Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2104573 times)

Online WarpTech

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Awesome! 4+ mN! Though you may want to wear a foil hat and some chainmail when you turn that on. Make yourself a Faraday cage around it, so you're safe before you do too many test. It will also eliminate the accumulation of static charge, considering that thing is not grounded. We just want you to be safe.

Offline aero

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If I did the calculation right, a volume change of ~125 litres would be needed to account for this apparent weight change, due to thermal ballooning of a sealed volume. That's far too high a change in volume that could be reasonably expected, so it can't be the whole story.  Did I calculate this right?
air density = 4*10-4 Kg/m3

1.225 kg/m3  http://en.wikipedia.org/wiki/Density_of_air
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Offline deltaMass

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If I did the calculation right, a volume change of ~125 litres would be needed to account for this apparent weight change, due to thermal ballooning of a sealed volume. That's far too high a change in volume that could be reasonably expected, so it can't be the whole story.  Did I calculate this right?
air density = 4*10-4 Kg/m3

1.225 kg/m3  http://en.wikipedia.org/wiki/Density_of_air
Oops yes - it's deltaVolume = 400 cc that's needed to account for all the upthrust.
Still too big to reasonably expect.
« Last Edit: 05/18/2015 04:20 AM by deltaMass »

Offline aero

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If I did the calculation right, a volume change of ~125 litres would be needed to account for this apparent weight change, due to thermal ballooning of a sealed volume. That's far too high a change in volume that could be reasonably expected, so it can't be the whole story.  Did I calculate this right?
air density = 4*10-4 Kg/m3

1.225 kg/m3  http://en.wikipedia.org/wiki/Density_of_air
Oops yes - it's deltaVolume = 400 cc that's needed to account for all the upthrust.
Still too big to reasonably expect.
I don't think you want the density of air, rather the change in density of air with temperature. If the it is a sealed volume then the total air mass will be the same at any temperature. But I guess you are calculating buoyancy which is the density of the outside-the-cavity air times the change in volume of the cavity.

That is just one reason to turn the cavity upside down and re-run the test.
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Offline deltaMass

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Yes, for the buoyancy calculation you need the density of air.
For example, a coke can with an internal temperature rise of about 30oC will give an upthrust of about 0.1 mg-wt due to slight ballooning of its thin walls.

And I agree that turning it upside down is the first sensible control experiment.
« Last Edit: 05/18/2015 04:31 AM by deltaMass »

Offline Iulian Berca

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If I did the calculation right, a volume change of ~125 litres would be needed to account for this apparent weight change, due to thermal ballooning of a sealed volume. That's far too high a change in volume that could be reasonably expected, so it can't be the whole story.  Did I calculate this right?
air density = 4*10-4 Kg/m3

The volume is not completely air tide sealed. Air inside can escape around the hole were the magnetron antenna goes inside.I will try more tests with this setup. I noticed when the magnetron is completely cold the thrust is a even higher.The test was done with the magnetron already heated up. So if the magnetron  stays cool then thrust is even higher. Water cooling is a good solution but is not easy to make a good setup and without creating vibrations.

Offline demofsky

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If any calculated results from Meep are relevant then note that Meep calculates the largest thrust, O(1.1/c), when the antenna is dead center in the cavity. That is a point source. A dipole source is centered and parallel to the base plates for electric stimulation, and parallel to the axis of symmetry for magnetic stimulation.

Moving the antenna away from center reduces the detected force/flux ratio.

Interesting.  For the fulstrum Eagleworks tested in a vacuum chamber, they used a loop antenna.  (I also have a vague memory of someone saying that Sawyer used a T antenna parallel to the major axis of the fulstrum.)

In any case I have to wonder if this is a major factor in the performance of these devices, reflecting your simulations.  Also the use of a magnetron seems to be important.


....

Be that as it may, the main reason that we went with the lower-Q TM modes was because they consistently produced higher thrust levels for a given input power than the TE modes.  I will grant you though that getting the most thrust out of a particular resonant mode depended very painfully on the size, placement and rotational orientation of the loop antenna in the frustum cavity.





Offline deltaMass

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A 30oC temperature change of the air inside the (non-sealed) cavity suffices to account for all the thrust, based on dm = V d(rho):

rho @20oC ~= 1.2 Kg/m3
rho @50oC ~= 1.1 Kg/m3
so d(rho) ~= 0.1 Kg/m3
so taking V ~= 6 litres = 6*10-3 m3, we get

dm ~= 6*10-4 Kg = 0.6 gm

http://www.engineeringtoolbox.com/air-density-specific-weight-d_600.html

So again, the most important next test is to flip it upside down.
« Last Edit: 05/18/2015 05:00 AM by deltaMass »

Offline Iulian Berca

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.

Offline deltaMass

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What's the cavity volume, roughly? (is 6 litres close?)

Offline CW

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.

I agree. Take some good headphones, crank up the volume. Pretty much immediately when the buzz starts, the scale's display shoots up. Next step should be to try and reverse the orientation and repeat. If it's very close to the previous value, but with positive sign, buoyancy can be scratched IMHO. You also have to try and exclude the possibility for eletromagnetically induced mechanical forces on the setup during high-power operation, coming from the power wires leading to the magnetron.
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Offline LasJayhawk

Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.
I agree on the filament heating time causing the delay. It is best if you can allow the filament to heat up before applying the anode voltage. Also note that the center frequency and spectrum of a magnetron changes with the temperature of the tube. You may be observing that effect as well.

Offline Left Field

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.
Well done!

Would it also be prudent after a normal test run to slide the scale out from under the beam and energise the magnetron again to demonstrate that there are no interference effects at play on its electronics (thanks to the copper shield)?

BTW: Get yourself a pair of these glasses:


« Last Edit: 05/18/2015 06:47 AM by Left Field »

Offline zen-in

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.

Congratulations!   You have shown a lot of ingenuity.   One question I have however:   What happens when you move the electronic scale a few inches so that it is not under the metal boom supporting the cavity and you apply power to the magnetron?    Have you ruled out the possibility the RF energy is causing a false positive reading?  Another possible source of a false positive is the stiffening of the power wires when the magnetron is on.   This is due to magnetic forces between the conductors.    Those are possible sorces of error in your experiment.    I admire your ability to quickly build a workable test system.

Offline Iulian Berca

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Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.

Congratulations!   You have shown a lot of ingenuity.   One question I have however:   What happens when you move the electronic scale a few inches so that it is not under the metal boom supporting the cavity and you apply power to the magnetron?    Have you ruled out the possibility the RF energy is causing a false positive reading?  Another possible source of a false positive is the stiffening of the power wires when the magnetron is on.   This is due to magnetic forces between the conductors.    Those are possible sorces of error in your experiment.    I admire your ability to quickly build a workable test system.

In the wires for the filament the voltage is AC so they can not have to much effect in only one direction, just some 50hz low  intensity vibrations.
The anode voltage is pulsed DC but the current is smaller ~ 0.2A.
I already tried the scale without weight and i do not have any disturbance in the  reading when i power on the magnetron.
I can use an external supply for the filament , in this way i hope to adjust the power and maybe the frequency. But is very dangerous because i will connect the cathode with 4Kv to my power supply. The capacitance in the transformer can send some hi voltage to the supply.
« Last Edit: 05/18/2015 10:03 AM by Iulian Berca »

Offline TheTraveller

Test 03 Success. I have thrust.
I modified the setup and now i weight the frustum. the precision is much better.

I will make a modifications to be able to adjust the cavity length to achieve the resonance, so i should have more thrust then.

Iulin Berca:

Congratulations on the success! I think this demonstration is fantastic. The fact that the peak thrust appears ~3 seconds after the power is turned on tells me it takes a little while for energy to 'build up' in the cavity. After the peak, the thrust slowly dies probably because the cavity walls are warping and you are losing resonance.

The adjustable end plate would certainly help to achieve a higher peak thrust, it just might take some trial and error. But I believe cavity will still heat up and warp and the thrust will taper off.

Maybe this thermal effect could be mitigated using some sort of heat sink?

I rather think the time difference between applying power and thrust is due to the time needed to heat up the filament (cathode) in the magnetron. After ~ 3.5 - 4 seconds you hear that buzz inside, exactly in that moment the thrust appears. After that the buzz drops a little bit and also the thrust. After work, i will turn the cavity upside down to see if i can have the opposite thrust.

Congratulations!   You have shown a lot of ingenuity.   One question I have however:   What happens when you move the electronic scale a few inches so that it is not under the metal boom supporting the cavity and you apply power to the magnetron?    Have you ruled out the possibility the RF energy is causing a false positive reading?  Another possible source of a false positive is the stiffening of the power wires when the magnetron is on.   This is due to magnetic forces between the conductors.    Those are possible sorces of error in your experiment.    I admire your ability to quickly build a workable test system.

In the wires for the filament the voltage is AC so they can not have to much effect in only one direction, just some 50hz low  intensity vibrations.
The anode voltage is pulsed DC but the current is smaller ~ 5.3A.
I already tried the scale without weight and i do not have any disturbance in the  reading when i power on the magnetron.
I can use an external supply for the filament , in this way i hope to adjust the power and maybe the frequency. But is very dangerous because i will connect the cathode with 4Kv to my power supply. The capacitance in the transformer can send some hi voltage to the supply.

Big test is to invert cavity & see weight gain. Repeat small end up & then down say 10 times. Also need to leave pwr on for 30 sec or so.

Consider using a USB scale and record the data for reference.

To eliminate air heating / buoyancy as thrust source, maybe drill 6 x 1mm dia holes around both ends & middle of your frustum so as to vent the cavity in a way to stop heated air causing false positives. No Rf should leak out as hole size way below cutoff.

Could use 2 pwr transformers. 1 to supply heater and the other to supply the high voltage DC. Then can independently switch each off/on.
« Last Edit: 05/18/2015 09:39 AM by TheTraveller »
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Offline deuteragenie

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Dear Iulian,

Very nice.  If I followed your 3 experiments setup correctly, I believe that in the last experiment you changed both the location of the magnetron (moved from the big side to the small one) AND the way to measure "thrust". 

Would it be possible for you to repeat the experiment with the magnetron on the big side, but with your new way of measuring?

Please disregard if experiment 2 was performed with the new way of measuring.

Also, I suppose that starting the experiment with the cavity pre-heated would be helpful in minimizing the thermal effects.
« Last Edit: 05/18/2015 09:22 AM by deuteragenie »

Offline Flyby

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 :o
Very exciting news to see another (apparent) positive result... - i use the word "apparent" because it is still not 100% validated, but it looks promising, for sure.

Can't wait for the other home-builders to join in and produce similar results.....

If we could have 3 positive results from independent testers and top that with the final results obtained from the Eagleworks research team (by July?), then i think a lot of the scientific community will turn heads and start wondering what's happening, instead of brushing it off as "impossible".

Gaining credibility is/was  the main goal...
Once that achieved, it will go fast... funding will unlock, researchers/engineers will be interested in participating...etc

Offline Star One

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It has been pointed out it causes a lot of RF interference during the test, could this in any way cause measuring issues especially using a digital balance?
« Last Edit: 05/18/2015 10:28 AM by Star One »

Offline Flyby

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Iulian answered that one (marked in red) :


In the wires for the filament the voltage is AC so they can not have to much effect in only one direction, just some 50hz low  intensity vibrations.
The anode voltage is pulsed DC but the current is smaller ~ 0.2A.
I already tried the scale without weight and i do not have any disturbance in the  reading when i power on the magnetron.
I can use an external supply for the filament , in this way i hope to adjust the power and maybe the frequency. But is very dangerous because i will connect the cathode with 4Kv to my power supply. The capacitance in the transformer can send some hi voltage to the supply.

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