Difference between revisions of "Elephants with spiderlegs"
m (→Math in more detail & making it work even better by "making the elephants hollow": added spaces (that where left out due to twitter char limit)) |
(→Math in more detail & making it work even better by "making the elephants hollow": added some elaborations) |
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we get | we get | ||
𝜎 = F/A ∝ L^0 | 𝜎 = F/A ∝ L^0 | ||
| + | |||
| + | Good! works for all scales :) | ||
| + | But speeds stay constants so frequencies drop. | ||
| + | Not so good. Can we do something about it? Yes ... | ||
| + | |||
hollowing stuff out | hollowing stuff out | ||
(as is possible in low gravity) | (as is possible in low gravity) | ||
| Line 39: | Line 44: | ||
changes | changes | ||
𝜎 = ∝ L^-1 | 𝜎 = ∝ L^-1 | ||
| − | so we can do | + | so we can do what we wanted (increase speeds along with size) |
v ∝ L^1 | v ∝ L^1 | ||
and be back at | and be back at | ||
| Line 48: | Line 53: | ||
When scaling to larger sizes forces from accelerations do NOT scale faster than the strength of the material. Given speeds are kept constant! <br> | When scaling to larger sizes forces from accelerations do NOT scale faster than the strength of the material. Given speeds are kept constant! <br> | ||
But if structures are hollowed out, as it is possible under low enough gravity, speeds can be scaled up along with the size. | But if structures are hollowed out, as it is possible under low enough gravity, speeds can be scaled up along with the size. | ||
| + | |||
| + | {{todo|How does this go together with the scale invariant [[unsupported rotating ring speed limit]]??}} | ||
== Conclusion == | == Conclusion == | ||
Revision as of 07:44, 24 August 2021
Contents
In fiction and art
In "star wars", "war of the worlds", and Salvador Dali's pictures
it's likely just an artistic choice to make it look alien/surreal by making it look like something
that cannot be found by a long stretch (pun intended) in our world.
The artists probably have not thought deeply about the physics involved.
Making it work by by reducing gravity
Despite clearly not working here down on Earth with our crushing gravity
interestingly this "gargantuan spiderelephant anatomy" might actually practically work
on low but not too low gravity celestial bodies like e.g. big asteroids where the k in
» F_grav ∝ k * L^3 «
is sufficiently small.
Pros:
- no continuously depleting propellant needed
- more control than jumping
Math in more detail & making it work even better by "making the elephants hollow"
F_inertial = m ω^2 r = m v^2 / r with m ∝ L^3 and assuming ★ v ∝ L^0 ★ r ∝ L^1 we get F_inertial ∝ L^2 with A ∝ L^2 we get 𝜎 = F/A ∝ L^0
Good! works for all scales :) But speeds stay constants so frequencies drop. Not so good. Can we do something about it? Yes ...
hollowing stuff out (as is possible in low gravity) changes m ∝ L^2 changes 𝜎 = ∝ L^-1 so we can do what we wanted (increase speeds along with size) v ∝ L^1 and be back at 𝜎 ∝ L^0 again
In words:
When scaling to larger sizes forces from accelerations do NOT scale faster than the strength of the material. Given speeds are kept constant!
But if structures are hollowed out, as it is possible under low enough gravity, speeds can be scaled up along with the size.
(TODO: How does this go together with the scale invariant unsupported rotating ring speed limit??)
Conclusion
Machines shaped like Salvador Dalì's Elephants Might actually work and exist in the future on asteroids. Heck space-probes could probably do this in the foreseeable future.
Related
External links
- "The Elephants" by Salvador Dali
- Originally posted here on twitter: [1]
