h a l f b a k e r yMake mine a double.
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This can be made from a plastic kitchen funnel.
Make
one side black with marker or paint and put it in
the
sun with the dark side up. The air in the cone of
the
funnel will heat up and expand. New, unexpanded
air
will be sucked in through the tube. After being
left
out in
the hot
sun for about 20 minutes, air will be
screeching through it and about 15 lbs of thrust
will
have developed. With two of these, this is enough
to
propel a skateboard + rider at up to 27 mph.
[link]
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//New, unexpanded air will be sucked in through the tube.// |
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Why? If the air in the funnel is expanding as it would be expected to, it will also expand back down the tube, preventing any air from moving in. |
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It's much easier for the air to go the other way. Air,
being lazy, will not want to go back into the tube. |
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If the air's momentum isn't enough to keep it flowing, maybe it needs a gas-turbine-like arrangement, with a small fan blowing air into the black-painted expansion region, and a large fan tapping some of the thrust to turn the smaller one. |
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Would heat be transferred into the air quickly enough for this to work? |
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//about 15 lbs of thrust will have developed// |
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Where did you get this figure? Did you calculate it or measure it? Either way, could you expand on this a bit? |
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This is an excellent idea, and I do not think we
should let the fact that it won't work, has no
grounding in reality, and cites spurious and
irrelevant numbers detract from that by one iota. |
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[jmvw], I have two questions: |
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A) If this could be constructed using only a plastic funnel
and some black paint, why didn't you make one and find
out for yourself that it won't work instead of throwing it up
here for us to ridicule? |
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3) If something so simple could actually provide motive
power, don't you think it would be in common use by now? |
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1. I may or not may have built this myself. But if I did
(and I am not saying that I did), I might not be able to
share this information with you as my life could be in
danger because of the obvious economic importance in
skateboard propulsion. I have to protect my work and I
may or not be in the process of perfecting this
invention (by selecting the best type of marker and so
on). |
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2 //Where did you get this figure?// |
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Thank you! I think sitting at a desk, eating bread and
drinking
beer really helped me get where I am today. |
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2. //could you expand on this a bit?// |
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The air expands on the outlet side of the funnel. |
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// I might not be able to share this information with
you as my life could be in danger because of the obvious
economic importance in skateboard propulsion. // |
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Do you think an old fashioned metal funnel might work better? |
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About the same, I would think. |
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I don't think so; beyond the obvious weight issues, there is
also thermal retention to consider. There would be an
advantage in conductivity, but I don't see it outweighing
the benefits of a lightweight plastic construction. |
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Of course, a carbon-fiber funnel would be ideal. |
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Bun for the exactitude of the estimated 27 mph skateboarder and because it inspired my
time machine idea. |
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Thank you for keeping this going. I appreciate the
comments, I really do. And I agree, carbon fiber is a
neat material for certain specialized applications. |
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But now I have no idea what got into me to write this
nonsense. It's nice weather outside and getting later
and I haven't gotten much work done yet today. It's
really time to stop playing and instead I need to
contort myself back into the sullenness that puts bread
on the table. |
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Dr. Remulac was right with his mock idea. My idea is
worthless. |
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So I apologize for wasting everybody's time in such a
trivial way. I'll come back if I think of a more effective
way to waste your time. |
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The real problem with this idea is that you didn't couch it in copious technical-sounding verbiage,
nor did you back up your point with several links of questionable relevance and scientific value.
Observe: |
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skateboard propulsion by means of solar-powered simulated "seebeck effect" |
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massive energy can be generated at nearly no cost except for paint and kitchen utensils by applying
free ubiquitous sunlight and converting it to heat energy |
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Through means of the well-known Seebeck Effect large quantities of power can be generated by
heating the junction of two dissimilar metal wires. As the point where the wires connect has
increased heat applied electricity (which is just a form of power useful to do work) is produced. A
similar process to the SE can be achieved by replacing the wire with two sides of a common kitchen
funnel and applying a coating of black paint in opposition to the white outside of the funnel. Thus
creating a dielectric that can be operated with no electrical charge, but providing the basis for the
SE to apply to the ambient air instead of charge carriers in the funnel (instead of the wire). |
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There are many processes for converting trapped solar heat energy to kinetic energy, and such a
process could be applied to the air that the dome of the funnel surrounds. Air in general will
undergo expansion when subjected to rapid heating, leading to movement and the transfer of energy
from the heat form to the kinetic form. As photons strike the coated interior funnel surface they
bounce off but leave a heat signature that is depleted rapidly by cooler air. But then the cooler air
in the funnel expands through the kinetic transfer process forcing the now cooler air out through the
neck of the funnel, completing the open Newtonian system. The ejection of the cooler air and the
partial vacuum created in the space the air previously filled causes the propulsion of the skateboard.
Based on the composition of sea level air being 78.084% N2 and 20.947% O2, with trace gasses
including Ar (0.934%) and CO2 (0.033%) and Ne (in quantities of 18.2ppm), the rate of propulsion
would be enough to accelerate a 60kg rider and skateboard total to a speed of up to ~72.5
kilofurlongs/fortnight. |
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While looking at the links to various kitten videos provided, think of the kitten as the funnel and the
fur as the paint, and the piano music as the air rushing in the funnel and out through the neck. |
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//It's really time to stop playing and instead I need to contort myself back into the sullenness that puts bread on the table. Dr. Remulac was right with his mock idea. My idea is worthless.// |
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Crazy entertaining ideas are worth a lot more than sullen table breading. Sometimes being the bread-winner should just consist of getting a couple of buns from the Halfbakery. We all need a break now and then. [+] |
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As a UK citizen I have to ask what is this "sun" you speak of? We have no knowledge of this mysterious, possibly legendary, phenomena. |
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//Thatcherism came in and flares went out of fashion |
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which was the greater tragedy? |
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jmvw - you might as well run this idea past S&P, they signed off on the collateralized debt, so they probably sign this one off too.. |
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//flares went out of fashion//
They did? Oh dear. Time to go shopping again. |
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[jmvw]--never apologize! Take your lumps with pride, use
incoming ridicule for targeting data, and turn all derision
into motivation! Stay proud, my friend. |
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/wasting everybody's time/ |
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I was thinking about this. |
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1: Only thin part of funnel is black. |
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2: Thin part is not only black but also freaking long. Maybe a metal tube attached to funnel. Maybe it has fins too - stylish, but also to increase surface area and captured heat. Or maybe it is flat with just a slot for air to pass. |
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3: /it will also expand back down the tube- MechE/ Inside funnel, juncture of cone and freaking long thin part has a propellor which spins only one way. It acts as a valve. Air cannot exit the long part back into the cone. It must shoot out the back. |
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4: A series of these could be placed atop a skateboard. The passenger (for purposes of the video) would be a gnome, bobblehead or comparably low mass test subject. |
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A small amount of the airflow should be diverted through a cutout, which would cause a sound to be generated. |
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Thus your over-speeding skateboard would wail its way, Stuka-like, through traffic... Safety feature, don't you think? |
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Only for a couple of years. Later in the war, ground-
pounders learned that the Stuka siren meant 'he's diving in
a straight line, if we shoot at him there's nothing he can do
about it'. Considering how irritating it is when
skateboarders are weaving through traffic, the same
phenomenon would probably take hold. |
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//As a UK citizen I have to ask what is this "sun" you speak of?// |
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As a Seattleite, I call him 'BOB', as in Big Orange Ball. He goes into semi-hibernation from mid-September to mid-April, occasionally poking his head out between the nice cushy clouds. He's shy, though, and any mention of BOB quickly results in his return to hiding. |
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When he does finally wake up in late Spring, he hangs out for a while and seems to be quite friendly. |
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