> This is a technology which could transform space travel and see craft lifting silently off from launchpads
Not with 12 millinewtons per kilowatt! In space, sure but not from launchpad.
Not with 12 millinewtons per kilowatt! In space, sure but not from launchpad.
So doing some napkin math with the article’s 12mN/kW, that’s close to a terawatt. For reference, I think worldwide electrical power generation capacity is around 10x that.
edit: made the math more explicit due to child comments and fixed spelling error
1 Watt = 1 Newton-meter/second
You're missing some values.
The work achieved (lifting some tons of rocket) is orders of magnitude less work than the power extracted from falling water (hydro, thousands of tons per second).
And the heat output of burning hydrocarbons and nuclear reactions worldwide were concentrated into a few rocket nozzles, that would be rather mind boggling!
Just out of curiosity, where is all the rest of the energy going?
If there is a genuine effect, and as EmDrive generates more thrust than photon drive for the same energy, it would mean that EmDrive does eject some small mass at large speeds (kind of like super ion thruster) - whether it is some mass chipped from the EmDrive (i'd bet it is the case) and/or created using the spent energy (say some smaller mass boson interaction with some field which looks less probable to me) - that we don't know yet.
This would make sense of the standard design, but doesn't seem to make sense for the photon loop described in the article. The photon loop seems to be an entirely closed system.
What's mysterious is where the energy and the impulse are going if thrust is real. We can point the drive in such a way that it slows rotation of the earth, so the earth's rotational energy and angular impulse are decreasing. Where should they be going? I don't know.
What this would be useful for is (by no coincidence) also the exact reason why it is considered crank science: you could use it to build a perpetual motion machine because it violates conservation of energy/momentum laws.
If the EmDrive actually worked, the correct use is to violate conservation of energy and momentum, not as a straightforward substitute for the engines we have now.
EmDrive looks like an accounting error to me, not something that actually works. Any energy it expends turns into heat, radiating in a predictable but not necessarily isotropic way. This radiation carries momentum, but much less than the EmDrive claims to be capable of.
A rocket or ion drive? The energy goes into the kinetic and gravitational potential of the exhaust.
(Aside: kilowatts are power, not energy).
How long would it take a nuclear powered EmDrive to push a fully loaded semitrailer from 0m/s to the speed of the interntional space station?
The maximum mass for a semi-truck fully loaded is 36000kg. The EmDrive generates 12millinewtons per kw. 1n = 1kg*(1m/s^2). Leo ~=7.66km/s^. A nuclear reactor produces ~1gw. We would need 275760000N to accelerate a semi truck to leo speeds. A nuclear powered EmDrive would take ~265 days to push a semi truck to low earth orbit speeds.
The escape velocity of Earth's orbit is 11.19 km/s, and if you were going to take humans on the trip you'd need much more cargo than 36000kg. Granted, you wouldn't have to move the craft from 11.19km/s to 0km/s and then 0km/s to 11.19 km/s every time you entered and left orbit, but it would be a slow ride regardless.
But it is 99.9999% not going to work at all, the emDrive would just be a cheat at space travel.
Something that can transform energy into momentum without shooting stuff back is the Holy Grail of space travel -- after a warp drive.