Re: Internal Rocket Effect
- From: The Ghost In The Machine <ewill@xxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 7 Aug 2008 20:26:11 -0700
In sci.physics, Spaceman
<spaceman@xxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote
on Thu, 7 Aug 2008 09:56:33 -0400
<7qGdnbfg3t6EYgfVnZ2dnUVZ_tTinZ2d@xxxxxxxxxxx>:
The Ghost In The Machine wrote:
OK, I gotta ask, if only to try to figure out exactly
how some here think, and hopefully I get this device
right. (I am convinced it will *not* work. You know
who you are. ;-) )
A sealed tube, containing some air, is somewhere in free
space (if one likes, somewhere between Earth and Moon,
Earth and Mars, or Earth and ... wherever). The tube is
surrounded by the usual solar panels, in order to extract
energy from Sol, converting it to electricity.
For the purpose of argument assume it is and of size
maybe 5 m in length with maybe a 50 cm inside diameter,
and initially motionless. [+] The air pressure might be 2
megaPascal, or 20 atmospheres, in the high-pressure side,
and maybe 10 milliPascal on the low-pressure side. [%]
A partition in the tube acts as a barrier, with two valves
in the middle dividing the tube into two largely sealed
halves, with the valves providing the only permeation
between. The valves are actuated by a reasonably simple
control system.
The low-pressure side contains an electrically powered
pump with a connecting tube to one of the valves; the pump
is designed to pump air from the low pressure side to the
high pressure side. The air is then quickly released back
into the low pressure side, at a rate far faster than the
pump can pump it back.
There are no harnessable electric or magnetic fields in
the device's immediate vicinity. [*]
How fast does this device accelerate?
[1] Not at all. The total momentum is always zero,
as is the angular momentum. At most, it will
jiggle and wiggle a little.
[2] The device will move extremely slowly in the
direction of the low-pressure end of the tube, as the
high pressure side gets hot, and the infrared radiation
will therefore push it just a smidge, if the solar
panels being pushed by sunlight and the solar wind
don't swamp the effect.
[3] The device will accelerate at a high rate of speed
towards the high-pressure end of the tube, as the gas
is released very quickly but the pump works slowly.
Over time, it will move faster than light if enough
energy is available.
[4] The device will accelerate at a high rate of speed
towards the low-pressure end of the tube, as the
gas creates a slight gravity gradient. This gravity
gradient is converted into momentum.
[5] The device will spin like a top and ultimately fly
apart because of the off-center valving required
by one of the valves.
[6] None of the above.
Standard physics answers [1]. A more refined physics might
answer [2], since light quanta do have momentum, although
the effect, expressable as p = E/c, is extremely small;
a 1 kW floodlight might exert a force of 33 microNewtons.
But there's at least one poster who thinks standard physics
is all wrong. (No, it's not me. I remain a skeptic,
especially given Deep Space 1, which, despite its emphasis
on novelle rocket technology, is still at its heart a
rocket -- with xenon instead of LOX and liquid hydrogen.
Once the xenon's gone, it's gone. Why didn't we use
a sealed tube instead? Because it wouldn't have worked.)
Now explain away, if you can! :-)
Why bother with the one poster crap.
It's me that you are talking about
Congratulations. You might have half a neuron after all. :-P
Either that, or hypersensitive.
and I do not say the physics
of momentum is all wrong so apparently you have already started
with a lie.
In your example 2 is the most likely answer
And i would not argue such so again your "one poster thinks
physics is wrong statement is dingleberry excrement..
But you have limited the space of the flow so you will
not be allowing any type of expansion that would allow the
diversion of exhaust to the sides and most of your flow
will directly hit the end of the "pipe".
Actually, the flow will pressurize the entire low-pressure
side of the tubing. That implies that the molecules
are hitting the sides.
The flow will also hit the back.
So..
Why don't we try a different type thought about why it could happen
now. (that is of course closer to my "internal propulsion" thoughts.
We set up a pool table that has 0 table friction but does have bumper
friction
Um...pool tables require gravity to operate. Did you want to
instead use a ball suspended in a box with some sort of
solenoid-actuated "cue stick", floating in free space?
A variant of zero-gee pool using 35 balls arranged in a
pyramid might be playable:
1+3+6+10+15 = 35
we will one side of the table with compressable balls,
and then we shoot about 10 compresseable balls into the 1000
balls we had gotten to fit with barely touchiong each other.
The ten balls we shoot come in a line of 2 at a time.
Where do all the impact forces go?
Does all the force hit the back wall?
Of does some get diverted and hit the side walls and some even gets
diverted and send balls back towards the shooting spot?
Depends on the setup of your 1000 balls. Most likely they'll
go all over the place if the incoming balls have enough energy.
--
#191, ewill3@xxxxxxxxxxxxx
Linux. The choice of a GNU generation.
Windows. The choice of a bunch of people who like very weird behavior on
a regular basis, random crashes, and "extend, embrace, and extinguish".
** Posted from http://www.teranews.com **
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