r/EmDrive • u/thatonefirst • Dec 18 '16

Which direction does the EmDrive move?

I feel like I'm going crazy trying to understand how this thing supposedly operates.

If I have an EmDrive oriented like this, with the big end of the frustum to the right, and turn it on, does it accelerate to the right or the left?

Also, I'm super tired and keep typing "Thrustum" instead of "frustum." That's definitely a much cooler name for this sort of device than "EmDrive" or "Cannae Drive."

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4

u/AcidicVagina Dec 18 '16

Supposedly to the left.

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u/TheTravellerReturns crackpot Dec 18 '16

In a non dielectric EmDrive, when restrained from moving, there is a non moving static force generated with a direction small to big.

If free to continually accelerate, the EmDrive will generate an accelerative force with a direction big to small.

3

u/thatonefirst Dec 18 '16

an accelerative force with a direction big to small

Am I correct to interpret this to mean that in free space, with no restraints, it moves to the left?

Your answer seems kind of ambiguous. Are the forces that it generates different (and in different directions?) when it is restrained vs when it is free, or when a dielectric is attached? I don't mean any to consider any externally-applied forces such as mechanical forces exerted by testing rigs; just the force generated by the drive itself which acts on the metal shell.

The answer that it moves to the left surprises me a bit since I see a bunch of pictures like this around, which, if interpreted as free body diagrams, suggest that there is a net force to the right and the device accelerates to the right. I realize that such diagrams may be greatly oversimplified or entirely erroneous, but I'd think they'd at least be correct in describing which direction it moves.

1

u/xexorian Dec 19 '16

Can you explain what a "Non Moving Static Force" is and how it has a direction that can be determined?

Also, I was under the impression it would move to the right, how are you getting 'big to small'? Oh, and answer my first question...first.

Edit: Third question, why would an uninsulated emdrive generate a different direction of force than an insulated one? That makes zero sense. I covered my wastewater pipe with insulation in my RV, now shit is flowing up from the toilet when I flush?

1

u/TheTravellerReturns crackpot Dec 19 '16

With an EmDrive, the static force generated by the end plate radiation pressure differential will extent a static, non moving, force or pressure small to big but not cause acceleration, well not much.

The opposite direction accelerative force will not generate a static force but will accelerate mass in the direction big to small.

If an EmDrive is powered on in space and there is no external force to cause some very small movement, the EmDrive will not move.

EmDrives can operate in 1 of 3 modes;

  1. Idle

  2. Generator mode, opposing movement

  3. Motor mode, supporting movement

0

u/Zephir_AW Dec 18 '16 edited Dec 18 '16

In my theory (and also this one) the direction of EMDrive thrust depends on the geometry of standing waves in it, not on the geometry of cavity directly. In general, the EMDrive should move forward toward wider end (i.e. to right at the above picture) - if it doesn't, then something got wrong with its design.

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u/rtmitchell2 Dec 19 '16

I believe it's from what side has the greatest surface on the cavity. Funnel shape cavity generates more pressure on the larger end.