Experiment replication to observe the thrust in EmDrive device.
The device uses a magnetron to produce microwaves which are directed into a metallic, fully enclosed conically tapered high Q resonant cavity with a greater area at one end of the device, and a dielectric resonator in front of the narrower end. The inventor claims that the device generates a directional thrust toward the narrow end of the tapered cavity. The device (engine) requires an electrical power source to produce its reflecting internal microwaves but does not have any moving parts or require any reaction mass as fuel. If proven to work as claimed, this technology could be used to propel vehicles intended for all forms of travel including ground travel, marine travel, sub-marine travel, airflight and spaceflight.
EmDrive is a device invented by Roger Shawyer in 1999 and replicate with success by a team from China led by Yang Juan and a team from Nasa this year. The device was also tested in vacuum with the thrust is sill present so the air convection or other possible air movement is ruled out.
I will replicate the experiment and try to observe the thrust.
Materials for the drive.
- Cooper sheet 0.3mm (initialy intended 0.6mm)
- transformer from a microwave oven (power ~ 800-1200W)
- Magnetron from microwave oven: Anode cathode voltage ~ 4kV , and 3-4V @13A for the filament. Frequency 2,45Ghz.
- solder, 4mm screws, pcb
Test equipment: Current measurement, voltage measurement, temperature measurement, micro-gram scale.
Frustrum 3D modeling in Autocad Inventor
Connection diagram for the magnetron. Warning: charged capacitors can kill very easy. Always discharge the capacitor by putting 100kOhm resistor on the ends and also to the external case for your safety. After discharge put the ends in short circuit and wait for a couple of seconds to be absolute sure that there is no voltage.
After i power on the temperature of the magnetron increased to 60 degree celsius.(140F) in around 5-6 seconds. If the magnetron does not have any load the temperature should rapidly increase i think, even though the microwave oven will not burn (overheat) if left on without any food inside.
In this paper : http://www.emdrive.com/IAC-08-C4-4-7.pdf they say that the thrust comes after 20 seconds you power the magnetron. But in 20 seconds the magnetron will be very hot without proper cooling ( or maybe because the magnetron has no load)
I still do not know if the waveguide in a microwave oven plays other role than just feed the microwave in to the cavity.
Another think i want to test is to try to reduce the current on the filament with a separate power supply in hope that i will decrease the power in “search”of some thrust.
In a few days i will receive 2 plates of PCB singe-sided, and i will try them instead of cooper ends.
Today i did the first test with the setup suspended in a pendulum. The power was applied for 40 seconds. No thrust resulted 🙁
i will post the video soon.
Tomorrow i will move the magnetron above the middle of the frustum, to the small end. After power on for 40 sec temperature was 85 degree Celsius.
Next step will be adjusting the current of the filament and maybe the frequency by adding 2 separate coils over the magnets with adjustable current, to try to change the oscillating frequency.
Test No. 2
Modifications: magnetron moved to the smaller side
Coil added to the magnetron to try to adjust the frequency.
Still no visible thrust in the pendulum
Test No 3, Thrust observed.
As you notice in the movie the weight of the foam on the frustum is 10.2gr and real weight is 3.58gr so the lever ratio is 1:2.894 in this way the real thrust was 0.508gr.
New tests will be done with the coil to see any change in thrust.
I will modify again the frustum and add adjustable length so resonance adjustment.
I did not have time time to do any new setup. Frequency counter has arrived, and i measured 2463Mhz. . By changing the current in the coil around the magnet i will change the magnetic field created, overimpose to that of the magnet. With this change in magnetic field, the frequency output should change. I hope i can change enough to find the resonance frequency of the frustum and hope for higher thrust. The other method of finding the resonance is to adjust the length of the cavity. This can be done with a movable plate and a screw . I can make that out of PCB.
Hi, guys, i`m still alive . Sorry if i did not post anything this days. I noticed some guys think i died , relay strange. I do not have a Tweeter account by the way.
I flipped the cone in the original setup and i have the thrust downwards (scale goes positive). Unfortunately the thrust downwards is around 7 times smaller. difference on the scale is only 0.20 grams and is consistent with the power on and off .
Temperature discussion: during the tests the temperature of the frustum does not change to much maybe 1-2 degree.
The biggest change in the temperature is on thee fins of the magnetron. Can be as high as 80 degree Celsius. Definitely the air is going upward from the fins. (What is this meaning the the change in weight?) The tests shows that after power off the frustum weight is continue to decrease. up to – 0.30 grams at least. How we can explain this ?
Andy P. said something interesting : “When comparing the different thrusts, you will also have to take into account that in test 3.1 the thruster has to fight against the upward force of the spring onto which it is attached. This will lower the observed weight change on the scale, but does not necessarily mean the thrust is lower.”
This fight “against the spring” is real or not ? Lets assume this: you put 1kg on a scale and push TARE button. When you remove the weight it should not indicate -1Kg if the fight against the spring was real. Inside the scale is also a “spring” to keep the weight the the test should be the same.
I`m working the modify the cone now. Test No 4 will be with new setup.
Because i do not have a cooler to the magnetron i can not put a servomotor to continuously adjust the cavity length because magnetron will heat fast. So i will need to manually adjust the length for each test to observe the scale and then let the magnetron to cool ant test again.
First i will adjust in bigger steps 1cm smaller for each test. then i will see witch one has the most thrust. After i will go around that value from mm to mm with the screw.
I do not own the picture with the adjustable setup. is from NasaSpaceflight forum.
Unfortunately i can not continue tests for the moment because i moved from original location (another country) and i left the frustum, magnetrons, transformer, there. I was not able to carry all my stuff.
I will continue tests, but i do not know when. 🙁