2 Stage Airship/Shuttle 2 Orbit

[marcel_leonard]

Airship, an aircraft that consists of a cigar-shaped gas bag, or envelope, filled with a lighter-than-air gas to provide lift, a propulsion system, a steering mechanism, and a gondola accommodating passengers, crew, and cargo. All extensions, like the fins and the gondola/control car, are attached to the envelope; the propellers are attached to the gondola/control car. <br /><br />How about two large airships attached by central launch control car; large enough to support the space shuttle, refitted w/ a stronger booster speed to reach orbit? <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[grooble]

Always had a similar idea myself, a sort of balloon platform or a floating town. I'm sure it's possible under the right conditions.

 

[nacnud]

Interesting idea, try googleing 'skycat 1000' for another airship that might be capable of lifting the required weight.

 

[rogers_buck]

Not sure that would help. The airships won't fly all that high nor will they go all that fast in a forward direction. If the plan is for them to drop the shuttle, there actually might be a negative relative momentum headed toward the center of the earth before the engines light (too close and you'll pop the air ships).<br /><br />

 

[bobvanx]

m_l,<br /><br />Stop it!<br /><br />There is no way to "float" to orbit!<br /><br />Floating partway there doesn't gain you much advantage, either!<br /><br />You've posted this idea in lots of ways, in many threads, and someone takes the time to explain the rocket equation to you, and you argue nits and "what if" while ignoring what the cold hard facts of mass and delta-V clearly show:<br /><br />that getting into orbit requires orbital velocity, not altitude! Our atmosphere is such a thin boundary that it adds useless complexity to design a system that takes advantage of it.<br /><br />It's like designing your car to use the thin stream of water in the gutter to get out into the street. Just drive over it!<br /><br /><br /><br />++++++++<br /><br />For any one else: It takes so much energy to boost a large mass up to orbital velocity, that what you are really fighting is just the inertia of the payload. Air resistance is neglegible after less than 10% of the boost phase has occurred. Your spaceship is only going about 2000mph by the time it exits the atmosphere. It still has to reach 18000mph to be in orbit. The air column <i>does</i> steal energy from your ship, but this energy loss has less and less impact, the larger your payload.<br /><br />Small payloads launched from high altitudes do get a useful increase. Every payload launched at sea level from the equator gets an even more useful 1000mph boost, just from the Earth's rotation. But a large payload, a shuttle class paylaod, sees such a small incremental improvement in launching at 50k or even 100k feet that the extra effort to design this mobile launch platform offsets any economies you might gain.<br /><br />In short: your spaceship has to reach 18000mph, no matter where you launch it from. Launching it high, you gain some small benefit from doing all your accelerating outside the atmosphere, but it's a really small advantage.

 

[nacnud]

Yes I'm well aware of the difference in delta-v required to go from high altitude to orbit, but there have been some interesting proposals put forward in this area. The rockoon principle is well known although I do agree that it currently only really worthwhile for very small payloads.<br /><br />Have you seen the JP Aerospace proposal for a dark sky station and even an orbital airship! I have no idea how the orbital airship could work but there must be something there as they have be funded by the airforce to develop a high altitude airship.<br />

 

[mrmorris]

<font color="yellow">"...but there must be something there as they have be funded by the airforce to develop a high altitude airship. "</font><br /><br />RRRRiiiigggghhhhtttt -- because no government agency would <b>ever</b> spend millions/billions on a boondoggle project...<br /><br />JPA's idea might work -- or it might not. But government sponsership isn't proof of their ability to do anything except write an interesting proposal.

 

[Peter the Dane]

the only real solution to high altitude lauch, are mount kenya.<br /><br />but then you have a fleet of green freaks running around with signs.... thats baaaad PR.... <img src="/images/icons/frown.gif" /><br /><br /><br />Peter Gotthardsen<br />

 

[marcel_leonard]

<font color="yellow">bobvanx-<br />There is no way to "float" to orbit!</font><br /><br />You seem quite **** sure of yourself there bob would you like to put some money where your mouth since? <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[bobvanx]

>>sure of yourself<br /><br />Hah! Sure of myself? No. Actually, I'm quite sure of the physics involved. I'll happily take your money. Here, let's define terms:<br /><br />"There is no way"<br />Never, in any length of time, under any circumstances<br /><br />"to float"<br />To use the principle of lighter-than-air flight<br /><br />"to orbit"<br />To place a craft in space around the Earth so that it makes at least one trip in 90 minutes around the Earth.<br /><br />The test will be whether anyone (and let's limit this to our lifetimes, 'cause we won't care after we're dead) ever floats to orbit, or if anyone ever bothers to publish a peer-reviewed paper about how it is impossible.<br /><br />There. Now all we need is someone to hold the cash for us, to act as our escrow agent. How much can you afford to lose? I'll wager US $2000.00

 

[mcbethcg]

Balloons to orbit.<br /><br />I think that it might be theoretically possible for a lighter-than-air object to leave the earth.<br /><br />Imagine a vast balloon with a membrane and no payload and pressure barely above external, just a molecule thick, enveloping hydrogen or helium that is steadily released to keep pressures almost equal. It would have to be inflated and released by a more standard high altitude balloon to avoid turbulence issues.<br /><br />How high could it go? Could it go high enough to be affected primarily by solar winds or radiation?

 

[bobvanx]

Sigh.<br /><br />Well, I really DO want to take M_L's money, but it's not fair to the genuinely curious to leave you all wondering about the "theoretical possibility" of ballooning to orbit.<br /><br />The problem is that we are used to <b>living at the bottom of the ocean of air,</b> and we want to take what we are familiar with and apply that instinctual knowledge into areas where it no longer applies.<br /><br />Orbital mechanics is one of those areas.<br /><br /><b>The atmosphere is very thin.</b> Most sources (Google it!) give a height of between 10 and 20 miles for the "top" (there is actually a very diffuse gas that goes out quite a ways). So anything that relies on lighter than air can "theoretically" get you to about 90,000 feet. At that point, your ship is like a cork on the ocean, bobbing along.<br /><br />That is <i>very</i> different from getting your vehicle up to 17,000mph.<br /><br />To help people rewire their instinctive sense about "floating" to something that perhaps grasps the actual properties involved, I made this illustration.<br /><br /><b>The red bars show how fast the vehicle travels.</b> ISS goes fast enough to stay in orbit. SS1 went fast enough to hop up into space, but look at how much of a speed difference there is. <i>Any vehicle, traveling less than about 98% of the speed of the ISS, is going to fall back to Earth instead of orbiting</i>. A balloon might get up to 120mph in the jet stream (which is down in some thicker air, by the way), but it is not even close to getting to orbit.<br /><br />I drew this to scale, so I could point out something else: look how thin the atmosphere is. A vehicle at the top of the atmosphere <i>is</i> 20 miles away from the surface of the Earth. So if you launch from there, you are 20 miles "closer" to orbit. Orbit is "only" 200 miles higher, right? Except that it's also 17,000 miles per hour <i>faster</i> from where you are.<br /><br />And check this: it's also <b>17,000 miles faster from the surface of the Earth.</b> S

 

[marcel_leonard]

We all know and agree the you need speed to obtain orbit. This is why I proposed a second stage booster in the first place. As for floating into orbit H/ He molecules do it every day, and twice on Sunday<img src="/images/icons/wink.gif" />!!! <br /><br />In the immortal words of Jerry McGuire "SHOW ME THE MONEY"... <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[bobvanx]

M_L,<br /><br />Thanks for the implicit retraction. Clarification about H/He, they actually float up to form a diffuse plasma, and some end up getting bounced/accelerated to escape velocity! So if you can build a vehicle with the same characteristics as a Helium atom, then floating to orbit would be possible. Choose an escrow buddy to hold our dollars, build that vehicle, and the money is yours.<br /><br />Regarding a "second stage booster," since it has to get to 17,000mph if you launch from the top of the atmosphere, and the same 17,000mph if you launch from the bottom of the atmosphere, I really doubt the concept has any utility.

 

[mrmorris]

<font color="yellow">" As for floating into orbit H/ He molecules do it every day, and twice on Sunday"</font><br /><br />No. They don't. <br /><br />The point bobvanx is making, and you're missing, either intentionally or because you are absolutely incapable of grasping it, is that being at an altitude of (picking a number) 400km and essentially zero horizontal velocity is <b>not</b> the same thing as being in a 400km orbit. H/He molecules don't magically accelerate to orbital speeds, they only rise to orbital <b>altitudes</b>.<br /><br />Even if you could float to an altitude of 400km -- you still must accelerate to 7.67 km/sec (pick any altitude you want -- the velocity will simply change -- I happen to know 400km off the top of my head). Working out the propellant required to perform this acceleration using an Isp of 400:<br /><br />7670 m/s = 400s * 9.8 m/s2 * ln (Wo/Wf) <br />7670 m/s = 3920 m/s * ln (Wo/Wf) <br />1.956632653 = ln (Wo/Wf) <br />7.075461372 = Wo/Wf <br />Wf/Wo = 14.1% (i.e. 85.9% propellant mass required)<br /><br />So a 10,000 pound payload (fairly small) would need ~71,000 pounds of propellant -- even discounting the mass of the booster itself. As bv said -- you're not <b>gaining</b> much of anything except added complexity by using the balloon. The only reason altitude helps in sub-orbital flights is <i>because they suborbital</i>. They don't need orbital velocity -- they're <b>only</b> interested in altitude.

 

[nacnud]

How about the difference in infrastructure need to launch a rocket (pad, etc) and an airship like the skycat 1000 (a field). Also the size of launch vehicles is determined as much as anything by how big a structure can be transported from factory to launch site, a skycat 1000 would mean that SRBs could be stacked in the factory and delivered whole. Ranges safety might be improved as the range could be anywhere the airship could get to.<br /><br />There is more to the airship idea than just a first stage but I dunno if any of these ideas would pan out against a more conventional aproach.

 

[mcbethcg]

Sigh. I didn't say ORBIT.<br /><br />How do you get 18 miles high as the highest possible altitude for a balloon?

 

[nacnud]

Well the Qinetiq ballon was aiming for 40km and the record for a manned ballon earlier this year, 18 miles seems reasonable.

 

[bobvanx]

>>Sigh. I didn't say ORBIT. <br /> <br />Yes you did. Perhaps I read your post more carefully than you wrote it?<br /><br />I got the 18 miles from the 90,000 feet that seems to be widely reported. I recall balloons going higher. Perhaps the 90,000 is a figure that takes into account things besides just the lifting power of a lighter-than-air craft.<br /><br />If you could make a weightless bubble of vacuum, it would then of course weigh as much as space does. If you were to release this weightless bubble of vacuum from the surface of the earth, it would float high enough that it could interact with the Van Allen Radiation Belts (these are thousands of miles above the Earth) and eventually, after floating roughly 15,000 miles high, the solar winds could pick it up and push on it.<br /><br />Engineers know exactly the material you could use to fashion the wall of your bubble. It's the extremely rare element called unobtanium.

 

[tap_sa]

> Assuming that the envelope is make out of carbon fiber, does anyone think this may be possible?<br /><br />Let's see. First, according to their pdf DoD funds only the atmospheric ship which shuttles from ground level to the DSS, telcos are interested in the DSS. Both like the idea of cheap quasisatellite, one for surveillance the other for data relaying. Current altitude record for manned and unmanned balloons are 134000ft and 170000ft. It appears the first two stages of JPA's plan are achievable. <br /><br />The V-shaped blimp/zeppelin/dirigible/whatever is specced to ascend 200000ft. That's way pass current state of the art, especially if it's supposed to be manned and carry considerable cargo. Atmospheric pressure (or the almost complete lack of) at that height requires the gargantuan size, 6000ft in length (nearly two kilometers). Diameter seems to be at least 100 meters, possibly much more.<br /><br />So, take a something roughly the size of Petronas Towers in Kuala Lumpur, stack four of them, lift that 200k feet up and then, accelerate to nearly 8km/s. This is the altitude of Columbia's final moments and it had slowed to suborbital speed. A shuttle with heavy TPS didn't make it and someone is considering an ultrathin bag of gas doing it? Yeah right. I'd be surprised the the ion engines would be able to give enough thrust to overcome the air currents (assuming there are some) at that height and keep the thing steady.<br /><br />Even if the hull could be constructed from first grade unobtainium the ship would need Daedalus-class nuclear drive to overcome the drag. Just think of that fallout from the exhausts, yuck. Fortunately all isotopes of Unob have such a short halflife that at some point in design phase they inevitably decay into more mundane Al/Ti/Fe-alloys, composites and such. World is saved and bobvanx gets to keep his money.<br /><br />A sidenote to bobvanx's illustration of altitudes and speed (which btw looks very professional, nice work!). SS1 resembles

 

[nacnud]

<font color="yellow">The V-shaped blimp/zeppelin/dirigible/whatever is specced to ascend 200000ft. That's way pass current state of the art, especially if it's supposed to be manned and carry considerable cargo. Atmospheric pressure (or the almost complete lack of) at that height requires the gargantuan size, 6000ft in length (nearly two kilometers). Diameter seems to be at least 100 meters, possibly much more.</font><br /><br />I think that the ion driven orbital airship that JP is considering that will go from 150kft to 200kft due to its inherent buoyancy and from there to orbit under ion power. It can climb to 200kft because it starts at 150kft and never has to cope with the lower atmosphere and therefore, it can be built much lighter.<br /><br />That is why the DSS is needed, to act as a staging post and as a place to assemble the orbital craft. <br /><br />The main stumbling block to the whole plan as I see it is not the balloon technology but whether the ion drives will be sufficiently light and powerful enough to overcome drag and get the airship into orbit.<br />

 

[mcbethcg]

The 18 miles you used is not a theoretical limit for an unmanned balloon, with a molecule-thin membrane, which is what I was positing.<br /><br />The 18 miles was an actual manned balloon that already flew.

 

[bobvanx]

Thanks for noticing that I was only illustrating demonstrated technology.

 

[bobvanx]

>>looks very professional, nice work!<br /><br />Thank you!<br /><br /> />>If you'd add numbers showing the energies involved that would show even more clearly how far even SS1 is from reaching orbit.<br /><br />The rocket equation gets posted around here with great regularity. I'm noticing it takes a special kind of mind to follow the numbers and get what they show. Most people can't look at the numbers and convert them into an intuitive sense about what is physically possible.<br /><br />Good point about the energies, BTW. Even at 17,000mph, if you thrust straight up, you'll come straight down. That would be an unpleasant ride. If your flight plan only had fuel for the outbound trip, then at the top of the atmosphere you'd be moving at roughly 2,000mph on the way up. But you'd be returning at 17,000mph, and probably explode like a bolide as you hit the atmosphere.

 

[jpowell]

There are some new pics posted of the 'impossable' airships at www.jpaerospace.com<br /><br />These are just baby, steping store vehicles, but you may find then interesting anyway.<br /><br />JP