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Yes, GW, I believe you wrote something like that. And I agree with you, when you state, that we can not be certain that something works, until it is really realized.
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I wrote:
"If one can accelerate a hyperloop-vehicle to 1000 km/hour,
it seems almost certain that China, Russia and the USA are already developing EMA-like structures for launching military planes."
When I wrote that, I did not think about aircraft carriers, but very long structures to get more acceleration.
On land.
If we can get it to work, it could be great for the defence of Europe against possible Russian aggression.
If Europe would build a few dozen EMA-like structures near the border and it is possible to launch a great number of drones in a short time, it would alleviate the threat of Russia.
But first we have to build one that actually works.
Andreas_Firewolf post 43 reply: EMA works on 3 magnetic arrangements repulsion, attraction and a combination of both to move the object that is in the tunnel tube that these are arranged within. The fields are pulsed to push or pull the object towards the end at velocity. While removing the air in front of the object would make it easier to move the issue is the in rush of pressure that will occur when you need to open it to make a launch possible from the arrangement of coils used to make it happen.
The tunnel tube must be perfectly straight as curves would cause friction and binding of the object to be launched. The object that is in the tube can also be inductive to making a field from the induced fields as well. A field can also be used to levatate the object within the tunnel tube as well to reduce friction. The longer the tube or tunnel arrangement is will allow for more speed to be picked up but there are limits as power of the fields to the mass of the object and how fast the fields can be turned on and off have limits based on materials to be used.
All of the fields are electrical and the power to make this happen is growing with each needed means to make it possible.
Perhaps you are right, but I am not completely convinced.
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If you accelerate an object without friction or resistance, and you keep the acceleration the same, then the amount of energy needed for the acceleration would remain the same.
In space you have conditions that are close to this ideal situation.
On the moon and on Mars you have to overcome gravity, but you are not troubled by air.
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Getting it to work on Earth would be difficult, to say the least.
Imagine an air-tight tube.
Before launching you suck out as much air as possible.
The tube is closed with an air-tight lit.
You launch the container and during the launch you continue to pump out air in front of the container.
When the pumps are controlled by a computer, this should not be a big problem.
Just before the container reaches the end of the tube, the lit is opened by the computer.
If the opening is 2000 or 3000 meters above sea-level, you have a lot less air.
That would alleviate the air-problem a bit.
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Another problem would be the resistance between the container and the tube.
If they make physical contact, it will not work.
But if there is a distance between the tube and the container, say 10 to 12 cm,
and the container is kept in the middle of the tube with electro-magnetism,
then the friction would be kept at a minimum.
If the distance between the tube and the container can be controlled and it can vary a little bit,
it might be possible to make a curved tube. As long as the curve is not to sharp.
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Hyperloop transportation is doing almost the same thing.
Developers believe they can reach a speed over 1000 km/hour.
The Delft hyperloop team (from the Dutch technical university of Delft) believe they can make that happen.
Moving from Amsterdam to Paris in 30 minutes.
And the trajectory can be curved a little bit.
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What I suggest is not much different.
But the speed I am aiming at, is much greater.
So I am not saying that it can be done. Engineers should answer that question.
But based on what hyperloop engineers expect to accomplish, I am quite confident
that a very large EMA for launching space-vehicles from Earth will become possible in the next decade.
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Perhaps I should put it a bit stronger.
If one can accelerate a hyperloop-vehicle to 1000 km/hour,
it seems almost certain that China, Russia and the USA are already developing EMA-like structures for launching military planes.
If you can launch small military planes like you shoot grenades, it would be a main advantage.
Your plane can stay in the air much longer, since you don't waste any fuel taking of.
Suppose an EMA would be build in the USA and one could use the Rocky Mountains to get elevation?
If you would build it on a flat surface, like the Great Salt Lake, you would have to build a construction going one or two miles up in the sky.
That might be a problem.
But if you would roughly follow the shape of a (stable) mountain, it might be more cost effective.
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A big question for engineers would be:
Must the EMA be absolutely straight or can it have a slight curve?
If it has a curve, is it possible to keep the container in the center of the tube with magnetism?
It seems mandatory to prevent direct contact between the container and the tube.
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Suppose the EMA is manufactured in segments of perhaps 20 or 50 meters.
Each segment has pumps, that pump out the air.
Before launching, the air is sucked out of the tube of the EMA as much as possible.
During the launch the pumps in front of the container could pump out remaining air.
It should be possible to control this with a computer.
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Perhaps it would help if the air that is pumped out in front of the container is pumped in behind the container,
but I have some doubts about that design.
Andreas_Firewolf likes the notion of electromagnetic accelerators. The science is good, the engineering technology still not so much. It's good enough now to build a railgun that throws a small artillery round. It was, until very recently, not good enough to launch even a small airplane or rocket, although the latest aircraft carrier has replaced the steam catapult with an electromagnetic one for trials.
This electromagnetic launch technology was first looked at about 1950, for flinging overweight bombers off the runway. Auxiliary rockets called JATO bottles proved to be far more practical for that application back then, and still are today. That is also exactly why some launch rockets add solid boosters. It's the same problem, just made worse by accelerating vertically upward directly against gravity.
GW
I do not have much practical knowledge about this subject, so I can not determine if you are right or wrong.
I am sure, your knowledge was sound a short while ago.
But in the past year there have been developments with hyperloop transportation. In a hyperloop system, the result largely depends on sucking out the air from the tube.
On Earth that is absolute essential. With a lot of air in the tube, you get an enormous heat problem as well as a resistance problem.
But when you suck the tube to near vacuum, it might work on Earth.
In space you do not have this problem. Neither on the moon or Mars. So perhaps it will work there without much effort.
When the science is solid, the question is not 'does it work' but 'are there engineers who can make it work'.
If engineers can make it work on Earth, it would make space-exploration a lot easier and probably safer.
Building a very large EMA in space
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In post 26 of this topic I proposed a very long EMA on Earth to launch vehicles to get to a space-station.
Suppose we design a modular EMA with modules of about 10 meters length.
We launch them into space and put them together.
With 100 of these modules we could get an EMA of 1000 meters.
We could use this EMA to launch robo tanker ships.
If we use an acceleration of 40 m/s2 and a length of 1000 meters, the tankers would get a speed of 1000 km per hour.
If we launch them before we launch the wheel-shaped space-ship, they could use the solar wind to gain speed.
And they could use jets and burn some fuel, when necessary.
If we want more much more speed, we could use a higher acceleration or make the EMA longer.
Mimicking gravity
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I started this topic with a proposal to accelerate and decelerate with 9 m/s2 to mimic gravity.
(And to reduce the duration of a trip to Mars.)
The absence of gravity is a serious problem for the human body, when you have to travel through space for half a year of longer.
Shielding against radiation seems more or less under control, if I have understood it right.
But how about gravity?
In StarTrek you simply switch on 'artificial gravity'. Butt that does not exist in the real world.
Another way of mimicking gravity would be to create a spinning wheel.
If we have a space-dock in which we can build space-ships that never have to touch Earth or Mars,
we can create such a vehicle.
Imagine a wheel with six or eight spokes and a radius of 100 meters.
This would create a circle with a circumference of 628 meters.
That would be enough space for a few dozen people.
Perhaps it is possible to get this wheel spinning by attaching fans around the wheel and using the solar wind.
But how can we gain velocity with this ship?
We can attach jets to the wheel and burn hydrogen and oxygen.
But if we want to get real speed we have to load an enormous amount of fuel.
The mass of it would be so huge, that we would hardly move.
The solution would be to tank oxygen and hydrogen during the trip to Mars.
If we create robo tanker ships, some with hydrogen and some with oxygen
and we get them in the path of the space-ship, we can tank during the journey.
We can not use an EMA (see above) to launch a wheel-shaped space-ship with a radius of 100 meters.
But with a large EMA we can propel tanker-ships with hydrogen and oxygen.
They could use the solar wind to adjust their speed to the space-ship.
It would require a lot of calculations, but I believe we can make it happen.
If we can make this happen, a journey to Mars would become acceptable.
Putting (about) four people in s small container and keeping them there for half a year in the absence of gravity,
seems a wrong approach to me.
But putting two dozen people in a ship with mimicked gravity and a lot of space to walk,
is not much different than putting a crew in a sub-marine for half a year.
It seems doable to me.
Last night I have been meditating on the very long EMA proposed above for launching from Earth.
At first I was thinking about a vertical EMA like an elevator shaft.
But we can design it to rise in another angle with the horizontal plane.
If we design a very long EMA rising 2000 meters above ground with an angle of 5 degrees with the horizontal plane,
the length of the EMA would be 2000 / sin(5) meters equals 22947 meters or roughly 23 km.
(5 degrees and 2000 meters elevation are just as examples.
What is practical should be decided by costs, available land and construction limits.)
With an EMA of 23 km you can accelerate a space-vehicle to the following speed:
With an acceleration of 10 m/s2 you accelerate to 2441 km/hour
With an acceleration of 20 m/s2 you accelerate to 3456 km/hour
With an acceleration of 30 m/s2 you accelerate to 4212 km/hour
With an acceleration of 40 m/s2 you accelerate to 4867 km/hour
That is not enough speed to connect with a space-station. So the space-vehicle should carry some fuel.
But it would be significantly less. So the mass of the cargo can be much higher.
When launching a rocket from earth, you have two disadvantages.
1. You have to carry extra fuel.
2. You have to overcome the resistance of the air, which is quite thick at sea-level.
This resistance also causes a heat problem.
When you launch a space-vehicle from Earth with a very long EMA
AND
you suck out the air in the EMA before launching
your heat problem will be significantly less,
and you can launch with much less fuel.
The launch of a space-vehicle with an EMA of 23 km would take 68 seconds when you accelerate with 10 m/s2
or 34 seconds when you accelerate with 40 m/s2
Sucking out the air from the EMA would be the most time-consuming.
If you can do that in 10 minutes, you can launch 6 space-vehicle per hour.
If you have enough electricity.
The space-vehicle would be in a container.
The EMA accelerates the container.
After the container is clear from the EMA, the space-vehicle could be expelled from the container with air-pressure or electro-magnetism.
The energy and the equipment for that could be in the container.
Once the space-vehicle is clear from the container, the container could land gently with parachutes.
It would be nice if we can re-use the container again and again.
The space-vehicles should be designed in such a way, that they can land safely on earth.
More like an air-plane than like a rocket.
It is more cost-effective if we can use the same vehicles for many years.
If we can make an EMA like this, it would be possible to send large amounts of cargo into space and build very large space-stations.
And we can build a space-dock to build space-ships in space.
While meditating on the problem, I came up with some insane ideas.
I do not know if they are already proposed.
And I do not know if they will be useful.
In any case, it was fun and educational writing them down.
Imagine an elevator shaft (or rather accelerator shaft) that accelerates an elevator (or container) with electro-magnetic force.
I will call the shaft EMA (short for Electro Magnetic Accelerator).
The EMA accelerates a container with in this container a space-ship.
The EMA is open at the end. The container will leave the EMA with the space-ship.
The space-ship then starts a little yet to push itself out of the container.
Once it is clear of the container, it can start the main propulsion system (if it has one)
to bring it to the desired or possible speed.
Since the space-ship does not have to carry fuel for its initial acceleration, it can reach higher speed.
Or it can carry more cargo.
Imagine two identical space-stations, one around Mars, the other around Earth.
They are massive, at least 100 times more mass than the space-ships they have to launch.
They have plenty of water, plenty of solar cells and plenty of fuel cells to reduce hydrogen and oxygen to water.
And both have an extremely long EMA.
You can use the solar panels to produce hydrogen and oxygen.
You reduce this fuel to water and produce the necessary electricity.
This is in essence an endless recycling of water.
It should be obvious, that the space-stations must have much more mass than the space-ship.
Otherwise, the space-station would be pushed away from the space-ship.
s = at2/2 (s = distance, a = acceleration, t = time)
If we accelerate with 10 m/s2 for 10 seconds we travel a distance of 500 meters.
To get a velocity of 100 m/s we need an EMA with a length of 500 meters.
But that is not much for a trip to Mars.
If we want to accelerate the spaceship to 40,000 km/hour or 11.1 km/s we need a longer EMA.
We 'only' have to build an EMA with a length of 620 km to get to that speed.
The previous sentence is written 'with tongue in cheek', that should be obvious.
I do not believe that such a construction is possible.
But engineers have surprised us again and again during the last century.
If we can build very large EMA's in space,
we can either reduce the duration of the trip to Mars or we could send more cargo.
It is up to engineers to come up with a reasonable design.
If this idea is worth pursuing.
Earth - moon traffic
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How about using EMA's for exploring the moon?
And how about using EMA's when launching vehicles from Earth into space?
If you have an EMA on Earth with a height of 2000 meters, you can accelerate a vehicle to 200 meters per second.
a = 10 m/s2
t = 20 seconds
v := 200 m/s
s := 2000 m
That would mean, that the vehicle can reach the required speed with less fuel.
The weight reduction of the fuel can be used for extra cargo.
If we would build a very large EMA on the moon, it can launch space-vehicles from the moon without fuel.
The space-vehicles only need small jets and a small amount of fuel to move towards a space-station around the moon.
The distance between the moon and Earth is about 384,400 km.
If you want to travel this distance in 72 hours, you need a velocity of 1483 m/s.
You would need an EMA of 102 km to get this velocity.
Perhaps this is possible.
An EMA of 10 km would give us a velocity of 447 m/s.
With that speed it would take 239 hours or 10 days to travel between the space-stations.
That might be acceptable for transporting humans. It certainly is acceptable for moving cargo.
With this technology it should be possible to build moon-bases and to travel at reasonable costs between Earth and the moon.
We can experiment with building moon-bases and then use the technology on Mars.
That seems better to me than to start with building a permanent base on Mars.
Exploring the Milky Way.
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Imagine that the space-station around Earth has an EMA that can be rotated
360 degrees in one plane and
20 degrees in another plane
in a right angle with the first plane.
Then you can propel a space-ship in any direction.
You can use the EMA for travelling between the Earth and the moon.
And you can 'point it at Mars' and reduce the duration of the Mars trip a little.
And you can use it to send out probes to every direction.
Currently we are like Europeans in the 14th century.
Europeans in the 14th century sailed the coastal waters around Europe, but never left the coastal waters.
At the end of the 14th century Columbus boldly sailed were no one did sail before.
(This is not entirely true. The people from Iceland had colonies on Greenland around the year 1.000 AD.)
We are the same. We are just leaving the solar system with the two Voyagers.
Suppose we are going to explore the Milky Way more seriously.
You can point the EMA on the space-station around Earth to any point in the Milky Way.
With it you can launch a rocket. At some point the rocket starts its jets and accelerates to its maximum velocity.
Then it propels a probe directed to some direction of the Milky Way.
Once the probe is clear from the rocket, it starts its tiny jets and accelerates further.
This could be a way to send out a few dozen probes with high resolution camera's
and enough energy to transmit the images to the rocket that helped launching it.
The rocket should be able to act as a relay station to transmit the images to Earth.
If an acceleration of 1 G is impossible, space-exploration seems almost impossible.
Suppose we can get a velocity of 0.01 c and we want to go to a planet at a distance of 50 light-years, it would take 5.000 years to get there.
I doubt if humans can survive in empty space for three generations. And now I am not referring to physical problems, which would be enormous.
I am referring to psychological problems as a result of cultural stagnation and boredom.
Spending half a year or longer in a metal can towards Mars seems horrible to me, but might be doable for some people.
But surviving 200 generations in empty space and remaining sane?
After some calculation I believe I found the error in my idea.
A Boeing uses oxygen from air. A spaceship has to carry the mass of its oxygen.
Energy in hydrogen 120 MJ/kg
Energy in hydrogen plus oxygen: 120/9 Mj/kg = 13.3 MJ/kg
Most energy would be used to accelerate the fuel, which is not very useful.
GW Johnson, am I right if I assume that we need to tame nuclear fusion energy before we can seriously explore space?
When you accelerate to 2.8 million km/hour or 1 * 10pow13 m per second and then you decelerate to 0
you can use E = mv2/2 to calculate the effective energy you need.
It is just the mass of the vehicle in Newton multiplied by the the velocity squared multiplied by 2 (acceleration and deceleration) divided by 2.
Multiplying by 2 and dividing by 2 cancel each other out.
So you are left with the mass of the vehicle multiplied by the desired velocity squared.
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I left out the resistance of space. I am not certain that this is right. Space is not completely empty.
On the other hand: The extra thrust you need when accelerating with some resistance should be almost equal to the diminished thrust you need when decelerating.
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That was the easy and a bit wrong calculation. It is only an approximation.
While you burn and expel hydrogen and oxygen, your spaceship looses mass.
When you leave the space-station you have more mass than when you achieve the highest velocity.
So deceleration would require less energy than acceleration.
I propose the use of hydrogen and oxygen because hydrogen has one of the highest energy densities related to its mass.
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The spaceship does not have to leave Earth's gravity. It should remain in space and never touch Earth or Mars.
The gravimetric pull of Earth is the gravimetric constant multiplied by the mass of Earth multiplied by the mass of the spaceship divided by the distance squared. If the distance of the space-station to Earth is large, then the gravimetric pull becomes small.
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I supposed that burning hydrogen and oxygen in a yet would give you a certain amount of thrust related to the energy that is released by burning.
Just like when you burn kerosene in a Boeing.
I am not sure about the efficiency of the conversion of this energy into thrust. I assumed that an efficiency of 20 percent should be possible.
If this is possible, you would need five times the amount of energy that would be needed for the acceleration and deceleration.
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The question or the challenge is: Can we build an engine that can burn hydrogen and oxygen in space and that has an acceptable efficiency in converting the released energy in thrust.
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I am under the impression that this is not rocket-science but applying the principles of an ordinary yet in space.
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When we have water and solar panels in space, we can simply use time to produce hydrogen and oxygen.
The spaceship simply tanks oxygen and hydrogen at the space-station.
If we want more energy, we put more solar panels in space.
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If I am mistaken about this, I really would like to know what happens to the energy that is released when you burn hydrogen in space.
The amount of fuel depends on the size of the spaceship, the humans do not add much to the mass. Engineers have to design a deflector shield strong enough to keep the people save. That is a lot of mass. Then you have the mass of the fuel tanks and the fuel. And the mass of the spaceship itself. I would be surprised if the mass of the humans would be more than one percent.
Pumping water from Earth does not appeal to me. But perhaps a modern version of the old fashioned canon? Say you have torpedo-shaped containers filled with water. You put them in a canon and with electro-magnetic force you propel them into space. I am not sure if this would work.
But we can not use water from Earth indefinitely. We have to get it from space.
There are a lot of ideas about going to Mars. But most plans have the same weakness.
The trip to Mars takes many months in space.
You can not put a few humans in a metal can and keep them there for half a year or longer.
Perhaps the biggest problem is the absence of gravity: It is detrimental for your health.
But when we reduce the trip to Mars to three days, we can go to Mars, spend a vacation in 'Las Vegas on Mars'
and be back within three weeks. It would be 'the time of your life'.
So the question should not be: How can we go to Mars?
The real question is: How can we reduce the trip to Mars to three days.
And that is quite easy. At least in theory.
First some basic facts. Gravity on earth is about 9.81 m/s2.
If we create a spaceship and we accelerate it with 9.81 m/s2 we have the same pressure on our body as when we are on earth.
What happens when we accelerate a spaceship with say 9 m/s2 for twenty-four hours?
We would reach a speed of 24 * 3600 * 9 meters per second or 2.8 million km/hour.
In that 24 hours we would travel 33.6 million km or 20.1 million miles.
When we decelerate with 9 m/s2 for 24 hours, we travel again 33.6 million km.
So in 48 hours we can travel 67.2 million km. and experience almost the same amount of pressure as Earth's gravity.
The distance between Mars and Earth varies.
When they are very close to each other, the distance is about 60 million km.
With such a 'small' distance we can travel to Mars in only two days.
The average distance is about 401 million km.
When we accelerate with 9 m/s2 for 24 hours
and we keep that speed for 120 hours or five days
and we decelerate with 9 m/s2 for 24 hours
we would travel 403.2 million km.
So in theory it is possible to travel to Mars with acceptable comfort in two to seven days,
depending on the position of Mars and Earth.
How can we do that in practice?
That should be quite easy.
Space is not completely empty, but the resistance of space is not very high compared to the resistance of air on Earth.
We have engines that can give a thrust for 24 hours, that is enough to accelerate with 9 m/s2.
We only have to design engines that can do that in space.
And we have to get fuel in space.
That is also quite easy. In theory.
This is what we should do.
1. We should build two identical space-stations.
When the first is finished, we send it to Mars and bring it in orbit.
The second will be in orbit around Earth.
2. We should build vehicles that can move between Earth and the space-station around Earth.
A vehicle to move people and another vehicle for cargo.
3. We should build vehicles that can move between Mars and the space-station around Mars.
A vehicle to move people and another vehicle for cargo.
4. We should build spaceships that can move between the two space-stations.
They don't have to land on Earth or Mars. They should be build in space and stay in space.
One type of spaceship will be used to move people and should be designed to travel very fast.
Another type of spaceship will be used to move cargo. This should be designed to travel at low cost.
The spaceship for people should have a massive deflector shield.
When you hit a piece of rock with a speed of 3 million km/hour without a deflector shield, your ship will be destroyed in an instant.
The engine of the spaceship for people can run on hydrogen and oxygen.
It must have large tanks with more than enough fuel when something goes wrong.
If you run out of fuel with a speed of 3 million km/hour, you will miss Mars and be out of the solar system within three months.
5. We should create large arrays of solar panels around Earth and around Mars.
The electricity of these panels will be used to split water into hydrogen and oxygen.
This will be the main source of energy for the spaceship for people.
6. We have to get water to the space-stations.
Perhaps this is the most difficult and costly operation.
At first, we can use water from Earth. But we can not continue to do so indefinitely.
Besides, moving water from Earth to the space-station is costly.
So we should explore the asteroid belt and search for asteroids of ice.
If we have solar panels and we can find water in the asteroid belt, we have everything we need to go to Mars.
Note:
I double checked my calculations. But it would not harm to check them again.
If you find errors, please let me know.
Confirming or rebutting Einstein:
Einstein stated, that nothing can go faster than the speed of light.
I do not believe this. See Rebuttal of Einstein.
(I am not allowed to post links. So you have to paste it yourself.
andreasfirewolf.com/index.php?pi=1556&n1=119
).
If we create a probe and we accelerate it with 10 m/s2 for a year, we go faster than the speed of light.
Or not. It would be interesting to see what happens.
If we ever want to travel to other star-systems, we will have to travel much faster than the speed of light.
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