There is a direct relationship between the strength of a magnet and how much it will attract to Earth's magnetic field.
Not only that but like a compass an electromagnet can be made to rotate with considerable force (by comparison of perhaps a Hall Effect rocket motor).
The trick is to turn the rotation into linear motion and we believe we have struck upon a way to do that.
PERMANENT MAGNETS IN CIRCLE OR PENDULUM PROPULSION JUST AS GOOD AS ELECTROMAGNETS AND REQUIRE ALMOST NO ELECTRICITY
There is no doubt in my mind now that this principle works. A permanent magnet or an electromagnet rotating off center like a compass in Earth's Magnetic Field will work in LOE (Low Earth Orbit) and would have practical applications for at least de-orbiting small satellites at the end of their life cycles if not as well for adjusting orbits.
The video above is a small model made from a 12 inch aluminum pan, some N42 half inch diameter Neodymium magnets and a toy robot that rotates and is used for a servo. Clay is used for weight. The clay is blue colored.
Rotating the magnets as opposed to using fixed electromagnets gives great control of the little "boat" floating in a tank of water. It makes the boat turn in the low friction of the water pretty responsively. (Remember however the video is time lapsed at 6X)
Here is how and why it works.
* When the head of the toy robot is turned the magnet turns and then the whole aluminum pan model turns as the magnets act like a compass seeking to point north and south.
* As the aluminum pan turns it does not turn around the center of the torque from the magnet nor does it turn at the center of its mass but at a third point. Magnetic torque is extremely powerful compared to magnetic attraction of opposite poles at a distance. (Someone help me with the math and engineering.)
* The aluminum pan since it turns at a point not its center of mass has one part of it turning that is more massive than the other (The part on the side of the magnet). That creates centrifugal force. There is no claim here this defies any laws of physics since the magnetic interaction with Earth is an external force applied to the model)
* The centrifugal force pulls the aluminum boat in a line.
* This invention translates rotation from magnetic torque from a powerful compass into linear motion. (or force to be technical)
To pick up from the last blog post I made some changes and had some success.
The first change was to reverse the polarity of the upper pointing electromagnet. I did this by loosening the nuts that hold the second foam board to the first and turning around the electromagnet rather than reverse the wires. Now when the electromagnets are powered on they don't oppose each other. Now they will make the top of the device be inclined to move towards one of Earth's magnetic poles and the bottom two towards the opposite pole.
The second change was to add permanent magnets at a right angle to the foam board near the top. Now when the electromagnets are off the permanent magnets are inclined to point north/south with Earth's magnetic poles.
The third change was to alter the Arduino sketch (program) so that the electromagnets only go on and off several times a second instead of reversing polarity.
Now it is set up as an earlier model that I somewhat understand. The device will oscillate as the electromagnets and the permanent magnets interact with Earth's magnetic field. Since the point where they oscillate is not the center of the mass of the whole device and neither at the center of the point of magnetic torque from the magnets acting like a compass and rotating, the device will go in a line.
As can be seen in the below (time lapse 6x) video this works.
The red cardboard 3 fold boards are reducing the effect of air draft and you can see the device accelerate a little over the several minutes it is on. Note that it is only turned on after some period of time to establish that it is standing still in the water.
Below is a second trial. (Also at 6x time lapse.)
This worked several times but then a problem with what I am almost certain is static electric charge occurred.
Here is what happens.
The 10 inch aluminum pan is used specifically as opposed to Styrofoam. In previous experiments Styrofoam caused this problem but now it happened anyway. I am not really sure exactly how it works but the static prevents the device from moving in the water, even when deliberately physically pushed. It will go for a short time then come to a perfect standstill. (My experience is that in any of the previous experiments a small push would make the model drift quite a bit.)
The thrust generated by this device is not powerful enough to overcome the resistance to motion from the electrostatic charge.
One thing that seemed to work in the past was to empty the container of water completely and refill it. I am now waiting for warmer weather to empty the water and try again. Also it may be that the choice of foam board for the structure of the model was not the best one.
20180125 Thursday - I did some math and realized that turning the magnets on and off at short intervals is not as effective as doing so at longer intervals. (Not necessarily with this exact model but it explains why this model is weak.)
To get a centrifugal force from a pendulum the speed of the pendulum's motion is important. The faster it moves the more centrifugal force. To show that it will move faster in one longer motion than in many shorter motions we only need to show that any velocity will be greater in one continuous acceleration from 0 than many small accelerations each from 0 and to do that we need to do some Calculus. But is it pretty easy Calculus.
Velocity = Acceleration * Time
So for our example we will compare a 10 second continuous acceleration from 0 verses 10 1 second accelerations from 0 and show that the 10 second continuous acceleration amounts to much greater velocity.
Since Acceleration will be considered a constant we will remove it from the equation or just call it 1.
For 10 separate accelerations of 1 second each from 0 the definite integral is:
10 Sum Time from 0 to 1
equals:
10 Time^2/2 where Time is 1 or 10 * 1/2 = 5 in lets say inches per second.
For one continuous acceleration for 10 seconds it is:
1 Sum Time from 0 to 10
equals:
1 Time^2/2 where Time is 10 or 1 *100/2 = 50 inches per second.
The difference between 5 inches per second maximum speed over 10 seconds and 50 inches per second maximum speed over 10 seconds is enormous.
Now when we consider earlier experiments where the device rotates completely in a circle it makes sense that it is a much more efficient use of energy to produce linear motion since the acceleration takes place continuously for at least several rotations until a terminal speed is reached due to factors such as friction.
THIS VERSION SEEMS TO WORK AND HAS NO MOVING PARTS
(IT DOES VIBRATE PROBABLY A BIT)
20180106 Saturday
Last
night I used foam board for two sides to hold 3 electromagnets in place
so they are 120 degrees apart and close together at the center. I want
to use bolts and washers to hold it all together. It will stand straight
up so will need some support pieces.I have all the electronics needed.
The electromagnets will all have like polarity pointing outward and
inward. The polarity will reverse 10 times a second in the hope that
this will drive the smaller aluminum pan as it floats in water. Some
small steering magnets will also be added.
The electromagnets
will be wired in series and batteries will be used to provide 1 to 1.5
amps so not to overheat our H-bridge controller.
I have it mostly set
up with the L298n, Arduino, 8 AA NIHM batteries, a 9 volt battery and a
quick little sketch (Arduino program).
The 8 batteries are 9.6 volts and I measured 1 amp so the 3 electromagnets are 9.6 ohms in series.
20180107 Sunday
I've
decided to use metal bolts as opposed to nylon bolts with consideration
for static electricity, a problem that keeps occurring in the water
tank and causes the boats to resist motion.
All ready to test after batteries are recharged.
20180108 Monday
Batteries are charged.going to use a fresh 9volt battery to. Seems the magnets weren't getting power.
It
works. It moved towards Earth's magnetic North Pole. The batteries have to be fully charged then it will work for
about 10 minutes. It moved about an inches per minute slightly
accelerating for a few minutes.
20180110 Wednesday
So far I noticed when the rechargeable batteries became drained the device didn't go so I considered that a reasonable control for these tests or experiments but I felt I should make a more formal control test with no power.
I placed the device in the water tank without the power connected to see how long it would stay in one place.
The results were for a time humbling. I noticed that in the first control trial while I stood behind the camera the boat drifted north very much like it did under power. OK, I'm not that skeptical so I tried some more and was able to get the boat to stay in one place for six minutes and catch that on video. I was able to do this several times while not always on video. The video was shortened to a minute by the video editor from Magisto.
To get an accurate indication I need to stand away from the water tank when I do the experiment with the power on and come back to check on it several minutes later to see if it worked.
I will soon do more experiments. In the meantime here is a control trial for six minutes shortened down to one minute for your approval.
My lesson learned is that I know that this may be important work in magnetic field propulsion near Earth's magnetic field so I want to be sure to take my time and not rush through it.
Also with this particular instance of magnetic propulsion the top speed was clocked at no faster the 1 1/2 inches per minute while other versions were much more powerful doing at least 2 or 3 or even 4 inches per minute. As I have learned 1 inch or 1 1/2 inches per minute is also the speed this particular device will go propelled by only the draft in my home.
I decided to get some of those science project cardboard fold out boards with three sides and surround the tank completely with them and I was able to get the device to stay still for close to a half hour. (That is it did not to move all the way to either end or to either side and more or less stay within about 4 inches of its starting position.)
This was a very nice project with the electromagnets and Arduino and working with foam board but I am afraid it isn't going to get me to outer space any time soon.:)
PERMANENT MAGNET PROPULSION DOESN'T USE MUCH ELECTRICITY
I am once again working with permanent magnets since it may be some time before I would be able to build a nice model with electromagnets that rotates on a needle point axle/bearing.
The advantage of permanent magnets is that they don't required very much electricity except for a motor to turn them. The motor uses very little electricity compared to a 30 to 70 watt electromagnet.
So first let me show my device and then discuss it. Here it is:
The red turning thing in the middle of the aluminum pan is a HexBug spider toy robot. I am using it as a remote controlled 360 degree servo. I have taped 14 0.5 inch diameter neodymium magnets to its rotating head as well as 94 grams of inexpensive clay (blue) to counter balance it. For it to work either it needs to be off center or the aluminum pan underneath needs to be out of balance.
Again it works because the center of the magnetic torque from the magnet interacting with Earth's magnetic field is at a different point from the center of mass where the device will tend to turn at. Since they are not in the same place the device will rotate around a third point and one side of that point will have more mass than the other side so momentum or if you will centrifugal force will move the device in a line.
Next we added an outer aluminum pan to rule out water current that might be generated as the device rotates a lot (Also this means it does not need to turn the whole craft to work) as seen below:
In this model of my device the clay counter balance has been removed from the top of the HexBug and the magnet has been centered. To arrange for it to still work the clay square weights around the inner aluminum pan are unbalance with three spread out around 180 degrees of the circumference of the pan and one missing from the opposite side. The inner aluminum pan is connected to the outer one with a washer and a thumb tack both embedded in clay. The washer is on the bottom of the inner pan and the thumb tack is pointed up on the outer pan so the point goes into the hole in the washer. The inner pan is filled with just enough water for the link to work and the friction to be very small. The inner pan floats in the water in the outer pan. The outer pan is floating in the water tank (a plastic storage container with about 5 inches of water in it.)
I have no doubt this is working. My issue is how could it be scaled up? Well I have a hunch that I will explore in a future post.
THREE COIL STATORLESS MOTOR ONE COIL OUT OF PHASE FIRST ATTEMPT
In one attempt at electromagnetic propulsion for spacecraft I used a stator less motor on an axle mounted on a delicate needle bearing.
Some time ago I built a stator less motor out of three spools of wire on a steel bolt. It was mounted on an axle and mostly built out of Lego parts but the axle had sewing needles at each end to reduce friction.
A stator less motor is just a motor that uses Earth as its permanent magnet (stator). As the electromagnet is powered it turns on the axis like a compass and points north and south. Then the polarity is reversed, in my case by an Arduino with a Relay Shield or separate relays or even a motor controller, so that it continues to turn in a circle. It is a motor.
Here is a similar model like the one I used in my electromagnetic propulsion experiment:
This stator less motor uses a photo cell and light for the governor to reverse polarity. It has to be pointed so that the semicircular piece of card stock that blocks the light from reaching the photocell turns just so the polarity reverses when the electromagnets are pointing north and south.
The actual model I used in the experiment was different in that the three coils were on separate controllers or relays so one on the end could be powered with it's polarity out of phase from the other two during half the cycle.
The two in phase electromagnets keep the armature spinning. The out of phase coil on the end transfers the momentum of the spinning armature through the axle to push the little model in one direction in the water.
This version of electromagnetic propulsion is very promising. My model needed a better version developed but did work. There were some setbacks due to the connections that I used to transfer the electricity to the armature and coils. I plan to make a better model of this in the not too distant future.
At any rate below is a video of this version in action. It can be seen to move towards the left of the screen. It is placed on a piece of Styrofoam and floated in water away from any magnetic or metal objects.
I have gotten to
the point where I have a somewhat working model of an electromagnetic
propulsion device that would work in low Earth orbit, at least in theory.
It is easy to see
how the magnet turns to align with Earth’s north and south magnetic poles just
like a compass and than how an electromagnet by changing its polarity is made
to rotate in a circle like a motor. We saw how adding a fin to push against the
water made my model move in a line through the water. We have farther more seen
that we can accomplish the translation from rotation to linear motion by
placing a weight on our model.
This may seem a
little mysterious so what are the actual mechanics of an electromagnet rotating
in Earth’s magnetic field like a motor translating to linear motion?
I have given this
a considerable amount of thought and I truly believe this is the easiest to
grasp explanation I can currently provide:
The torque from
the electromagnet interacting with Earth’s magnetic field is applied at one
point on the device. That is the force of rotation provided by the
electromagnet.
The device has a
tendency to rotate around its center of mass, which is at a different point. I
am not sure what physical law states that is so but it seems self evident.
Since there are
two points where rotation is ‘trying’ to take place the actual rotation occurs
at a third point. Again this is a little intuitive but shouldn’t be hard to
grasp.
So when the
device rotates around the third point, which is not the center of mass, the heavier
or more massive portion of it moves in an arc. This is also intuitive since if
the center of rotation is not at the center of mass one side or the other of
that mass must be greater.
That portion of
the device with the more mass pulls the whole device with it as it rotates.
This is from centrifugal force or you may want to think of it in terms of
movement and momentum. (Physicists say there is really no such thing as
centrifugal force, but that is beside the point.)
MORE TO CONSIDER ON PRACTICALITY To use this as it
now is in concept would require the spacecraft to mostly consist of the
electromagnets and also that the whole spacecraft would need to rotate. Here
the concept is only in its baby stages and might be developed to the point
where it could rotate on an axle that would then be attached to the spacecraft.
Also does the
device only have the capacity to go in one direction? That is something to
consider.
Actually I have some ideas on this some of which I have already tried out.
The first way to control the direction of linear motion is to control the direction of rotation. The opposite direction of rotation will make it go in a different direction. Next the direction may be affected by changing the timing of the reversal of polarity of the electromagnets. I have done some experiments and this seems to be the case. Also, the position of the secondary electromagnets would alter the direction of linear rotation.
Of course it can go in any direction along the plane parallel to the lines of Earth's Flux if it instead of rotating swings side to side like a pendulum.
Centrifugal Force and Propulsion When an External Force Moves the Pendulum
Inertial propulsion systems in various forms such as with gyroscopes or pendulums that swing in smaller arcs at one end of a circle than at the other don't work. At least none has ever been demonstrated to work.
That being said there is still a way they can be used as long as the force driving the pendulum is external to the pendulum system.
In this case I used the Earth's magnetic field.
To understand this we will imagine a pendulum and 4 rocket thrusters floating in micro gravity. Imagine there are two thrusters close together on each side of the arm of our pendulum near the end opposite the weight. Those thrusters would then be imagined to go on and off in such a way that they would swing the pendulum back and forth. While the pivot point of the pendulum where the thrusters were would not stay still there would be a sort of overall cycling swing of the pendulum in our micro gravity. The thrusters observe Newtons law of action and reaction.
The swinging of the pendulum would create centrifugal force in only one direction and cause the model to accelerate in that direction.
Now let's apply this to Earths magnetic field and electromagnets acting similar to a compass.
The electromagnets make the pendulum swing side to side but also observe Newtons law. The force of Earth's magnetic field interacting with the electromagnets makes the pendulum swing in a way that we would not consider unusual.
As the pendulum swings the centrifugal force pulls it in one direction just as with the thrusters.
There is no magic here.
So in the below video my model is floating in water to simulate low gravity and friction. The electromagnets are at right angles to each other and swing the model side to side.
My model may look like a bunch of wires and stuff on some styrofoam discs but actually is pretty simple. It consists of some homemade electromagnets, batteries and an Arduino. There is an IR TV remote control circuit to turn the power on so that the model can settle still before starting when the button is pressed. The Arduino is programmed to turn the electromagnets on alternating so that the model generally swings side to side as the electromagnets at right angles to each other each align north and south with Earth's magnetic poles like a compass.
