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Balloon-O-Stat
Insert this device into a pair of balloons to fly them remotely | |
A little remote control motorized car you insert into a
balloon before you
blow it up which has a rotating magnet on the bottom. In a
second
balloon, you put a round magnet to which the magnet on
the
little car in the first balloon attaches itself, so the two
balloons are held
together
but may rotate freely as the little car runs.
When you turn the little car on, it starts the balloon it's in
turning and since the other balloon is attached via the
rolling magnet the two balloons counter-
rotate respective to each other and should fly through the
air
due to the friction on the backward rotating portion of the
balloons.
Magnus effect
http://en.m.wikiped.../wiki/Magnus_effect
Odd, yet real. [8th of 7, Mar 23 2014]
Balloon-o-stat schematic
https://www.dropbox.../BALLOON-O-STAT.jpg
Little remote control car makes it go forward or backwards. Wonder if you could make it turn as well? [doctorremulac3, Mar 24 2014]
[wbeaty] explores a similar concept
http://amasci.com/a.../vortgen.html#blimp
But much more complicated to implement than yours. [scad mientist, Mar 24 2014]
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Description (displayed with the short name and URL.)
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I sort of get this, but I don't see how the
counterrotating balloons generate lift. |
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It's called the Magnus effect. |
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The magnus effect, per se, generates a force at right
angles to the principal direction of motion (as in a
curve-ball). |
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Spinning a balloon, or a pair of balloons, will not
necessarily achieve much. |
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Where the balloons make contact, the effect is negated. Opposite the contact point, the moving balloon surfaces push the two balloons along. Not very fast or very efficiently, but they would move. |
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Yep. Like a cross section of a vortex ring with a teeny center. If these balloons had little hairs on them they would truck right along, but then that would be cilia. |
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[2fries], your suggestion bristles with
impracticalities … it might just work, but it
would probably be a close shave. |
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If the pair of rotating balloons is symmetrical about a horizontal
plane which passes through the interface how can it produce a
net vertical force? |
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It would move horizontally, not vertically, with the
car holding balloon being at the top and the round
magnet balloon being on the bottom. |
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I don't get that at all then.
The way you just described it, both car and magnet end up sandwiched between doughnuts and your center of mass makes the whole thing tip on its side. |
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It must be a semantics thing,
by //rotating magnet on the bottom// do you mean in-line with the little cars' motion, or perpendicular to it, or horizontal to the little car? |
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By //round magnet// in the second balloon, do you mean like a cylinder or like a sphere?
How does this fly if its travel is horizontal? |
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It worked in my head only a minute ago and now it's just gone. Any chance of a sketch?... |
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//Any chance of a sketch?...// |
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Ah. It will work but your car won't remain upright. |
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Sure it will. Is the heaviest part of the assembly so
it hangs down at the bottom of the top balloon. It's
too heavy to climb up the side of
the balloon so the balloon just rolls under it. |
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The bottom ballon is just hanging from the underside
of the heaviest element which is the car and it's
rolling magnet. |
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To visualize it, just ignore the bottom balloon for a
second. The car just rolls around the trying to climb
up the balloon walls but can't because the balloon is
rolling under it treadmill style. Then you add the
bottom element that rolls in mirror image to the top. |
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If the car is the heaviest element then it will want to hang upside down unless only the upper balloon is helium filled or the magnet roller outweighs the car. |
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If both weigh the same and the balloons are air filled then it will tip and travel horizontally. |
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Ohh, I get what you're saying. I forgot about the lift
from the lower balloon. Yes, you're absolutely right.
Duh. |
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Consider the drawing an overhead view. |
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Or, as you've pointed out, just put air in the bottom
balloon. |
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Yes, that should work. I hadn't realised that the whole assembly was neutrally buoyant. |
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//neutrally buoyant// [marked-for-tagline] |
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I went back to the original notation and re-wrote it
in English since the original post was written in sort
of a coffee break rushed Englishesque fashion. |
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Should make a little more sense now. |
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A very similar concept was documented by [wbeaty] on his own site <link>. It's similar in the way that it would fly but would be complicated to implement. [doctorremulac3]'s version should be pretty simple to implement, but probably won't have quite the performance that [wbeaty] was hoping for. Acceleration would be limited by the magnetic force holding the balloons together. |
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It seems like you might be able to have some vertical control if you designed the car to shift its weight forward of back relative to the position of the magnet. That would allow it to point up or down slightly. |
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Although ladies might visualize something more,
ahem... masculine,
depending on their mindset. |
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Oh. I thought you said "flying bobbles", re Vernor Vinge. |
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This should work very well but... post-
acceleration, the speed of the outer balloon walls
is zero wrt the outside air, and the speed of the
cars along the balloon wall is 2x the speed of the
entire craft. The cars would have to race pretty
fast. |
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How long would batteries last, i.e. how efficient is
this compared to using tiny propellors? Tiny
propellors are *very* inefficient. But tiny cars
racing through a helium atmosphere would need
good aerodynamic design, like say those yearly
entries in the solar-powered race across Australia. |
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Also, this toy might have very good brakes: if the
cars suddenly stop, the balloons probably halt
instantly in midair. Don't forget that air density is
about 2lbs per cubic yard, so the toy is connected
by viscosity with many many pounds of room air. |
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Build an underwater version! How fast could it go
before turbulence would screw up the propulsion
effect? |
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> the ladies might visualize |
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Your invention could become the propulsion for a
huge blimp! Place a pair of giant helium-filled
spheres near the rear, so any trailing turbulence
isn't dragging across the blimp surface. Then turn
on the magnet wheels, and the blimp thrusts itself
rapidly across the Empyrian, like some enormous |
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Colonel: What is it, son? |
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Johnson: I don't know, sir, but it looks like a giant |
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Pilot: Take a look outta starboard. |
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Dick: Oh, my God! It looks like a huge-- |
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Bird-Watcher 2: Oh, where? |
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Bird-Watcher 1 : Wait! that's not a woodpecker. It
looks like someone's-- |
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Army Sergeant: PRIVATES! We have reports of an
unidentified flying object! It is a long, smooth
shaft, complete with-- |
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