Em drive good news...

[Nuke]

14 hours ago, Scotius said:

I bet it's due to the alluring simplicity of EMdrive While Mach thruster would require exotic and expensive materials to get the best results, EMdrive basically is a sheet of bent copper with a part of a microwave welded on

if you want high q you need a machined cavity. in fact the cannae drive does that. the best drives seemed to have a dielectric in the cavity so it makes me wonder if some kind of virtual capacitor is forming (and if perhaps the em drives work through mach effect).

on the math side the mach effect thruster makes sense out of the box, and we know what it can do, we know why it works, and its just a materials engineering problem. most importantly all the labs testing the thrusters, on vastly different apparatuses, are getting the same results (em drive is really all over the place in this reguard). if you can solve the problem of the pzt stacks wearing out too fast, you might have a thruster. new electrostrictives exist, but woodward, etc have been having trouble sourcing them. woodward thinks a solid state device is the way to go, but if it turns out the resonant cavity based drives are working via mach effect, i can see advantages of having a device that has a more robust all metal construction.

[PB666]

On 1/12/2017 at 9:16 AM, wumpus said:

Sort of.  The whole idea of the device was dreamed up because the shape implied a difference when fed through the equations implied difference in momentum applied to the two sides.  Some experimental data appears to confirm this (it is sufficiently small to be inconclusive).

Even going between Earth-Mars, you could presumably pick up enough Xenon (or Argon if you used too much) for each trip.  An em drive is pretty silly for anything other than interstellar (where the mass for the ion drive will eventually run out).  I'd still think you could use cyclotron tricks to get a lot more Isp out of your ions if you cared enough (i.e. if you were going interstellar, once you hit 4 figures of Isp for interplanetary missions other factors become more important).

And yes, this really reminds me of the time that a credible research team kept seeing objects going faster than light... eventually they found the cable plugged into the wrong place.

Its an even worse idea for interstellar because of the power requirements, unless you mean it has a magical always 20 years in the future fusion drive.

Even then fusion drive would probably not work without a significant robotics.

Let me just say how bad the circumstance is, the thrust they are reporting is < 0.00001 newtons. A fusion reactor at its minimum would be 50 kilotons. It might generation 1 TW (1012 of power) but and lets say that could power 1 million drives. weighing a 10kg each. So the mass is 10E6 + 50E6 = 0.00001 x 1E6 would be 10N. And then divided that bout 50E6 puts us in the 0.5 micrometers/sec^2

To get to the .1 speed of light at 1 m/s2 would take about 10 months. This thing would take 2 million years. So yo use this device you would need to pick a target that would be close to earth in about 3 million years (About the time of the evolution from advanced australopithicus to homo sapiens (one hominid speciation cycle).

And why would you do this, if you had a fusion reactor on your ship, you can use the fusion waste as accelerant for your ion drive, and they with a lower mass ion drive unit.

THis type of drive would be suitable for shuttling between low dV stations or station keeping (such as a space telescope). So for instance if you had a few hundred dV to shuttle supplies between mars L1 and Earth L2, and the supplies were not perishable (say underwear, space toilets, freeze dried food or food frozen to -80'C) then you could say have a 5t vessel and some solar panels and a few million seconds (86400 seconds in a day, about 11 days for a million). So it takes a several months to accelearate to transfer max and several months to slow down factoring the reduction in power at Mars orbit. You could also ship kerosene (and O2 if you could find a way to store effectively), when its done you could send it back.

The problem however is that during testing this thing blew lots of electronics in a vacuum. So its electronics may not be capable without significant overengineering to last in space for several years of near continuous operation.

 

[Nuke]

cool thing about a solid state mach effect thruster, you might be able to make a mems device out of it. can haz chipsats?

[magnemoe]

7 hours ago, PB666 said:

Its an even worse idea for interstellar because of the power requirements, unless you mean it has a magical always 20 years in the future fusion drive.

Even then fusion drive would probably not work without a significant robotics.

Let me just say how bad the circumstance is, the thrust they are reporting is < 0.00001 newtons. A fusion reactor at its minimum would be 50 kilotons. It might generation 1 TW (1012 of power) but and lets say that could power 1 million drives. weighing a 10kg each. So the mass is 10E6 + 50E6 = 0.00001 x 1E6 would be 10N. And then divided that bout 50E6 puts us in the 0.5 micrometers/sec^2

To get to the .1 speed of light at 1 m/s2 would take about 10 months. This thing would take 2 million years. So yo use this device you would need to pick a target that would be close to earth in about 3 million years (About the time of the evolution from advanced australopithicus to homo sapiens (one hominid speciation cycle).

And why would you do this, if you had a fusion reactor on your ship, you can use the fusion waste as accelerant for your ion drive, and they with a lower mass ion drive unit.

THis type of drive would be suitable for shuttling between low dV stations or station keeping (such as a space telescope). So for instance if you had a few hundred dV to shuttle supplies between mars L1 and Earth L2, and the supplies were not perishable (say underwear, space toilets, freeze dried food or food frozen to -80'C) then you could say have a 5t vessel and some solar panels and a few million seconds (86400 seconds in a day, about 11 days for a million). So it takes a several months to accelearate to transfer max and several months to slow down factoring the reduction in power at Mars orbit. You could also ship kerosene (and O2 if you could find a way to store effectively), when its done you could send it back.

The problem however is that during testing this thing blew lots of electronics in a vacuum. So its electronics may not be capable without significant overengineering to last in space for several years of near continuous operation.

 

Agree, unless efficiency is improved a lot this is mostly for satellite station keeping and small probes, taking over the ion engines role in most cases. 

The electronic used in the vacuum experiment was not rated for vacuum, for lots of parts that would require space rated gear who was out of budget. Far cheaper to just live with the fails. 
 

[Nuke]

8 hours ago, magnemoe said:

Agree, unless efficiency is improved a lot this is mostly for satellite station keeping and small probes, taking over the ion engines role in most cases. 

The electronic used in the vacuum experiment was not rated for vacuum, for lots of parts that would require space rated gear who was out of budget. Far cheaper to just live with the fails. 
 

they tested it on a new unit with ceramic caps, it was in one of those ssi presentations.