XPost: sci.space.policy, sci.physics
From: fjmccall@gmail.com
Sergio wrote on Mon, 18 Jun 2018 22:17:21 -0500:
>On 6/18/2018 8:06 PM, Alain Fournier wrote:
>> On Jun/18/2018 at 2:45 PM, Sergio wrote :
>>> On 6/16/2018 8:54 AM, Alain Fournier wrote:
>>>> On Jun/15/2018 at 11:34 PM, Fred J. McCall wrote :
>>>>> JF Mezei wrote on Fri, 15 Jun 2018
>>>>> 22:13:01 -0400:
>>>>>
>>>>>> On 2018-06-15 19:21, Alain Fournier wrote:
>>>>>>>
>>>>>>> Yes. But I think I am a little less optimistic than you about it
>>>>>>> becoming practical in the future. If we have fantastic materials
>>>>>>> in the
>>>>>>> future, maybe an elevator will become more practical,
>>>>>>>
>>>>>>
>>>>>> Apart from lifting geostationary satellites to just below orbit and
>>>>>> then
>>>>>> let them use their own thrusters to position to their assigned
>>>>>> slot/longitude, what other use would a space elevator have ?
>>>>>>
>>>>>
>>>>> You go above the GEO point on the cable and get flung on
>>>>> interplanetary trajectories.
>>>>
>>>> Yes!
>>>>
>>>> You would also likely put at least one cable above GEO rotating in a
>>>> plane perpendicular to the main cable. So you can give an extra push for
>>>> interplanetary trajectories and to fine tune in which direction you
>>>> depart for said trajectories.
>>>>
>>>> You can also jump off at an altitude of about 15000 km (that figure is
>>>> from the top of my head, it might be more or might be less). From there
>>>> after a few passes of aero-braking you can reach LEO with very small
>>>> thrusters.
>>>>
>>>> For polar orbits, you use the rotating cable above GEO mentioned above.
>>>> But instead of using it for extra push you get off while it is
>>>> subtracting some speed but not quite in the direction of rotation of the
>>>> cable. So you subtract some speed in the direction of rotation of the
>>>> cable and give some speed in the north-south axis. You then use
>>>> aero-braking again to lower apogee, and a small thruster to raise
>>>> perigee. Note however that using the elevator to reach polar orbits in
>>>> this way isn't obvious. You would want a long and fast rotating cable
>>>> and you would want it far above GEO, it might not be practical to do so.
>>>>
>>>> Building an elevator, with current technologies, is outrageously
>>>> expensive. But if you have one, it can be very useful.
>>>>
>>>
>>> we don't have one, and never will. It is a joke among Engineers.
>>>
>>> What would is the monthly insurance payment for it? if it fell over ?
>>
>> You put the cable on an east coast. You also put a system to cut the
>> cable at something like 10000 km high. If the cable breaks below that
>> 10000 km the upper part doesn't fall it goes up, the bottom part falls
>> in the ocean, where it isn't likely to cause damage. If the cable breaks
>> higher than 10000 km, you cut it at 10000 km, the bottom 10000 km falls
>> once again in the ocean. The two other parts won't fall to the ground,
>> the lower part will probably be in an elliptical orbit, the higher part
>> might be in an escape trajectory. So the damage from a cable breaking
>> doesn't have to be high. It might be a little difficult to explain that
>> to an insurance company, but if you can pay for the cable, you should be
>> able to cover the damages.
>>
>
>how much does 10,000 of cable weigh? 100,000 #
>the center of gravity is directly over the support, so you have 100,000#
>of steel cable crashing onto it.
>
Nope. The Earth spins, you know. And STEEL? That's cute.
>
>nothing will go into orbit as the accelleration vector is stright down,
>gravity.
>
Well, no. When whole, the cable is under tension, not compression.
Remove weight from the bottom or break the tether point and it goes UP
above the break, not down.
>
>>
>>> how many miles would the top swing back and forth ?
>>
>> Why do you care?
>>
>
>I asking to see if you know what you are talking about. 20,000 km is
>12,427 miles, if you support the tower it will swing at least 2 degrees
>sin 2 degrees = 0.035 times 12427 = *434 miles*
>
>does the tip swinging wider than most states bother you ??
>
You're not smart enough to be asking questions. It's not a 'tower'.
>>
>>> How much sideways force is pushed on it by a 20 mph wind ?
>>
>> Why do you care?
>
>...to evaporate your imagination with facts.
>
That would be refreshing. When are you going to start?
>
>>
>>> how much does one guy wire weigh ? (assume 20,000 km elevator height)
>>
>> Why would you put a guy wire? Don't assume 20,000 km elevator height,
>> assume 70,000 km, you want the top of the cable to pull up the bottom of
>> the cable, so you have to go beyond GEO height.
>
>so what is the weight of 70,000 km of cable to support 500# ?
>
That rather depends on what it's made of.
>
>[there is no cable that will support itself 70,000 km, darling)
>
There is no cable that will support its own weight like that YET. You
really need to STFU until you educate yourself.
>
>>
>>> how much does one copper cable weigh if moving 200 amps ?
>>
>> Don't put a copper cable. Send energy to the climber using some kind of
>> beamed energy. (A laser on the ground, maybe another one in
>> geosynchronous orbit, and photocells on the climber to convert back to
>> electricity. Or something of that kind.)
>
>Use McGinn's patented plasma's and water vapor it up. What happens
>when you use a 1000 watt laser to shoot power to it ? the beam heats up
>the air and defocuses the beam and the power splinters out, the power
>does not get there.
>
>there is no know laser that can meet the dispersion requirements either
>(google dispersion laser)
>
Hogwash.
>>
>>> What voltage is needed at the ground to feed the copper wires ? assume
>>> 500 V AC needed at the top.
>>>
>>> How much does the tower weigh counting only the copper wires, main
>>> cable, and guy wires ?
>>
>> The copper wires and guy wires are nonexistent and therefore weigh
>> nothing. As for the main cable, it weighs way too much. That is why I
>> said in the message to which you are replying that "Building an
>> elevator, with current technologies, is outrageously expensive." I don't
>> think we will ever have one.
>
>it is joke bate by Engineers,
>
You wouldn't know an engineer if you tripped over one.
--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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