how high can a small, lightweight rocket go? what if it had a big head start?
instead of spending millions on rocket fuel to get huge satellites into orbit, why not send smaller satellites up this way:
first you build a huge lattice of hydrogen balloons (like weather balloons) with a lightweight
aluminum or plastic platform and put a small rocket on it. Weather sounding balloons can easily get up to the upper stratosphere (24 miles!). I don't know how much the gravity is reduced when you get that high. with that and with little to no air friction, maybe it's possible that a small rocket carried up on a balloon lattice can make it into orbit with a small payload - miniature unfolding communication satellites and the like.
Maybe it's possible to use the hydrogen from the balloons as an initial explosive burst upwards... to overcome some of the inertia.
most of the current shuttle's weight is made up of fuel. I was trying to think of a half-baked way of getting around that. What do you guys think?-- pixelswisher,
Jun 26 2000
Zero Gravity Monorail
http://www.halfbake...0Gravity_20MonorailFor pixelswisher [st3f, Sep 02 2002, last modified Oct 04 2004]
How a rocket works
http://www.howstuffworks.com/rocket1.htmfor [Max_Power] [krelnik, Oct 04 2004, last modified Oct 21 2004]
Hobbiest altitude record
http://www.hobbyspa...vanced/records.html116km's from the ground. [Zimmy, Jun 24 2007]
Air Force Explores Balloon-Assisted Launches
http://www.space.co...oonarch_012103.html [ldischler, Jun 24 2007]
http://www.astronau...com/lvs/rockoon.htmRocket + balloon [baconbrain, Jul 09 2007]
Trebuchet_20Space_20Mission... a no-goer unfortunately, at least here on Earth [BunsenHoneydew, Jul 18 2007]
zero2infinity balloon rocket
http://www.gizmag.c...ocket-launch/34315/ [xaviergisz, Oct 26 2014]
The gravity 24 miles up is only 0.6% less than the gravity at the earth's surface.
On the downside, if you launch from the stratosphere, you won't get that 1000 mile-per-hour boost that you get from the earth's rotation at the equator.-- dominus,
Jun 26 2000
How high does the shuttle orbit, and at what point do the astronauts start to feel weightless?-- pixelswisher,
Jun 26 2000
pixelswisher: On a standard globe (about a foot across) the height of a shuttle orbit is less than half an inch (sorry I'm too lazy to find the actual number, but I feel this is actually a useful picture).
The weightlessness they feel is not directly due to their distance from the earth but the fact that they are falling towards they earth (and constantly missing). It's the same "microgravity" you can feel if your plan were to drop out of the sky. Nothing in the spacecraft appears to have any weight because all of it's falling at the identical rate.
Heh. I made a rhyme.-- centauri,
Jun 26 2000
so, theoretically, it's possible to be 'weightless' a few hundred feet off the ground, provided you are going haul-ass fast enough to be continually falling over the horizon...
so if we built a big vacuum tube and accellerated a car on a magnetic field, so as to minimize friction, there might be in effect weightlessness in that car...
Jun 26 2000
And ghod help you if the vacuum failed...-- StarChaser,
Jun 27 2000
The cheapest way to put something in Orbit would be to leave all the fuel on the ground. You can achieve that by building a magnetic cannon that shoots objects to orbit. There was a guy that tried to build such super cannon. The cannon could also be used as a weapon.-- razgalili,
Jun 27 2000
I think pixelswisher's got the beginnings of a good idea. We've all seen films where people get sucked out into the cold vacuum of space, so why don't we just stand his tube on it's end with the top poking up above the atmosphere? That way people could just get in at the bottom & the vacuum would suck them up & fire them out into space. Of course you'd have to have a big net to catch them at the other end or they'd just keep going forever or until they bumped into something hard. You'd also have to have an elevator on the outside of the tube so that they could get back down again. Oh, and you'd have to remember to shut the door when you got in at the bottom otherwise all our atmosphere would be sucked out into space with you.-- DrBob,
Jun 27 2000
Surely gravity is able to penetrate glass? If the door were left open, then air would whoosh in until the pressure in the tube was the same as the earth's atmosphere. Once they were the same, no more atmosphere would be lost to space. Now if you could operate the tube like a peashooter and fire yourself out of the tube using the pressure change as a propellent - that would surely work?-- ashworth,
Jun 27 2000
I'm not sure what to comment on first. How about something about orbits and weightlessness in space. Space is not weightless unless you are outside the solar system, and then you have galaxies to worry about. Even Pluto doesn't get far enough out to escape. The only real weightlessness is when you are freefalling towards whatever big thing is closest. Gravity in orbit is esentially the same as on the surface. We are only talking 50 or 100 miles up or so if I remember right. It's not that far away. The weightlessness is phoney. It's just centrifugal force caused by the _extreme_ speed! That's why there is all the drama of "going up" and "re-entry" it's not going up- that's easy. It's spinning around the earth so fast you STAY up. It's really a wonder they don't get dizzy. You could in fact do it on the earth's surface, but you would probably burn up from shear air friction because the speed is something like mach 20 or 30 if I remember right. The shuttle is going THAT fast to stay up, and it almost burns up just coming back. I imagine a lot of the fuel is used just to get going that that fast and that's with no air resistance. I think most of fuel is used within the first mile of launch or so because it has to lift ITSELF- all that fuel, straight up off the ground. Millions of pounds of fuel, and all kinds of fuel would have to burn just to keep that fuel laiden lead zepplin level in the sky, let alone accelerate straight up. It's terribly inefficient. Years before NASA the X-15 rocket plane FLEW into space using much less fuel in a tiny craft, because wings take care of holding a crafts weight in the sky. The engines only maintain speed and allow altitude gain.
But rockets are all very impressive and the public loves it, so we have huge rockets and explosions that make people go "oooo wow man!", but we will be back to flying into orbit soon. The only advantage of big rockets that make big rackets is they are very fast into orbit.
I always wondered why no one ever found a way to carry that huge liquid external fuel tank (hydrogen/oxygen) all the way into orbit and use it for living area or to add to living areas or structures. Seems like it would be perfect for that and it seems like it's most of the way into orbit when they drop it, but I don't know.
I believe balloons only go that high because they have almost no weight. An easy way into orbit? It's been done in the 1950's and some of those guys even went high enough to get astronaut's wings.
[Dominus] The statosphere, like the rest of the earth's atmosphere rotates with the earth (not withstanding wind currents). As the stratosphere has a larger circumference that the earth's surface, it must be travelling a bit FASTER than the earth's surface.-- Autonome,
Sep 02 2002
Can someone explain the physics of how propelent in the OMS works in Space. If space is a vacuum, then there is nothing to "push" against right? How then does the OMS exert force on the orbiter?-- Max__Power,
Feb 04 2003
Newton's Third Law. See link.-- krelnik,
Feb 04 2003
The idea of a vacuum tube to
space seems to have some merit -
but you would still need a massive
amount of power to pump
however many trillions of gallons
of air out of the tube.
Perhaps if you built a sabot around
the orbiter you could get it to
Nov 26 2003
Autonome, while flying part of the way into space does help save fuel sometimes, you're missing a crucial distinction- being in space is not the same as being in orbit. In orbit, you're moving around the globe as fast as you're falling towards its surface. You CAN fly an X-15 up into space, but it will only stay there till the fuel gives out and then it falls back down. The shuttle on the other hand could stay up nearly forever. (Well, the people suffocate after a few weeks but so what?)-- Madcat,
Nov 26 2003
I wonder if all of NASA's zero-G experiments are wrong -
the shuttle astronauts are actually experiencing the
exact same gravitational acceleration as a person on
earth, and it's only their point of reference that affects
the appearance of zero-G. You could achieve the same
results with a balloon and a few minutes of free-fall.
Except for a few seconds on the Apollo flights, no one has
really experienced true zero-G, when the sum of all the
gravitational vectors is zero.
Perhaps a station at a LaGrange point (L4 or L5, probably)
would give us different results from those on the shuttle.-- Macwarrior,
Nov 27 2003
Launching from a balloon system as mentioned eliminates drag from the atmosphere, but you still have to get going about 25,000 mph (slightly less for low earth orbit) once you're up there.
After looking at the size of an Athena 2 rocket, I can't help but think this idea just might work with huge balloons. (I've done no math yet - mostly because I will have to re-learn a lot of things in order to do it and I'm somewhat lazy if I'm not getting paid for it.)
I can't believe I'm looking up info on this again, and again I find the same halfbakery idea that lured me here in the first place maybe 4 years ago.-- Zimmy,
Jun 23 2007
uhmmm... how about using balloons to hoist a super-cannon up to >30km, where there is so little air that the friction it generates would hardly factor into the energy required for a LEO insertion?
sure, the cannon would have to be fairly strong, but it needn't be as sturdy as its terrestrial counterparts which are designed to survive repeated firing and various other forms of ill treatment.
i'm imagining a football-shaped craft, like a zeppelin, with an aluminum and carbon-fiber cannon running from back to front along the central axis. it could be inflated with hydrogen and designed to absorb much of the recoil, perhaps sustaining a destructive level of damage during a firing. it wouldn't matter, as only the chute system need survive to bring the parts back down for a rebuild.
just before firing, some final calculations would be made and 'bleed vents' on the cannon opened appropriately to adjust the gas pressure and hence final velocity of the projectile. the airship/balloon/cannon would tilt up/swivel to the correct angle using a small maneuvering rocket, then as the computer senses it is passing perfectly through the correct firing angle - bang. the micro-satellite is shot, literally, into orbit.
i like the idea. +
cheap, clean, and i bet it really can be done.-- TIB,
Jun 24 2007
30km is probably the limit for balloons. It may be quite a bit less considering the weight that would have to be lifted.
My searching today let me find that some model rocket hobbiest have launched from the ground to 72 mi's (116km). I have no idea how much they spent on the effort.-- Zimmy,
Jun 24 2007
How about a really big trebuchet? With a long enough arm and a heavy enough weight, one could easily launch Hummers into low earth orbit. Of course it would help if they were carried inaerodynamically shaped containers.-- nuclear hobo,
Jun 24 2007
To fill in a numerical gap left earlier in the anno's, the orbital speed at sea level is 7,913.3m/s (28,487.9km/h, Mach 23.25). Not a heck of a lot faster the the ISS in orbit (~7700m/s) but there's all that air in the way...-- neutrinos_shadow,
Jun 25 2007
You could easily use this method for putting those aluminum pot pie things into orbit. You might even have enough juice in a hydrogen balloon to put a cell-phone minicam onto the the pot pie thing as well. I'm thinking "damn, that is the cheapest $200 hindenburg/sputnik combo that anybody ever put into low earth orbit." [+]-- quantum_flux,
Jun 25 2007
//How about a really big trebuchet? With a long enough arm and a heavy enough weight//
Wow. Someone should really punch out the maths on that idea. [nuclear_hobo} may I suggest you spin off "Space Trebuchet" as a new idea so we can get started?-- BunsenHoneydew,
Jul 07 2007
Yes, please do. I just want to watch the anno string.-- normzone,
Jul 08 2007
I just added a link to an article on Rockoons. (They were launched from the USCG icebreaker _Eastwind_--I was on that ship, much later.)-- baconbrain,
Jul 09 2007
// //How about a really big trebuchet? With a long enough arm and a heavy enough weight//
Wow. Someone should really punch out the maths on that idea. [nuclear_hobo] //
Someone already has [link]
// a vacuum tube to space / but you would still need a massive amount of power to pump / air out of the tube. //
Not so. You'd need a massive amount of energy (power x time). Low power pumping would just take longer.
Once upon a time, there was a proposal to use a tube sunk into the ocean and drained of water in a similar fashion. Perhaps if we used that as Stage 1, and passed the craft into the Evacuated Tube as Stage 2, we might get some useful velocity.-- BunsenHoneydew,
Jul 18 2007
Rocket fuel is not the reason why the Shuttle is so expensive. It is the thousands of people needed to process the shuttle and SRBs and manufacture the External Tanks for each flight that keep this system's costs so horrendously high.
If you really want to reduce the cost (in dollars per unit mass delivered to orbit) devise a system that requires very few people to process, is completely reusable and can make a large number of flights. Carefully note, it does not have to be a Single Stage Orbiter, although that would be ideal. Remember: the goal is low cost per unit mass delivered to orbit. No one particularly cares how you do it.-- Moonguy,
Jun 25 2008
You can build some big models with lego.-- wjt,
Oct 26 2014