heh, yeah, he takes things pretty seriously.

it is an interesting approach for sure, one problem I see with it is that rope/cable(if I understood idea correctly) will sage and on the 50km length required, it should probably be a significant drop, to the tower may need to be high enough, but how much is a question I'm thinking about that atm

the paper i like about the concept is by Geoff Landis, have you seen it?

but generally, it will restrict the thin or by location or by the need to f huge excavation

no, didn't

"Analysis of a Lunar Sling Launcher" - this I guess

yeah, you beat me. i should have just searched for 'sling launcher' instead of trying to delve into my huge collection of links :]

i'll put the link, though, in case it comes up later.

home.earthlink.net/~geoffrey.landis/Lunar_Sling_Launcher.pdf

yeah, google is at that point a database

oaky, it looks like cable mass is underestimated, about an order of magnitude (tapered value)

I may be wrong, but for a payload 2.8t, with 3550m/s on the tip, from fiber 2.7t/m3 2.8GPa strength it is about 70000 t

@MolbOrg i had a feeling there was something wrong there, but i had nothing to back it up.

i could have put my nose in the formulas Hoh used in the tether tool, but i didn't want to step away from model work long enough to think that through.

I descided to excercise myself and write a script which gets me numbers, may be wrong, would say 80% sure in that regard

wish to figure out the sag in the sable in those conditions, but stuck atm

okay, I was wrong, used different strength number

okay, the mass was correct

i did try plugging the numbers into the tether tool, and was surprised to find that it isn't all that bad for skyhooks around the Moon.

not good enough to use it over zylon, but not as bad as i thought.

yeah, used 2GPa instead of 2.8GPa and there is huge difference

but there is no safety factor along the cable, it works on the limit

2GPa instead of 2.8 could be considered like 1.5 safety factor along the cable

he does mention a design factor in the spreadsheet, which i think is what he means there. however i didn't sort through the formulas to see if he'd done it right.

he actually contacted me because he recalled i'd suggested using a carousel approach for a sling launcher, using many arms with smaller cables and payload dispensers on the ends that release a set of payloads, one per revolution when the arm is pointing in the right direction

i thought it could minimize the stress on the cables and the central tower due to recoil.

however, that was for a very particular application, where the payloads didn't weigh much but there were lots of them.

anyhow - how a material deals with recoil, going from having a big strain to suddenly having none at all, strikes me as a big unknown factor here.

yes it is a problem to some degree - but is just a question of release time(it can be done a gently release based on magnetic effects or magnetic friction(do not recall how it is called))

some 3-5 km release part of the thing.

there will be a problem of limited speed of a sound wave in the material, but i guess it can be solved by combination of ho payload is accelerated and how it is released

no trilled by the option, but it is an option

not thrilled because of limitations, because of it still massive and because of problems of production, and because of low throughput, and and and

yeah, i agree

i'm quite happy with a combination of skyhooks, mass drivers, and nuclear ships

probably one of the features which may or may not be important - is that it can release payload in any of 360 degrees direction. it may be important feature, it may not. idk