Stephen A. Lawrence wrote:
10 MW is a measure of power. "Strain" is, technically, a measure of
deflection due to an applied force IIRC, but the way you've used it
it's a measure of tension on a cable, which is just force.
Yes, I am well aware of these differences, but I was writing
informally. (Meaning: in a sloppy manner.) I know a lot about
railroad locomotives.
Megawatts are a measure of power. "Load" on a cable is a measure of
force. The two are completely different; the phrase "... a load of
10 MW" is meaningless.
I know, but I meant the load that operating a 10 MW generator on the
ground would put on the cable.
Power generated by a laddermill would depend on cable tension and on
how fast the mill turned, and without knowing (or guessing at) the
latter you can't say anything about requirements on the former.
The mill would have to have gears.
It is easy to guess at how quickly the cable would move. For one
thing, it would have to move a huge unwieldy string of kites which
can only rise and fall at a certain speed. Second, the cables would
not move much faster than the fastest cables used in excavation
equipment, elevators, cable cars, ski lifts and the like. People have
been using cables for a long time. If they could make them move much
faster, I expect they would.
There are enormous cables on excavation equipment that are actuated
with megawatt motors, but these cables are extremely heavy and I do
not think any excavator motor is as large as 10 MW. I think the
largest in history was "Big Muskie" which had a 2000 hp dragline
motor (1.5 MW).
I recall reading that some of them could hold back something like
100 railway locomotives.
You have carried the simile too far and it fell over a cliff.
You're no longer talking about power from the engines, you're now
talking about power applied to the wheels. Power applied to the
wheels is the product of torque and rotational velocity. When the
locomotives are stationary, they are applying ZERO power to the wheels.
Obviously I meant that 100 locomotives from a standing start could
not pull hard enough to break the cable. If it moves fast enough even
1 locomotive can break any cable. For example, if you drop the
locomotive from the Oort cloud to Earth.
- Jed
