Difference between revisions of "Elephants with spiderlegs"

Revision as of 08:34, 24 August 2021

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
hollowing stuff out
(as is possible in low gravity)
changes
m∝L^2
changes
𝜎 = ∝ L^-1
so we can do
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.

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

• Scaling law

External links

• "The Elephants" by Salvador Dali
• Originally posted here on twitter: [1]