Well this is as good a place as any to post half or quarter baked
ideas!
You have a lunar colony. You need transort, right? You also need
electricity, right? So, here goes: You make a railway around the
equator of the moon, its a mile or so long, maybe 50 feet wide.
Then you top it off with solar cells, the whole thing. With 30%
efficient cells, you get about 10 MEGA watts of power.
Now the thing is, the train never stops. In order to maintain the train
in sunlight, it only has to go about ten miles an hour. (Do the math,
it rotates on its axis once in 28 days) So it never has to go
more than a fast walk speed so you can get on and off anytime you
want. It feeds power to a network which distributes power around the
colonies. That way you don't have to have a nuke plant, you get
power 24 hours a day and you get transport, if a bit slow.
You can also have many of these trains on the same track since there
is room for thousands of them end to end. Well hundreds anyway. All in the sun all the time. I'll bet SVW could write a nice story about
them. How bout it Mike?
Keep in mind that a train on the moon would have the same momentum and kinetic energy as it would have back on Earth going the same speed, but would have only one sixth of the tractive force. Grades would have to be kept very modest in order to keep wheels from slipping while pulling uphill or braking downhill.
Originally posted by Paul Diracmaglev!
Keep in mind that a train on the moon would have the same momentum and kinetic energy as it would have back on Earth going the same speed, but would have only one sixth of the tractive force. Grades would have to be kept very modest in order to keep wheels from slipping while pulling uphill or braking downhill.
Originally posted by zeeblebotMaglev would be possible but very expensive. I don't think lack of
maglev!
friction would be a problem because its in a vacuum. I would think
you would more have to worry about the wheels welding themselves
to the track! Besides if if were a mile long, all the wheels would have
to be driven with electric motors so all the wheels could be driven.
That would mean when it comes up to a grade, the back part of the
train would have good traction even if the front wouldn't.
The other thing is, the speed only wants to be 10 MPH or so, wouldn't
need a whole lot in the way of traction or power for such a slow train.
10 MPH on the equator, it would be more like 5 MPH closer to the
northern latitudes. One of the key features of this is it would want
to be as light as possible, thin PV cells, light structures BECAUSE of
the gravity, you don't need massive spars and such.
Like you said, the friction force might be less but it would need less
also. To load stuff on board, you could have big disks which would match the speed at the edge, allowing egress and exit with no
change in velocity. You wouldn't be walking anyway, you would have
to be in some kind of small vehicle or spacesuit. A 60 % slope
on the moon would take the same power as a 10% slope on earth
so the grades wouldn't even have to be that gentle!
i guess they would have to be pretty big disks, considering only the tangent would be available for transfers ...
instead of maglev, you could use sleds ... coat the rails with teflon ... put cogs (spoke vs. spoke rather than rack vs. pinion, for speed) on the upgrades ... or detachable sleds with cables ...
Originally posted by zeeblebotI like the cog idea, but don't think it would be a problem anyway.
i guess they would have to be pretty big disks, considering only the tangent would be available for transfers ...
instead of maglev, you could use sleds ... coat the rails with teflon ... put cogs (spoke vs. spoke rather than rack vs. pinion, for speed) on the upgrades ... or detachable sleds with cables ...
Figure 10 mph, 88/6 FPS (my referance, 60 MPH is 88 FPS)
so thats 14 2/3 feet per second. Suppose the wheels were 2 feet in
diameter, 6 1/4 feet circumferance about works out to just over
140 RPM, not very fast at all. If the wheels were about 4 feet in dia.
it would be about 70 RPM, even slower. That indicates electric
motors would be just right, max torque at low rpms, good match.
Wonder if it will ever be seen as advantageous?
if it was 50 foot wide and 100 foot cars, there would only be about
50 cars on the train, I think earthy trains can get longer than
one mile. so say you have 8 wheels on each car, times 50 would be
about 400 wheels, surely enough for traction if it doesn't weld
together. The vacuum on the moon is orders of magnitude better than
most vacuums on earth so it concievably could be a problem. The
temps between night and day side would have to be carefully
thought out also, minus 200 in the dark, plus 200 in the day, so
at least a 400 degree differential in regular 28 day intervals.
Originally posted by sonhousewhy not make the train length equal to the circumference of the moon ... and use external impellers ...
if it was 50 foot wide and 100 foot cars, there would only be about
50 cars on the train, I think earthy trains can get longer than
one mile. so say you have 8 wheels on each car, times 50 would be
about 400 wheels, surely enough for traction if it doesn't weld
together. The vacuum on the moon is orders of magnitude better than
most vacuums on earth ...[text shortened]... e dark, plus 200 in the day, so
at least a 400 degree differential in regular 28 day intervals.
even if it wasn't that long, you could use the impellers ...
some guys out in california that do Junkyard Dogs kind of stuff made a weapon ... two tires spinning in opposite directions but almost touching, driven by a car motor ... fed two by fours through and demolished a shed with it ... use something like that ... think i've seen something similar on some of the theme coasters at disney ...