Rockets, spaceplanes, orbiters, Von Braun and other topics

[Taylor (imported)]

You have me at a disadvantage as I have severe difficulty with advance mathmatics (that is a discussion for another time).

I acquese to your calculation and agree that a 10g acceleration is far, far too much strain. However, my suggestion isn't for the sole use of a rail catapult but some kind of hybrid.

Worst case scenario, if a rail catapult some 300 miles long is required, then build it. Hell, if we can build oil pipelines across Alaska, Europe, and entire continents, then a rail catapult that length is doable. It could even be built underground.

Another possibility is to build the rail catapult in the form of a large circle and only alter the courst to the vertical once sufficient velocity is reached and then a booster system to give it the extra push to orbit. (Something like the Hadron supercollider but on an even larger scale.)

Where this a will, there is a way.

T.

[DeaconBlues (imported)]

First off, I would like to say THANKYOU "fhunter" for actually "doing the math" and offering some idea of how long a track/mag-lev rail/cannon barrel would have to be to launch living payloads into space.

Second, I am sorry Taylor, but I think you and others are missing my point. The point I am trying, with little success, to make is that the ability to launch NON living payload safely and cheaply into space is going to be a "lynchpin to success" in the next century. As it is now, we are able to launch payload, living and non-living into space, at tremendous costs. We are paying for a luxury of low g-force launch for a LOT of non-living payloads that could easily be engineered to withstand the 25g load of a super-gun launch.

The image that comes to my mind when I think about the current situation of the human race and to a lesser degree the "western nations" is the image on the Tarot cards of "The Fool." He seems totally unaware that he is walking off the edge of a cliff, behind him the buring sun, no matter which way he goes he is in for trouble.

Depending on how you look at our current situation, we are surrounded by dangerous and unpleasant choices... or, IF, IF we can just figure out a few little problems, then we are surrounded by AMAZING opportunities. I am actually not sure myself that "figuring out a few little problems" would be a good or bad thing in the long run. Look to history, a long time ago, someone "figured out a little problem" as he or she saw something rolling, knew it would be an easier way to move things than a primitive drag or sled, and in the blink of an eye, the concept of "the wheel" was developed. And... was this "wheel" used to make wagons and carts and greatly improve human life? Yes.... but it was really perfected for CHARIOTS for war... and the wars cost human life and civilization. You can point to ANY great discovery, and quite reasonably argue that the human race might well have been better off, might well have developed actually better, if it had NOT been discovered.

One thing for sure, any great technological achievement will in some way or another be quicky turned by people into a method of coercing other people into being slaves of one sort or another. So it is with a mixture of tremendous enthusiasm and horrible dread that I contemplate our current situation....

This point that we are at in time, I believe to be very similar to a point about 500 years ago, after Colomus "discovered" the Americas (truth is, he was LOOKING for India, and bumped into a couple of other continents). If ever there was a "fool" so totally unaware of his reality as the fool on the Tarot card, it was the great "discoverer" who found the islands in the Carrabean Sea, and called them "Indies" thinking they were somewhere in the Indian Ocean. But yet, even though they really had no concept of what they had initially discovered, they quickly turned this goof to their advantage, well at least for a while. Spain quickly amassed staggering amounts of treasure.

We are in a similar situation, only it is not new continents, but space that we for the first time are able to use, not merely observe, but use for our advantage. Instead of sailing ships and conquistadors, it will be our "space lift" capabilities that will determine just where we stand among our friends, allies and enemies in the next century. I predict that the next "Spain" will be the country that first develops a practical space lift capability. ANY of the space fairing nations has this capability just within their grasp, it was quite nearly in the grasp of Saddam Hussein when he was frighteningly close to having an operational super gun. I believe that Saddam Hussein clearly was developing the super-gun for it's potential as a weapon, but even Saddam would have greatly benefitted from being able to launch low earth orbit sattellites at a FRACTION of the cost of current methods, had he been able to put the gun in operation, I am certain that it would have been used for both purposes eventually.

My own wildly ambitious ideas, for a space borne power station, and weather influencing sun-blocker/reflector sattellites, are only a few or the benefits we could reap if we could actually put stuff in space cheaply, quickly, and safely. Of course for the living payloads, and for things that just could not be designed to fit in a "penguin" projectile, we would need to keep the rocket launch systems. But the advandages and the capabilities to put in orbit payloads so easily, would completely change the limitations that we currently have to deal with. IF, we could have put payloads into orbit without having to contend with the current limitations on weight.... imagine, we could have put all the parts for a huge Mars lander, the fuel, the roving robots, even living quarters for the first manned Mars mission. The "rocket wagon train" could have been assembled in the near zero gravity in orbit, and then with a MUCH smaller ammount of fuel sent off to Mars, or Venus, or any other planet or even off on a many many year long mission to the nearest star (four light years away... damn, we better get going soon if we expect to be alive when that probe radios back it's first close up pictures - and they are gonna be four years old when we recieve them!)

We are in that "fool" situation, are we going to take our next step carfully? Or maybe we are going to go over the edge of that cliff and "try to construct a pair of wing on the way down?" In fifty years... will my grandchildren look up at the sky and think "the space reflector makes in fun to go for an artificial moonlit walk even on new moon nights..." are they going to blissfully enjoy moderated weather and think of "global warming" as a silly thing that only old people had to worry about? Or maybe... they will look to the dark and frigid noon day sky and curse, and say, "DAMNIT! The Chinese have put another solar embargo against us! When will they have enough of our labor slaves to give us back our sunshine?" I know, that scenario may sound a bit extreme, but seriously, I would rather we be the country with the massive sun-blocker at our command.

[A-1 (imported)]

Yoli here,

I remembered that Dad got a kick out of this re W. v. Braun.

http://www.youtube.com/watch?v=kTKn1aSO ... feature=iv

Enjoy!

Vapor traaaaaaails to yoooouuuu, untilllll we meeeet againnnnnn.

Y.

U-TUBE gave me the following message...

The URL contained a malformed video ID.

[A-1 (imported)]

On length - for the astronauts to accompany payload, acceleration must not be greater than 10g, being conservative - 6g.

Minimal speed, that must be reached by the projectile in this catapult - 7900m/s.

S=a(t^2)/2

v=at.

Getting time from here - t=v/a

S=(v^2)/(2a)

S=(7900^2)/(2*9.1*6)=571520meters. or 571km (approximately).

Doesn't look easily doable to me.

For 10g - I calculated the length of 343 km.

It is a little too simplistic of a calculation for the problem. First of all, acceleration is meters/second**2 (Squared)

A force that causes 1 G of acceleration would just make a payload weightless. The whole problem being air friction that causes wind resistance, because without it an object accelerated by just a small constant force would just keep accelerating until it reached escape velocity.

Don't forget the force exerted by gravity is a constant force and would therefore cause a constant acceleration were it not for the friction of air which exerts a force in the opposite direction. This is what causes a terminal velocity to be reached by any object in free fall. The greater the resistance of the air, the lower the terminal velocity. Technically, at terminal velocity an object is in equilibrium.

It just doesn't seem that way for a skydiver because they are experiencing the air resistance but the feel of gravity is not felt. It is also why objects hitting the Earths atmosphere at tremendous speeds burn up. The kinetic energy of the moving object is changed to heat energy.

The higher in the atmosphere you would get, the less air resistance would be encountered so the problem requires a pretty severe differential equation to do correctly. Plus, the air resistance is calculated and changes with velocity and altitude due to the decrease in atmospheric density (pressure) as your altitude increases. Any object fired from a cannon in the Earth's atmosphere would start to de-accelerate as soon as it left the barrel of the cannon, being affected not only by the Earth's gravitational force but also by air friction forces.

The problem with the cannon is the acceleration. Leaving the barrel the object would have to reach a speed exceeding the escape velocity of orbit which is around 17,000 miles per hour. That's around 24 times the speed of sound at sea level because it would be de-accelerating all the way after it left the barrel until it left the Earth's atmosphere.

To give you an idea of the speeds that we are describing here the house and garden variety of High-Powered rifle fires a projectile at only 2,500 miles per hour (or so).

The boost idea using an electromagnetic track (surface friction free) would be a big help to objects trying to attain orbit but there would have to be some sort of other self-contained thrust to make it work after it left the track. Plus, hit some birds or an animal, well, you know what happend to that airliner that ditched in the East River in New York.

This problem is very complicated. It is especially so in rockets since as the fuel burns the rocket gets less massive and therefore takes less Force to accelerate.

It is really more than I plan on calculating today.

[fhunter]

It was approximation. Probably should have mentioned conditions, on which I calculated this.

The order of numbers would be the same.

Yes, I know that what I calculated looks like "harmonic oscillations of spherical horse in vacuum". My physics is rusty, I admit it.

[A-1 (imported)]

It was approximation. Probably should have mentioned conditions, on which I calculated this.

The order of numbers would be the same.

Yes, I know that what I calculated looks like "harmonic oscillations of spherical horse in vacuum". My physics is rusty, I admit it.

Well, I commend you for biting this thing off and chewing on it for a while.

The problem being that harder you chew it the tougher it gets.

[Dave (imported)]

It was approximation. Probably should have mentioned conditions, on which I calculated this.

The order of numbers would be the same.

Yes, I know that what I calculated looks like "harmonic oscillations of spherical horse in vacuum". My physics is rusty, I admit it.

And what is wrong with a first approximation?

You need to add more energy to account for wind resistance. A good way of doing it is to use "no" resistance as the lower energy estimate and total atmosphere all the way up into space as the higher estimate. the real number would be somewhere in between. If you can know wind resistance, find the height where the air thins to half of its normal density and then use that figure as the second approximation.

This might be rocket science but it's not impossible to get an idea of the power required.

[Taylor (imported)]

Please....no more math...head hurts....must save the brain....

(Brute force. If it isn't working, you're not using enough.)

Ok, one thing we agree on is that it can be done. If a private company can figure out how to do it economically then there is an entire new sector of the economy waiting to grow.

Imagine the mining opportunities on the Moon, iron and nickel rich asteroids (some of them are absolutely huge), exploration for the sake of exploration and knowledge, and who knows what other opportunities will be found.

Advances in the fields of science, medicine, engineering,etc., have ALWAYS made huge leaps on the backs of explorers.

Oh, poop. I'm starting to ramble.

[A-1 (imported)]

What's that you say, Taylor?

Brute force, eh? Well,

Oh! Just SCREW the ROCKETS and TRY...

THIS (http://en.wikipedia.org/wiki/Project_Or ... ropulsion))



...a GREAT way to decommission nuclear weapons...

Also,

...Shows Kim Jong ILL (as in SICK!) what's what!...

[Taylor (imported)]

Heh, heh. One of the most interesting propulsion ideas.

We could have had a functioning Orion type spaceship a couple of decades ago but people are put off by the use of a series of nuclear detonations.

It would work and people shouldn't be afraid since the detonations would occur in space. The ship isn't designed to lift-off from earth.

Actually, the idea is being quietly dusted off by NASA but to keep people from getting into a tizzy, they are removing any reference to nuclear, detonations, explosions, etc.

----

RE: Brute force. If it isn't working, you aren't using enough.

I have a friend who has a similar saying: It it doesn't fit, get a bigger hammer.

T.