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Re: starship-design: Timothy's beamed power paper
On Mon, 21 Jul 1997 11:23:32 +0100 TLG.van.der.Linden@tip.nl (Timothy van
der Linden) writes:
>>12b It would be preferable that the sail is at the Earth-side of the
>>ship, this way the ship itself is not "shined" upon (and not heated).
>>This also means the sail needs to push the starship which may be more
>>difficult than the pull (parachute) method.
>>
>> Here we run into the problems of tension vs. compression
>members.
>> Example, take a short length of wire, doesn't matter how long. Hang
>it
>>up and add weight to the free end. This is tension, or pulling,
>stress.
>>Now stand the wire on end and add weight to the top. This is
>>compressive, or pushing stress. Try it if you like, but you can
>probably
>>guess that the wire in compression will fail with less weight than
>the
>>wire in tension. The end result is that compression members, like
>you're
>>proposing, will be heavier than tension members needed to handle the
>same
>>mass of vehicle.
>
>True, the parachute design would likely be easier and lighter. The
>mean
>reason for pointing out the above problem was that you'd realize that
>we
>needed some extra shielding.
>
I thought of a simple solution to this a few hours after sending that
message.
000
PAYLOAD----> 000 /\
000 | DIRECTION OF TRAVEL
00 |
00
SAIL | SAIL
________________________________ | ________________________________
\ |
/
\ |
/
\ <-----TENSION | <-----Compression
/
\ MEMBER | Member
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\ |
/
\
| /
\
| /
\ |
/
\ | /
\ | /
|
Lighter than the compression member only idea, and only a little heavier
than the tension only, especially since it should reduce the shielding
problem.
Jim