"Anti-Gravity" Gyroscopes

Kess · 15th April 2006, 12:57 AM

As a child I was fascinated by the gyroscope and the way it could appear to defy gravity, able to hang with its axle horizontal. Reading up on how it works (there's quite a good description at http://science.howstuffworks.com/gyroscope1.htm ), it seems it's all down to precession - a horizontal gyroscope "defys" gravity by converting the downward pull of gravity into a rotation around the point at which it's supported.

Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the *opposite* direction to the precession create an upward thrust?

I suspect there's a silly misunderstanding somewhere in my thinking, but can't see where and I haven't found a website clarifying this. Can anyone explain where I've gone wrong?

Kess

Timothy · 15th April 2006, 01:56 AM

Originally Posted by Kess

Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the *opposite* direction to the precession create an upward thrust?

Depends on what you mean by "propulsion."

Given a traditional toy gyroscope with one end on a free-to-swivel post and the other end unfixed, axis of rotation horizontal, if you push in the opposite direction to precession the axis will dip down. You need to push along the direction of precession and you will get an upward force.

But your question seems to ask about it somehow floating or being propelled in the air. Nothing of the sort happens. You input a force which, when combined with the existing forces in the spinning wheel, produces a torque in the system. One end of the axle is constrained, hence the torque acts to rotate the system upright. It is only "propulsion" if you also consider lifting upright a tall box that has tipped over on its side to be "propulsion".

- Timothy

Dragon · 15th April 2006, 03:37 AM

Kess - you might want to check out the work of the late Prof. Eric Laithwaite - these BBC and Wikipedia links would be a start - I don't know if anyone picked up on his gyroscope stuff, so perhaps it was a dead end ..

Kess · 16th April 2006, 01:23 AM

Originally Posted by Timothy

Depends on what you mean by "propulsion."
Given a traditional toy gyroscope with one end on a free-to-swivel post and the other end unfixed, axis of rotation horizontal, if you push in the opposite direction to precession the axis will dip down. You need to push along the direction of precession and you will get an upward force.

That's pretty much the configuration I was thinking of.

Quote:

But your question seems to ask about it somehow floating or being propelled in the air. Nothing of the sort happens. You input a force which, when combined with the existing forces in the spinning wheel, produces a torque in the system. One end of the axle is constrained, hence the torque acts to rotate the system upright. It is only "propulsion" if you also consider lifting upright a tall box that has tipped over on its side to be "propulsion".

I think I get it. The upward force you mentioned earlier can only occur if the gyroscope is connected to a rigid post, constraining its movements. If I understand you correctly, in a free-floating system any attempts to manipulate the gyroscope will lead to torques that cause the overall system to twist and rotate in various directions, but no linear force or thrust is developed.

Oh well, back to the drawing board...

Thanks for the explanation.

Kess

Soapy Sam · 16th April 2006, 10:56 AM

Kess- Congratulations on asking a rational question.
No end of people have been seduced by gyroscopes into all manner of hopeless schemes.
They are great fun though.

Kess · 17th April 2006, 12:36 AM

Originally Posted by Soapy Sam

Kess- Congratulations on asking a rational question.
No end of people have been seduced by gyroscopes into all manner of hopeless schemes.
They are great fun though.

I'm sure I've read of a number of (presumably failed) attempts by people over the years to use combinations of gyroscopes, probably acting against one another in some manner to produce a linear thrust.

To be honest, I still have the gut feeling there ought to be some clever way to use gyroscopes to provide propulsion, but I suspect that's just down to a lack of understanding on my part.

Crossbow · 17th April 2006, 06:17 AM

Originally Posted by Kess

I'm sure I've read of a number of (presumably failed) attempts by people over the years to use combinations of gyroscopes, probably acting against one another in some manner to produce a linear thrust.

To be honest, I still have the gut feeling there ought to be some clever way to use gyroscopes to provide propulsion, but I suspect that's just down to a lack of understanding on my part.

In a zero gravity situation gyroscopes could provide propulsion, but not in the way you may think.

Supposing you had a massive gyroscope spinning at high rate (thereby generating a considerable amount of gyroscopic force) which is installed in a gimbals structure that would allow it point in any direction independent of the orientation of the chamber in which it is placed. Further suppose that the chamber itself is essentially massless.

Now then, if a motor of some sort was connected to the gimbals and the motor is firmly fixed to the body of the chamber,
When the motor is activated, the gyroscope would remain in its original orientation, but the chamber would rotate about the axel of the motor.

In this case, the gyroscope would be more of tool of inducing a rotation as opposed to propulsion.

As far as Earth based gyroscopic propulsion goes, about the only case I know of was back in the 1970's when there was some experimentation done gyroscope powered cars and buses. Also, there was some talk about using gyroscopic batteries because a gyroscope spinning at a very high rate can store far more energy than could a battery of a similar weight. In both cases, the results were not all that good because to store an adequate amount of energy, it involved the gyroscope being spun to a very, very rate (I think something like 60,000 RPM) which would destroy the flywheel.

I hope this helps!

Meffy · 17th April 2006, 07:29 AM

The use of gyroscopes to rotate space vehicles is well established. This violates no principles of science; the physics involved is thoroughly understood and there is nothing mysterious or paranormal about it. Free gyroscopes cannot provide linear propulsion, just rotation. Large gyroscopes provide stabilization for ships at sea, and IIRC there are even gyros in certain large buildings to help keep them from swaying as severely during earthquakes (this last might have been speculation about possible future application; I'm not certain).

In the 1970s (and perhaps following) there was research into using flywheels -- not "gyros" as such -- simply to store kinetic energy for later use. In this case the flywheels' gyroscopic effect was decidedly UNwanted, as it "fights" attempts to turn the vehicle. The latest I heard concerning addressing the high-speed self-destruction problem was using a kind of rotary bristle brush rather than a solid wheel. Filaments can be very tough compared to solid castings, and singly shed bristles are more easily intercepted without damage than dozens of massive chunks.

The gut feeling that gyros ought to be able to work against each other has no payoff. It's just a feeling. It would be nice if such machines could be made to work, and much ingenuity has been employed in constructing them, but so far no such propulsive effect has been exhibited. I don't think it can be done, any more than perpetual motion.

Dragon · 18th April 2006, 02:49 PM

Originally Posted by Meffy

....

The gut feeling that gyros ought to be able to work against each other has no payoff. It's just a feeling. It would be nice if such machines could be made to work, and much ingenuity has been employed in constructing them, but so far no such propulsive effect has been exhibited. I don't think it can be done, any more than perpetual motion.

Meffy, in simple terms, is this because there is no "place to stand" for the gyros to work against?

This Guy · 18th April 2006, 06:10 PM

Just an FYI -

Newer gyros used for inertial navigation have no axle. They are simply a spinning ball, inside a round case, with very tight tolerance. The balls are levitated using EMF (basically), then using another EMF (basically) that in effect rotates around the case, the balls are caused to spin. The balls are imbalanced, so there is a wobble effect inside the case. This wobble causes the balls position inside the case to be able to be determined via a capacitive pickoff. This eliminates the effects of friction (the case is evacuated, so friction is very minimal). Monitoring the balls location inside the case, allows a determination to be made of the case's position in reference to the spin axis of the ball. This allows for a drive signal to be developed to drive the platform back to it's starting position, leaving the accelerometers level, and able to sense only acceleration of the platform, not the unaccounted for effects of local gravity that would be felt, if the platform were allowed to tilt, dipping the accelerometers into/out of local gravity.

Some tidbits -

The balls spin at about 10,000 RPS
A human hair would not fit between the balls and the cases.

This is based on 1990ish tech. Who knows what's out there now.

Meffy · 18th April 2006, 07:11 PM

@Dragon: Intuitively that seems right, but I couldn't say whether it's meaningful in terms of practical physics. It's a quarter of a century since my college days, and I never was terribly solid on this kind of thing. Come to think of it, gyroscopes gave at least one of my profs a little trouble too. Not the maths but the "what's behind it." IOW I know it won't work but am too dumb to explain just why.

@This Guy: Coolness! I've played with war surplus gyros but never anything modern like that.

Dilb · 18th April 2006, 10:39 PM

Originally Posted by Dragon

Meffy, in simple terms, is this because there is no "place to stand" for the gyros to work against?

Yep. Any system always obeys conservation of momentum. Even more than energy is always conserved (sometimes energy is "lost" as heat), momentum always perfectly adds up. Gyroscopes and such illustrate the importance of angular momentum, but they don't do anything with linear momentum.

To get linear momentum, you can either push something away (like rockets, jet engines, propellers), and work out how much momentum it has, or apply a force against something. Strictly speaking you always transfer momentum between objects by means of a force, but it's annoying working out the momentum of the earth when you jump up, or even more annoying to try and work out the exact forces applied to your jet engine.

So if you want to have some self-contained device inside your ship that provides propulsion, it needs to have linear momentum. Linear momentum is mass*velocity, so unless it's moving in a straight line it can't move the ship foreward. Another way to look at it is to add all the velocities of a gyroscope together. For any point on a gyroscope moving foreward, there's an equal point on the opposite side of the axis that's moving backwards at the same speed. Add everything together, and it comes out to zero.

ceptimus · 19th April 2006, 01:57 AM

Originally Posted by This Guy

The balls spin at about 10,000 RPS

Wow! 600,000 RPM. I didn't know they could spin them that fast.

Matabiri · 19th April 2006, 04:09 AM

Originally Posted by Kess

Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the *opposite* direction to the precession create an upward thrust?

Notice also that the gyroscope only appears to defy gravity, whereas it's actually balancing on a spike (and hence, falling involves an applied torque). It's a perfectly valid solution to the gyroscopic equations for it just to fall straight down in the same orientation if the spike is removed.

Hazen · 19th April 2006, 04:18 AM

Originally Posted by This Guy

This is based on 1990ish tech. Who knows what's out there now.

Gravity probe b uses this type of technology:
http://www.nasa.gov/centers/marshall...05/05-160.html

This Guy · 19th April 2006, 05:22 AM

Originally Posted by Hazen

Gravity probe b uses this type of technology:
http://www.nasa.gov/centers/marshall...05/05-160.html

Cool!

What we were using were 6 cm balls. Made of Beryllium, with a couple wires made of a heavier metal inserted for the unbalancing.

It might have been 6000 RPS, but I'm pretty sure they were 10,000 RPS. The older systems we had with more conventional gyros spun at 6000 RPM I believe. But, the 6 and 10 may be backward. I do know the older stuff was RPM, and it's RPS for the newer system. In either event, touching the stable platform while the gyros were spinning would change the beryllium balls ,magically, into beryllium dust ;-)

Our stuff wasn't as stable as the gravity probe either. But the newer system was way more stable than the older one. A lot of that was due to the reference system used. The older system was Earth referenced (gyro input axis pointing N/S, E/W and vertical. The newer system had the gyro input axis referenced to space, and a dedicated computer to do Earth transformation of the velocity data (convert the spaced referenced data to it's N/S, E/W and vertical components). This meant the gyros didn't have to be torqued for earth rate ( the earth's spin. About 15.04 Deg/hr of torque, that resulted in a 24 hour sine wave of error induced mostly by the heat caused by torquing the gyros to maintain the N/S, E/W, vertical orientation). Rho rate (travel over a round earth) torquing wasn't required on the newer system either. This helped a bit too. Of course the newer system's platform had 3 degrees of freedom (?) I always get confused on that. The platform could rotate 360 degrees in all directions. The older system could only rotate about it's azimuth by 360 degrees, there were physical stops for vertical rotation.

Both systems were still affected by gravitational anomalies though. Underwater mountains and valleys tend to cause a shift in what is apparently down (TLV or True Local Vertical). The accelerometers would sense the pull, or lack of pull, and react as if it were due to ships acceleration. This would cause a Schuler (sp?) oscillation. A sinusoidal error wave of velocity with a period of about 74 mins, if I recall correctly. It's the same period that a pendulum, with a shaft the length of the radius (circumference maybe?) of the earth would have. These would mostly cancel out, and could be minimized (dampened) by having a good reference velocity to provide some feed back. But there would be some positional errors, especially at the peaks (well, once the velocity errors had time to drive the position off anyway:-).

This is all submarine navigation stuff BTW. How we could know pretty dang close where we were at any given time without having to stick an antenna out of the water risking detection.

15th April 2006, 12:57 AM	#1
Kess Thinker Join Date: Aug 2002 Posts: 193	"Anti-Gravity" Gyroscopes As a child I was fascinated by the gyroscope and the way it could appear to defy gravity, able to hang with its axle horizontal. Reading up on how it works (there's quite a good description at http://science.howstuffworks.com/gyroscope1.htm ), it seems it's all down to precession - a horizontal gyroscope "defys" gravity by converting the downward pull of gravity into a rotation around the point at which it's supported. Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the opposite direction to the precession create an upward thrust? I suspect there's a silly misunderstanding somewhere in my thinking, but can't see where and I haven't found a website clarifying this. Can anyone explain where I've gone wrong? Kess
Kess Thinker Join Date: Aug 2002 Posts: 193	__________________ "Many have made a trade of delusion and false miracles, deceiving the stupid multitude." - Leonardo Da Vinci

15th April 2006, 01:56 AM	#2
Timothy Muse Join Date: Feb 2005 Posts: 544	Originally Posted by Kess Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the opposite direction to the precession create an upward thrust? Depends on what you mean by "propulsion." Given a traditional toy gyroscope with one end on a free-to-swivel post and the other end unfixed, axis of rotation horizontal, if you push in the opposite direction to precession the axis will dip down. You need to push along the direction of precession and you will get an upward force. But your question seems to ask about it somehow floating or being propelled in the air. Nothing of the sort happens. You input a force which, when combined with the existing forces in the spinning wheel, produces a torque in the system. One end of the axle is constrained, hence the torque acts to rotate the system upright. It is only "propulsion" if you also consider lifting upright a tall box that has tipped over on its side to be "propulsion". - Timothy
Timothy Muse Join Date: Feb 2005 Posts: 544

15th April 2006, 03:37 AM	#3
Dragon Graduate Poster Join Date: Mar 2002 Location: London, UK Posts: 1,403	Kess - you might want to check out the work of the late Prof. Eric Laithwaite - these BBC and Wikipedia links would be a start - I don't know if anyone picked up on his gyroscope stuff, so perhaps it was a dead end ..
	__________________ "We must favour verifiable evidence over private feeling. Otherwise we leave ourselves vulnerable to those who would obscure the truth." Richard Dawkins - The Enemies of Reason

16th April 2006, 01:23 AM	#4
Kess Thinker Join Date: Aug 2002 Posts: 193	Originally Posted by Timothy Depends on what you mean by "propulsion." Given a traditional toy gyroscope with one end on a free-to-swivel post and the other end unfixed, axis of rotation horizontal, if you push in the opposite direction to precession the axis will dip down. You need to push along the direction of precession and you will get an upward force. That's pretty much the configuration I was thinking of. Quote: But your question seems to ask about it somehow floating or being propelled in the air. Nothing of the sort happens. You input a force which, when combined with the existing forces in the spinning wheel, produces a torque in the system. One end of the axle is constrained, hence the torque acts to rotate the system upright. It is only "propulsion" if you also consider lifting upright a tall box that has tipped over on its side to be "propulsion". I think I get it. The upward force you mentioned earlier can only occur if the gyroscope is connected to a rigid post, constraining its movements. If I understand you correctly, in a free-floating system any attempts to manipulate the gyroscope will lead to torques that cause the overall system to twist and rotate in various directions, but no linear force or thrust is developed. Oh well, back to the drawing board... Thanks for the explanation. Kess
Kess Thinker Join Date: Aug 2002 Posts: 193	__________________ "Many have made a trade of delusion and false miracles, deceiving the stupid multitude." - Leonardo Da Vinci

16th April 2006, 10:56 AM	#5
Soapy Sam NLH Join Date: Oct 2002 Posts: 25,885	Kess- Congratulations on asking a rational question. No end of people have been seduced by gyroscopes into all manner of hopeless schemes. They are great fun though.
Soapy Sam NLH Join Date: Oct 2002 Posts: 25,885

17th April 2006, 12:36 AM	#6
Kess Thinker Join Date: Aug 2002 Posts: 193	Originally Posted by Soapy Sam Kess- Congratulations on asking a rational question. No end of people have been seduced by gyroscopes into all manner of hopeless schemes. They are great fun though. I'm sure I've read of a number of (presumably failed) attempts by people over the years to use combinations of gyroscopes, probably acting against one another in some manner to produce a linear thrust. To be honest, I still have the gut feeling there ought to be some clever way to use gyroscopes to provide propulsion, but I suspect that's just down to a lack of understanding on my part.
Kess Thinker Join Date: Aug 2002 Posts: 193	__________________ "Many have made a trade of delusion and false miracles, deceiving the stupid multitude." - Leonardo Da Vinci

17th April 2006, 06:17 AM	#7
Crossbow Seeking Honesty and Sanity Join Date: Oct 2001 Posts: 6,294	Originally Posted by Kess I'm sure I've read of a number of (presumably failed) attempts by people over the years to use combinations of gyroscopes, probably acting against one another in some manner to produce a linear thrust. To be honest, I still have the gut feeling there ought to be some clever way to use gyroscopes to provide propulsion, but I suspect that's just down to a lack of understanding on my part. In a zero gravity situation gyroscopes could provide propulsion, but not in the way you may think. Supposing you had a massive gyroscope spinning at high rate (thereby generating a considerable amount of gyroscopic force) which is installed in a gimbals structure that would allow it point in any direction independent of the orientation of the chamber in which it is placed. Further suppose that the chamber itself is essentially massless. Now then, if a motor of some sort was connected to the gimbals and the motor is firmly fixed to the body of the chamber, When the motor is activated, the gyroscope would remain in its original orientation, but the chamber would rotate about the axel of the motor. In this case, the gyroscope would be more of tool of inducing a rotation as opposed to propulsion. As far as Earth based gyroscopic propulsion goes, about the only case I know of was back in the 1970's when there was some experimentation done gyroscope powered cars and buses. Also, there was some talk about using gyroscopic batteries because a gyroscope spinning at a very high rate can store far more energy than could a battery of a similar weight. In both cases, the results were not all that good because to store an adequate amount of energy, it involved the gyroscope being spun to a very, very rate (I think something like 60,000 RPM) which would destroy the flywheel. I hope this helps!
	__________________ A man's best friend is his dogma.

17th April 2006, 07:29 AM	#8
Meffy Anthropomorphic Skunk Join Date: Feb 2004 Location: Unincorporated Territory of Croatan Posts: 4,232	The use of gyroscopes to rotate space vehicles is well established. This violates no principles of science; the physics involved is thoroughly understood and there is nothing mysterious or paranormal about it. Free gyroscopes cannot provide linear propulsion, just rotation. Large gyroscopes provide stabilization for ships at sea, and IIRC there are even gyros in certain large buildings to help keep them from swaying as severely during earthquakes (this last might have been speculation about possible future application; I'm not certain). In the 1970s (and perhaps following) there was research into using flywheels -- not "gyros" as such -- simply to store kinetic energy for later use. In this case the flywheels' gyroscopic effect was decidedly UNwanted, as it "fights" attempts to turn the vehicle. The latest I heard concerning addressing the high-speed self-destruction problem was using a kind of rotary bristle brush rather than a solid wheel. Filaments can be very tough compared to solid castings, and singly shed bristles are more easily intercepted without damage than dozens of massive chunks. The gut feeling that gyros ought to be able to work against each other has no payoff. It's just a feeling. It would be nice if such machines could be made to work, and much ingenuity has been employed in constructing them, but so far no such propulsive effect has been exhibited. I don't think it can be done, any more than perpetual motion.

18th April 2006, 02:49 PM	#9
Dragon Graduate Poster Join Date: Mar 2002 Location: London, UK Posts: 1,403	Originally Posted by Meffy .... The gut feeling that gyros ought to be able to work against each other has no payoff. It's just a feeling. It would be nice if such machines could be made to work, and much ingenuity has been employed in constructing them, but so far no such propulsive effect has been exhibited. I don't think it can be done, any more than perpetual motion. Meffy, in simple terms, is this because there is no "place to stand" for the gyros to work against?
	__________________ "We must favour verifiable evidence over private feeling. Otherwise we leave ourselves vulnerable to those who would obscure the truth." Richard Dawkins - The Enemies of Reason

18th April 2006, 06:10 PM	#10
This Guy Master Poster Join Date: Mar 2006 Location: On the corner of WALK and DON'T WALK Posts: 2,000	Just an FYI - Newer gyros used for inertial navigation have no axle. They are simply a spinning ball, inside a round case, with very tight tolerance. The balls are levitated using EMF (basically), then using another EMF (basically) that in effect rotates around the case, the balls are caused to spin. The balls are imbalanced, so there is a wobble effect inside the case. This wobble causes the balls position inside the case to be able to be determined via a capacitive pickoff. This eliminates the effects of friction (the case is evacuated, so friction is very minimal). Monitoring the balls location inside the case, allows a determination to be made of the case's position in reference to the spin axis of the ball. This allows for a drive signal to be developed to drive the platform back to it's starting position, leaving the accelerometers level, and able to sense only acceleration of the platform, not the unaccounted for effects of local gravity that would be felt, if the platform were allowed to tilt, dipping the accelerometers into/out of local gravity. Some tidbits - The balls spin at about 10,000 RPS A human hair would not fit between the balls and the cases. This is based on 1990ish tech. Who knows what's out there now.

18th April 2006, 07:11 PM	#11
Meffy Anthropomorphic Skunk Join Date: Feb 2004 Location: Unincorporated Territory of Croatan Posts: 4,232	@Dragon: Intuitively that seems right, but I couldn't say whether it's meaningful in terms of practical physics. It's a quarter of a century since my college days, and I never was terribly solid on this kind of thing. Come to think of it, gyroscopes gave at least one of my profs a little trouble too. Not the maths but the "what's behind it." IOW I know it won't work but am too dumb to explain just why. @This Guy: Coolness! I've played with war surplus gyros but never anything modern like that.

18th April 2006, 10:39 PM	#12
Dilb Muse Join Date: Oct 2004 Posts: 738	Originally Posted by Dragon Meffy, in simple terms, is this because there is no "place to stand" for the gyros to work against? Yep. Any system always obeys conservation of momentum. Even more than energy is always conserved (sometimes energy is "lost" as heat), momentum always perfectly adds up. Gyroscopes and such illustrate the importance of angular momentum, but they don't do anything with linear momentum. To get linear momentum, you can either push something away (like rockets, jet engines, propellers), and work out how much momentum it has, or apply a force against something. Strictly speaking you always transfer momentum between objects by means of a force, but it's annoying working out the momentum of the earth when you jump up, or even more annoying to try and work out the exact forces applied to your jet engine. So if you want to have some self-contained device inside your ship that provides propulsion, it needs to have linear momentum. Linear momentum is mass*velocity, so unless it's moving in a straight line it can't move the ship foreward. Another way to look at it is to add all the velocities of a gyroscope together. For any point on a gyroscope moving foreward, there's an equal point on the opposite side of the axis that's moving backwards at the same speed. Add everything together, and it comes out to zero.
Dilb Muse Join Date: Oct 2004 Posts: 738

19th April 2006, 01:57 AM	#13
ceptimus puzzler Join Date: May 2003 Posts: 3,316	Originally Posted by This Guy The balls spin at about 10,000 RPS Wow! 600,000 RPM. I didn't know they could spin them that fast.
ceptimus puzzler Join Date: May 2003 Posts: 3,316	__________________

19th April 2006, 04:09 AM	#14
Matabiri Graduate Poster Join Date: Oct 2003 Posts: 1,734	Originally Posted by Kess Anyway, I've always wondered if a gyroscope could be manipulated to provide propulsion, perhaps even a vertical upwards thrust against gravity. For example, if the gyroscope counters the downward pull of gravity by precessing, then shouldn't forcing the gyroscope to turn in the opposite direction to the precession create an upward thrust? Notice also that the gyroscope only appears to defy gravity, whereas it's actually balancing on a spike (and hence, falling involves an applied torque). It's a perfectly valid solution to the gyroscopic equations for it just to fall straight down in the same orientation if the spike is removed.
	__________________ "That's the kind of thing you can't look up on the internet, because it's the kind of thing you get taught at school." - Ashley Pomeroy

19th April 2006, 04:18 AM	#15
Hazen Bringer of Lunch Join Date: Sep 2005 Location: UK Posts: 228	Originally Posted by This Guy This is based on 1990ish tech. Who knows what's out there now. Gravity probe b uses this type of technology: http://www.nasa.gov/centers/marshall...05/05-160.html

19th April 2006, 05:22 AM	#16
This Guy Master Poster Join Date: Mar 2006 Location: On the corner of WALK and DON'T WALK Posts: 2,000	Originally Posted by Hazen Gravity probe b uses this type of technology: http://www.nasa.gov/centers/marshall...05/05-160.html Cool! What we were using were 6 cm balls. Made of Beryllium, with a couple wires made of a heavier metal inserted for the unbalancing. It might have been 6000 RPS, but I'm pretty sure they were 10,000 RPS. The older systems we had with more conventional gyros spun at 6000 RPM I believe. But, the 6 and 10 may be backward. I do know the older stuff was RPM, and it's RPS for the newer system. In either event, touching the stable platform while the gyros were spinning would change the beryllium balls ,magically, into beryllium dust ;-) Our stuff wasn't as stable as the gravity probe either. But the newer system was way more stable than the older one. A lot of that was due to the reference system used. The older system was Earth referenced (gyro input axis pointing N/S, E/W and vertical. The newer system had the gyro input axis referenced to space, and a dedicated computer to do Earth transformation of the velocity data (convert the spaced referenced data to it's N/S, E/W and vertical components). This meant the gyros didn't have to be torqued for earth rate ( the earth's spin. About 15.04 Deg/hr of torque, that resulted in a 24 hour sine wave of error induced mostly by the heat caused by torquing the gyros to maintain the N/S, E/W, vertical orientation). Rho rate (travel over a round earth) torquing wasn't required on the newer system either. This helped a bit too. Of course the newer system's platform had 3 degrees of freedom (?) I always get confused on that. The platform could rotate 360 degrees in all directions. The older system could only rotate about it's azimuth by 360 degrees, there were physical stops for vertical rotation. Both systems were still affected by gravitational anomalies though. Underwater mountains and valleys tend to cause a shift in what is apparently down (TLV or True Local Vertical). The accelerometers would sense the pull, or lack of pull, and react as if it were due to ships acceleration. This would cause a Schuler (sp?) oscillation. A sinusoidal error wave of velocity with a period of about 74 mins, if I recall correctly. It's the same period that a pendulum, with a shaft the length of the radius (circumference maybe?) of the earth would have. These would mostly cancel out, and could be minimized (dampened) by having a good reference velocity to provide some feed back. But there would be some positional errors, especially at the peaks (well, once the velocity errors had time to drive the position off anyway:-). This is all submarine navigation stuff BTW. How we could know pretty dang close where we were at any given time without having to stick an antenna out of the water risking detection.