pippin - 12/8/2007 8:50 AMQuoteA_M_Swallow - 12/8/2007 8:49 AM1. Leaving a reusable motor unit on the Moon and just throwing the payload into space has many cost and efficiency advantages.2. a. Rotating the cable. The linear motors form part of the towers and actually lift the cable. Since the cable weights several thousand tons it will take a lot of starting and stopping. If the cable rotates permanently at 2.38 km/s then stationary vehicles need attaching to the cable without touching it. This design is not easily spun off as an inter-village transport system.3. b. Nuclear power and/or solar power on the ground, motors in the vehicles. A method of getting the power up to the vehicle is needed. Power beaming is difficult because within seconds the vehicle will be over the Moon's low horizon. Large friction forces between the power collection arms and the power cables produce unwanted wear and heat.Sorry, but I recommend that you read a bit about how maglevs work, for example here: http://www.wikimaglev.org/The basic idea of a maglev, aside from the levitation, of course, is to have the motor in the track, this way you can adapt power to topology and need. And you don't have to move/accelerate the motor. And this way you can get HIGH acceleration without big losses, so I don't understand why you don't want to use it.
A_M_Swallow - 12/8/2007 8:49 AM1. Leaving a reusable motor unit on the Moon and just throwing the payload into space has many cost and efficiency advantages.2. a. Rotating the cable. The linear motors form part of the towers and actually lift the cable. Since the cable weights several thousand tons it will take a lot of starting and stopping. If the cable rotates permanently at 2.38 km/s then stationary vehicles need attaching to the cable without touching it. This design is not easily spun off as an inter-village transport system.3. b. Nuclear power and/or solar power on the ground, motors in the vehicles. A method of getting the power up to the vehicle is needed. Power beaming is difficult because within seconds the vehicle will be over the Moon's low horizon. Large friction forces between the power collection arms and the power cables produce unwanted wear and heat.
pippin - 14/8/2007 8:00 AMThat Motor uses eddy currents if the aluminum structure to be moved to generate the force. See my comments above.It also uses a gap of 1-1.5 mm between the motor and the moving plate. It has an attractive force so you need to find a way to seperate the two. Especially if they have a relative velocity of 2.3 km/s. Again: see my comments above.Sorry, no way.
pippin - 14/8/2007 8:00 AMAh, and btw: Why do all this is it consumes so much Ares V flights? Easier to just move fuel for rockets up there.
A_M_Swallow - 10/8/2007 10:00 PMQuotekhallow - 10/8/2007 6:02 PMKeep in mind there's also regular, old-tech train tracks, for when you're not in a big hurry. The thermal flexing might make them high maintenance, but you can ship a lot of cargo and people on cheap aluminum rails. Good, solid 19th century tech on the Moon!You had better make the rails on the moon they are too heavy to lift from the Earth.According to this web page good old UK railway track (UIC60) weights 60 kg/mhttp://www.railway-technical.com/track.shtml#TrackFor a 1210 km track 2 * 60 * 121000 = 145,200,000 kg = 145,000 mTThe sleepers are a lot extra.To carry a 50 mT vehicle a tether mass of 2.5 kg/m should be possible using 2006 technology. Any embedded magnetic particles needed are more mass.
khallow - 10/8/2007 6:02 PMKeep in mind there's also regular, old-tech train tracks, for when you're not in a big hurry. The thermal flexing might make them high maintenance, but you can ship a lot of cargo and people on cheap aluminum rails. Good, solid 19th century tech on the Moon!
khallow - 14/8/2007 1:00 PMGood of you to spot the strength in my proposal. Presumably it'll be a while before the tether can be manufactured on the Moon. So it'll have to be brought from Earth. On the other hand, low tech aluminum rails can be made on site. Just bring a starter factory and you can eventually produce these rails with no further input needed from Earth (aside from customers for the rail).Incidentally, a lot of these high tech designs as used on Earth depend on having a lot of volume to fund the trains. I don't see that existing on the Moon for some time. A low tech rail solution which can be made on the Moon provides good results for low investment.
A_M_Swallow - 14/8/2007 10:37 AMQuotekhallow - 14/8/2007 1:00 PMGood of you to spot the strength in my proposal. Presumably it'll be a while before the tether can be manufactured on the Moon. So it'll have to be brought from Earth. On the other hand, low tech aluminum rails can be made on site. Just bring a starter factory and you can eventually produce these rails with no further input needed from Earth (aside from customers for the rail).Incidentally, a lot of these high tech designs as used on Earth depend on having a lot of volume to fund the trains. I don't see that existing on the Moon for some time. A low tech rail solution which can be made on the Moon provides good results for low investment.The big problem with rail on the moon is that trains operate on the flat, anything over 2 degrees causes problems. On Earth this is solved by using bridges, embankments and tunnels. We do not know how to automate the building of these and there is insufficient man power on the Moon. Now if we can design a train that runs along "rope" bridges with 100 mile spans...
renclod - 14/8/2007 4:20 PMA_M_ what's killing your concept is the 3g limitation and that is because you think manned vehicles.But people might not need so frequent launches from Luna as lunar-made LOX (LLOX), for example.I like the circular maglev rail idea, as opposed to linear maglev. I like the gradual buid-up in velocity.What about the 7km radius rail, 2.4km/s velocity to low energy escape, 82g - a case we are discussing in the neighbour lunar sling thread. What if we can find a good candidate crater for this ?And build on the crater's rim ?
renclod - 14/8/2007 4:20 PMA_M_ what's killing your concept is the 3g limitation and that is because you think manned vehicles.
A_M_Swallow - 14/8/2007 10:37 AMNow if we can design a train that runs along "rope" bridges with 100 mile spans...
Jim - 15/8/2007 1:04 PMQuoteA_M_Swallow - 14/8/2007 10:37 AMNow if we can design a train that runs along "rope" bridges with 100 mile spans...Spans are too long.
A_M_Swallow - 15/8/2007 10:00 AMOn the Moon spans of several hundred miles are possible using Kevlar and its rivals because Kevlar is over 10 times as strong as steel, much lighter and the Moon's gravity is 1/6 of the Earth's. This allows enormous structures.
A_M_Swallow - 14/8/2007 7:37 AMQuotekhallow - 14/8/2007 1:00 PMGood of you to spot the strength in my proposal. Presumably it'll be a while before the tether can be manufactured on the Moon. So it'll have to be brought from Earth. On the other hand, low tech aluminum rails can be made on site. Just bring a starter factory and you can eventually produce these rails with no further input needed from Earth (aside from customers for the rail).Incidentally, a lot of these high tech designs as used on Earth depend on having a lot of volume to fund the trains. I don't see that existing on the Moon for some time. A low tech rail solution which can be made on the Moon provides good results for low investment.The big problem with rail on the moon is that trains operate on the flat, anything over 2 degrees causes problems. On Earth this is solved by using bridges, embankments and tunnels. We do not know how to automate the building of these and there is insufficient man power on the Moon. Now if we can design a train that runs along "rope" bridges with 100 mile spans...
A_M_Swallow - 16/8/2007 2:11 AMRail tracks can be made out of Kevlar or one of its rivals. A metal coating may permit Maglev vehicles to use them.
A_M_Swallow - 15/8/2007 6:00 PMThe maximum span for a material is a function of the maximum cable length and the tower height.Lmax = M/(Dg) cos (A)Where Lmax = maximum length of cable in mM = maximum stress in N/m/m.D = density in kg/m/m/mg = gravity in m/s/sA = angle between the cable and the vertical at the tower in radiansAssume that the sag to length ratio is tower Height/Length is 1/10, so that A = 1.2 radians,