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The Space Hose

by gutemine
Tags: hose, space
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mugaliens
#55
Sep14-10, 08:29 PM
P: 595
Quote Quote by jarednjames View Post
As for "balanced on a column of air" I'd like to see you do that. What you are proposing is firstly erecting a 100km tower and then expecting the atmosphere to have no effect what-so-ever (wind etc) and then being able to keep it so steady a 9 to 19 gram satellite could balance on it. Yeah, good luck with that.
I hear you - there are some serious control issues to overcome for this idea to actually work.
JaredJames
#56
Sep14-10, 08:29 PM
P: 3,387
Quote Quote by mugaliens View Post
The spirit of the N-Prize is well-expressed in the rules. They're looking for out-of-box thinking and innovation, which I think gutemine is clearly doing.

Some appear to be troubled by this and are making every attempt to cram the ideas and concepts back into their version of in-the-box thinking, which is contrary to the N-Prize intent.

Again, for the nth time, the N-Prize organizers have clearly and repeatedly stated their interest is one of achieving altitude and duration by means of out-of-the-box thinking.

If you can't tolerate this for some reason, I respectfully suggest to reexamine the goals, pupose, and spirit of the N-prize as clearly stated in their rules before revisiting this thread.
I've read the rules and the spirit of the competition is to get a 9 to 19kg satellite into orbit by any means necessary. Holding it on top of a tower is NOT in orbit.
JaredJames
#57
Sep14-10, 08:37 PM
P: 3,387
Quote Quote by DaveC426913 View Post
But neither do I think they have been granted this. I think glutamine is misunderstanding.
I completely agree, I think they have granted him the go ahead to launch via the tower (I don't know how but perhaps get it to the top somehow and use a rocket to achieve the orbit for the satellite etc).

He is proposing using the air velocity of the tower to launch the satellite, but I can't see how he achieves orbital velocity with this approach, surely it would just shoot off into space and then be pulled back by gravity (this is assuming the launch is vertical so no horizontal component comes into play and without accurate numbers for weight and launch speed I can't say how long that will take). (Besides, not so much an orbit, more a failed attempt at reaching the ISS )
Redbelly98
#58
Sep14-10, 08:55 PM
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Note, the OP claims he has checked with the judges:
Quote Quote by gutemine View Post
Well, I already checkd with Paul (who IS the 'jury' - because he invented the prize and took care of the funding). He agreed that my proposal meets the spirit of the competition and I would be allowed to partizipate with this approach. And yes, I have sent him the slides and he said the space hose would qualify as a launch device to space!
Qualifying as a launch device is not the same as being "in orbit", so you may want to clarify that point with them. Or perhaps you have already, and just didn't express it clearly to us.

This thread has taken two tracks ... whether it qualifies as an N-Prize entry, or whether it can be made to work.

It is up to the OP to ask the competition judges about meeting the prize criteria. People have expressed their concerns, I see no reason to keep harping on that front.

How about if we now focus the discussion on whether this thing could work, in terms of lifting an object to 100 km? N-Prize or not, it is an interesting idea.
mugaliens
#59
Sep14-10, 09:16 PM
P: 595
Quote Quote by jarednjames View Post
He is proposing using the air velocity of the tower to launch the satellite, but I can't see how he achieves orbital velocity with this approach, surely it would just shoot off into space and then be pulled back by gravity (this is assuming the launch is vertical so no horizontal component comes into play and without accurate numbers for weight and launch speed I can't say how long that will take). (Besides, not so much an orbit, more a failed attempt at reaching the ISS )
Let's assume for a moment the N-prize folks change their minds and require an orbit unsupported by anything except orbital velocity. How might this be achieved by means of the air tower? Rail gun?

10 grams is 154 grains, which is slightly larger than the rounds I carry in my 9mm. Those achieve a velocity of approximately 300 m/s. With an electromagnetic rail gun the size of a car one might be able to propel a 10 gram bullet to the 100 km orbital velocityof 7,847 m/s. Just so people have a better feel for the mass, .45 ACP ammo falls squarely in the N-Prize weight range.

On the other hand, is there any requirement for there to be a payload? What if a balloon hauled a large, but gossamer-thin solar sail of 15 grams to, say, 50 km (164,000 ft). Would that be high enough for solar wind to accelerate it into space? Or is that still far too deep in the Earth's atmosphere for a solar sail to work? I suspect the latter, so what might be the absolute minimum altitude at which a solar sail with no payload but itself could be blown further away from the Earth's atmosphere?

Short of a balloon/rocket/X approach, where X is a solar sail or some sort of high-tech, super-lightweight railgun, I see no way of remaining in budget while achieving 9 orbits. And if it's any sort of gun, the rocket will have to take it to at least 100 km. Perhaps a balloon/rocket/railgun/solar sail, where the sail would work for final orbital insertion. With a good enough railrun we might be able to eliminate the rocket stage and just do a balloon/railgun/solar sail. I don't think an ion drive would withstand the massive g's produced by a railgun, and there remains of the issue of how to control the solar sail once it's deployed above the atmosphere.

Truly a gnarly problem!

Quote Quote by Redbelly98 View Post
How about if we now focus the discussion on whether this thing could work, in terms of lifting an object to 100 km?
Understood.

First, is it even possible, or like the much smaller car dealership versions, will it simply flap all over the place? If it can be made to be reasonably stable, would it be enough to lift a small payload, such as packaged gossamer sail? I don't think deploying the sail would be difficult - simply package it in a rocket-spun hocky puck then deploy. If it's circular it'll just fan out and ill be gyro-stabilized to mainain both shape and orientation. How long would it take the thinnest of sails to accelerate at 100 km? If it's too long, then we'll have to haul up a small rocket to at least start it on it's way. We might discover the sail acceleration is so slight that a rocket would have to be used to get it, say, 90% of the way there, at which point why not use it to take us all the way there?
JaredJames
#60
Sep14-10, 09:24 PM
P: 3,387
Quote Quote by mugaliens View Post
Let's assume for a moment the N-prize folks change their minds and require an orbit unsupported by anything except orbital velocity. How might this be achieved by means of the air tower? Rail gun?

10 grams is 154 grains, which is slightly larger than the rounds I carry in my 9mm. Those achieve a velocity of approximately 300 m/s. With an electromagnetic rail gun the size of a car one might be able to propel a 10 gram bullet to the 100 km orbital velocityof 7,847 m/s. Just so people have a better feel for the mass, .45 ACP ammo falls squarely in the N-Prize weight range.

On the other hand, is there any requirement for there to be a payload? What if a balloon hauled a large, but gossamer-thin solar sail of 15 grams to, say, 50 km (164,000 ft). Would that be high enough for solar wind to accelerate it into space? Or is that still far too deep in the Earth's atmosphere for a solar sail to work? I suspect the latter, so what might be the absolute minimum altitude at which a solar sail with no payload but itself could be blown further away from the Earth's atmosphere?

Short of a balloon/rocket/X approach, where X is a solar sail or some sort of high-tech, super-lightweight railgun, I see no way of remaining in budget while achieving 9 orbits. And if it's any sort of gun, the rocket will have to take it to at least 100 km. Perhaps a balloon/rocket/railgun/solar sail, where the sail would work for final orbital insertion. With a good enough railrun we might be able to eliminate the rocket stage and just do a balloon/railgun/solar sail. I don't think an ion drive would withstand the massive g's produced by a railgun, and there remains of the issue of how to control the solar sail once it's deployed above the atmosphere.

Truly a gnarly problem!
Exactly how I've been looking at it.

He's quoting some extreme numbers, air velocities of over 5000m/s. Just not possible, let alone in the setup he describes of a 'space hose'. The only requirements are that it completes 9 orbits, weighs between 9 to 19 grams and you must be able to track it to prove it completes all the orbits.

Even if the tower could be erected to 100km and you could launch something up the inside to the altitude required, you would then have to use some form of rocket propulsion to attain orbital velocity. The basic concept is sound, but the reality is that the tower would be dangerously unstable, the pressure requirements would be too much, attaining orbit requires some serious, but precision controlled acceleration once at the top.
JaredJames
#61
Sep14-10, 09:27 PM
P: 3,387
Ignoring the technical feasibility, with every complication comes increased cost. I can't see how it is possible to remain within the 999.99 budget. In fact, I think doing it this way adds far more complication and cost than simply using a conventional rocket.
mugaliens
#62
Sep14-10, 09:31 PM
P: 595
Let's also talk about rockets for a minute. Only the final 10 grams needs to reach orbit. Accelerating the empty propellant case of a rocket any further than is necessary is wasteful. Therefore, if there's a cheap way to build nozzles (they don't have to last very long), it might be much more efficient to create multiple stages. The final stage might simply be a conventional gun, perhaps a small-caliber, high-powered hunting rifle. A larger caliber might be used to deploy a mildly exploding shell, releasing a sheet of mylar onto which has been fixed (or sealed between two sheets) a bunch of radar-reflectant chaff. With the radar attuned to the chaff, it doesn't take much of a radar to spot it from a long way off, though trying to build a radar for less than 999.99 would be problematic!
gutemine
#63
Sep15-10, 11:42 AM
P: 59
Sorry for not coming back earlier.

I agree with the argument that it would be probably better to split the thread into two - one where we look for the perfect orbit definition (and maybe what is within the N-proze rules) and another one on the technical feasability of the space hose.

Regarding material cost - PE foil prize goes mainly with the thickness and because the extrusion is continuously it is more the materials that are driving the cost (eg. 12micrometer foil seems to be cheaper then 25 micrometer,...) But it is not linear off course because of the fixed cost. The real manufacturing prices also dramatically differ from the cost you find at various shops selling packaging materials. So the 1cent/m number to get the whole hose for 1000 EUR ist maybe a little bit low but not totally unrealistic.

And again you are not really getting the spirit of the N-prize:

If you would achieve the goal a 100% and would overrun the budget only by 1 pound this would mean NO proze money. BUT it would be still an amazing achievment, and maybe ask for a slightly better calculation on the next try!

Paul has set the budgetl imit to encourage people to try it with budgets magnitudes lower then the normal ones and by ordinary people - and this approach needs to be accepted, and not laughed at if people decide to build their own high atmosphere ballons from PE foil - or even a space hose :-)

And the prize money is actually so low that it is not wort doing it just for this either - it is about partizipating, trying, coming up with new ideas - and very likely to fail.

So I simply decided that I liked this approach and started the journey (and maybe asked you for a little company and some help with the map).

Regarding the wind forces here is what I wrote at the half bakery when this question comes up (and there Paul is active as MaxwellBuchannan - confirming that he likes the idea):

I found the time to use the proper air resistance force formular:

A=0,25*15000=3750m (the 15km we agreed multiplied with the 10" diameter)
C=0,1 (drag coefficient)
v=13,89m/s (a 50km/h "breeze")
F=airdensity*vAC/2 = 1,293*13,89*3750*0,1/2=46766N

actually this still is too high calculated because air density goes down to already 50% in 5km and 1/8 in 15km - but let us stay with this, because maybe the C value is too optimistic or the wind blows harder.

If I read the Dyneema Wiki entry right a single 8mm thick Dyneema string could hold this (58000N tearing strength, and 50kg/km) This string would have a weight of 750kg on these 15km. Probably your would use a bundle of smaller strings for better structural suppor
DaveC426913
#64
Sep15-10, 01:18 PM
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P: 15,319
Update

You will be astonished as I am.

I have been in contact with the N-prize judge myself. Here is the transcript:


Q: Hello. Can you please define your use the the term 'orbit'.

For example, some who might wish to interpret your rules as liberally as possible might consider a satellite sitting on top of a 100km tall tower to be in "orbit" (since it will ultimately go around the Earth once every 24 hours). Would this qualify?

A: As long as it's at 100km without touching anything else, it would qualify. ... So, if you had a "tower" but could somehow hold the satellite there at the top without touching the tower itself, that would be OK.

Q: " without touching anything else": does that include, say, a column of air?
A: Ah, yes, could be. As for "touching" - I think that's OK. ... the air pressure at the "orbital" point would be very close to the external pressure at 100km anyway, so no problem.

Q: This tower does not move, which means the satellite will *not* orbit the Earth 9 times (one of the N-prize requirements) unless you very liberally allow Earth's own daily rotation to count. Does that still qualify?
A: As for "orbits" - the earth's own rotation does count, so as long as it stays up for 9 days....



It would appear that the N-prize judge is perfectly happy to allow this non-orbit to qualify, despite the requirement in the rules.

gutemine, I owe you an apology. You indeed did confirm your N-prize entry will be considered. Furthemore, you have no need to develop any tangential veolicity component; your tower qualifies as-is.



Now, that being said, the N-prize rule-writers are still wrong. They cannot make up their own definition of a existing word and use it in their rules more than a half dozen times.

They are in for a world of trouble. If they let this entry in, they may well be up against legal proceedings for misrepresentation, depending on how they have structured their contest.
gutemine
#65
Sep15-10, 01:42 PM
P: 59
I'asked here for advice - so there is no need to excuse for anything.

If the space hose would have had to compete for the X-prize the discussion would have been much shorter :-)

And you have to be aware that the N-prize is about creativity and have fun trying (and failing) - and not only about following the rules. The rules are there to enforce creativity and unusual approaches - not to be hammered in stone to prevent them.

The real problem is that after I had the idea I took the formulars and feeded them my assumptions, and realized that the results are not that bad as I assumed when having the idea.

There are lots of amazing findings that I already had:

100km of thin foil is something you can buy for a reasonable budget and load on a pick-up.

The amount of blowing needed to provide sufficient frictional lift is only approximately 10x your household vacuum cleaner's power.

But what really drives me crazy is the fluid mechanics - it doesn't look completely wrong, and all the losses you normally experience against you are actually with (!) you in this case.

I used the achiemedic screw example not for comparing myself with Achimedes, but it is the device which is the closest to what I suggest - on the first glance it looks strange that the screw can build up hydraulic pressure at all, even when it leaks heavily. But it does, and works up to amazing heights compared to the hydraulic pressure water has (remember - 10m equals 1 bar for water)

At the first glance my hose looked to me also like the typical physics teacher booring and unrealistic purely theoretic example, but then I tried to do the math as good as I could and ended up with results that iritated me, so I decided to ask for help.

Which brings us now back to my original question - besides stability and strength (and even these two problems seem not that bad when you look a little bit more accurate then just saying are you nuts) would the pneumatics part work this way (or what would happen if we really start blowing) ?

Because this is the same then the standard wing problem. If the pysics say you get lift you still have to solve the problem that it is enough lift and to build a suitable strong wing to support the plane. A problem which the Wright brothers solved with cheap piano wire, wood and linnen to proove that they were right - so PE foils is not that far off at all. And their engine had only less then 10kW horsepower for a 340kg plane - so the power/lift ratio numbers are almost identical to the suggested space hose.

PS: We all know that the duraluminium wings of the latest Boing plane land the x000kW horsepower jet engines look and feel much more comfortable when sitting inside - but you have to start somewhere.

PPS: And I was reading also the forum rules - they state that even in you ask for help with your homework, you have to proove that you tried with considerable effort. So I think I should be allowed to ask for help - and solutions are off course also welcome :-)

gutemine
JaredJames
#66
Sep15-10, 02:46 PM
P: 3,387
Quote Quote by DaveC426913 View Post
Update

You will be astonished as I am.

I have been in contact with the N-prize judge myself. Here is the transcript:

.........

It would appear that the N-prize judge is perfectly happy to allow this non-orbit to qualify, despite the requirement in the rules.

gutemine, I owe you an apology. You indeed did confirm your N-prize entry will be considered. Furthemore, you have no need to develop any tangential veolicity component; your tower qualifies as-is.
I don't believe it, they really are making up their own interpretations of words as they go. They should just say "no rules, just give us your idea and we'll decide if it's ok".

Anyway, it still does state that it must not be touching the tower, now air column aside, if the satellite is released at that altitude without the correct orbital velocity, it will just fall back to earch (unless you can get it to travel outwards away from earth and then let it fall back via the force of gravity, a feat which would have to last nine days to qualify. I don't see how you would get it to remain on such a column of air for 9 days.
DaveC426913
#67
Sep15-10, 03:07 PM
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Quote Quote by jarednjames View Post
Anyway, it still does state that it must not be touching the tower,
Personally, I do not see why they consider a gaseous support to be somehow different from a support in any other state of matter. I could support the satellite on air but not on a liquid?

Quote Quote by jarednjames View Post
now air column aside, if the satellite is released at that altitude without the correct orbital velocity, it will just fall back to earch (unless you can get it to travel outwards away from earth and then let it fall back via the force of gravity, a feat which would have to last nine days to qualify. I don't see how you would get it to remain on such a column of air for 9 days.
You seem to be conflagrating two distinct ideas here.

It can rest on the column of air as long as you keep the air blowing upward. And the column of air need be no more than be one inch high. It's a technicality to get around the "not touching" requirement.

If you could fire the satellite outward such that its arc takes 9 days to come back, that would be an impressive feat. But that doesn't involved a column of air (except as the initial propulsion). In this scenario, the satellite cannot maintain a position above the tower, as the two will be on completely different trajectories - one attached to Earth, the other ballistic.
JaredJames
#68
Sep15-10, 03:15 PM
P: 3,387
Quote Quote by DaveC426913 View Post
Personally, I do not see why they consider a gaseous support to be somehow different from a support in any other state of matter. I could support the satellite on air but not on a liquid?

You seem to be conflagrating two distinct ideas here.

It can rest on the column of air as long as you keep the air blowing upward. And the column of air need be no more than be one inch high. It's a technicality to get around the "not touching" requirement.

If you could fire the satellite outward such that its arc takes 9 days to come back, that would be an impressive feat. But that doesn't involved a column of air (except as the initial propulsion). In this scenario, the satellite cannot maintain a position above the tower, as the two will be on completely different trajectories - one attached to Earth, the other ballistic.
I didn't intend it to be read as mixing the two, I meant to ignore the column of air idea would mean you have to either achieve orbital velocity to maintain a nine day orbit or launch the satellite out from the tower in such a way (ballistic trajectory) to maintain >100km of altitude for a period of nine days.

I just don't see how you would maintain a stable enough scenario for the column of air idea to work and so the only other to options I can see are the two I point out above.

I agree, why they would consider being supported by a column of air as orbit I cannot fathom.
gutemine
#69
Sep15-10, 03:26 PM
P: 59
ask a bouncing ball in a fountain - he knows the answer.

If we only have the suggested 100Pa surpluss (to the 100Pa of the vacuum there) at the top due to the diffusor you can already do a lot with it.

Our N-SAT weights only 9,99 gram, meaning we have to create 100N lift - which is feasable with a 1m 'parachute' of aluminium foil out of the 100Pa. And the 1m are also sufficient for radar detection - and the aluminium foil then would be probably almost the entire N-SAT

But I would assume that both the airspeed and the pressure surpluss at the top would be much higher then the numbers I started my calculations with.

But as already explained, I still think there is a 50% chance to blow out also at orbital speed or erect the space hose beyond the 100km, but we first have to find out what speed gradient we would have inside the hose up to the top. If this is clear an we know what pressure and speed our air has there we can start immediately solving the 'second stage airlift to orbital speed' problem - promised :-)

PS: One more question before I have to go to bed - orbital speed is easy to calculate but for a circular orbit, is there a formular or table telling you what speed and starting angle you would need for an eliptical orbit with no height below 100km ? There is even a speed which allows to orbit when you fly straight up - because of the 0,4km/sec groundspeed (42000km/24h) which will make you still go sidewards and bypass earth if your fly out and fallback takes long enough

gutemine
DaveC426913
#70
Sep15-10, 04:15 PM
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Quote Quote by jarednjames View Post
I just don't see how you would maintain a stable enough scenario for the column of air idea to work...
Quote Quote by gutemine View Post
ask a bouncing ball in a fountain - he knows the answer.
gutemine is correct. A ball will balance on a column of water, and even air.

This is a trick you can do with your vacuum cleaner and a small ball. The uprushing column of air causes the ball to actually resist lateral movement, making it stable in the airstream.

http://www.thenakedscientists.com/HT...ing-pong-ball/

(I do not know if being in the near-vacuum of space will result in the same phenomenon, but that's a proof-of concept thing.)
JaredJames
#71
Sep15-10, 08:17 PM
P: 3,387
I know you can do it, I've done it myself.

I meant, first you have to get thing up there, let's assume you've done that. Then you have to balance it there. Now on a relatively still system, yes, you could do it. I just can't see how you could keep the top of that tower still enough to hold it there. You're talking of keeping a 100km tower stable and upright. I know it's a poor comparison, but given what they have to do to keep sky scrapers steady (counter balancing weights) I'd say it ain't so easy and I'd be very interested in a solution to this problem.
mugaliens
#72
Sep16-10, 12:37 AM
P: 595
Quote Quote by DaveC426913 View Post
You will be astonished as I am.
DaveC, thank you for your forthrightness.

Lol, I know it doesn't meet our long-held definition of "orbit," but let's consider a couple of things, beginning with the goal of the N-prize. It wasn't necessarily to place something into a traditional orbit, but to elevate something useful, even if it's only 19.99 grams, to a sustainable "orbital" altitude. From what I've read, the original idea was 99 orbits, but I think their shortening it to 9 orbits makes sense, as orbital decay for a 15 gram object at 100 km is rather fast.

Now, that being said, the N-prize rule-writers are still wrong. They cannot make up their own definition of a existing word and use it in their rules more than a half dozen times.
Well, they're the ones fronting the money, which is actually not very much. Have you considered fronting a somewhat more reasonable amount, say, 10,000 pounds, in the hopes someone might achieve a more technically accurate definition of "orbit at 100 km?"

Evan that may be contrary to the N-Prize goals. Have you considered the fact that the actual goal wasn't to get people to come up with a NASA-ideal solution at all, but to kick them very, very far out of the box, to weed out all the rest, so as to come up with one or two truly innovative solutions which bear absolutely no resemblance to anything like what we've ever seen before?

Wouldn't that be something! Imagine if Westinghouse had said in the 1900s, "we're offering an E-Prize for anyone who can illuminate a room with the same degree of illumination as a 100W light bulb, but with just 33 W, and the light bulb must last 5,000 hours.

Naturally, everyone would dive on the idea of using an incandescent, and perhaps halogen varients might have been quickly realized, but would any of them have come up with a CFL in 1900?

Hmm... I've spend the last two days working on the logistics of a multiple balloon and parachute-supported trebuchet-like system which might be able to fling a 100 lb payload to 200,000 feet.

I got the idea from Fantastic Contraption, which itself encourages people to think outside the box. Most of the issues can be solved via straight-foward mechanical engineering, but some of the solutions I've found on Youtube are utterly, incomprehensibly brilliant - unlike anything I've ever seen!

I have little doubt that most of us could muddle our way through the FC 1, 2, and 3 problems, but what I'm really interested in are the incredibly insightful and totally out-of-the-box solutions I find on YouTube. Absolutely unbelievable! Totally beyond the bounds of what could possibly conceive! Make no mistake, though - they deliver the payload to the target area. They achieve the objective.

I think this was the N-Prize creators' objective. We know how to spend $1B dollars and put a payload in orbit. Heck, I can do that with $1M using a very large rail gun and a solid rocket orbital insertion module.

But for $2,000???

There is simply no way to get there from here using conventional technology, and that's precisely their point: Don't use conventional technology. Instead, achieve the objective and call it a day.


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