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#101 2017-12-09 20:11:52

SpaceNut
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From: New Hampshire
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Re: Running on Compressed Air?

Which is part of the issue when using it to make methane.
So once we start to compress the CO2 for that we can use any excess gasses that are exhaust from that process to be used for this type of rover. Since this can use heat to help with the power stroke we can also keep it closed loop in that the exhaust from the engine being reprocess via a radiator to recool the exhaust gasses. A compressor attached like the AC pump on your car can bring in more CO2 while we drive around to keep pressures up.

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#102 2017-12-10 08:32:52

elderflower
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Re: Running on Compressed Air?

CO2 can be collected using an amine adsorbent. This can then be pressurised and thermally stripped. The CO2 will then be at a higher pressure than you started with. That might need a few stages if it is at all possible at Mars pressures.  Perhaps Oldfart can advise on the possibility.
Otherwise industrial sized vacuum pumps would be employed as the low pressure stage. I know they can do this compression.

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#103 2017-12-10 15:15:58

SpaceNut
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Re: Running on Compressed Air?

We can also use cabin stripped co2 from the scubbers to aid in boosting the pressure we are keeping and give the means to use waste CO for the working gas as well. Since we will want more oxygen from insitu sources to replentish the cabin with.

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#104 2017-12-10 17:35:52

kbd512
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Re: Running on Compressed Air?

SpaceNut,

I like it.  It fits in with the air tools for Mars design methodology.  If a re-purposed gas powered vehicle can go that far on a single tank of CO2, imagine how far a lightweight purpose built motorcycle could go.  There are no electronics to boot.  Having simple and reliable propulsion like this motorcycle can make or break a surface exploration or construction mission.  NASA should get their hands on one of these things and test the durability and longevity of the design.  It looks like a winner to me.

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#105 2017-12-17 08:43:10

SpaceNut
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From: New Hampshire
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Re: Running on Compressed Air?

To covert the stream of gasseous energy to electrical we could design a permanent magnet alternator generator as a means to to the end. This link is about how to retrofit a car alternator but the equations and how to make one are all still pertenant to making it for any application.
http://digitalcommons.calpoly.edu/cgi/v … ntext=eesp

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#106 2018-03-18 20:21:00

kbd512
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Re: Running on Compressed Air?

SpaceNut,

In Queens, NY, the improper disposal of a Lithium-ion battery caused a 5 alarm fire that resulted in rail service suspensions in the surrounding area.  The takeaway from this should be that Li-ion batteries in their present form are not the technology of the future.  Solid polymer electrolytes or other forms of electrolytes and anode or cathode materials incapable of runaway "thermal events", as GM likes to call them, are badly needed.  The first time one of these uncontrolled reactions burns a grid Li-ion battery bank to the ground, then perhaps someone else will reach the same conclusion.  Although mobile applications, particularly vehicles, require extreme energy density, eventually what we end up with functions a lot like a conventional explosive in terms of the energy involved in the chemical reaction, which would be what fossil fuels are.

Perhaps some combination of battery and compressed gas power can service the mobile power requirement in a less dangerous manner.  The compressed gas could quickly accelerate a vehicle, whereupon a battery would provide sustainment power, given the substantially lower power requirement to simply stay in motion at a given velocity.

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#107 2018-03-18 21:37:11

SpaceNut
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Re: Running on Compressed Air?

Lithium fires not good as water helps them continue....

Make Your Own Miniature Electric Hub Motor

Hydraulic fuilds will also work to make a turning at low rpm....

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#108 2018-03-19 04:48:54

elderflower
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Registered: 2016-06-19
Posts: 1,087

Re: Running on Compressed Air?

Unscheduled discharge of large quantities of energy are going to cause trouble, regardless of the storage technology employed. Failing pressure vessels, disintegrating flywheels, shorted lead/acid batteries or capacitors or bursting dams spring to mind.

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#109 2018-03-19 20:15:04

SpaceNut
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Re: Running on Compressed Air?

That is where design testing is done to ensure that problems do not show over repeated uses.

high-pressure hydraulic fluid to capture and reuse energy

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#110 2018-03-20 21:49:56

kbd512
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Re: Running on Compressed Air?

SpaceNut,

The work that Danielle Fong has done is very interesting, with respect to this topic.

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#111 2018-03-21 20:30:47

SpaceNut
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Re: Running on Compressed Air?

Lotus prototyped active hydraulics in its F1 racecars.

http://opensourceecology.org/wiki/Hybri … lic_System

I am still researching alternative methods to build and materials that are light weight is another factor

Building an Ultra Light-Weight Car, Part 1

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#112 2018-03-23 03:24:06

elderflower
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Re: Running on Compressed Air?

Light weight cars will suffer greater deceleration when they run into massive objects (trucks, buildings and structures, boulders, heavy cars) than will current cars. Vehicle mass helps protect the occupants. Careful design may improve the situation but it can't be eliminated.
Not so much of an issue on Mars, for the early days, of course.

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#113 2018-11-11 23:04:26

SpaceNut
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Re: Running on Compressed Air?

You guessed it we are talking again about using CO2 to make a vehicle move.

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#114 2018-11-12 08:26:12

kbd512
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Re: Running on Compressed Air?

In this case, I think we want to protect the greater number of people living in the highly pressurized structures more than a lone rider on a light motorcycle.  People don't ride motorcycles because they're "the best" at providing protection for the rider.  They're light, small, cost effective to operate, and thus incredibly useful for younger and healthy riders who use good judgement about how to use them.  That last part is obviously critical to the continued health of the rider, but I would hope that ANY transportation in use on Mars is operated by thoughtful people who recognize that poor driving habits are bad for their health.

The vehicles in use on Earth are heavy out of necessity to their structural integrity after all the optional extras are crammed into the design.  Lighter vehicles are not necessarily less well protected than their heavier counterparts, since it's provably false that a SUV is better protected than a race car a third of its weight, but priority-based design generally leads to poor design when features far less important to crashworthiness are given a much higher funding priority.  The number of cup holders (SUV's) or electronic gadgets (EV's) is not indicative of a good vehicle design, for example.  It should therefore be recognized that actual occupant protection is relative to another design and closely related to design priority, where occupant protection is dictated by government tests instead of prudent design practices.

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#115 2019-03-28 20:55:02

SpaceNut
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#116 2019-03-28 23:59:03

kbd512
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Re: Running on Compressed Air?

What does this pedal-power option actually do for someone wearing a space suit?

Is this simply a thought experiment or some sort of worthwhile design feature?

The objective of any ground transportation on Mars should be getting from Point A to Point B and arriving without injury, with minimal complexity or reliance on systems that the harsh surface environment could degrade or destroy over time.  I think the best way to do that is with a CO2-powered vehicle design, of whatever type people believe will work well enough in the terrain they'll operate in, that doesn't rely upon any electronics to run.  It would be entirely mechanical, like the O2 Pursuit motorcycle, with a few useful optional electrical extras like running lights and IR cameras to identify the thermal signatures from other vehicles and people during dust storms.

We should standardize a portable stainless steel gas cylinder that can store H2O / O2 / N2 / H2 / LCO2 / Ar / He / etc, that any man / woman / teenage child can lug a short distance.  The gas cylinders can be filled at filling stations.  The cylinders will then be used to power bikes or quads in the vicinity of structures that provide adequate radiation protection from SPE's and CME's.  There's no use case, at least that I can think of, for an optionally pedal-powered vehicle that normally runs off of a stored gas or battery pack.  If your vehicle won't run, for whatever reason, then you need to be within a 15 minute power walk or bunny hop of a suitable radiation shelter.  The astronauts who used the lunar buggy had to remain within walking distance of their lunar module to contend with mechanical failure.  Many millions of miles from Earth, I have a very hard time believing that there wouldn't be some similar mandate attached to light vehicle use.

Why shouldn't we just come up with a well-thought-out design for a robust and easy to maintain CO2-powered light personal vehicle that's optimized to do what it needs to do and nothing more?

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#117 2019-03-29 16:02:43

SpaceNut
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Re: Running on Compressed Air?

Pedal power extranl use is only going to work in a MCP type suit and only with in a sealed environment for all other applications.

Since we will need to keep fit via exercise we will want to make use of that sweat to do something with its efforts. Which will be every day for a minimum of an hour and upward depending on other activities.

So what can we turn rotational motion into, that can be saved for later use?
What is the work that we can do with it?

I am in agreement with you post much like we have been doing in the other light mass rovers, recumbent topic plus the bike topics in that these are for quick short duration of use where cache bottles can be swapped if needed to extend there range of use.

I also believe in the reduced use of electrical and electronics would be benefitial so as to not become dependant on things that can break down and stop working that are not able to be repaired without a resupply from Earth.

The first few missions must focus on exploration of insitu and building for expansion not keeping things working.

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#118 2019-03-29 17:01:32

kbd512
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Re: Running on Compressed Air?

SpaceNut,

If it was me, I would connect stationary bikes to a bank of super capacitors.  The power would then be used to charge mobile devices, wash clothes, filter water, cook food, etc.  Why provide power for electronic toys or pumping when we have a crew who can do that?  This is modern technology meets old west living.  We provide enough power to ensure that we keep you alive, but additional power for activities that you're responsible for is provided by you, the crew member.  That's essentially what they're already doing in some of those Mars analog stations here on Earth.  Mass and power are at an incredible premium here.  We provide lots of technology to help you out, but you're going to get your hands dirty and do real work for the privilege of being sent to another planet at tax payer expense.  That's just life in a frontier environment.

Let's say we have a mobile habitat for surface exploration.  A large pressurized vehicle of some sort.  It would contain external nuclear batteries (RTG's, essentially, or something like it) and a bank of super caps.  Both are highly reliable technologies that can survive for decades in a harsh environment.  However, they're not exactly the most power dense systems known to man.  The RTG's alone would provide sufficient power for life support / electronics / communications.  The super caps would allow for short distance movements over a few tens of kilometers from a trickle charging received by the RTG's.  So...  If the crew wants more power to use their electronic toys and whatnot, then they provide that additional power from their daily exercise.  They're supposed to do that anyway as part of their health and wellness routine.  The exercise bikes are just used to incentivize healthy lifestyle habits and provide supplemental power for ad-hoc activities like washing clothes or filtering water or making hot water for hot showers.

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#120 2019-04-03 19:04:44

SpaceNut
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Re: Running on Compressed Air?

kbd512 wrote:

If all you're trying to do is move 10kg a single kilometer, then the easiest way to do that will be a small rover with a CO2 rotary engine.  That negates the need for any fantastic power-to-weight requirements.  We already have air powered motorcycles that can take riders 10's of kilometers over rough terrain on a single charge of a SCBA tank.  By way of comparison, this little vehicle would be rather small and light.  There's obviously terrain to navigate around on the ground, but that's still a heck of a lot easier than managing vertical takeoffs and landings and fantastically more efficient in terms of compressed CO2 expended per kilometer travelled in most cases.  If that's not enough of a challenge, then a lighter than CO2 vehicle with a CO2 powered motor could deliver the payload without navigating around terrain.

The dynamic pressure of the wind is so low that significant power would not be required for a balloon to cover that kind of distance.  The atmosphere of Mars is so thin that any type of winged aircraft would have to be more harrier than normal airplane.  Still doable?  Sure, but at what cost?  The entire idea is to deliver a small payload (emergency consumables / medical supplies / small replacement parts, perhaps) to someone who needs it.

Maybe you should try all three (ground rover, balloon, harrier) just to determine what the energy requirements for each happen to be and general utility / use cases.  I'm guessing that the balloon would be lowest, followed by a ground rover, and the harrier would likely consume the most energy.  There would be other trade-offs, though.  The balloon might only work at low to moderate speed and above ground, obviously.  The rover could enter caves or habitat modules, unlike the other two, but would have difficulty in rough terrain.  The harrier would probably be the fastest, out of necessity.  It might rocket up into the atmosphere, follow a ballistic trajectory to the target, drop the payload by parachute or soft land it with a last second hover maneuver to reduce vertical descent speeds, and then rocket back to base and touch down there.

Anyway, just some different ideas to play with.  Like I said, there are significant trade-offs associated with all 3 methods.

AS part of co-topic posting the ideas are very valid for this topic as well.

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#121 2019-04-03 21:34:24

SpaceNut
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Re: Running on Compressed Air?

http://hackedgadgets.com/2006/01/27/air … d-engines/

_air_motor.JPG

https://www.motherearthnews.com/diy/hom … az78jazgoe

diagram-build-a-homemade-air-compressor.gif

Air Compressor Terms

PSI—Each type of pneumatic tool requires its own rating for pounds per square inch (PSI) rating. For example, a spray gun usually needs 50 PSI, while a nailer often requires 90 PSI. Single-stage compressors can normally handle a combined 135 PSI, which will suffice for most garage-scale operations.

CFM—When choosing a compressor, the most crucial detail to note is its cubic feet per minute (CFM) rating, because that will determine the number of tools that you’ll be able to operate at one time, as well as the overall power capacity. Each tool that you connect to a compressor will have its own CFM needs, so it’s best to choose a unit with maximum CFM. This will ensure that your compressor properly runs the full array of tools in your arsenal. Tools that demand the highest CFM include grinders, sanders and other pieces of equipment that often run continuously. Tools that are only used intermittently, such as wrenches, tend to require lower CFM ratings.

Horsepower—An air compressor’s power measurement is known as its horsepower (HP). In a compressor, this would apply to the motor. Depending on the size or design of a compressor, it could boast anywhere from 1.5 to 500 HP. Compressors with high HP tend to be more flexible and generate higher CFM/HP.

SCFM—This stands for “Standard Cubic Feet per Minute,” which means CFM on the extremely rare machines that have nothing but standard conditions. Though this term rarely applies to air compressors anymore, it’s worth knowing about should you ever encounter this acronym.

I am not a machinist but its still a good document to design from.
http://www.john-tom.com/myplans/steampl … zelco2.pdf

https://www.brighthubengineering.com/hv … tors-work/

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#122 2019-04-07 11:04:10

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,597

Re: Running on Compressed Air?

Feed the output to the wheel drive and we have a vehicle.
https://bhushandarekar.com/wp-content/u … -13-56.pdf
Cold Gas Propulsion System for Hyperloop Pod

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#123 2019-08-08 16:57:06

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,597

Re: Running on Compressed Air?

Getting from mars thin atmosphere the air to allow for it to do work is very energy intensive relying on compressors and other processes to get the air so that we can use it.

https://www.popularmechanics.com/home/h … sors-work/

This application of a bike to pedal power a compressor but the way this is being used after storage its to supplement pedal torque when going up hill as an assist mode use..

https://bikeportland.org/2016/03/02/por … ike-176698

pneu-Cory-lead-ted-540x532.jpg

dual valve from rotation
pneu-bike-close-ted-540x384.jpg

pneubike-2-540x360.jpg

Little is working on building an exchangeable high-pressure tank and designing a pneumatic clutch that will allow for “regenerative braking abilities.” Initial versions of the system used only a 130 psi tank which limits the engines power. Little is currently working on a system with a 4500 psi tank. He also says the next version of the engine will have a lighter, carbon fiber air tank

one could also add in a solar panel to power a small compressor when the bike is idle recharging the storage tanks pressure for immediate use.

https://www.ijsr.net/archive/v4i1/SUB15258.pdf

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#124 2019-08-16 20:57:04

SpaceNut
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Re: Running on Compressed Air?

Ditch the Batteries: Off-Grid Compressed Air Energy Storage

Compressed Air Energy Storage (CAES) is usually regarded as a form of large-scale energy storage, comparable to a pumped hydropower plant. Such a CAES plant compresses air and stores it in an underground cavern, recovering the energy by expanding (or decompressing) the air through a turbine, which runs a generator.

Unfortunately, large-scale CAES plants are very energy inefficient. Compressing and decompressing air introduces energy losses, resulting in an electric-to-electric efficiency of only 40-52%, compared to 70-85% for pumped hydropower plants, and 70-90% for chemical batteries.

A simulation for a stand-alone CAES aimed at unpowered rural areas, and which is connected to a solar PV system and used for lighting only, operates at a relatively low air pressure of 8 bar and obtains a round-trip efficiency of 60% -- comparable to the efficiency of lead-acid batteries. [7]

However, to store 360 Wh of potential electrical energy, the system requires a storage reservoir of 18 m3, the size of a small room measuring 3x3x2 metres.

In another study, it was calculated that it would take a 65 m3 air storage tank to store 3 kWh of energy. This corresponds to a 13 metre long pressure vessel with a diameter of 2.5 metres, shown below.

Furthermore, average household electricity use per day in industrialised countries is much higher still. For example, in the UK it’s slightly below 13 kWh per day, in the US and Canada it’s more than 30 kWh. In the latter case, ten such air pressure tanks would be required to store one day of electricity use.

Small-scale CAES systems with high pressures give the opposite results. For example, a configuration modelled for a typical household electrical use in Europe (6,400 kWh per year) operates at a pressure of 200 bar (almost 4 times higher than the pressure in large-scale CAES plants) and achieves a storage volume of only 0.55 m3, which is comparable to batteries. However, the electric-to-electric efficiency of this set-up is only 11-17%, depending on the size of the solar PV system.

They found that 57 interconnected cylinders of 10 litre each, operating at 5 bar, could fulfill the job of four 24V batteries for 20 consecutive hours, all while having a surprisingly small footprint of just 0.6 m3.

Interestingly, the storage capacity is 410 Wh, which is comparable to the 360 Wh rural system noted earlier, which requires an 18 m3 storage vessel – that’s thirty times larger than the modular storage system.

The electric-to-electric efficiency for the 3-cylinder set-up reached a peak of 85% at 3 bar pressure, while the estimated efficiency for the 57-cylinder set-up is 75%. These are values comparable to lithium-ion batteries, but adding more storage vessels or operating at higher pressures introduces larger losses due to compression, heat, friction and fittings.

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