complexity means fewer critical failure points.

Ability to shut down a failed Pulsed Chemical Rocket engine on a wheel and still maintain electric power production.


Such rocket power wheel ICE power units on the Moon might be useful.
     
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #311 on: 02/25/2014 09:46 pm »
And burning aluminum or magnesium in a Pulsed Chemical Rocket Power Wheel with either H2O2 or H2O as the oxidizer produces H2 as an exhaust gas 'waste product' that also has some value for diverse purposes such as being used in fuel cells, as propellant for various types of rocket engines, and being burned in turbine and diesel engines.

And the 'waste' H2 generated could also be burned with H2O2 or LOX in a Pulsed Chemical Rocket Power Wheel.

TANSTAAFL, but sometimes you can get great pizzas at half price.   
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #312 on: 02/25/2014 11:04 pm »
Within the first two or three meters from the Lunar PSR surface, any deposits of H2O could contain H2O2 that is being produced by GCRs.

Some questions seem to pop out:

Are there pure aluminum and magnesium 'dust' particles mixed in with the PSR H20/H2O2 ice?"

What percentages of the Moon's surface aluminum and magnesium are relatively pure non oxidized metals?

Are there Lunar caves that contain mixtures of liquid H2O and H2O2?

What does the possible presence of H2O2 in liquid deposits of H2O2 mean in regards to the prospects of life in such dark wet Lunar environments? Or in dark wet environments on Ceres?

Can H2O2/H2O ice, aluminum, and magnesium be 'harvested' or mined in PSRs?

If the relatively pure Lunar aluminum and magnesium dust exists and can be 'harvested', could it be used as fuel and burned in a Pulsed Chemical Rocket Power Wheel ICE with a 'harvested' H2O2/H2O oxidizer? 
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #313 on: 02/28/2014 01:48 pm »
....
Thus, for H2/O2, specific energy is 13 MJ/kg. Assuming an ICE-hybrid system with 50% efficiency, that's still 6.5 MJ/kg. Throw in 10% for tankage, and you're still looking at 5.9 MJ/kg. Yes, I know that 50% is probably not going to be the systems thermal efficiency (i.e., the stored energy converted to rotational energy), but if you can make use of the "waste" heat for heating and cooling purposes, that's got to count for the overall efficiency of the system.
....


....
Very interesting paper, albeit a bit dated: states the specific energy of batteries for a Honda EV are 0.25 MJ/kg, whereas the Tesla Model S has got it up to a whopping 0.475 MJ/kg. ;D


That is interesting: a Catherine Wheel generator. Could take advantage of the higher theoretical thermodynamic efficiency of rocket engines (that are technically a type of ICE). No air resistance on the Moon. Depending on the radius, you could generate amazing amounts of torque....

I like it! Good call Hap! Better slap a patent on that one!

As for AL/H2O2 engines, I see your point about the polishing effect. And in any case the engine would only need to last a couple hundred hours at most. However, density isn't the prime consideration: specific energy--how many Joules can be packed into a kilogram--is the main determinant for loiter time of an ICESIP prospecting rover. Density does help in that your tankage requirements are less. I'd be curious to know the Al/H2O2 specific energy.


"In Alydro reaction the aluminium is melted at elevated temperatures and water is injected into the aluminium melt in the form of steam. The reaction splits the water molecules into hydrogen and oxygen which in turn oxidizes the aluminium forming aluminium oxide.

    2 Al + 3 H2O → Al2O3 + 3H2

The reaction is exothermic - each kg of aluminium produces 15.3 MJ of heat and 110 g of hydrogen carrying 15.7 MJ."

And, "The Alydro reaction consumes a kg of water for each kg of aluminium."

From: Alchemy Research    Wikipedia
At: http://en.wikipedia.org/wiki/Alchemy_Research


The above suggests over 7.6 MJ of heat energy per kilogram from burning a dense monofuel/oxidizer mixture of H2O and aluminum nano particles.

If 7.6 MJ of heat energy would come from burning H2O with aluminum nano particles, H2O2 being burned with aluminum nano particles should offer a good deal more than that because half the oxygen used from the H2O2 doesn't have to use energy to be stripped off a water molecule and the released H2 could also be burned at the above noted "H2/O2, specific energy is 13 MJ/kg" rate of energy production.

In other words, in burning aluminum nano particles with H2O2 we should be getting a high energy level per kg and doing it with a dense 1.88 g per cc mono-propellant that can be stored in very lightweight tanks and at room temperatures, and thus it seems superior to the numbers of the "Tesla Model S has got it up to a whopping 0.475 MJ/kg".   
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #314 on: 02/28/2014 09:33 pm »
See:

Aluminum: a safe, economical, high energy density material for energy storage, transport and splitting water to make hydrogen on demand   By Jerry M. Woodall Purdue University
At: http://nanohub.org/resources/6568/about

Supporting documents
At: http://nanohub.org/resources/6568/supportingdocs
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Offline HappyMartian

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #315 on: 03/01/2014 05:00 am »
That is interesting: a Catherine Wheel generator. Could take advantage of the higher theoretical thermodynamic efficiency of rocket engines (that are technically a type of ICE). No air resistance on the Moon. Depending on the radius, you could generate amazing amounts of torque....

I like it! Good call Hap! Better slap a patent on that one!

As for AL/H2O2 engines, I see your point about the polishing effect. And in any case the engine would only need to last a couple hundred hours at most. However, density isn't the prime consideration: specific energy--how many Joules can be packed into a kilogram--is the main determinant for loiter time of an ICESIP prospecting rover. Density does help in that your tankage requirements are less. I'd be curious to know the Al/H2O2 specific energy.


A lithium battery (non-rechargeable) has a 1.8 MJ/kg specific energy.

Data from: Energy density  Wikipedia
At: http://en.wikipedia.org/wiki/Energy_density


The catalytic decomposition of H2O2 releases 2.9 MJ/kg of energy at standard temperature and pressure conditions assuming the end product remains as liquid H2O. However if the water is turned into hot steam a lower heating value of hydrogen peroxide of 1.6 MJ/kg is used, and this number is almost equal to the above noted energy density of a non-rechargeable lithium battery.

Some of the above information is from the paper Warren Platts noted previously: Analysis and Design of a Novel Power Supply for Mobile Robots  By J. W. Raade, H. Kazerooni, and T. G. McGee  Department of Mechanical Engineering, University of California, Berkeley


Attached is a very interesting paper on a H2O2 ICE that is proposed as a nice "anaerobic" (and, I might add, a nice "heterotrophic") power supply for robots. There's been some talk the proposed RPM/RESOLVE lunar rover might be landed by a MoonEx lander running H2O2. Presumably they will land with a certain amount of margin; perhaps the residual propellant could be leveraged to power a small 25 cc ICE that would last longer within the PSR than the battery it's currently configured to use?


Since half the mass of the proposed aluminum nano particle/H2O2 mono-propellant is H2O2 instead of H2O, we can add a .6 MJ/kg to the previously noted 7.6 MJ of heat energy per kilogram from burning a dense monofuel/oxidizer mixture of H2O and aluminum nano particles.

About 8.2 MJ/kg, or more, is the heat energy per kilogram released by burning a dense 1.88 g per cc monofuel/oxidizer mixture of H2O2 and aluminum nano particles. This value compares favorably to the previously noted H2/O2 specific energy of 13 MJ/kg.

Why? Much smaller and lighter tanks. Minimal need for pressurization. Room temperature fuel/oxidizer that could also be used as rocket propellant for the Lander. Systemic simplicity. Compactness with a corresponding reduction in the mass needed to wrap the Lander in a thick insulation blanket.

The Lander, because of the built-in easy access to the propellant tank for the main rocket engines and the significant amount of residual Aluminum/H2O2 mono-propellant that could be available for the Pulsed Chemical Rocket Power Wheel or diesel ICE auxiliary power unit, should be the rover.

The inherent benefits of burning dense aluminum nano particles with dense H2O2 are retained even if they are stored separately and burned as bi-propellants, and in such a case we would gain the option of the easy and reliable control of very low thrust levels for the main engines, with low temperature exhaust gases, when landing and only using the the catalytic decomposition of the H2O2 to provide thrust.

The mobility needs of the Lander on the Lunar Permanently Shadowed Region, or PSR, surface could be best quickly accomplished by a series of mini-hop flights. As was noted previously by Warren Platts it is difficult for a rover to safely climb into or out of a PSR crater because of the steepness of their walls.

Using mini-hop flights to minimize the time spent in gaining access to various drilling and sampling sites that are spread out in an area of many square kilometers across a 12 kilometer diameter PSR crater could enhance the amount of data quickly gathered at those widely dispersed sites while also improving the chances of successfully completing the Lander's ground truth research mission in a tough and unforgiving ultra cold -397 degrees Fahrenheit environment. 

In other words, there is no need for wheels on the bottom of the Lander/drill unit. This simple design could also be eventually used with a crasher stage to enable much more propellant in the Lander's tank upon landing and thus offer the option of a hop flight to another polar PSR crater, or another area of interest, after the completion of several mini-hops near the original landing site.

This basic Lander design should also allow for eventual options of refueling and extended reuse if a propellant tanker lands nearby. Such a refueling operation would probably have the highest probability of success if it were conducted in a sunlit polar location.   

Keep the Lander/drill unit as simple, reusable, and sustainable as possible. Eventually, such a Lander type could make use of ISRU aluminum and H2O2.

Various types of ISRU propellant production on both the Moon and Mars would be useful because both spheres are very large and robots and humans will need quick mobility to fully and efficiently explore and tap the many resources of those vast and distant lands.

Note:

"Based on these data sources, scientists think that the most abundant chemical elements in the martian crust, besides silicon and oxygen, are iron, magnesium, aluminum, calcium, and potassium."

From: Composition of Mars   Wikipedia
At: http://en.wikipedia.org/wiki/Composition_of_Mars


"In 1994, world production of H2O2 was around 1.9 million tonnes and grew to 2.2 million in 2006,[14] most of which was at a concentration of 70% or less. In that year bulk 30% H2O2 sold for around US $0.54 per kg, equivalent to US $1.50 per kg (US $0.68 per lb) on a '100% basis'.[15][16]"

From: Hydrogen peroxide   Wikipedia
At: http://en.wikipedia.org/wiki/Hydrogen_peroxide

Edited.
« Last Edit: 03/02/2014 02:05 pm by HappyMartian »
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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #316 on: 03/04/2014 01:59 pm »
Burning dense H2O2 with dense aluminum also releases hydrogen and that hydrogen is very useful. Note that extra hydrogen can always be released by burning aluminum with H2O.
 

"Aluminum-fueled engines, used to propel orbital transfer vehicles (OTV's), offer benefits to the Space Transportation System (STS) if scrap aluminum can be scavenged at a reasonable cost. Aluminum scavenged from Space Shuttle external tanks could replace propellants hauled from Earth, thus allowing more payloads to be sent to their final destinations at the same Shuttle launch rate."

And, "The combustion of aluminum by oxygen is very energetic. Most of the energy is released aluminum oxide condenses from the gas phase. Aluminum oxide condensation in the rocket nozzle is a rapid process."

And, "An oxygen-hydrogen-aluminum engine with a mixture of 3:1:4 is expected to have a specific impulse of over 400 seconds and eventually it might achieve a specific  impulse of over 450 seconds (Cutler 1984)."

I added the bold.

From:Aluminum-fueled rockets for the space transportation system By Cutler, A. H   1992

At: http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1992NASSP.509B.109C&db_key=AST&page_ind=3&data_type=GIF&type=SCREEN_VIEW&classic=YES
 
Edited.
« Last Edit: 03/06/2014 12:54 pm by HappyMartian »
"The Moon is the most accessible destination for realizing commercial, exploration and scientific objectives beyond low Earth orbit." - LEAG

Offline Warren Platts

Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #317 on: 04/25/2014 08:55 pm »
Abstract to be submitted to PTMSS conference in Golden this year. If anyone else is thinking of submitting an abstract, this afternoon is the deadline....



ICESIP: Internal Combustion Engine Solar Independent Propulsion for Lunar Polar Exploration Rovers

Warren J. Platts
Groundhog Geoscience, LLC

W. Corey Dyess
American Performance Technologies Group, Inc.


Abstract: The very idea that internal combustion engines (ICEs) could play a role in outer space exploration seems absurd. After all, there is no air available for combustion in outer space, and the thermal efficiency of ICEs is usually considered to be low. Nevertheless, United Launch Alliance (ULA) has recently announced the development of a 6 cylinder, “flathead” ICE to be used in its Centaur 3rd Stage. Its function is 3-fold: (1) rotary power will drive an electrical generator; (2) “waste” heat will be used to pressurize the liquid hydrogen (LH2) and liquid oxygen tanks (LO2); (3) the exhaust will be vented out a rocket nozzle to provide settling of the LH2/LO2 tanks. The total efficiency of the system is expected to approach 100%, and the mass savings is expected to be on the order of 1 tonne.

Another potential application of ICEs in outer space could be providing power for lunar polar exploration rovers (LPERs) designed to operate in permanently shadowed regions (PSRs) of the Moon. The Lunar PSRs are potentially the most resource-rich areas of the Moon. Evidence from the LCROSS mission estimated potential gold and silver electrostatic placer ores with concentrations measured in parts per thousand—if these results pan out, they could possibly close an economic case for commercial mining. In addition, many so-called anomalous craters have been identified by the Chandrayaan and LRO orbiters: these craters have high radar circular polarization ratios (CPRs) on their inside, but low CPRs outside of their crater rims. This pattern has been interpreted as representing relatively pure ice sheets with a minimum 2 meter thickness; such craters would have much higher water contents than the few percent reported by LCROSS.

However, exploring these craters represents a huge engineering challenge. For example, Whipple Crater (notable because it borders a relatively large plateau of permanent illumination) has 30° slopes. Such a crater could not be explored by a Resource Prospector Mission (RPM) LPER because such rovers can only handle slopes of 15° to 20°. Thus, to explore Whipple Crater, the LPER would have to land within the interior of the crater. Assuming this could be done, any solar panels would be useless. Therefore, a LPER would be required to carry with it all energy required for the mission. A plutonium powered LPER would be highly desirable, but such rovers are expensive, with costs measured in billions of USD. Hence the desirability of an affordable LPER that would not require a nuclear power plant.

To explore this possibility, we undertook preliminary engineering calculations based on the clean-sheet SonicFlow™ 2-cycle engine being developed by American Performance Technology. The advantages of this unique design are several: (1) zero oil consumption; (2) three times the power of similarly sized 4-stroke engines; (3) high power density (~170 W/cm3); (4) best in class torque output; (5) internal noise attenuation to reduce vibration; (6) 40% thermal efficiency. Our model assumed an RPM sized rover with a 30 kg mass budget for an ICE-electrical hybrid power plant, and an average 200 W power. Assuming 20% margin, after accounting for tankage, 12% boiloff of LH2, ~21 kg of LH2/LO2 could potentially power the LPER for up 6 days. In contrast, a battery-only LPER equipped with Tesla Roadster batteries would last perhaps 18-19 hours. Even if equipped with batteries having 2 MJ/kg specific energy, the battery-only LPER would last ~2.6 days. The ICESIP LPER also compared well to fuel-cell powered rovers.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline TrevorMonty

Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #318 on: 09/05/2014 07:08 am »
Warren's idea of using the engine from ULA upper stage has a lot of merits. If Masten ever develop their centuar based Xeus lander it will most likely have one of these engines. Given the fuel reserves on this lander it would make sense to power a rover with a ICE, especially during a lunar night.

Offline Nilof

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Re: Internal Combustion Engines (ICEs) on the Moon
« Reply #319 on: 10/12/2014 11:36 am »
While we are discussing possible ways to power spacecraft on the moon, what about Sr-90 RTG's? The short half-life isn't an issue for the Moon because of the short trip times involved, and Sr-90 is plentiful as opposed to Pu-238 which isn't.
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

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