Aerial ropeways

Calliban · 2022-02-11 18:59:47

I wasn't aware of there being a thread on this topic, so I decided to create one.
https://www.lowtechmagazine.com/2011/01 … sport.html

Aerial ropeways have been used for freight transportation on Earth for centuries. They appear to be extremely energy efficient, although I can find no data on actual energy consumption. In situations where material is transported down a gravitational gradient, no power supply is needed and the ropeway is powered by gravity, as with this example in the UK.
https://m.youtube.com/watch?v=6RiYXI1Tf … e=youtu.be

On Mars, the reduced gravity makes a ropeway more practical than on Earth, as larger spans can be supported between towers and frictional losses will be even lower. Towers could be made from stone or brick, reducing the amount of steelwork needed. Wind loadings and seismic loadings are much lower on Mars, allowing towers to be slender compared to Earth. Bracing cables would improve their stability even further.

Aerial Ropeways can be used to transport ores from distant mines over distances of hundreds of km. Compared to a road, relatively little engineering work is needed, as the cable can be stretched between towers hundreds of metres apart. Carbon fibre or polymer ropes could increase the span even further, due to their improved strength-weight ratio.

This mode of transportation usually transports freight slowly, typically at around human walking speed. Given the low friction of steel wheels on wire rope and the absence of air resistance on Mars, we could power these ropeways by loading the buckets at a higher level than the receipt facility. Hence, no motors are needed, only pulleys. A quarry or mine located at a high elevation, like a Tharsis volcano, could in fact generate excess power, with a generator employed as a brake.

Last edited by Calliban (2022-02-11 19:13:28)

kbd512 · 2022-02-12 13:09:11

Calliban,

I wonder how the cables would fare over time with the abrasive dust, but it would be worthwhile to scope out roughly how much power is needed for Iron ore mining. I'm sure that it will easily best the power required by any off-road wheeled or tracked vehicle by a lot.

These people are claiming 100Wh/passenger/km:

Ropeway Redux: Highlights From Doppelmayr’s Comprehensive Magazine

They're calling a passenger 70.8kg, the system described above can transport 3600 people per hour (254,880kg), so 360kWh to transport almost 255t to a distance of 1km. I don't think it's possible to get much more efficient than that- 1.41kWh per metric ton per kilometer traveled. This requires no new technology, either.

tahanson43206 · 2022-02-12 19:28:51

For Calliban re new topic....

The term you have highlighted definitely deserves it's own topic.

However, I see some interesting similarities in this topic: Gravity Energy Storage

SpaceNut led off with an image that seems to show something similar to what I understand from your opening post.

The forum archive contains numerous instances of the word gondola, although I'm guessing most are about something other than your topic.

(th)

SpaceNut · 2022-02-12 19:50:17

Seems from the first link that its more about how things can be moved over a cable suspension system and brought to a place that would otherwise not be quite so easy to get there if it were not used.

louis · 2022-02-12 20:22:16

I would agree we need to look into this sort of transport solution. But I suspect when you factor in offloading, infrastructure and maintenance etc, solar powered robot transporters (working off transponders and/or GPS) will prove more cost effective.

Calliban wrote:

I wasn't aware of there being a thread on this topic, so I decided to create one.
https://www.lowtechmagazine.com/2011/01 … sport.html
Aerial ropeways have been used for freight transportation on Earth for centuries. They appear to be extremely energy efficient, although I can find no data on actual energy consumption. In situations where material is transported down a gravitational gradient, no power supply is needed and the ropeway is powered by gravity, as with this example in the UK.
https://m.youtube.com/watch?v=6RiYXI1Tf … e=youtu.be
On Mars, the reduced gravity makes a ropeway more practical than on Earth, as larger spans can be supported between towers and frictional losses will be even lower. Towers could be made from stone or brick, reducing the amount of steelwork needed. Wind loadings and seismic loadings are much lower on Mars, allowing towers to be slender compared to Earth. Bracing cables would improve their stability even further.
Aerial Ropeways can be used to transport ores from distant mines over distances of hundreds of km. Compared to a road, relatively little engineering work is needed, as the cable can be stretched between towers hundreds of metres apart. Carbon fibre or polymer ropes could increase the span even further, due to their improved strength-weight ratio.
This mode of transportation usually transports freight slowly, typically at around human walking speed. Given the low friction of steel wheels on wire rope and the absence of air resistance on Mars, we could power these ropeways by loading the buckets at a higher level than the receipt facility. Hence, no motors are needed, only pulleys. A quarry or mine located at a high elevation, like a Tharsis volcano, could in fact generate excess power, with a generator employed as a brake.

Calliban · 2022-02-13 09:16:32

From the Low Tech magazine article:

'The Garrucha ropeway, an installation at iron ore mines in Almeria, Spain, was 9.75 miles (15 km) long. The construction of the line took only 6 months. It had a daily transport capacity of 420 tons (working ten hours per day), powered by a 100 HP engine.'

1HP is about 0.75kW, so that is 750kWh per day, to transport 420 tons over 15km. So that is 0.12kWh/ton-km, or 0.133kWh/tonne-km. About the same as rail.

These ropeways operate at slow speeds, so all of the energy losses are the result of friction in the bearings and of the ropes on the pulleys. In Spain in the early 20th century, bearings would have been simple friction bearings. The cold may be a problem on Mars even if stainless steel ropes are used. Bearings must be lubricated and must be sealed as well as possible to keep out dust. The atmosphere of Mars, thin as it is, may provide enough pressure to prevent high flash point oils from evaporating. It may be difficult to find a lube oil that remains liquid at such low temperatures. Hexane perhaps?
https://en.m.wikipedia.org/wiki/Hexane

Last edited by Calliban (2022-02-13 09:56:13)

kbd512 · 2022-02-13 16:16:36

Louis,

Using Calliban's Earth-bound cable car example, and given that Mars gravity is only 38% of Earth gravity, a 38hp motor should be able to move the same tonnage of cargo over 10 hours while consuming 285kWh of energy. A robotic off-road vehicle, whether wheeled / tracked / legged, may be able to move the same tonnage of cargo, and it may even be powered by a 38hp electric motor, but I seriously doubt it would consume less energy to do it.

A car tire's coefficient of rolling resistance over hard pavement is 0.02, but it's 0.2 to 0.4 over loose sand, which means a wheeled vehicle rolling over loose sand consumes 10X to 20X more power to overcome rolling resistance to move the same weight. Tesla's semi truck is purported to require 2kWh per mile, which seems plausible if they're using 120kW / 161hp to travel at 60mph over smooth and level pavement. Using Tesla's claimed 0.36 drag coefficient, by my calculation roughly 58.8hp is used to overcome aerodynamic drag if the frontal area is 9.476m^2 (slightly less than the 2.5m x 3.96m / 9.9m^2 of a Tesla). That means the rest of the power was used to overcome rolling resistance.

We're going to ignore drag force on Mars because it's so small when compared to Earth sea level. If the truck weighs 38% of what it does on Earth, then the power required drops to 28.5kW, but now we're rolling through a medium (fine sand) the creates 10X more friction so now we're consuming 285kW per hour to drive our robotic truck through the sand at an unrealistic 100km/hr. So cut that power figure in half for a more practical 50kmh travel speed, and after 5 hours of driving with the loads, we've already consumed 712.5kWh before accounting for the power required to return and pick up the next load. Tesla's semi could actually deliver the required loads using a single charge and complete the task within a 10 hour time frame if a fast-charger was available to recharge the battery at some point during the day, but that's how much power we would minimally consume driving through fine sand at half of highway speed. The rolling resistance curves for semi-truck tires between 0 and 50km/h are very near to a horizontal line.

I honestly don't know what the power calculation would be for a legged vehicle, but maybe this document is the best study we have to date on comparing all manner of biological locomotion with the wheels and tracks that most modern vehicles use:

From cockroaches to tanks: The same power-mass-speed relation describes both biological and artificial ground-mobile systems

SpaceNut · 2022-02-13 16:51:49

This is an example of not being able to get your vehicles from one side to the other due to slope and conditions such that we still can get cargo from one side to the other at a low energy cost once poles are set by brute force of those that have the muscle to bring it down the side until it rests where its going to be placed.

kbd512 · 2022-02-13 17:53:59

SpaceNut,

That research paper from the US Army makes it pretty clear that for all ground-mobile vehicles, irrespective of the means of locomotion used, there's a nearly invariant relationship between power, mass, and speed. The increased efficiency of an electric motor, relative to an internal combustion engine, will certainly help lower the total power requirement, but never below the minimum required to counteract friction in all its various forms- a simple fact of life that should not be the least bit surprising.

I fail to see the greater magic in robots, no matter what ultimately powers them. They're vastly more complex variants of basic vehicle designs, they all have nearly identical power requirements to move a given weight to a given distance at a given speed, and someone has to have the electrical and mechanical knowledge to maintain them. The truly autonomous robots that we already have on Mars cost billions of dollars and don't move as fast as a toddler can crawl, because faster movement would endanger the machine.

I wish someone could explain the underlying point of such endeavors. What other intangible thing(s) does automation add to the viability of a crewed mission? The end goal is to have people permanently living on Mars, is it not? If we're not going to send people there to do any useful work, then why bother sending them there at all? We already have plenty of robots on Mars.

At this point, we have a pretty good idea about what's on the surface of Mars, but we still haven't sent anyone there to confirm what our instruments have been telling us. Why is that? We keep sinking billions of dollars into robotic exploration while we fail to do a single 6 month long mission where we don't resupply the mission with a single kilogram of anything that wasn't already aboard when the mission started. A 2 year mission without resupply, even if it never left LEO, would be a better gauge of our ability to do a crewed mission to Mars than every robotic experiment imaginable.

Calliban · 2022-02-13 18:14:25

A ropeway represents a capital investment, but has low energy costs per ton-mile after that. The energy consumption of rough track ground vehicles will depend upon the gradient of the terrain and soil conditions. There are other infrastructure options that could be considered as well, like small gauge railways. The right choice in each circumstance, will need to balance capital cost against operating cost. It will be further complicated by the fact that some options can be more easily manufactured on Mars than others.

The key to practicality of a ropeway is being able to manufacture it relatively easily on Mars using native materials. The towers need not be high on Mars, as they do not need to cross any other infrastructure. So my first thought would be a mild steel tube filled with some sort of cement to provide both compressive and flexing strength. We could fill the tubes with wet sand and allow it to freeze, providing a compressive infill. The sand wet sand mixture would also be useful as a foundation cement fixing the poles into holes dug into the ground. A steel I-beam would be welded to the top of each pole and the outgoing and return cables would be mounted on pulleys on either side. With only 38% gravity, towers could be over twice as far apart as on Earth. A significant cost saving.

The buckets would be low alloy carbon steel, as would the pulley wheels. The cables could be constructed from stainless steel, but corrosion will not be the problem on Mars that it is on Earth and gravity is only 0.38. We could use a carbon steel cable with a basalt fibre core. This would give better strength-weight than a stainless cable, presumably allowing longer spans.

We could run the ropeway 24/7, but this would mean operating the system in the cold of the Martian night, when lubricants will freeze and steel will be brittle. I suspect that even in space suits and heated vehicles, it will be undesirable to have people working during Martian night at temperatures of -90°C. So I would suggest that the ropeway is a good candidate for direct solar power. We couple the PV panels directly to a DC motor driving the hoist at the receipt end (our base). The speed of the ropeway then varies according to sunlight strength. No batteries or other storage is needed. A very simple system. There would need to be arrangements for loading and unloading at each end. Maybe we can tip the ore or whatever else is being carried into a a gravity chute?

Another option that those ingenious Germans came up with at the turn of the 20th century: electric road trains.
https://www.lowtechmagazine.com/2009/07 … -1950.html

These were very simple, low speed vehicles that drew electric power from a cable via a trolley pole. No batteries needed. This is how the Germans kept an industrial economy running during WW1 and WW2, without so much as a drop of diesel fuel. We could probably build vehicles like this quite early on Mars. They would probably have a fixed gear ratio and a single DC motor driving all four wheels through a single drive shaft and two sets of bevel gears. Very mechanically simple. Basically, with the exception of the motor, the entire construction is various grades of carbon steel. Again, the power supply could be directly coupled solar panels, with cells built up in series to achieve the desired voltage, maybe ~200v to the catenary cable. A vehicle like this needs a solid road of course. And that road is a considerable investment of energy and man hours, even if it is made from compressed native stone and gravel. The same if true of a railway. It was this realisation that led me to suggest the ropeway for the continuous movement of ores and other goods. The widely spaced towers will be cheaper than roads.

Last edited by Calliban (2022-02-13 18:51:28)

kbd512 · 2022-02-15 19:29:25

Calliban,

We could use a triangle truss tub with dual top rollers. The materials could be transported using abrasion-resistant CNT fabric / cloth bags to carry ore or Iron nuggets. We would simply dump the material out using quick-release cotter pins activated by a pawl at the receiving end. After the material has been dumped, the sack would be so light that it could simply dangle on its return trip. The cotter pins would be reinstalled on the loading end, with the bags refilled using a hopper. If we keep the individual bag load limit to something sane, say 100kg or so, then we could have hundreds or even thousands of bags of materials moving along this aerial-conveyor-like transport system.

Maybe we could get some of those robots Louis was talking about to load the bags and weigh the materials. I agree with using straight solar power with no other unnecessary complications. Whatever work can get done in a day will happen between sunrise and sunset. This enforces a set work schedule, but that's not necessarily a bad thing. Farming here on Earth works the same way. After the Sun goes to bed, it's about time for you to go to bed.

Calliban · 2022-02-18 10:03:05

kbd512 wrote:

Calliban,
We could use a triangle truss tub with dual top rollers. The materials could be transported using abrasion-resistant CNT fabric / cloth bags to carry ore or Iron nuggets. We would simply dump the material out using quick-release cotter pins activated by a pawl at the receiving end. After the material has been dumped, the sack would be so light that it could simply dangle on its return trip. The cotter pins would be reinstalled on the loading end, with the bags refilled using a hopper. If we keep the individual bag load limit to something sane, say 100kg or so, then we could have hundreds or even thousands of bags of materials moving along this aerial-conveyor-like transport system.
Maybe we could get some of those robots Louis was talking about to load the bags and weigh the materials. I agree with using straight solar power with no other unnecessary complications. Whatever work can get done in a day will happen between sunrise and sunset. This enforces a set work schedule, but that's not necessarily a bad thing. Farming here on Earth works the same way. After the Sun goes to bed, it's about time for you to go to bed.

Sounds like a viable plan. According to the low tech article, ropeway systems have been built with lengths of several 10s of km in the past. These systems will never be quite as energy efficient as rail because of the energy consumed in friction within the cable as it flexes and between the cable and hoists. They remain more energy efficient than road transportation even over tarmac and an order of magnitude more energy efficient than trucks over gravel roads.

The advantages of material ropeways (we are taking about freight here) are good energy efficiency, lean infrastructure required per tonne-km and ability to transit over uneven ground. They appear to be technologically simple systems. I would feel confident about being able to build systems like this using insitu manufacturing. Towers can be mostly stone or steel tubes with compressive infill. The cable can be extruded through dies. The pulleys cast from mild steel and turned on a lathe. Power provided by a single large DC motor.

A small gauge railway would have superior operational energy efficiency over relatively flat ground. But work would be needed to prepare a bank of compressed regolith on which the track can sit. And rail becomes difficult if gradient is greater than a few degrees. Large parts of Mars are relatively flat. But outside of the northern Great Plain, it is a rugged planet and ground conditions are highly variable.

I have previously looked into the possibility of transportation of ores and non-perishable freight using barges, floating in pipelines, with water pumped down the pipelines at 1-3 m/s carrying the barges along with the stream. Whilst this could provide energy efficient freight transportation on Earth, I believe that Mars is simply too cold for something like this to be viable. Pure water would certainly freeze and it would take too much energy and infrastructure to keep it suffiently warm. Saturated brine may remain liquid, but the viscosity of water increases rapidly beneath 0°C. At typical Martian temperatures it would be almost like syrup and a lot more pumping power would be needed to keep it moving. I haven't carried out a quantitative analysis yet, but the concept doesn't look promising for Mars. On Earth, it looks more interesting. Rather like canal barges without the labour costs. I have looked into using direct mechanical wind power to provide water pumping, with the rotating shaft directly coupled to a screw pump.

Last edited by Calliban (2022-02-18 10:20:51)

tahanson43206 · 2022-02-18 11:10:28

For Calliban re #12

With focus on your mention (again) of barge-in-water on Mars ...

The Winter Olympics are in progress, and ice skating (along with many other sports) are on display.

Your mention of the possibility that water might freeze on Mars was presented as a drawback for a floating barge design. However, that method of material movement would be slow, compared to what is possible if you let your imagination flow (is that the right word?) to travel on ice.

Travel on ice has been a practical concept for many years, and it is still practiced today.

If you were to convert your barge tunnels to ice sled tunnels, it seems to me your goods would/could move more rapidly, and the efficiency of the transport would be good to excellent, depending upon the design of the sliding shoes, and the condition of the ice.

PS ... do you have any friends in other engineering disciplines who might be willing to help out with Large Ship. That initiative has been gelling for a couple of years, and is on the verge of being ready for serious evaluation. The human species ** needs ** Large Ship (whether they know it or not) and it will inevitably be built by someone. This group has the significant advantage of being first at the starting gate, but others will soon grab the lead if this group fails to maintain the lead.

I'm specifically thinking about SpaceNut's decision to work on the magnetic radiation deflector. I am (reasonably) confident he would welcome collaborative participation in developing a proposal sound enough for funding a feasibility study.

(th)

Calliban · 2022-02-20 12:00:22

TH, that is a novel idea. According to this reference the friction coefficient of steel on ice is 0.02.
http://www.smas.org/2-kongres/papers/12961.pdf

On Mars, a force of 75N would be needed to push a 1 tonne vehicle. That is 75KJ/t-km (0.02kWh/t-km). Very efficient. Ice trains anyone?

louis · 2022-02-20 19:56:39

Does sound good. The issue might be the summer afternoons on Mars when air temperatures can reach 20 celsius.

I would run with truck-sized robot Skidoos. With robot control they could form trains but wouldn't need to be connected (laser and radar would keep them the right distance apart).

Calliban wrote:

TH, that is a novel idea. According to this reference the friction coefficient of steel on ice is 0.02.
http://www.smas.org/2-kongres/papers/12961.pdf
On Mars, a force of 75N would be needed to push a 1 tonne vehicle. That is 75KJ/t-km (0.02kWh/t-km). Very efficient. Ice trains anyone?

kbd512 · 2022-02-22 20:18:27

Calliban,

That friction coefficient of 0.02 is about the same as the rolling friction coefficient of a car tire on asphalt.

For some reason that doesn't sound very promising, even if the force applied to sustain motion at a given speed is only 38% of that on Earth.

Are you sure it's not closer to 0.002?

Steel train wheels on steel rails is 0.001 to 0.002 for comparison purposes. That would require 10X less power to sustain motion.

If the coefficient of friction of polymer-on-steel is only half that of steel-on-steel, then perhaps we should specify some kind of Teflon roller to roll across the steel rail, with a series of brushes used to clear accumulated dust / grit.

Micro shot peening (WPC treatments) drastically reduces metal-on-metal friction, so that's another potential way to use a single durable material for the steel tubing and rollers.

Calliban · 2022-02-23 06:46:09

kbd512 wrote:

Calliban,
That friction coefficient of 0.02 is about the same as the rolling friction coefficient of a car tire on asphalt.
For some reason that doesn't sound very promising, even if the force applied to sustain motion at a given speed is only 38% of that on Earth.
Are you sure it's not closer to 0.002?
Steel train wheels on steel rails is 0.001 to 0.002 for comparison purposes. That would require 10X less power to sustain motion.
If the coefficient of friction of polymer-on-steel is only half that of steel-on-steel, then perhaps we should specify some kind of Teflon roller to roll across the steel rail, with a series of brushes used to clear accumulated dust / grit.
Micro shot peening (WPC treatments) drastically reduces metal-on-metal friction, so that's another potential way to use a single durable material for the steel tubing and rollers.

Friction factor depends upon how the two surfaces deform in contact. Ice is a soft and brittle ceramic. Any sliding steel will cause a lot of wear and generate a lot of dust a.k.a snow. Friction factor will never be stellar and will increase with increasing load as the surface starts to crush. The surface will need to be periodically remelted.

It is hard to beat the rock bottom rolling resistance afforded by steel wheels on steel rails. If we are going to the expense of laying things like pipelines, it is hard to see a small gauge railway being much more expensive. The amount of freight transported is proportional to speed. A railway will always shift a lot more tonnage per hour than a canal or pipe of similar diameter. In the past, railways have been built with gauge as little as six inches. Some were purpose built tourist attractions, but small gauge rail has been used for ore transportation since the early years of the 19th century. On Mars, we could power such railways using solar panels mounted along the track. These could feed DC directly into a conductor rail parallel to the track.

tahanson43206 · 2022-02-23 08:01:44

For Calliban ... recognizing that ** this ** topic is about ** aerial ** transport systems, and also noting the excellent examples from Human history on Earth that you have shown us, I ** do ** think that recent excursions into non-aerial transport systems deserve to be quoted into their appropriate topics.

Instead of depending upon moderators or administrators to perform that sort of topic adjustment, I'd like to introduce a new concept into the mix. When we (as a content creator) find ourselves inspired with thoughts that are off topic, finish the off-topic thought but ** then ** quote the entire post and paste it into the appropriate topic.

This will accomplish two things (and maybe more) ... it w[ll save the topic manager the discomfort of having to deal with the unwanted diversion, and it will allow others to pick up the new idea and run with it in the appropriate topic.

I will try to follow my own recommendation by looking to see if we have an existing topic for ice roadways on Mars.

(th)

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#1 2022-02-11 18:59:47

Aerial ropeways

#2 2022-02-12 13:09:11

Re: Aerial ropeways

#3 2022-02-12 19:28:51

Re: Aerial ropeways

#4 2022-02-12 19:50:17

Re: Aerial ropeways

#5 2022-02-12 20:22:16

Re: Aerial ropeways

#6 2022-02-13 09:16:32

Re: Aerial ropeways

#7 2022-02-13 16:16:36

Re: Aerial ropeways

#8 2022-02-13 16:51:49

Re: Aerial ropeways

#9 2022-02-13 17:53:59

Re: Aerial ropeways

#10 2022-02-13 18:14:25

Re: Aerial ropeways

#11 2022-02-15 19:29:25

Re: Aerial ropeways

#12 2022-02-18 10:03:05

Re: Aerial ropeways

#13 2022-02-18 11:10:28

Re: Aerial ropeways

#14 2022-02-20 12:00:22

Re: Aerial ropeways

#15 2022-02-20 19:56:39

Re: Aerial ropeways

#16 2022-02-22 20:18:27

Re: Aerial ropeways

#17 2022-02-23 06:46:09

Re: Aerial ropeways

#18 2022-02-23 08:01:44

Re: Aerial ropeways

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