Exploring the N-Prize Problem with a Space Hose Solution

[JaredJames]

Gutemine, I see little point in you replying to anything else regarding your entry into the N-Prize unless you can explain how you will get around rule 11 as I have pointed out above.

Anything?

In the rules it say's you have to prove it completes 9 orbits and that they have to be satisfied with the evidence. The "I broadcast, so I am here" business let's you know exactly what it is you are tracking, a simple radar reflection does not.

Besides, how would you deploy 1m^2 of foil with less than 19.99 grams to work with? A simple transmitter and battery would take far less than any device for constructing a foil sheet.

First you remove orbit by sitting it on a tower and then you plan to use foil to track it, I think you are making far too many assumptions about what is "within the spirit of the n-prize" and what they will accept as orbiting and proof of 9 days worth of orbital existence.

 

[gutemine]

Before you can say strength is not an issue, you need to actually calculate the pressure required inside the hose at the bottom. Of one thing I can guarantee you without doing the calculation: the pressure will not be trivial. It will matter.

I actually calculated the pressure as good as I could (and included this in the slides). I'm fully aware that the calculation is good only for maybe the first few km at the bottowm (and I'm not even sure about this), but because the airpressure goes down dramatically beyond a few km (50% after 5km) these are the critical ones, so using this formula up to the top should OVER estimate the problem, shouldn't it ?

The question is so badly conceived as to be unanswerable. If you supply 1 bar of pressure at the bottom of the hose, no air will flow because that's the static pressure of the column of air. You need to provide greater than 1 bar of pressure to make the air flow.

Sorry for the bad wording, but this is a language problem for me (Englis is not my mother language) If the hose would be vertically - one end 1 bar (standard athmosphere) and the other end of the hose open to a huge vacuum chamber, allowing for a reasonable time of stationary flowing would be probably have been a more precise description.

But if I understand you right the pressure gradient should be similar to a hose at 1 bar all the time and 1 bar surpluss at on end (=2bar) , and open to the 1 bar atmosphere at the other end ?

Without the weight of the hose, you can't calculate the pressure gradient.

This is what the slides do - asuming a minimal size of the hose which would be reaslistically within the N-proze budget (I just googles PE foild prozes and checked what diameter and thickness I could afford)

After getting this weight (300-1000kg for 100km = amazingly low) I checked how fast the flow would need to be to create this weight as friction loss = power on the wall of the hose in the direction of flow.

So you need to select a possible material first, find its weight, then calculate the required friction force to hold it up. Based on what you said in your second post, it sounds like you deceived him. Did you tell him that it was at 100 km altitude and supported by the hose? Because in your second post, you said "being outside of the launch device" which makes it sound like it isn't still supported by the hose.

This is exactly what I did (but I decided on a payable and available material first - as the slides say - I hate to wait for nano-tubes) Paul is fully aware of this - but other teams which plan to combine balloon with rocket launch also decided first to build and test their balloon for reaching the 30km (and not any real orbital speed there either - even on a very windy day) - and he didn't bann them either - why should he, because they also meet the spirit of the N-priize and have the same unrealistic chance to succeed.

And it should be possible to feed air ONLY with the needed kinetic energy to be eaten up by the friction and not a dramatic pressure surpluss too, but the slides also contain the calculation for the 0,6 bar needed if all pressure loss would have to be feeded. And I checked with the tank strength formula that the pulling strenght of dyneema could hold this not really exciting pressure (unless you are a thin PE foild) even at the bottom. But I'm not even sure if this pressure surpluss strength would be needed. That is the great thing about Bernoully that he shows how easily you can convert pressure and flowspeed (only a diamter change away) - and the friction is going up with the v² in case of turbulent flow. You now get ecactly the weakness point in the inflatable space tower approach, and the strength of using the friction force. But the slides also contain a calculation on the wors case (hose closed at the top), then the pressure is only slightly higher even in the worst case of a cyclinder with all the 300km weight on top - simple piston formula what supressure you get - but I' m not sure if this is correct to be overlayed on top of the hydrostatic pressure ?

In the rules, it says the satellite cannot be attached to the launch vehicle. So it is clear to me that just sitting on top of a tower - at any altitude - does not qualify. You're missing the point: just achieving 100km of altitude and sitting on a tower doesn't solve the problem they are trying to solve. Getting into orbit is a big problem and solving it is the goal of the N-Prize. Just sitting on a 100km tower - as daunting a challenge as that is - is much easier than getting into orbit. Once you are clear with the N-Prize organizers about the concept, they will realize that your device does not meet their criteria.

Yes, but if somebody would be able to build a canaon on ground which creates orbital speed on its outlet (but no height at all - the inverse problem of the space hose) he would also qualify if he at least has an idea how to solve the height problem (maybe by pointing it upwards, double the speed and overcome the air resistance by using a big buble gum ball shield conitinuously bringing as isolation for protecting the N-SAT inside -- why not let him participate and have fun trying ? And yes, I'm aware that his N-SAT would be smashed when leaving a normal cannon (unless maybe it would be just rolled alluminium foil and not expensive electronics - sorry for the joke)

 

[gutemine]

Gutemine, I see little point in you replying to anything else regarding your entry into the N-Prize unless you can explain how you will get around rule 11 as I have pointed out above.

Anything?

In the rules it say's you have to prove it completes 9 orbits and that they have to be satisfied with the evidence. The "I broadcast, so I am here" business let's you know exactly what it is you are tracking, a simple radar reflection does not.

Besides, how would you deploy 1m^2 of foil with less than 19.99 grams to work with? A simple transmitter and battery would take far less than any device for constructing a foil sheet.

Sorry, I'm still not finishing answering the old questions and you have already a new one :-)

The aluminium foil N-SAT was just an illustrative example to overcome another problem.

If I would decide not to put the N-SAT on top (see the slides for details - for example because I need to blow it out) I could for example make it go up inside the hose with a balloon or a parachute (remember I have air flowing up to 100km with a pressure of at least 200PA and pretty fast too - meaning a balloon is not only relying on buoyancy) - and the later would maybe already have all the Aluminium foild I need.

Just another example of creative thinking: Cut a circular 1m² piece of Aluminium foil, then cut stripes to the center of let's say 5cm (yes, you will loose a lot of triangualr foil pieces due to the diameter loss). If you then roll the aliminium foil arms by your fingers to the center and would take this device to space - the arms would unroll without any problem or extra energy on relief and if you would release it from your hand with only a minimum spinn it would form a nice christmas star in space.

But you are asking already for the propellor - could we discuss/finish the wings first ?

PS: But don't be discouraged, input and ideas are welcome - I just share mine with you and asked for help - remember the beginnign of the thread?

 

[JaredJames]

Just anotehr example of creative thinking: Cut a circular 1m² piece of Aluminium foil, then cut stripes to the center of let's say 5cm (yes, you will loose a lot of triangualr foil pieces due to the diameter loss). If you then roll the aliminium foil arms by your fingers tpo the center and would take this device to space - the arms would unroll without any problem on relief and if you would release it from your hand with only a minimum spinn it would form a nice christmas star in space.

Can anyone verify this unrolling of the aluminium foil in space? Based on the foil I have, when I roll it up with my fingers it shows no sign unrolling when released, it just holds its shape. Even if I give it a 'nudge'. I don't see why this would be different in space.

I know I sound really discouraging right now, but I prefer to see solid proof any of what you propose is possible.

 

[gutemine]

So by the logic I'm seeing here, everything is orbiting the planet earth, plants, animals, pebbles, the ocean... (you get the idea).

Anyway, if my understanding of what Gutemine is saying, if you were to build a skyscraper 100km high, he (and apparently the N-Prize judges) would consider anyone on the top floor to be in orbit. And if they were to fly a kite that would be considered a successful satellite launch and orbit (despite still being attached). Am I correct?
Which means they must also consider a person in a 1km skyscraper (or any of the above examples) to be in orbit. The only reason they can't win is because of the "must be above 100km" rule. I think that's a fair assessment of the situation here. This 'space hose' is simply an extension of the Earth in the same way as Mount Everest, in fact, why not just deploy from atop such a mountain so you don't need such a long pipe.

On a more serious note, where would you get 100km of such a hose within the budget? What would you use to pressurise it? I've never heard of any systems that could apply a suitable pressure over 100km, especially not vertically into space.

The hose material and its cost are in the slides and also a very basic energy calculation for the blowing power needed - and because the blower would be only supporting the launche device it doesn't could for the budget - only the fuel cost.

But off course such thin PE foil would probably not really work beyond a few km even on a windless day, even if you add a pendular stabilized diffusor o top pulling it upwards by finally blowing the air downwards.

But as a POC within the budget this is not more or less then what others spending thousands of dollars on prototypes or reasearch (also not counting for the budget) before their first test flight would do.

And achieving 1km with such a weird approach (a model air plane motor and propeller could support in this case the 8kg of weight if you use PE foild that you can buy from the next grocery literally speaking) is a similar archivement then a 30km weatcher balloon launch to test the nice N-SAT that you might have built.

And as I already said at the half bakery - if somebody is willing to try it I will bring the beer !

 

[gutemine]

Can anyone verify this unrolling of the aluminium foil in space? Based on the foil I have, when I roll it up with my fingers it shows no sign unrolling when released, it just holds its shape. Even if I give it a 'nudge'. I don't see why this would be different in space.

I know I sound really discouraging right now, but I prefer to see solid proof any of what you propose is possible.

Thanks for trying - you are now subcontracted to find a way to MAKE it unrolling (which should be a solvable task - but not sure about the easiness) :-)

But you now get the idea - Congratulation !

You think/make up a possible solution, check/calc/try it - and maybe have to come up with the next/better one.

Even the space hose is just a creative combination of existing ideas when I tried to figure out their problems and tried to overcome them (and created new ones which I'm pleased to hear from you, and maybe even solve with you together)

PS: That's why I included the parachute or the aluminium balloon in the slides (and not the Chistmas star) - they would work much better (actually the balloon on ground would be very similar to the parachute anyway - because you can hardly fill it to allow for the expansion on top (if it is not an hyper-ellastic weather ballon), but with 3.5m/sec you can already blow a lot upwards if it is only 9,9 gram). And some aluminium foil on the outside of the hose every few 100m would work definitely and form a nice dotted line to space on radar and also reflect the sun compared to the black foil hose - no need for expensive monitoring devices there either.

So sorry for misleading you - it was only for educational purpose (and hopefully you will not charge me for the foil).

 

[JaredJames]

Please can you answer regarding rule 11, with point A I still don't see how you achieve orbital velocity? Point B speaks for itself.

 

[gutemine]

Please can you answer regarding rule 11, with point A I still don't see how you achieve orbital velocity? Point B speaks for itself.

Now you are getting to an interesting point - remember I asked for advice and did some calculation already :-)

What really amazed me was when I did the ideal gas formula between top and bottom - due to the huge pressure difference (approximatel 1:1000) the expansion would be also HUGE (but less then the 1:1000 due to the temperature drop)

If the hose diameter would be fixed the speed of the air in the hose without any diffusion or diameter change would be already pretty close to orbital speed (aprox 5400m/s in my assumed example, and orbital speed is about 7400m/s if I remember right - it is late already, and the excact number is in the slides).

I know that this is by far hypersonic even at the low 100Pa pressure in 100km height. So you have 2 ways - try to find out if such a hose can withstand that (I think in the slides I asked 2x if this hose would work like a kind of upright standing de La Valle nozzle with fixed diameter by using not the diameter change to accelerate but the decreasing hydrostaic pressure of the medium)

And don't say instantly no - we still can do the Dnymeema strengthening as on the bottom, and still outside pressure and inside pressure should not differer that much on a hose (0 without friction I think - but not sure about this). So maybe you already have air at orbital speed in the hose without knowing ?

Actually this would be pretty logic in my understanding - because of the expansion into vacuum after leaving the hose this air is more likely to mix with the sorrounding air at very low but similar pressure, instead of dropping like a stone because of the not orbital velocity argument (Paul was pretty clever by stating some loose particles in orbit don't qualify).

But even if you keep the speed down in the hose by increasing/decreasing hose diameter (depending if flow is above or below sound speed) or by a diffusor recovering some of the flow energy and pressure loss you still have 620m³/hour going to 100km height and you could convert this to amazing speed as the ideal gas law would suggest (that's how the de Laval nozzle blowout made it into the slides - because it can work also as a diffusor to recover some pressure).

This means we should first check the math for the gasflow (then for the friction) and if we know which calculation is right (pressure drop due to friction is pressure surpluss, or only speed surpluss because of hose not pipe) hypersonic or not.
Just do some simple math with fixed temperature - if you start with 3,5m/sec flowspeed if you had isothermic flow after dropping the pressure approximately 1:100 you would be beyond the 340m/sec of the speed of sound - actually this 1000Pa is present approximately at the height of 45-50km - If I remeber right my physics lesson this is one of the reason why there the temperature recovers to almost 0 degree of celsius (so it is actually almost isothermic - but not on the way in between) after having dropped to -60 degree of celsius between 10.20km. And don't be too afraid of the sound barrier - remember we are expaindig here very slow over multiple km - this is as smooth as a turbulent flow probably can get.

So half of the hose could be flowing below and half above the speed of sound (up to orbital speed) ? Not very likely - but input/critics is welcome ?

Finally you would still have all the remaining classical options like rocket start from top too if you feel more comfortable with that - remember you 'only' need to add 30,5MJ of kinetic energy for 1kg, which means peanuts for the 9,9 gram - and yes, I know that it is not that easy, that's why I would prefere to use what we already have (see previous paragraph)

And I already pointed out, even standing on the top of such a structure and still not leaving it on the 99th testflight would be quite an achievment and would give an ant or a cockroach astronaute wings at the NASA :-)
gutemine

 

[JaredJames]

30.5 MJ - that's 30.5 Mega Joules

Are you sure, that's a huge amount of energy?

EDIT:

even standing on the top of such a structure and still not leaving it on the 99th testflight would be quite an achievment and would give an ant or a cockroach astronaute wings at the NASA
gutemine

Why would standing on top of a 100km structure cause you to leave it? You wouldn't be traveling at orbital velocity to overcome Earth's gravity. The only time you would 'take off' from a structure would be when you are past the 36,000km mark. Or am I misreading it?

 

[gutemine]

32MJ is amazingly small - it is the burning energy of 730g of jet fuel and is the quivalent of 1km in orbit (pure cinetic and height energy needed)

I didn't say that standing there would make you leave - but I actually would enjoy the view (and the lack of sickness due to freefall). I just came back to the point of climbing that height is also nothing you should not feel proud of.

Could somebody please comment on the cas dynamics and speed question, because the real answer on getting (or having already) the needed orbital speed lies there in my opinion.

PS: If you use flowing air as 'fuel' to get there containing all the needed energy it would be idiotic to use something else for the final step to orbit anyway.
Just think about your gardening hose - inside the hose the water flows pretty slow, but after it goes trough the nozzle you can entertain the neighbour with it :-)

but I have to get some rest know - n8

 

[mugaliens]

So by the logic I'm seeing here, everything is orbiting the planet earth, plants, animals, pebbles, the ocean... (you get the idea).

No, as there remains the 99.9 km height ruling.

Anyway, if my understanding of what Gutemine is saying, if you were to build a skyscraper 100km high, he (and apparently the N-Prize judges) would consider anyone on the top floor to be in orbit. And if they were to fly a kite that would be considered a successful satellite launch and orbit (despite still being attached). Am I correct?

That's what I read in the rules.

On a more serious note, where would you get 100km of such a hose within the budget?

It's pretty inexpensive stuff, about $6 for 100 m, which means 100 km of it would cost $6,000.

What would you use to pressurise it?

A fan.

I've never heard of any systems that could apply a suitable pressure over 100km, especially not vertically into space.

Ok, then - the bleed air from a turbofan engine.

My primary concern is how does one get the column to rise? I would imagine it could be laid out on a straight, 100 km stretch of road somewhere, but once it's pressurized, it will not magically rise into the air, nor would an articulated exhaust "lift" nozzle at the end be able to lift it's entire length. In fact, you'd need many such computer-controlled and articulating nozzles along its length, which would require a tapering design to manage the airflow properly.

There are some huge challanges with this approach, no doubt.

 

[DaveC426913]

That's what I read in the rules.

How could you continually misread it? The word 'orbit' is used numerous times.

 

[JaredJames]

Ok, I was going for sarcasm with the first two paragraphs about "the ocean being in orbit".

I understand the whole orbit situation, I was simply asking for clarification on what gutemines understanding of the rules where by using those examples.

Regarding the 99.9km rule, I did mention that later on to say why someone couldn't win it by standing on the ground.

I'm still waiting for an explanation of how he would pass rule 11. Again, scenario a) requires the satellite to be at orbital velocity, I don't see how he will achieve this. Scenario b) is clearly breaches the rules.

$6000 is not cheap when the budget is supposed to be under £999.99 (about $1500).

 

[mugaliens]

Yes. Their use of the term orbit.

No, that's your definition, Dave. That's not what's specified in the rules.

If he updated his proposal such that it claimed to do nothing more than sit at the top of the tower, I guarantee...

Unless you're one of the N-prize judges, you can make no such guarantee.

http://www.n-prize.com/assets/rules_in_full.pdf" . It's up to them, not you.

"These rules may be amended at any time without prior notice. Such amendments will normally (but not necessarily) be made in order to clarify points, to close loopholes in order to ensure that all entrants remain within the spirit of the N-Prize, or for unavoidable legal reasons. Therefore, all entrants are strongly advised to contact the organisers before and during the preparation of their entry."

Gutemine did so. They (the N-prize judges) confirmed his design meets the rules. You're trying to second-guess their decision, which has already been made, according to gutamine.

If you don't like their ruling for some reason, talk to them.

I'm still waiting for an explanation of how he would pass rule 11. Again, scenario a) requires the satellite to be at orbital velocity...

Actually, this is a misnomer. All the rules state is "but orbits will not count toward the 9 orbit target until such over-weight items have been jettisoned or consumed. As noted, other items (spent rockets; shielding etc) may enter orbit with the satellite, but must not remain attached to it."

Therefore, he could meet the rules with a 15 gram ball balancing on the column of expended air, like a ball balancing in the breeze of an upturned fan.

Let's get back to the spirit of the N-Prize itself, something many here keep forgetting: "it is possible that loopholes in these rules may make it possible to complete the challenge in a spirit not intended by the N-Prize organisers." However, what is that "spirit?" Is it to think inside the box like we always have? Or is it to put a small object 100 km or higher and keep it there for 9 days?

Let's go back to the rules: "The N-Prize is aimed at amateurs, enthusiasts, would-be boffins and foolhardy optimists." and "Any method of attaining orbit is acceptable, provided it does not breach the rules or spirit of the N-Prize Challenge. Examples might include (but are by no means limited to) conventional rockets; balloon-launched rockets (rockoons); gun-launched projectiles; or combinations of these or other methods."

The organizers have already stated that a 100 km geostationary orbit meets both the spirit and the rules of the N-Prize. It's a matter of altitude and duration, not orbital velocity.

$6000 is not cheap when the budget is supposed to be under £999.99 (about $1500).

You are absolutely correct! I think one might be able to find it for less. How much less I haven't a clue, but possibly a lot less, as the small amount I found is retail quantity, and I have no idea what the diameter was. I just did a couple of quick searches.

 

[DaveC426913]

No, as there remains the 99.9 km height ruling.

Let's just be clear; that is a separate criteria, independent of achieving orbit.

Achieving orbit can be done without achieving 100km altitude.
Achieving 100km altitude can be achieved without acheivng orbit.
The N-prize requires both.

That being said, this chair and the oceans are not in orbit by any criteria, let alone the rules of the N-prize.

Like the chair and coean, the satellite on top of the tower is also not in orbit.

 

[DaveC426913]

No, that's your definition, Dave.

No it isn't.

That's not what's specified in the rules.

It is. By their use of the word.

 

[JaredJames]

That being said, this chair and the oceans are not in orbit by any criteria, let alone the rules of the N-prize.

Like the chair and coean, the satellite on top of the tower is also not in orbit.

Ok, really clarifying now, I was not saying the oceans etc are in orbit, I was simply pointing out that under the terms they have granted gutemine for the n-prize challenge, all could be considered it. (The fan + hose + item on top of tower would still be resting on the ground, in the same way a chair or the oceans are). But they can't win because they are below the 100km rule.

I completely agree that unless the satellite leaves the tower, it is not in orbit. The moment it leaves the tower, if it is not at orbital velocity, it will fall back to earth. Period.

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.

 

[mugaliens]

The spirit of the N-Prize is well-expressed in http://www.n-prize.com/assets/rules_in_full.pdf" . 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 http://www.n-prize.com/assets/rules_in_full.pdf" before revisiting this thread.

 

[DaveC426913]

Ok, really clarifying now, I was not saying the oceans etc are in orbit, I was simply pointing out that under the terms they have granted gutemine for the n-prize challenge, all could be considered it. (The fan + hose + item on top of tower would still be resting on the ground, in the same way a chair or the oceans are). But they can't win because they are below the 100km rule.

You get it and I get it. Mug and glutamine don't.

But neither do I think they have been granted this. I think glutamine is misunderstanding.

 

[mugaliens]

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]

The spirit of the N-Prize is well-expressed in http://www.n-prize.com/assets/rules_in_full.pdf" . 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 http://www.n-prize.com/assets/rules_in_full.pdf" 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]

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]

Note, the OP claims he has checked with the judges:

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]

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!

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]

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]

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]

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]

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 formula:

A=0,25*15000=3750m² (the 15km we agreed multiplied with the 10" diameter)
C=0,1 (drag coefficient)
v=13,89m/s² (a 50km/h "breeze")
F=airdensity*v²AC/2 = 1,293*13,89²*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]

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]

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 formulas 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 physics 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]

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]

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?

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]

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]

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 feasible with a 1m² 'parachute' of aluminium foil out of the 100Pa. And the 1m² 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 formula 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]

I just don't see how you would maintain a stable enough scenario for the column of air idea to work...

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/H...nce/exp/the-aerodynamics-of-a-ping-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.)