Author Topic: Upper Stratosphere "near-space" station for "space" tourism?  (Read 27694 times)

Offline AlexCam

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I know that JP Aerospace doesn't seem to make much headway with their "airship to orbit" concept.

Still, I wondered whether their concept of a stratospheric station (based approximately 140,000 feet above sea level or about 40km up) would be an interesting addition to the sub-orbital "space"travel crowd. Yes, it is technically not in space and no, there is no weightlessness involved, but the view would be quite stunning and could be enjoyed for some time, not just a few minutes.

Day trips or one-night stay-over trips up there including "dinner with a view"  could be an interesting (cheap?) alternative to the 250k 6 minute joyrides with Virgin Galactic.

Here are some stunning views from weather balloons from the upper stratosphere, you can clearly see the Earth's horizon as round:
http://2.bp.blogspot.com/_Dx_J1JC8mag/S6uNMR23W1I/AAAAAAAABk0/R0RXBqcNogs/s1600/Helium-balloon_2__701051a.jpg
http://spacekate.com/http://spacekate.com/wp-content/uploads/2010/09/High-Altitude-Balloon-206.jpg
http://diegoguevara.com/blog/wp-content/uploads/2010/04/TheeBlog-IcarusProject4.jpg

Offline hop

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I know that JP Aerospace doesn't seem to make much headway with their "airship to orbit" concept.
A huge surprise ;)
Quote
Still, I wondered whether their concept of a stratospheric station (based approximately 140,000 feet above sea level or about 40km up) would be an interesting addition to the sub-orbital "space"travel crowd. Yes, it is technically not in space and no, there is no weightlessness involved, but the view would be quite stunning and could be enjoyed for some time, not just a few minutes.
If you could make such  a station, it would also be quite attractive for astronomy and cosmic ray research. Depending on location, it could also serve as a communication relay. Depending on how your transport worked, you could also get quit a bit of free-fall on the way down. For the adventurous, you could offer the option of jumping :D

But building something with such a large payload and indefinite life at that altitude appears quite challenging. Especially if you want to maintain it at a relatively fixed location.
Quote
Day trips or one-night stay-over trips up there including "dinner with a view"  could be an interesting (cheap?) alternative to the 250k 6 minute joyrides with Virgin Galactic.
6 minutes is the zero G time, the whole flight is a bit longer, and both the powered portion and reentry should be quite thrilling in their own right.

Edit:
There has been some successful work done with long duration high altitude balloons with fairly significant payload, e.g. http://www.csbf.nasa.gov/balloons.html

However, these are at the mercy of the wind, and the payloads are still small in comparison to what is being discussed here.
« Last Edit: 08/07/2011 07:59 pm by hop »

Offline gbaikie

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I know that JP Aerospace doesn't seem to make much headway with their "airship to orbit" concept.
A huge surprise ;)
Quote
Still, I wondered whether their concept of a stratospheric station (based approximately 140,000 feet above sea level or about 40km up) would be an interesting addition to the sub-orbital "space"travel crowd. Yes, it is technically not in space and no, there is no weightlessness involved, but the view would be quite stunning and could be enjoyed for some time, not just a few minutes.
If you could make such  a station, it would also be quite attractive for astronomy and cosmic ray research. Depending on location, it could also serve as a communication relay. Depending on how your transport worked, you could also get quit a bit of free-fall on the way down. For the adventurous, you could offer the option of jumping :D

But building something with such a large payload and indefinite life at that altitude appears quite challenging. Especially if you want to maintain it at a relatively fixed location.
Quote
Day trips or one-night stay-over trips up there including "dinner with a view"  could be an interesting (cheap?) alternative to the 250k 6 minute joyrides with Virgin Galactic.
6 minutes is the zero G time, the whole flight is a bit longer, and both the powered portion and reentry should be quite thrilling in their own right.

Edit:
There has been some successful work done with long duration high altitude balloons with fairly significant payload, e.g. http://www.csbf.nasa.gov/balloons.html

However, these are at the mercy of the wind, and the payloads are still small in comparison to what is being discussed here.

Nice link.
One thing apparently not done and/or has little interest, is trying to make balloons go fast.
I would suppose that the fastest any balloon has gone is due to wind speed, but can you make a balloon have a faster velocity than say 300 mph and not due to wind speed. And I mean in the sense of drag race or stunt. You have a land speed record for a car; what would a balloon speed record be?

The way I would think you would do this [get a balloon speed record] is by using buoyancy [rather than engines/jets] and so it would be speed going straight up.

Because of my strange interests, I think of balloons as not just lighter than air, but also as lighter than water. Or if you like, anti-gravity machines [they are the only anti-gravity machines that have actually ever been made].

So in the classification of balloons or anti-gravity machines what could the fastest speed attained?

I tend to think that lighter than water "vehicles" could go the fastest- they seem to me to be the easiest to get to 300 mph or faster. Or for a few thousand dollars or less, a lighter than water vehicle could "achieve this record speed" with what I tend think as less trouble than a lighter than air vehicle could do it.
Or said differently if the "race" is to reach fastest velocity below the speed of sound- I bet water could do this the fastest and cheapest, but to reach supersonic speeds perhaps air balloon would faster and cheaper to develop. [Though I would exclude the speed possible from falling- such as tying a brick to a balloon and having balloon burst at 80,000':).]
« Last Edit: 08/07/2011 10:09 pm by gbaikie »

Offline Andrew_W

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Quote
I tend to think that lighter than water "vehicles" could go the fastest- they seem to me to be the easiest to get to 300 mph or faster. Or for a few thousand dollars or less, a lighter than water vehicle could "achieve this record speed" with what I tend think as less trouble than a lighter than air vehicle could do it.

I can't find a link but there was a proposal for a positive buoyancy submarine or bottom launched torpedo that would "fly" up to attack surface ships with only its buoyancy and hydrodynamics to get pretty good lateral speed, from memory 30knots(??), a few years ago that I read about it, its big advantage was its stealthiness.
I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
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Offline gbaikie

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Quote
I tend to think that lighter than water "vehicles" could go the fastest- they seem to me to be the easiest to get to 300 mph or faster. Or for a few thousand dollars or less, a lighter than water vehicle could "achieve this record speed" with what I tend think as less trouble than a lighter than air vehicle could do it.

I can't find a link but there was a proposal for a positive buoyancy submarine or bottom launched torpedo that would "fly" up to attack surface ships with only its buoyancy and hydrodynamics to get pretty good lateral speed, from memory 30knots(??), a few years ago that I read about it, its big advantage was its stealthiness.

Hmm. I don't think lateral speed is a strong point in regards to using a torpedo in terms of buoyancy. Nor stealth.
I would use conventional propulsion for lateral direction.
So maybe have torpedoes "range the depths" with conventional propulsion [and 30 knots seems like about right cruise speed] and because of sheer depth be more stealthy. And once within range of a target, use buoyancy to punch upwards, and reach target at such velocity that avoiding being hit is impossible [and at such high speed the torpedo would be quite "visible" on sonar, but it is a second or so away from impact].

The problem with this type of torpedo, is it doesn't seem to fit the needs of US navy, and perhaps would be better for enemies of US navy. Mainly because US navy doesn't have any problem killing any target, whereas the enemy does have to struggle to hit US assets.

Offline gbaikie

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"I tend to think that lighter than water "vehicles" could go the fastest- they seem to me to be the easiest to get to 300 mph or faster. Or for a few thousand dollars or less, a lighter than water vehicle could "achieve this record speed" with what I tend think as less trouble than a lighter than air vehicle could do it."

I wanted to put some numbers to this assumption and get a closer approximation.
So start with a tube 16 meter long and 1 meter in diameter with 1 cm thick walls. And put a conical cap on one end.
If placed vertically in water [ocean] and pushed it 33' below the water, the air inside would compress to 1 atm and the volume of air would half.
If pushed to it 132' under water, the air would compress to 4 atm and the volume of air would half again. Or:
Each 33' or 10 meters under the water is 1 atm
33' 14.7 + 14.7 = 29.4 gauge
Doubling 29.4 is 58.8 psi- 4 atm
Doubling 58.8 psi is 117.6 psi- 8 atm
So,
33' halves volume
132' quarters
264' 1/8th the volume
If you go below 264' the volume of air will be less than 1/8 the length of tube or less than 2 meters of the 16 meters. And you need about 2 meters of tube to be fill with air to float. Or at some point below 264' the tube will sink and increase it's velocity of sinking the deeper it goes.

And around 264' it's neutral buoyant. And as it rises, the volume of air will increase and it will accelerate upwards.
So roughly the maximum depth of water should be around 250' to 300'.

I imagine, that before the top of tube reaches the surface, it will probably be going faster than anything as ever travel underwater. But I am hoping that a significant amount speed will added AFTER the top of tube is at the surface and doesn't have as much drag from the water AND at this point it has the most buoyancy- about 7-8 gees of thrust [but at that high level of buoyancy it will only be for a brief moment [maybe a second].

If one isn't interested in adding velocity after the top of tube reaches the surface, one could use a much smaller tube [shorter and less diameter]. And perhaps start from a deeper depth.

The first thing I will "test" is my assumption that before top of this tube reaches the surface, it will be going fairly fast- by which I mean over say 100 mph.
Rough rule thumb, less than 30 mph no significant drag. 30 to 60 mph requires say 1 gee, 60 to 80 2 gees, and 80 to 100 mph somewhere around 3 gees.
And this "test" requires a more precise description. So:
Have 10 meters of tube made from aluminum walls and bottom part made of steel walls:
10 meter length mass: .848 tonnes of Aluminum
6 meter length mass: 1.47 tonnes of steel
Giving total mass of 2318 kgs, and make it 2.4 tonnes.
It's weight in the water will less than 2318 kgs. but we can ignore this.
The air in the tube and the less massive aluminum will cause to tube to point upwards. And the different masses of material is more significant in this regard, once it reaches surface.
The total/maximum  buoyancy is 12.56 cubic meter and slightly more than 12.56 tonnes in saltwater. And 1/8th is 1.57 tonnes of lift vs about 2.4 tonnes vehicle mass [it sinks]. And 1/4 is 3.14 tonnes of lift vs 2.4 which results in .7 tonnes of upward force. And 1/2 is 6.28 tonnes which results in 3.88 tonnes of force.
So some of it's velocity will occur between 132' and 33' below the surface and we can assume the .7 tonnes or less could result in speed of 30 mph [13 meters per second]. So how fast does it go between 132' and 33'?
Which is 99' or 33.1 meters. Without any acceleration at 13 meters per second it will travel further than 33.1 meters in 3 seconds. And so the acceleration time has to be less than 3 seconds and the range of acceleration is .7 to 3.88 gees [6.86 m/s/s to 38 m/s/s].

[An important aspect of this will depend upon water drag at higher speed, but I will first ignore this and later try to include it. And btw, it might possible that this drag "allows" higher speed, because it might allow fractions of seconds "longer" in higher acceleration "environment".]

Now, there two "points of interest", the top of the tube as it nears the surfaces and the level of the air inside the tube [relative to surface- and fraction of the tube filled with air].
The point of .7 gee and 132' under the water is 132' from bottom of air inside the tube [or top water inside tube]. And 1/4 of tube fill with air is the length of tube divide by 4- and so, 4 meters from top of tube. And as the tube goes up the air in the tube goes down {relative to tube].
To characterizes the less than 3 second during which acceleration goes from .7 to 3.88 gees, the last second of the less than 3 seconds will have greatest difference, meaning it will have something like 1 to 3 gee in a period of one second. And because of accelerate time involved will around 2 seconds instead of less than 3 second.
So from 13 meter per sec add about 10 meters/sec of acceleration in first second and last second when going 23 m/s add 6 and 12 m/s
having total of 41 m/s [91 mph].

So traveling around 41 m/s when air in tube is 33' from surface, and acceleration in next second is 3.88 gees [minus water/air drag] to 5.23 gees at max and lowers to zero within that second. And since tube is 16 meter long and half is filled with air at this point, the top is 2 meters from surface, or in less than 1/20th of second it will go above the surface. And once bottom of tube goes above surface of the water all acceleration ceases- this occurs in less than 9/20th of a second or 8/20th of second after top of tube reaches surface.
Hmm. So in that second 38 m/s/s peaking to 51 m/s/s and rapidly decreasing to 0 m/s/s. So adds about 15-20 m/s.
And giving top speed of around 55 to 60 m/s [122 to 133 mph].

Not as fast as I thought but fairly fast for a balloon.
« Last Edit: 08/09/2011 03:13 am by gbaikie »

Offline RanulfC

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"How fast can a balloon go?"
REAL tricky question, you need to define both "balloon" and the "fluid" it's going through.

We've tested "inflatable" structures at high-mach speeds but they weren't "just" pressure supported like a "normal" balloon is. Since it was a "reentry" design in the first place it was more geared towards high-drag (and slowing down) than it was to being speedy. The JP Aerospace design is also a balloon in the normal sense so I'm not sure how they are going to go about getting something like that "up-to-speed" as it were.

The nice thing about a "hotel" balloon is it doesn't have to go "fast" but just be able to stay "in-place" which will probably have to be some sort of electro-thruster type as I don't think "propellers" work at very high atitude. Shouldn't be a major issue since you can use a good portion of the "surface" area to base solar cell arrays on.

gbaikie; something to "add" to your calculations. Specifically a "balloon" in water has a way to cut the drag WAY down on the way up: By expelling air under high pressure out the nose cone you can effectivly break-up the water and surround the balloon in a "low-drag" gas zone allowing REALLY high speed.
(Supercavitation is what it's called See:
http://www.popsci.com/scitech/article/2004-06/supercavitating-torpedo
http://www.tech-faq.com/supercavitation.html
Unfortunatly it doesn't work in air that I'm aware of)

Oh, and what Andrew_W was talking about was that the "bottom-based" torpedo would be able to not only stealthy in a vertical direction but be able to move a great distance horizontally by using manuevering surfaces to trade part of it's upwards speed for horizontal speed. There are concepts to use alternating positive-negative buoyancy control for both propulsion and steering. Both under water and for Lighter-Than-Air (LTA) airships:
http://www-pord.ucsd.edu/~rdavis/publications/4Gliders.pdf
http://www.fuellessflight.com/
http://gradworks.umi.com/32/73/3273254.html

The idea being that as a vehicle rises or sinks within a medium, like a glider it can "trade" part of its vertical velocity into horizontal movement. By alternating between a "positive" and "negative" buoyunt state a vehicle can move great distances horizontally with little or no active propulsion use.

Well, in theory anyway, in practice especially with airships you tend to need more propulsion energy than you could get with just using buoyancy control and the energy requirements for changing your buoyancy isn't trivial either. Still for "shuttles" going to and from the "hotel" there are possibilities....

One idea I havent' seen yet is the idea of "tethering" the Aerostat Hotel to the ground and running "shuttles" up and down the tethers. Additive to that you could have the main 'tether' members being hollow and use a partial "fountain" concept to offset some of the hotel mass.
(The "Fountain" has a ground level electromagnetic accellerator portion which fires high speed "projectiles" inside of the hollow members. By reducing the air pressure {vacuum is better but probably cost prohibitive near the surface} inside the members the projectiles retain more energy from the accelerator for a longer period of time. The idea is that the projectiles reach the top of the "loop" and are deflected by magnets on the "Hotel" and turned to drop back down another hollow leg of the system where they fall to the bottom completing the "support" system. Part of the energy they gain in falling is extracted to {again} turn the projectile around and accelerate it up again which reduces the overall energy needs of the system somewhat.)
http://www.orbitalvector.com/Orbital%20Travel/Space%20Fountains/Space%20Fountains.htm
(Yes I know it's for an RPG, but they folks who play Traveller have some of the BEST explanitory articles for REAL science I've ever found :) )
http://www.strangehorizons.com/2003/20030714/orbital_railroads.shtml
http://www.wisegeek.com/what-is-a-space-fountain.htm

Of course like most "neat" concepts the up-front costs are going to be a bear to deal with, but the fountain has the advantage that it can actually be built from the "ground-up" which helps a bit :)

Randy
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British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline sanman

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Guy with balloon wants to do "near-space" tourism:

http://www.wired.com/autopia/2011/08/inbloon/

Offline RanulfC

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Guy with balloon wants to do "near-space" tourism:

http://www.wired.com/autopia/2011/08/inbloon/
I seem to recall JP had/has a similar concept but using a powered version.
Hmmm, maybe someone can get the Strato-Bowl re-opened as a launch site?
http://stratocat.com.ar/bases/56e.htm

The problem with a "simple" balloon is the needed ground-launch, in-flight tracking and recovery assets come pretty close to being the same as with a rocket and with less "turn-around" time reduction capability. I've yet to see someone manage to get the business case to close. (The again I see the same "issue" with the idea of a "near-space" station itself :)

Having said that though the NSS with a ground connect tether has the possibility of some sort of "high-speed" ground-to-station transportation that eliminates the majority of the issues with balloon operations. Of course the "getting-down" is always easier than getting up :)

The "Near-Space Corporation" http://www.nsc.aero/is using a modification of the FMX-4/5 design as a "Near-Space data/sample return" vehicle:
http://www.eaa.org/experimenter/articles/2010-01_facetmobile.asp
A "full-size" version might have "possible" applications, but it still comes down to the economics of the whole venture and what kind of "target-market" you are serving, how, and how much cost-vs-income the actual con-ops will be. Not something that is easy to figure out or even research due to a lack of hard data.

There are a LOT of assumptions and more than a bit of probably "wishful-thinking" in the idea of a the NSS as a tourism attraction or a viable money-making concept. I'm not sure how, or who, would pay for the professional and needed research and data collection but it's something that really badly needs to be done to either put the idea to rest or move it forward.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline grakenverb

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This company has been promising a high altitude airship for around 10 years, but not much has come of it.........


http://www.wsgi.com/stratellite.php


Online FutureSpaceTourist

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Just found this thread.

I know that JP Aerospace doesn't seem to make much headway with their "airship to orbit" concept.

Yes it's hard to see progress as they do a lot of testing on such a small scale (and it is a 30 year programme that they're only a bit over halfway through!).

Things are due to get a bit larger scale in the relatively near future. They're hoping to fly their scale 90 foot Ascender by the end of this year: http://jpaerospace.com/blog/?p=5147
« Last Edit: 04/27/2013 06:53 pm by FutureSpaceTourist »

Offline Asteroza

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Don't forget the LiftPort guys, they seem to be using their kickstarter momentum to get back into the high altitude tethered balloon game.

Offline JasonAW3

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What about a thin shell hard structure?

     Perhaps made from layers of Graphene paper, bonded together with a sort of aerogel polymer?  100 layers should give a fairly substantial structure, (Ribs and girders could be molded directly into the overall structure, to minimize mass and increase potentile lift) and should be able to handle fairly high speeds that soft skin ballones couldn't.

     You might even be able to create a negative boyancy strurcture out of this craft, (Or fill it with a hydrogen / silicon based aerogel, with a negative boyancy factor).

Just a thought...

JasonAW3
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Offline Vultur

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The Dark Sky Station concept strikes me as something that could well work (no physics problems like the orbital airship) but it would likely take WAY more funding than JP Aerospace could reasonably get to build a full-size one.

The envelope(s) would have to be simply massive, and the cost of helium would likely be prohibitive. It might even be a significant drain on helium reserves.

I guess you could use hydrogen (how flammable is it with oxygen at that partial pressure at 140,000 ft?) but if this is going to be a tourism thing,  safety regulations might kill it. (Though I guess you could base it in some country that doesn't have those regulations).

Offline QuantumG

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The last plans I saw were to use hydrogen for the Dark Sky Station. It's very safe at that altitude.
Human spaceflight is basically just LARPing now.

Online FutureSpaceTourist

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Whereas the Ascender airship that goes from the ground to the Dark Sky Station uses helium: http://nextbigfuture.com/2011/10/floating-airship-could-radically-reduce.html

Quote
Question: Wouldn't a combination of hydrogen with flame-retardant materials be more cost-effective?
Hydrogen is about one-fifth the cost of helium, and gives slightly better performance. But working with hydrogen requires permits for everything. Due to much larger insurance costs and permit costs, it actually turns out that using helium is cheaper than hydrogen. Helium is somewhat scarce, but it is actually an artificial scarcity - helium is vented in the U.S. in order to keep the price up.

Offline Garrett

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Guy with balloon wants to do "near-space" tourism:

http://www.wired.com/autopia/2011/08/inbloon/
Interesting. Looks like they're good at it.
http://www.0ll00.com/2012/11/microbloon-2-0-soars-to-the-edge-of-space/

I presume the folks who built the Red Bull Stratos balloon (ATA Aerospace) could also pull off something like this with their existing tech?
« Last Edit: 05/13/2013 09:31 am by Garrett »
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Offline Robert Thompson

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Offline ChrisWilson68

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Just found this thread.

I know that JP Aerospace doesn't seem to make much headway with their "airship to orbit" concept.

Yes it's hard to see progress as they do a lot of testing on such a small scale (and it is a 30 year programme that they're only a bit over halfway through!).

Things are due to get a bit larger scale in the relatively near future. They're hoping to fly their scale 90 foot Ascender by the end of this year: http://jpaerospace.com/blog/?p=5147

The JP crowd seems to be in denial about basic physics.  You simply cannot have lift from the atmosphere without also having drag, whether that lift comes from buoyancy or aerodynamics.

Go up where the atmosphere is thin and you can have lower drag, but that means lower lift from buoyancy or aerodynamics.  If you add a large surface area, you can get back lift, but drag comes right back along with it.  It's those same gas molecules bouncing off your craft that give both lift and drag.
« Last Edit: 06/18/2013 09:25 am by ChrisWilson68 »

Offline QuantumG

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The JP crowd seems to be in denial about basic physics.  You simply cannot have lift from the atmosphere without also having drag, whether that lift comes from buoyancy or aerodynamics.

Go up where the atmosphere is thin and you can have lower drag, but that means lower lift from buoyancy or aerodynamics.  If you add a large surface area, you can get back lift, but drag comes right back along with it.  It's those same gas molecules bouncing off your craft that give both lift and drag.

Who said otherwise?
Human spaceflight is basically just LARPing now.

Offline ChrisWilson68

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The JP crowd seems to be in denial about basic physics.  You simply cannot have lift from the atmosphere without also having drag, whether that lift comes from buoyancy or aerodynamics.

Go up where the atmosphere is thin and you can have lower drag, but that means lower lift from buoyancy or aerodynamics.  If you add a large surface area, you can get back lift, but drag comes right back along with it.  It's those same gas molecules bouncing off your craft that give both lift and drag.

Who said otherwise?


Anyone who takes the airship-to-orbit concept seriously says otherwise.  The ion engines that gradually accelerate the airship to orbit are supposed to overcome drag through high mach numbers while gravity is being countered by a combination of buoyancy and aerodynamic lift.

Offline QuantumG

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Anyone who takes the airship-to-orbit concept seriously says otherwise.  The ion engines that gradually accelerate the airship to orbit are supposed to overcome drag through high mach numbers while gravity is being countered by a combination of buoyancy and aerodynamic lift.

I'm sorry, but your point is still alluding me. Rocket engines regularly provide sufficient thrust to overcome drag.. that's kinda what they're for.

Human spaceflight is basically just LARPing now.

Offline R7

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[I'm sorry, but your point is still alluding me. Rocket engines regularly provide sufficient thrust to overcome drag.. that's kinda what they're for.

They do, and are, but they also require copious amounts of propellant to do that and they propel slim aerodynamic rigid bodies instead of gargantuan blimps.

May I offer some simple math to further illustrate the challenge here. Have not seen exact schematics of the ATO ship anywhere, but the JPA pdf offers imagery and information (length of the ship 6000ft) from which some crude assumptions can be made (in the attached image).

The pdf says ATO uses buoyancy to climb at 200kft. According to 1976 Standard Atmosphere the air density at that height is 0.000254864 kg/m3

Let's simplify ATO volume calculation by assuming that it is roughly the same as cylinder whose length is twice the diagonal 1.75km line and diameter same as ATO's. So volume is

V = pi * 732 * 1750 * 2 = ~59 million cubic meters, quite a blimp

How much lift force you get from that with buoyancy at 200kft? Let's assume the airship skin and structure is made of 187Nomassnium and is filled with vacuum. AIUI per Archimedes the theoretical ultimate lift force is equal to the weight of displaced fluid

59,000,000m3 * 0.000254864kg/m3 = ~15,000kg

15 tons for airship structure and payload  :-\

How is the drag at that height for such vehicle? Let's use the drag equation with frontal reference area estimated by the 1.33km line. What's the actual drag coefficient for ATO's geometry is beyond me but I SWAG it is somewhere between ball (0.47) and streamlined body (0.05). We'll try relatively good 0.1, small initial velocity of 100m/s and see how that flies.

Fdrag  = 0.5 * 0.000254864kg/m3 * (100m/s)2 * 0.1 * 146m*1330m = ~25,000N

Begin to see the problem here? Only 15 tons of mass to distribute to create the behemoth, and requirement is for 25kN thrust just to get barely moving. Drag is proportional to the square of velocity so at 500m/s you need 625kN and 1000m/s 2.5MN. The thrust requirements are nowhere near current SEP SoA and chemicals are pretty much off the table as too massive.

Did not touch aerodynamic lift, what's the L/D coefficient of such geometry?

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Here's what JP Aerospace say about drag: http://nextbigfuture.com/2011/10/floating-airship-could-radically-reduce.html

Quote
The 3 remaining potential showstoppers:

1. Scaling active drag reduction.

Active hypersonic drag reduction has been demonstrated in the lab for 30 years. Can we take it out in the real world and scale it up to the airship to orbit requirement?

[...]

So they're very aware of the problem. From other interviews etc I've seen, they think they know what approach(es) to use to solve it but are a long way currently from proving it'll work/scale-up.

Offline gbaikie

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"The final version of JP Aerospace’s first-stage Ascender airship will be among the largest airships ever constructed, with an expected volume (57 million cubic feet) greater than seven times that of the Hindenburg."
http://en.wikipedia.org/wiki/Orbital_airship

There would be quite difference between 59 million cubic meters and 57 million cubic feet

Anyways, what about something like 100 meters in diameter 1 km long.
That's is 7.85 million cubic meters.
Or about 257 million cubic feet.

Such a thing would be hard to deploy. Maybe it would deployed in building which is 110 to 120 meters in diameter cylinder, say 100 meters high. Though one might make it much shorter, say 20 meters tall [6 stories high]. And one want very still air deploying it maybe elevation of the mile high city of Denver type elevation. So selecting site which normally has low wind conditions.
So such building with larger than football field "roof" [lacking one or having a temporary one] is pretty expensive. To make a smaller building, one could balloon diameter expand as it gains altitude [as it typical of such balloon launches].
So, perhaps have blimp like inner structure- a balloon within a balloon.
The outer balloon is limited in that it just displaces atmosphere and inner balloon has such strength to enable it take loads.
So inner one could be say 50 meter in diameter, and it is inflated to be blimp-like or rigid and the 25 meter donut surrounding it, only gets inflated at a higher elevation.
This way instead 110 meter diameter building, one limit it to say 60 meter diameter building [still quite large but smaller than football stadium. One might rent such an existing building- if in a good location].

continuing:
So the "inner tube" has everything that one could call a "hard point", such as valves which open. Also it could sectional and accessible. Whereas the donut is just like a very high altitude balloon- minimal load bearing and continuous and not sectional. Though it could be- it could be balloons attached to inner tube and have hundreds of them. This could be easier to deploy [perhaps].
So inner tube could have 50 meters section per the 1 km- so, 20 sections. So first section could inflated and be rigid, and then you inflate lower sections, having entire balloon rises until has enough buoyancy to lift entire balloon structure, and continuing to inflate all the inner tube and the outer donuts as it gains in elevation. 

Edit, continuing:
So maybe the limit of a balloon launch is 1 km in height, or 500 meters or whatever, one could have two or more dock them together. So one could
have very tall structures. So say 5 km by 100 meters in diameter. And connection being inner tube to inner tube. One also remove the sections
every 50 meters so it's continuous open space, which was 1 to 5 km and 50 meters in diameter. And do weird things like have elevators/air tube lifts inside this space, allowing the transporting 1 or 5 km upwards.
So in other words each 50 section is a "hard point" which can start as structural support to allow pressurization [low pressure, but still have quite a load] and once at elevation one doesn't need such pressurization or these membranes separating the space. So you could cut off the 50 meter diameter part and leave the "hard point" ring it was attached to. And attach other stuff to these hard points.
So such "hard points" would be made something strong per it's weight- plastics or titanium alloys and will have considerable weight regardless of what made of, but the inner tube itself would be stronger material than donut, so it might be that hard point is around same mass as 10 meter length/height of this inner tube blimp. Or perhaps it's possible that removed 50 meter diameter sectional membrane is around it's mass/weight.
But in any case it has to be supported, and it's seems it would be tensional in nature- or compressional is implausible. One will be using helium or hydrogen gas and it will be warmer than atmosphere and around same pressure [a vacuum {less than 1 psi}].
But with such large structures even near perfect vacuum condition the gas has some mass, but mass of structure and mass of gas must be equal to the displaced volume of very low density gas of the atmosphere.
And what I am talking about must have less mass at the top than at the bottom [gravity gradient keeps to vertical]. But whole purpose is to have some payload, so having most payload/structural mass at bottom, "resolves this". But if have body of air in gravity, there will be more gas density at bottom than at the top- even if all the gas temperature is the same- and won't be- hot air rises.
Good news about hot air, is that in near vacuum one has very little convection losses of heat- radiant heat loss would be more significant and one would use reflective materials to lower such losses. Anyways lots of details to deal with in terms of thermal control. Of course I am kind of focus on inner tube and most lift and thermal area will be related to donut part of balloon. If donut is comprised of many smaller balloon these balloon can attached to the 50 meter sectional part of inner tube,
and this gives vector of the tensional force. It's not so much vertical as somewhat sideways. I mean it's not combination of vertical loads, but rather each section is being supported individually.

Anyways, so one 100 meter by 1 km gives 7.85 million cubic meters
and if had it 5 km it's roughly  7.85 million times 5 or 39.25 million cubic meter, which less than "59 million cubic meters" number, so if asume 15 tons per 59 million cubic meters at 200,000 ft is correct. I have around 50% less payload or less than 8 tons. So according given reference at
150000 feet there is 0.00170221 rather than the 0.000254864 of 200,000 feet. So roughly 6 times more lift. And 5 km is 16400 feet.
So, I guess one probably shouldn't go as high as 200,000 feet.
« Last Edit: 06/18/2013 04:03 pm by gbaikie »

Offline ChrisWilson68

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Anyone who takes the airship-to-orbit concept seriously says otherwise.  The ion engines that gradually accelerate the airship to orbit are supposed to overcome drag through high mach numbers while gravity is being countered by a combination of buoyancy and aerodynamic lift.

I'm sorry, but your point is still alluding me. Rocket engines regularly provide sufficient thrust to overcome drag.. that's kinda what they're for.



Yes, and the rocket engines have to expend some of their thrust to overcome gravity losses.  For that reason, high thrust is needed -- they need to quickly ramp up to orbital speed because every second along the way they're expending energy fighting gravity.

The benefit of the airship-to-orbit concept is supposed to be that a combination of buoyancy and aerodynamic lift counter most of the gravity loss so the engines can use low-thrust, high efficiency engines, such as ion thrusters.

My point is that if the airships are fighting gravity with buoyancy and/or aerodynamic lift, they will inevitably have much, much higher drag than today's launchers, which go up out of most of the atmosphere to avoid drag before picking up most of their speed.

Offline QuantumG

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Yes, and the rocket engines have to expend some of their thrust to overcome gravity losses.  For that reason, high thrust is needed -- they need to quickly ramp up to orbital speed because every second along the way they're expending energy fighting gravity.

The benefit of the airship-to-orbit concept is supposed to be that a combination of buoyancy and aerodynamic lift counter most of the gravity loss so the engines can use low-thrust, high efficiency engines, such as ion thrusters.

My point is that if the airships are fighting gravity with buoyancy and/or aerodynamic lift, they will inevitably have much, much higher drag than today's launchers, which go up out of most of the atmosphere to avoid drag before picking up most of their speed.

Yep, it's definitely a tradeoff. JP seems to think that's a workable tradeoff, but he doesn't show his work (or hasn't even figured out how to work it yet) so we can't evaluate whether or not his solution will work.

That's a far cry from your original claim of being "in denial about basic physics".

In the mean time he's flying student experiments to high altitude, for free. What's not to like?
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Offline Vultur

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A few points:

-Ascender is not the same thing as the orbital airship. In the proposed system, Ascender goes from Earth surface to the Dark Sky Station, and the orbital airship goes from the Dark Sky Station to orbit. So the wildly different volumes make sense, since they're totally different vehicles.

-I thought by 200k ft, it was supposed to be supporting itself by aerodynamic + buoyant lift? So the mass could be greater than the ~15 metric tons allowed by buoyant lift alone... right?

However, I still don't think it can possibly work. Even if they have more than 15 metric tons to work with, it probably isn't enough.

And I severely doubt ion engines can give enough thrust to deal with the drag on a vehicle that size even at that altitude.

And can it possibly deal with the heating induced by moving at near orbital velocities even through that sparse atmosphere? It can't really have any kind of shielding at all, given the weight constraints...

Offline QuantumG

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However, I still don't think it can possibly work. Even if they have more than 15 metric tons to work with, it probably isn't enough.

Which is no doubt why you're not working on it.

Quote
And I severely doubt ion engines can give enough thrust to deal with the drag on a vehicle that size even at that altitude.

Who said anything about ion engines?

Quote
And can it possibly deal with the heating induced by moving at near orbital velocities even through that sparse atmosphere? It can't really have any kind of shielding at all, given the weight constraints...

Now you're asking a question that someone could actually answer.. has there been any big hypersonic Mylar balloons flown in the upper atmosphere? Well yeah, with significant challenges overcome.. http://history.nasa.gov/SP-4308/ch6.htm

That doesn't mean JP Aerospace can do it, but nothing will.. until they do it.
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Offline ChrisWilson68

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Yes, and the rocket engines have to expend some of their thrust to overcome gravity losses.  For that reason, high thrust is needed -- they need to quickly ramp up to orbital speed because every second along the way they're expending energy fighting gravity.

The benefit of the airship-to-orbit concept is supposed to be that a combination of buoyancy and aerodynamic lift counter most of the gravity loss so the engines can use low-thrust, high efficiency engines, such as ion thrusters.

My point is that if the airships are fighting gravity with buoyancy and/or aerodynamic lift, they will inevitably have much, much higher drag than today's launchers, which go up out of most of the atmosphere to avoid drag before picking up most of their speed.

Yep, it's definitely a tradeoff. JP seems to think that's a workable tradeoff, but he doesn't show his work (or hasn't even figured out how to work it yet) so we can't evaluate whether or not his solution will work.

That's a far cry from your original claim of being "in denial about basic physics".

I stand by my claim that they're in denial of basic physics.  If they're getting enough lift from either buoyancy and/or aerodynamics to have any significant affect on gravity losses, the drag will be overwhelming.  There's no way their low-thrust engines will get them going even a few hundred mph with that kind of drag, let alone to orbital speed.  Buoyancy comes from having enough gas molecules striking your vehicle to prop it up.  So does aerodynamic lift.  Those same gas molecules cause drag.

Offline ChrisWilson68

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Quote
And I severely doubt ion engines can give enough thrust to deal with the drag on a vehicle that size even at that altitude.

Who said anything about ion engines?

JP Aerospace says "electric propulsion":

http://www.jpaerospace.com/atohandout.pdf

Quote
The third part of the architecture is an airship/dynamic vehicle that flies directly to orbit. In order to utilize the few
molecules of gas at extreme altitudes, this craft is big. The initial test vehicle is 6,000 feet (over a mile) long. The
airship uses buoyancy to climb to 200,000 feet. From there it uses electric propulsion to slowly accelerate.

Note that it says "electric propulsion" and "slowly accelerate".  The obvious interpretation of that is an ion engine, with low thrust but high efficiency.

They could be leaving open to tethers, too.  That would push against the Earth's magnetic field and it's another form of electric propulsion.  But it has the same key properties as ion engines: high efficiency but low thrust.

I think all the points about ion engines apply to any low-thrust electric engine.

Quote
And can it possibly deal with the heating induced by moving at near orbital velocities even through that sparse atmosphere? It can't really have any kind of shielding at all, given the weight constraints...

Now you're asking a question that someone could actually answer.. has there been any big hypersonic Mylar balloons flown in the upper atmosphere? Well yeah, with significant challenges overcome.. http://history.nasa.gov/SP-4308/ch6.htm

That doesn't mean JP Aerospace can do it, but nothing will.. until they do it.

The link you gave is about project Echo.  That was an inflatable satellite system.  It was launched deflated and only inflated once in orbit, and out of essentially all atmospheric drag.  That's not really a hypersonic balloon.

Offline QuantumG

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I think all the points about ion engines apply to any low-thrust electric engine.

Not at all.. ever heard of plasma thrusters?

Quote
The link you gave is about project Echo.  That was an inflatable satellite system.  It was launched deflated and only inflated once in orbit, and out of essentially all atmospheric drag.  That's not really a hypersonic balloon.

You actually have to read the link.. there was a whole test program which involved deployments in the upper atmosphere.

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I stand by my claim that they're in denial of basic physics.

Lots of people said that about JPA's claim that they could use propellers at 100k ft altitudes. Then they demonstrated propellers working at c 100k ft! Of course they don't break the laws of physics, people had misunderstood/mis-applied their knowledge to what JPA were doing.

There are plenty of crackpots who propose perpetual motion machnes etc. But given what they've achieved I give JPA a lot of credit that they're not crackpots. They clearly understand about drag and are not in denial about it. They may be wrong about whether they can get the technology to work, or even if the technology in principle gives them the drag reductions they need, but it seems pretty unlikely to me that they've missed a basic physics gotcha.

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http://nextbigfuture.com/2011/10/floating-airship-could-radically-reduce.html

Quote
Question: For the airship going to orbit, would the engines be chemical, ion, or some sort of hybrid?
The engines would be a hybrid, employing both ion thrusters and chemical propulsion. At certain points we will be using ion thrust, and at other points we will be using chemical. There is a tradeoff between efficiency and time to orbit, the more efficient you are, the longer it takes to achieve orbital velocity. Rockets are measured in terms of specific impulse, which provides an indication of the efficiency of the system, with higher being better. The specific impulse of our hybrid is about 1100, which compares to about 450 for chemical rockets and 30,000 for ion thrusters. So this hybrid can either be viewed as being the most efficient chemical rocket ever, or the least efficient ion rocket.

Question: So this rocket is half ion and half chemical?
Yes, it is almost always half and half. The final insertion is all chemical. The chemical rocket will use wax/nitrous oxide. That is what we are currently testing. With sufficient R&D, I am confident that we could get a hybrid engine up to 2,000 specific impulse. That would obviously have a beneficial effect on payload capacity, perhaps as much as a quarter increase in payload.

Offline ChrisWilson68

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I think all the points about ion engines apply to any low-thrust electric engine.

Not at all.. ever heard of plasma thrusters?

Plasma thrusters are a subset of ion thrusters.

Quote
The link you gave is about project Echo.  That was an inflatable satellite system.  It was launched deflated and only inflated once in orbit, and out of essentially all atmospheric drag.  That's not really a hypersonic balloon.

You actually have to read the link.. there was a whole test program which involved deployments in the upper atmosphere.

Yeah, in the upper atmosphere in the same sense the ISS is in the upper atmosphere.  The ISS needs periodic reboosting because of the drag of the tiny bit of atmosphere up there.

But the ISS is also considered to be in orbit.  All the balloon deployments mentioned in the link involved first putting the balloon into orbit, then inflating it.  A part of the motivation was to watch the decay of the orbit of the balloon satellites to learn about drag in that region.

But I still think it's not really accurate to call that "big hypersonic Mylar balloons flown in the upper atmosphere" any more than it would be accurate to call the ISS a hypersonic vehicle.  People generally don't consider objects in orbit to be engaging in hypersonic travel even though there is a small amount of atmosphere that is slowly decaying their orbits.

Offline ChrisWilson68

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I stand by my claim that they're in denial of basic physics.

Lots of people said that about JPA's claim that they could use propellers at 100k ft altitudes. Then they demonstrated propellers working at c 100k ft! Of course they don't break the laws of physics, people had misunderstood/mis-applied their knowledge to what JPA were doing.

Whoever said propellers couldn't be used at 100k ft was clearly wrong.

But I didn't say that.  And the fact that someone else was wrong in criticizing claim A really has no logical bearing on my criticism of claim B.

There are plenty of crackpots who propose perpetual motion machnes etc. But given what they've achieved I give JPA a lot of credit that they're not crackpots. They clearly understand about drag and are not in denial about it. They may be wrong about whether they can get the technology to work, or even if the technology in principle gives them the drag reductions they need, but it seems pretty unlikely to me that they've missed a basic physics gotcha.

You think they have a secret technology that they won't tell anyone about and have never demonstrated to anyone that would re-write every basic textbook on drag?  Good luck with that.

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And the fact that someone else was wrong in criticizing claim A really has no logical bearing on my criticism of claim B.
 

It does when criticisms of both claim A and claim B imply the same claim C (that JPA don't understand basic physics). I was giving counter evidence to claim C.

As I'm sure you're aware, by the law of logic known as the contra-positive that means criticisms of both claims A & B are invalid. :)

To re-iterate, I'm not saying it'll work - I'm saying they're more competent than you appear to give them credit for.

Edit: fixed typos and improved wording
« Last Edit: 06/19/2013 06:52 am by FutureSpaceTourist »

Offline ChrisWilson68

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And the fact that someone else was wrong in criticizing claim A really has no logical bearing on my criticism of claim B.
 

It does when criticisms of both claim A and claim B imply the same claim C (that JPA don't understand basic physics). I was giving counter evidence to claim C.

As I'm sure you're aware, by the law of logic known as the contra-positive that means criticisms of both claims A & B are invalid. :)

Actually, in the specific quote I was responding to, you were using the fact that someone had erroneously criticized claim A as evidence claim B was also suspect, which does not logically follow.

Offline QuantumG

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Plasma thrusters are a subset of ion thrusters.

No they're not. Plasma is not ions, by definition.

Quote
All the balloon deployments mentioned in the link involved first putting the balloon into orbit, then inflating it.

Seeing as you're disinterested in actually reading what was linked, can you please stop commenting on it like you have?
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Offline QuantumG

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You think they have a secret technology that they won't tell anyone about and have never demonstrated to anyone that would re-write every basic textbook on drag?  Good luck with that.

Not at all.. we're saying you made a claim about John Powell and his supporters that was completely unsubstantiated.
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Offline ChrisWilson68

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Plasma thrusters are a subset of ion thrusters.

No they're not. Plasma is not ions, by definition.

Actually, plasma is ions, mixed in with electrons.  Turning a gas into a plasma is called "ionizing" it.

The Wikipedia entry for "Plasma propulsion engine" starts with "A plasma propulsion engine is a type of Ion thruster..."

Offline QuantumG

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Actually, plasma is ions, mixed in with electrons.  Turning a gas into a plasma is called "ionizing" it.

The Wikipedia entry for "Plasma propulsion engine" starts with "A plasma propulsion engine is a type of Ion thruster..."

Yah! Score one point for Chris.
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Offline ChrisWilson68

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Seeing as you're disinterested in actually reading what was linked, can you please stop commenting on it like you have?

It seems more likely you're the one who is uninterested in actually reading what was linked, since what I've said is consistent with the article while what you said is not.

If you think I misrepresented anything in the article you linked to, please quote the specific part of the article and what I said that you claim is inconsistent with it.

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*Sigh*

Summary of QG's link:

- Shotput I test used Sergeant X248 Sergeant XM-33/ABL X248 powered suborbital rocket to send Echo prototype up to test how it inflates.
- Rocket burnout happened at 60miles (~320kft!), then payload separated and started to inflate.
- Residual air intentionally left inside folded mylar balloon expanded too quickly in near vacuum, damaging the balloon.
- Balloon pieces feel back down creating spectacular light show.
- The public was told uplifting news story which didn't mention the failure at all and gave false impression that the balloon fell into sea intact. You know, cold war and all, would have been embarrassing to admit failure while the Russians were seemingly(their censorship was at least as good ;)) getting everything right.


So yeah, technically big mylar balloons have been flown hypersonic through atmosphere ... while safely riding packed under rocket PLF.

edit: fixed the rocket description, those are the first and second stages of the sounding rocket.
« Last Edit: 06/19/2013 08:59 am by R7 »
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Offline QuantumG

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.. and five more flights. Including a completely successful deployment.

But hey.. way to reward the know-it-all who can't even read a chapter.
« Last Edit: 06/19/2013 08:41 am by QuantumG »
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Offline R7

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.. and five more flights. Including a completely successful deployment.

Yes, when done at least 60 miles up  ;)

edit: from the article
Quote
... the Shotput tests, whose ABL X248 carried the test balloons only to 200 to 250 miles above the surface ...
« Last Edit: 06/19/2013 09:26 am by R7 »
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Offline Vultur

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http://nextbigfuture.com/2011/10/floating-airship-could-radically-reduce.html

Quote
Question: For the airship going to orbit, would the engines be chemical, ion, or some sort of hybrid?
The engines would be a hybrid, employing both ion thrusters and chemical propulsion. At certain points we will be using ion thrust, and at other points we will be using chemical. There is a tradeoff between efficiency and time to orbit, the more efficient you are, the longer it takes to achieve orbital velocity. Rockets are measured in terms of specific impulse, which provides an indication of the efficiency of the system, with higher being better. The specific impulse of our hybrid is about 1100, which compares to about 450 for chemical rockets and 30,000 for ion thrusters. So this hybrid can either be viewed as being the most efficient chemical rocket ever, or the least efficient ion rocket.

Question: So this rocket is half ion and half chemical?
Yes, it is almost always half and half. The final insertion is all chemical. The chemical rocket will use wax/nitrous oxide. That is what we are currently testing. With sufficient R&D, I am confident that we could get a hybrid engine up to 2,000 specific impulse. That would obviously have a beneficial effect on payload capacity, perhaps as much as a quarter increase in payload.

Hmm, well, that provides some hope. Although I'm still skeptical what the ion engines can actually contribute...

Offline Vultur

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I looked at the Echo link and I don't see anything stratospheric/mesospheric. There was one failed deployment at 60 miles, but the air's far thinner there than ~200k ft (~38 miles). What am I missing?

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Recent Facebook updates suggest JPA are making progress with their next Ascender:

https://www.facebook.com/jpaerospace/posts/517502808298901:0

Quote
Inside the tail of the new Ascender

https://www.facebook.com/jpaerospace/posts/520246294691219:0
Quote
Putting away the port Ascender envelope at the end of the day.

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