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Which is why you'd need a cleared roadway, perhaps one with a shroud to keep out dust. At which point you've created something similar to Hyperloop, I know, but much rougher (basically shovelling the topsoil out of the way and a shroud over it) and designed for much slower (100-150 km.p.h?) speeds. Though you'd still be sucking in air from the front and blowing it under the craft.
Perhaps it would provide something similar to railways on Terra.
Use what is abundant and build to last
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I see you indicated a continuum between hovercraft and hyperloop.
Elon Musk thinks hyperloop could work without the tube on present day Mars.
I am going to add something else into the mix, not because it in itself is a practical solution but with the possibility that a unique device can be created for Mars that will not require a totally groomed trail.
Ground Effect Vehicle:
https://en.wikipedia.org/wiki/Ground_effect_vehicle
Although they may look and have related technical characteristics similar to seaplanes, ground effect vehicles are not aircraft, as they are unable to fly freely in the air. They are also dissimilar from hovercraft or hydrofoils. Ground effect vehicles constitute a separate category of transport.
I am hoping that a ground air cushion travel device can be arrived at that can take advantage of smooth groomed ground whenever possible, and that could "Portage" over rough ground by temporary flight when needed.
For power, I would think Methane & Oxygen combustion, and adding in Liquid CO2, and Liquid Hydrogen. But maybe a fan can be involved, I have not limited the combustion device to rockets. I would think that a high speed is preferred, since it will likely have humans as it's primary cargo, and mobile life support is not cheep.
You can read the article about advantages and disadvantages. Some of it would apply to Mars.
I am just throwing this into the mix, in hopes that someone might think about some type of vehicle unique to Mars that might borrow from Hovercraft, Ground Effect Vehicles, and Hyperloop.
I will also say that if a trail is groomed enough for such a vehicle, then it will be sensible to have refueling stations, where Oxygen, Liquid CO2, Liquid Methane, and Liquid Hydrogen will be available to refuel the craft along the way, and also such stations would serve as emergency life support if a craft is crippled in some way.
Last edited by Void (2017-01-07 10:45:16)
I am starting to ask seriously "Why do I do this?"
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A railroad might be easier to construct once you have steel and a rolling mill. Ties might be some form of concrete, like on earth, or steel perhaps.
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Perhaps, but Hyperloop is possibly the new coming rail system.
Before that however, just moving rocks out of the way and having a trail might make a specially crafted vehicle able to move rapidly across the Martian surface.
I am starting to ask seriously "Why do I do this?"
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This topic appears to have swerved a bit, over time.
I'd like to try to bring it back with this report of a research project:
https://www.engadget.com/2018/11/21/mit … aft-flies/
Apparently the aircraft has been developed to the point it can fly a few feet on Earth, in air.
I'd be interested to read any comments forum members might have on the suitability for this propulsion method on Mars.
(th)
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tahanson43206,
An ionic wind propulsion system produces approximately 50 times more thrust per unit of input power than any conventional aircraft propulsion method at Earth sea level. The ionization energy of CO2, in electron volts, is slightly lower than that of the N2 that the system reacts with here on Earth. The problem is that the atmospheric density at Mars sea level is just 1/166th that of Earth sea level. There's precious little reaction mass. That said, there's also that much less dynamic pressure that you have to push the vehicle through.
It should be possible to get a small drone airborne, if it's made of extremely light but strong super materials.
BNNT (insulator and structural material)
doped CNT (NASA's copper conductor / wire replacement; made as conductive as copper by applying dopants to the individual strands of fiber)
Graphene (conductive skin panels that take the voltage from the wiring to ionize the CO2 gas; you need a large surface area to ionize enough CO2 to provide enough thrust; panels would be affixed or bonded to the BNNT insulator fabric or would be nonstructural surfaces, i.e. semi-monocoque design)
For craft that carry humans and cargo, only very large but lightweight blimps filled with heated H2 and taking full advantage of those super materials have any chance of staying in the air. They won't fly thousands of feet above the ground, either. They'll just fly along the ground and take advantage of the reduction in resistance to movement through the atmosphere and low dynamic pressure winds. H2 should be inflammable in a 95% CO2 atmosphere, unless any arcing and sparking from the propulsion system produces a 700C+ temperature. Tests with Mars atmosphere simulants would need to confirm that.
Edit:
YouTube video of a small airship model using ion propulsion:
History of the World's First Plasma Propelled Airships / 2005 - 2008 - Ion Thruster
Edit #2:
NASA report:
An Investigation of Ionic Wind Propulsion
YouTube presentation on ionic wind propulsion:
Using Ion Propulsion in Model Aircraft
Last edited by kbd512 (2018-11-21 17:39:08)
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The ionic wires would possibly cause arcing as carbon is a mild conductor which is what resistors are made from as a result of the high voltage. Which means that we would be slowly electrolysis co2 to carbon and oxygen....
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SpaceNut,
Yes, but the issue revolves around whether or not the gas is explosive. Presumably, the airship is moving through the air and the atmosphere will disperse the limited quantities of byproducts produced through electrostatic discharge. I'm more concerned about arcing and sparking from the iron oxide dust in the atmosphere.
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Yup iron oxide dust... seems I mentioned that elsewhere on another topic for the same issue of electrostatic charge paths....Which I suggested a magnetic field to do the filtering on that topic....
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Here's what JPL's 1997 Mars Geoscience Aerobot project came up with:
Mars 2001 Aerobot / Balloon System Overview
Mars 2001 Aerobot / Balloon System Overview - Additional Info
Mars Balloon Trajectory Model for Mars Geoscience Aerobot development
I presume that lighter and stronger materials would enable a heavier payload and 20 years of electronics advancement would negate the need for a heavier payload for aerial observation, but it's not necessary to invoke the use of any new materials just to create something that would work from a physics standpoint.
Roughly 500,000 cubic meters of balloon would be required to lift a 1,000kg payload. That's 2.5 times the volume of the Hindenburg. I don't envision such airships will be traditional spheres or blimps, but very large donuts attached at multiple points to cargo pods slung below. The French experimented with balloons that circled the Earth at altitudes of 35km decades ago. Their longest duration flight was about 69 days.
A 1t lift capacity toroidal balloon would have a major radius of 50m and a minor radius of just over 22.5m. A series of CNT ropes (these can now be purchased as commercial products, even if they're still obscenely expensive) would suspend the cargo beneath the balloon. An evacuated double-wall torus could be significantly smaller or carry significantly more cargo.
The surface area is many thousands of square meters, which provides adequate area for a sizable thin film solar array for electrical power and a propulsive surface for the ionic wind thrusters to push off of. It won't be a speed demon, but doesn't require much infrastructure to ship supplies over great distances to field geology teams hunting for resources.
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So what are typical windspeeds in the lower parts of the Martian atmosphere? How long do high wind periods last?
The Martian atmosphere is much more variable than ours. South pole summer liberates a lot of CO2, raising the atmospheric pressure across the planet and the huge range of relief between Hellas' bottom and Tharsis' tops means that one blimp design can't visit a lot of places if it must carry a useful payload.
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Beamed energy also comes to mind to power this craft from a distance from surface and or orbit along a predicted path.
We do also have Balloon topics as well here...
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The wind speeds in the lower atmosphere are 2m/s to 5m/s (edit: can't recall if the NASA doc said 5m/s or 7m/s, but the difference is still negligible) or thereabouts. The winds in the upper atmosphere can top 50m/s.
A very large toroidal aerostat could also lift thin film solar arrays draped over the top of the aerostat as the payload, in order to rise above most of the dust in the lower atmosphere. A lightweight conductor would carry the power back to a battery on the surface. This would reduce the variability of the power received as a function of the Tau of the atmosphere and permit easier mission planning around photovoltaic power.
Last edited by kbd512 (2018-11-23 19:58:40)
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Unique shapes that add lift is and will be a plus with regards to directional control of the floating platform.
Fabric that is sealed by an epoxy resin that sets up with UV to hold shape would seem to be the best of mass and flexibility of shipment from earth.
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So to get reliable positioning at altitude the device must be capable of exceeding the windspeeds applicable at that height, as well as of controlling its buoyancy. This can be done with a tether, but a tether will be heavy and will reduce the payload. Also a tethered device cannot be used for deliveries. Such a system might have use as a communications hub over a fairly wide area, however the possibility of failure will mean the tether may come crashing back to the surface.
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Sounds like a goes use for carbon nano tube string to me or possibly Kevlar twine and others that are less in mass.
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Elderflower,
Staying in position in a neutrally buoyant airship is about generating enough force with the distributed propulsion system to push against the oncoming flow with equal force. Wind velocity is only one component in the equation used to determine how much force must be generated to "push back", such as it were. Force over a unit area is equal to the air mass multiplied by the square of the acceleration. It's that old force equals mass multiplied by acceleration equation.
Edit: "0.012" is the mass of the Martian atmosphere at sea level.
F = (1m^2) * [0.012(kg/m^3)] * [7(m/s)]^2
F = 0.012 * 49; F = 0.588kg-m/s^2; F = 0.588N; F = 0.132lbf/m^2; F = 0.0123lbf/ft^2
If we considered a sphere a flat plate area, which it certainly is not, then the force applied over a 50 square meter flat plate isn't much in the extremely low density of the Martian atmosphere. 50 square meters is equal 538.196 square feet.
0.0123 * 538.196 = 6.62lbf
However, Viking measured wind gusts of up to 26m/s at the surface during a dust storm.
0.012 * 676 = 8.112N or 1.824lbf/m^2 or 0.169lbf/ft^2
0.169 * 538.196 = 90.96lbf
I've been trying to determine how the thrust produced by the ionic wind propulsion experiments is affected by the mass of the working fluid (CO2, in this case). There's a pretty substantial difference between ionic wind and jet engines. MIT's thruster generated about 110N/kW of input power, compared to a jet engine's 2N/kW.
Last edited by kbd512 (2018-11-25 18:11:10)
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https://www.popularmechanics.com/milita … -15326499/
https://www.smithsonianmag.com/innovati … 180970877/
https://en.wikipedia.org/wiki/Corona_di … #Mechanism
The plane weighed about five pounds (2.45 kilograms) and had a wingspan of 15 feet (5 meters), and traveled about 180 feet (60 meters), so it’s a long way from efficiently carrying cargo or people long distances.
http://news.mit.edu/2013/ionic-thrusters-0403
We use a thin filament or wire that is charged to +20,000 volts using a lightweight power converter, which in turn gets its power from a lithium-polymer battery. The thin filaments are called emitters, and are nearer the front of the plane. Around these emitters the electric field is so strong that the air gets ionized – neutral nitrogen molecules lose an electron and become positively charged nitrogen ions.
Farther back on the plane we place an airfoil – like a small wing – whose leading edge is electrically conductive and charged to -20,000 volts by the same power converter. This is called the collector. The collector attracts the positive ions toward it. As the ions stream from the emitter to the collector, they collide with uncharged air molecules, causing what is termed an ionic wind that flows between the emitters and collectors, propelling the plane forward.
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SpaceNut,
This entire question revolves around how much thrust a conductive graphene fabric can produce per unit area with an atmospheric density of 0.012kg/m^3. If I get an answer to this question from the available research documents I've been reading through, then I'll post it here.
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Reading through the links and looking at some videos of those claiming to do the same have lead me to some are using RF energy repulsion, some are using magnetic plate repulsion and creating vertical lift via the change in power or voltage into the electrode elements.
That is not what the images of the MIT project are http://news.mit.edu/2018/first-ionic-wi … parts-1121
To rise and climb in altitude and to fall means a charge place potential must be sloped between all of the electrodes to produce the flow that is desired. \ means to rise just like the wings of a plane and / would mean to drop in altitude
I went looking at the other type of ionic unit in the form of the air cleaning which is similar.
http://www.instructables.com/id/How-to- … r-ionizer/
The energy charges the plates to attract the dust to the plates.
So the cords that make up the energy ion field is pulsing from back to forward on each simulated wing surface.
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SpaceNut,
The MIT bubbas are using pulses of current to create electrostatic repulsion of ionized Nitrogen gas molecules from the atmosphere to create thrust or force to push the craft through the air.
My proposed airship would use a bonded grid of conductive Graphene or CNT threads with a very large surface area on the skin of the inflatable structure to push it around in the atmosphere. Discrete propulsion units might work acceptably well in a denser atmosphere, but this airship has to be exceptionally light, so the fabrics that create the electrostatic repulsion must be integrated into the inflatable.
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Re-post will follow this up with some other items I saw today in reading....
Capacitor
Flexible, foldable supercapacitors for energy storage
The term "supercapacitors" is reserved for devices that hold over 10 times as much energy per unit volume as a traditional capacitor, and that can charge and discharge quickly. Carbon, taking the form of carbon nanotubes in today's capacitors and supercapacitors, contains the ideal properties for storing energy efficiently. Since the 1950s, researchers have exploited its strength and excellent thermal and electrical conductivity; carbon is also strong, elastic and flexible so that it can bend and stretch easily.
The team of researchers investigated the structure of commercial supercapacitors and produced one that uses one sheet of carbon nanotube paper with different layers. They used barium titanate to separate the layers, which is more economical than any alternative compounds. The new paper superconductors can store energy efficiently even if they are rolled or folded.
Couple that with the thin film plastic substrate solar cells.
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SpaceNut,
I was actually thinking of what could be done without onboard energy storage, but I also think that super capacitors with the required voltage capability could quickly store and discharge their stored energy to create a form of pulsed plasma propulsion. I guess you could think of them as impulse bits from an arcjet thruster.
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Lets start with what is the base equation for the plane to operate.
F =M * A
Force is the gravity and component for motion
Mass does not change for Mars or Earth
Acceleration is the motion from the power source where time is the capacity of the energy and the rate of use
I noticed the MIT had a platform for take off and that while it rose initially once disconnected from the power that it dropped almost in a straight line. This is what a resistive load would do with a dropping voltage to the ionizer elements.
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Mars is a Co2 economy away once we have the equipment to gather and process it for use.
http://www.wickmanspacecraft.com/marsjet.html
Hybird magnesium powder co2 engine for flight
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