'Impossible' rocket drive works and could get to Moon in four hours

a reply to: intrptr

I think once we nail down sustainable fusion energy, many of our problems in space propulsion systems will no longer exist.

There is always the problem of inital launch, though.

a reply to: neoholographic

I read this on another site and one commenter asked a very good question:

"how do you slow it down?"

Does this EM drive have some kind of 'retro thrusters' that counteracts inertia or would conventional rockets still be needed to slow it down?

a reply to: Wide-Eyes

OK, you are wrong.

Source

originally posted by: EarthPilgrim

originally posted by: Nibbles
Oooer...

Hoping with 4 hours getting to the moon that the first vessels will not be manned???

Just a quick calculation here : If the average distance from the Earth to the moon is around 384,403 km (semi-major axis)

Then that means that the speed for travelling would be roughly 96,000 km per hour.... Thats a hell of a lot of G force?

creation.com...

But then again, maybe I am wrong?

Plus, I am wondering how the craft would actually land without crashing flying at those speeds?



Kindest respects

Nibs

a reply to: neoholographic

Hey Nibbs, I might be wrong but gravitational forces are only relevant when near planetary bodies no? I'm not an expert by any means and I probably should have looked this up before posting (I'm feeling lazy) but I believe - perhaps wrongly, that in the dead of space, G forces would not apply.

You would feel g-forces any time you change velocity -- accelerate, decelreate, or change direction. However, if you travel at a constant speed in a straight line, you wont feel just like you were standings still (no matter how fast you are moving).

The gravitational pull of another body has nothing to do with the term "G-force" when talking about the forces exerted on a body by a change in velocity.

a reply to: Thecakeisalie

Mostly likely reaction wheels or RCS (reaction control systems) would spin the spacecraft into a retrograde position and thrust would be applied by the engine.

a reply to: ScientificRailgun

Yeah...I didn't understand a word of that. My bad.

I was thinking of Newtonian physics first and not how such a drive could slow itself- however the probe would be useless in a interstellar dogfight.

originally posted by: windlass34
to get to the Moon in 4 hours would require a constant acceleration of at least 7.3 G for two hours and then constant deceleration -7.3 G for two hours, maximum speed achieved would be around 53 km/s (33 miles per second) which is roughly 190,000 km/h (177,500 miles per hour). Nothing like this was ever achieved.

Dang, I'd rather take a 16 hour trip to the Moon that would get me there alive rather than a 4 hour trip that would get me there dead.

a reply to: Thecakeisalie

Hmm. Imagine you have a rocket strapped to your back and you're on a giant ice-skating rink. When the rocket fires, you move forward. If you want to slow down, you spin so the rocket exhaust is facing the direction of your momentum and fire the rocket again.

a reply to: ScientificRailgun

That makes perfect sense.

But how does the ice skater spin the rocket around? I can understand how it can work with convential rockets, so how does this proposed drive do the same thing? this is way over my head.

a reply to: Thecakeisalie

The systems I referred to earlier do that job. In the case of Reaction Wheels, think of cat that rights itself before it hits the ground. The system uses spinning wheels to affect angular momentum on the craft, spinning it.

RCS (Reaction Control Systems) Usually use a type of pressurized gas a specific points on the body of the craft to apply small bursts of thrust to spin the craft into the desire orientation. Shuttles and Resupply Pods to the ISS rely heavily on RCS to properly dock.

If I understand this correctly, NASA is testing this engine out to see if it creates thrust, and they have detected some, but the thrust it may be creating is possibly due to heat. My question is, so what? If it's getting thrust from heat, yet it's using no fuel source, isn't that pretty good? So we're using solar energy to get it started, which in turn kicks on the microwaves, which gives us thrust and heat. Awesome. Another question I have is what keeps the microwaves going once you get away from a solar source?

a reply to: ScientificRailgun

You answered my own stupid question, thank you.

I was thinking of complex maneuvering instead of straight forward navigation, I was getting ahead of myself.

a reply to: Thecakeisalie

Maneuvering in space is deceptively simple, yet also deceptively complex. It's okay! I'd be just as confused as you if I weren't an avid "Kerbal Space Program" enthusiast.

a reply to: Soylent Green Is People

To add to this, if you were to make even a slight course correction in space while traveling at the speeds mentioned in the OP, everyone/everything in the ship could most probably be splattered against a wall. Even Star Trek knew this and that's why they had "inertial dampeners"

a reply to: BlackmoonJester

They'd probably have to use a radiothermalitic generator, similar to Voyagers 1 and 2, New Horizons, Curiosity, etc. Not quite what we normally think of as a nuclear generator, but close. Normally powered by a plutonium isotope. They've been used for decades both in space and on earth, and are long-lived, reliable and remarkably safe.

originally posted by: Thecakeisalie
a reply to: neoholographic

I read this on another site and one commenter asked a very good question:

"how do you slow it down?"

Does this EM drive have some kind of 'retro thrusters' that counteracts inertia or would conventional rockets still be needed to slow it down?

well you could put the thing in a gimbal and rotate it and thus the thrust direction around. or assuming you could miniaturize them enough (operating frequency would have to go up as dimensions went down which presents materials engineering problems) you could have arrays pointed in X Y and Z axis for directional control.

originally posted by: BlackmoonJester
If I understand this correctly, NASA is testing this engine out to see if it creates thrust, and they have detected some, but the thrust it may be creating is possibly due to heat. My question is, so what? If it's getting thrust from heat, yet it's using no fuel source, isn't that pretty good? So we're using solar energy to get it started, which in turn kicks on the microwaves, which gives us thrust and heat. Awesome. Another question I have is what keeps the microwaves going once you get away from a solar source?

if it is heat; there is no point because there are numerous ways to do that which have better trust.if it is simply a standard rocket in disguise there is no reason to pursue it. the various EM drive camps (pro side) beilve it is not a standard known force and is reactionless though they all have their theories of why it works. the NSF DIYers (engineers, Physicists, and just talented fabricators) are swarming all over it with thier own theories and more importantly thier own equipment builds.

I'm... really confused.. I read the article, but still confused..

So, what did they do?

They ... built an EM Drive already or what?

Is it only theories on paper? That were proven to work with another new set of theories on paper?

Or the scientists actually built the damn engine already? Or they've only tested the supposed theory in principle and then discovered it actually works?

I'm just trying to wrap my head around all this, as the title is very sensational but the reality maybe kind of dull or boring. As in, how far are we until we can publicly witness these new space ships/rockets?

How far are they from achieving Mars travel in 70 days? Alpha Centaurie in 100 years?

When they travel so fast, any G force concerns? Any slow down concerns? What's the dealio here?

Sorry, didn't go through 9 pages all together

a reply to: Nibbles

The space shuttle hits about 4g max on liftoff, lets say 40 m/s^2 for easy numbers.
To get 192,200 km at ~37 m/s^2 takes about 53 mins, so roughly 2 hours for a trip to the moon from ground to ground, with less forces on the occupants than current space flights.

Nothing that seems problematic. The issue with long distance space travel is fuel usage and exhaust velocity, both seemingly solved with this EmDrive.

On a side note, it is pretty disturbing that 9 pages of this thread are filled with people failing basic grade 9 math on acceleration...

a reply to: Rocker2013
I think the scenario goes maybe like this,"I think they've broken the first unbroken law of physics, but we still have the other seven that they don't know that it can be broken too " ...