h a l f b a k e r yIt's as much a hovercraft as a pancake is a waffle.
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So building a bridge is a massive infrastructure undertaking. Can we do
something more fun? Physics of cannon balls and gliding is well known,
and
we have the math right for control of gliding, and light propulsion engines.
The Catapult Plates for cars works by using your car's momentum as the
initial energy, magnetically locking and clamping your car to the plate, and
then using
the
rail-gun technology to accelerate it to the speed of say
over
500 mph over a short distance, so that relatively small wings on the sides
of
the plate would be enough for your car to fly over a distance without road
(such as a mountain range, a large crevice, or just about any two places
of
the city).
Your car would take a near-quadratic equation trajectory to reach the
destination,
every time feeling near-0G experiences in the midst of it.
The plate would have mini liquid fuel rocket engines to adjust the glide to
precision-align with the plate capturing end, which would decelerate by
recuperating the kinetic energy to the large high capacity condensers, to
be
used by another other ride towards the opposite direction.
To avoid the in-air collisions, the mini rocket engines would be used as
well,
allowing for a controlled in-air car flows between two points of a city.
Slash the road infrastructure development costs by large margins. And,
can't see how this wouldn't work for capsules with individual humans too.
Could be
closest thing to teleportation, and a direct application of projectile control
technology.
Previous 'art'
https://www.nfb.ca/...evil_at_your_heels/
KenCarter, shades of early HB and RedGreen [Sgt Teacup, Nov 20 2019]
Lift to drag ratio
https://en.wikipedi.../Lift-to-drag_ratio
Largely dictated by the aerodynamics of your vehicle. [Frankx, Nov 20 2019]
[link]
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What could possibly go wrong ...? [+] |
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I'm picturing a brown-out, in which power to the rail gun is not
shut off completely but is reduced enough for the glide-plate and
payload to fall a bit short of the off-ramp. |
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<Sets up GoPro to capture Epic Fail/> |
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// What could possibly go wrong ...? // |
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Like, re-accelerate and jump again at the other end, like flat stones on
water? |
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A very small change to the specification would produce "Catapult Plates for Cats". |
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We will buy the entire IPO for that, cash down. |
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//I'm picturing a brown-out// What's needed, shirley, is a
system powered by gravity, since gravity rarely fails. You
just need a spiral road climbing up to the top of a very tall
ski-jump type slope. Drive to top; put car in neutral; wait.
The car should leave the ski-jump with sufficient speed to
arc gracefully across the river and land gently on a ramp on
the other side. |
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Obviously, the ramp should be made of orange plastic. For
fun, one or two loop-de-loops could be incorporated. Such
a system has the advantage that it will be self-calibrating
with respect to vehicle mass. |
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// Such a system has the advantage that it will be self-calibrating with
respect to vehicle mass. // |
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So, even trucks could pay in gravitational potential? Still, trucks would
need a longer board and much more energy. Passenger vehicles, being
small, lightweight and nimble, with slight variance in weight, and
dimensions, seem much more practicable. |
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//trucks would need a longer board// No, all vehicles can
use the same board, assuming that they have a low
(negligible) rolling resistance. |
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Thought experiment as follows:
(1) Build 2 ramps side by side, suitable for cars
(2) Send 2 cars simultaneously down the ramps; both cars
make the jump
(3) Repeat (2), but with a layer of glue between the two
cars as they jump side-by-side; nothing significant has
changed, so they'll jump together.
(4) Replace the glue with a welded joint. Again, nothing
important has
changed, so the two cars jump side by side
(5) If (4) works, then a truck weighting the same as 2 cars
will also work. |
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// shirley, is a system powered by gravity, since gravity rarely fails // |
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Terminal velocity upon gravity may be insufficient for gliding desired
distances with small wings. Though, the wings on the plates may be
made larger of course, small velocities may still be sufficient for jumping
over small rivers, but not over larger, like River Thames. Or, for getting
from one city district to another. |
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The example by [Sgt Teacup] of KenCarter stunt driver trying to make a
mile, shows how small velocities with a too steep
trajectory end up ending. |
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// How efficient are gliders? // |
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"A ratio of 30:1 means that in smooth air a glider can travel forward 30
meters while losing only 1 meter of altitude."
(Wikipedia:Glider_(Sailplane)) |
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As a toy experiment, I'd start with a brick on wheels that catches on a
cardboard wing. |
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//gliders//
Gliders only achieve ratios of 30:1 by having very
long wings and very very low drag (or rather, high
L/D ratios) |
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// having very long wings and very very low drag // |
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That's precisely why I think higher velocities are needed, beyond terminal
velocity upon natural gravity, as in what [MB]'s imagined. |
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// a brick on wheels that catches on a cardboard wing // |
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Boeing seem to have a lot of Prior Art in that area ... |
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//terminal velocity//... only applies to things falling under
gravity in an atmosphere. It's the velocity at which upward
aerodynamic drag balances weight. |
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It's not usually applied as a concept to aircraft or ballistic
trajectories. |
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