tag:blogger.com,1999:blog-3596550435682943926.post1932480923316424202..comments2017-06-22T09:43:33.884-07:00Comments on Hop's Blog: Zylon Mars ElevatorHollister Davidhttps://plus.google.com/114678369190318229821noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-3596550435682943926.post-47751077963003249722017-06-15T13:41:28.993-07:002017-06-15T13:41:28.993-07:00Bumblebee,
"Is there any merit in an exceptio...Bumblebee,<br /><i>"Is there any merit in an exceptionally slowly rotating rotovator?"</i><br /><br />Long thin objects want to hang vertically in a gravity field due to tidal effects.<br /><br />The slower it is rotating, the quicker it will stabilise, hence the more energy will be required for keep it turning against this tidal braking.<br /><br />That said, if most of your mass is moving down-hill - for example, supplies from Earth for the colonists, fuel from Phobos for ships, etc - then a rotovator tether below Phobos' orbit will have net positive momentum which will raise its orbit. Using moving masses along the tether, synced to the tether's rotation, it might be possible to harvest that extra momentum and convert it to rotation.<br /><br />Paul451http://www.blogger.com/profile/12119086761190994938noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-46700097410487694322017-06-15T13:30:11.717-07:002017-06-15T13:30:11.717-07:00Matter Beam, Secondary cable? What's the mass ...Matter Beam, Secondary cable? What's the mass of this secondary cable? Do you imagine a loop with a pulley on each end? How much mass is the pulley? How many newtons of stress can the junctures with pulleys withstand? Going around a pulley would induce bending and flexing thus wear and tear on the tether.<br /><br />A straight line isn't a valid assumption. Elevator cars going up or down will have Coriolis force pushing the tether sideways inducing oscillations. <br /><br />Also how much horse power will the elevator cars have? Or how much horse power would the engines driving the pulleys have? How many kilograms are the engines and power source?<br /><br />1 km/s can easily be achieved if you use lots of hand wavium.Hollister Davidhttp://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-6033439977009669492017-06-15T07:08:51.285-07:002017-06-15T07:08:51.285-07:00I see.
So for every 1kg of climber, you'd ne...I see. <br /><br />So for every 1kg of climber, you'd need 192kg of Zylon and 1200kg of counterweight?<br /><br />You know, the situation can be flipped around if we consider much faster travel times. A free wheeling mass pulled up by a secondary cable attached to the tether and travelling through vacuum is unlikely to limit itself to 260mph. 1km/s can easily be achieved. After all, the tether is very straight and after the initial boost, you'd only need to counter gravity drag. You can also just drop the empty bucket once it reaches the top. It could be completely used up instead: a spool unrolling as it travels with the remains adding to the counterweight mass.<br /><br />The elevator is 19700km long or 17000km? That's a travel time of 5.5 to 4.7 hours and not having to travel back down would mean the elevator can double its mass in 24 trips using a factor 1.03, or about 5.5 to 4.7 days. Within a year... well, it adds up extremely quickly. Matter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-23362037386903073412017-06-13T13:09:22.574-07:002017-06-13T13:09:22.574-07:00Matter Beam, go to The Whole Shebang section. For ...Matter Beam, go to The Whole Shebang section. For the lower part of the elevator as well as the upper part to counterblance, you will need 1,920 tonnes of zylon to accommodate a 10 tonne payload. 10/1920 = .00521. About 5%.<br /><br />And that's with a safety factor of one. Hollister Davidhttp://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-77347443265628234772017-06-12T17:46:23.403-07:002017-06-12T17:46:23.403-07:00Hollister David:
I'm sorry, but how did you g...Hollister David:<br /><br />I'm sorry, but how did you get the 0.5% figure?Matter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-40454574332154162312017-06-12T01:42:55.534-07:002017-06-12T01:42:55.534-07:00Is there any merit in an exceptionally slowly rota...Is there any merit in an exceptionally slowly rotating rotovator? Where the only real purpose of the rotation is to transport material from point A to point B without the need for a elevator car?Bumblebeenoreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-51342190174525304322017-06-10T10:57:47.709-07:002017-06-10T10:57:47.709-07:00Matter Beam, let's say average speed of elevat...Matter Beam, let's say average speed of elevator car is about 260 miles per hour. It'd take two days to ascend and two days to descend the elevator. The elevator and contents can be about .5% of the tether mass even if you're daring and optimistic and use the safety factor of 1. The elevator engines and power source are going to take some mass so let's say the contents of the elevator car contain .3% of the elevator mass in Zylon. 1.003^230 is about 2. So it would take 230 4 day trips to double elevator mass. And that's using some very optimistic assumptions.Hollister Davidhttp://www.blogger.com/profile/12923433894475072056noreply@blogger.comtag:blogger.com,1999:blog-3596550435682943926.post-46588850465896216182017-06-09T17:14:41.874-07:002017-06-09T17:14:41.874-07:00What about a tether that is built gradually?
You ...What about a tether that is built gradually?<br /><br />You run a very thin tether down from your spaceship. It can carry a few dozen kg at most. The first step is to run a second line up, and add mass to the spaceship.<br /><br />After a few weeks, you'll have the massive propellant depot needed as counterweight, and the large bundle of tether strands needed to provide the tensile strength. <br /><br />The propellant depot/counterweight can fuel spaceships to complete their journey and artificially increase the throughput of the tether to increase its usefulness. Matter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.com