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Blimps... In... Space...
LandGator writes "MSNBC reports a California company with an alternate launch site in Texas, JP Aerospace, is on their third test of a blimp system specifically designed to fly to space. Blimps. To Space. At payload costs around a dollar a ton to LEO. Their concept, first unveiled at the Space Access '04 conference in Phoenix last month (with a blog report here, include the Ascender, a ground-to-near-space blimp, which docks to a helium-inflated two-mile-long station at the edge of space, over 20 miles up. Another ship, also a blimp but specifically designed to reach orbit, takes the payload from there to LEO, using well-proven electric propulsion (AKA 'ion drive'). That trip to LEO would take up to nine days, but that's a good thing; for, what goes up fast, must come down fast, and speed is energy which must be bled off by either massive amounts of expensive and explosive rocket fuel, or through ablative heat transfer which has its own problems (as we have seen before). JP Aerospace has flown many PongSats -- micropayloads the size of a ping-pong ball -- for balloon or rocket-launch. Over 1,500 PongSats have flown to date, which demonstrates a track record in near-space few of the X-Prize contenders can approach. Oh, yes, the Air Force is interested."
Incase there are actually people not reading the linked article, the interesting part is quoted here:
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Blimps into space looks insane but they have flown some of the parts of a 3 stage to orbit system and they are talking about costs to space of a dollar a ton/mile. Ton mile.
Still.
OH THE HUMANITY!
Fortunately this time we should have the sense not to paint the blimps with highly flammable doping.
Saskboy's blog is good. 9 out of 10 dentists agree.
Low Earth Orbit.
Yea, good and explosive. While it may not be particularly dangerous to people, losing payloads to accidents involving hydrogen explosions in the atmosphere would jack the potential cost up.
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Because...
On Apple Input Peripherals: They're okay, I guess, but I was really hoping for a one-key keyboard and a 109-button mouse
uhm... no. hydrogen is 1/4 the weight and therefore has ((airdensity)-(heliumdensity))/((airdensity)-(heli umdensity/4)) the buoyancy. In this case the density of air is so much higher that the increase in buoyancy isnt even 25%, let alone the 300% you say.
Half the weight. Hydrogen is diatomic.
The Hindenburg was filled with hydrogen, not helium. Hydrogen burns, helium does not. Besides, the Hindenburg was painted with some rather flammable compounds..
Well, let's work it out. Assuming an ion Drive can produce a net thrust of 0.01g (.0931 m/s). LEO is around 7600m/s. That gives 81362 seconds, or 22 hours. Obviously they're planning on much lower accelerations than even that, but low forces build up over time.
TODO: Something witty here...
No, which is still a long way from a fuel cell one of these.
An Education is the Font of All Liberty
Although the Hindenburg is often perceived as an advertisement against hydrogen, it was, in reality, more of an advertisement against using cellulose nitrate or cellulose acetate to add rigidity to the skin of a dirigible.
In all likelihood, it was the flammable nature of the skin that led to the ignition. Sure, having all that hydrogen there didn't help once the fire started, but there were a lot of successful hydrogen-filled blimps and dirigibles up to that point (the survival ratio was at least as good, if not better, than that of hydrazine or solid-propellant rockets).
Eloi, Eloi, lema sabachtani?
www.fogbound.net
Which brings up the interesting question of what there is in the upper atmosphere... is there enough oxygen for hydrogen to burn?
--
Evan "Not a meteorologist"
"$30 for the One True Ring. $10 each additional ring!" -- JRR "Bob" Tolkien
Can you really accelerate a big inflated condom to escape velocity with an ion drive? I mean, it can only get so high on He, and I'm assuming that at its apogee there will still be an appreciable amount of atmosphere. Would an ion drive be able to overcome the drag force? Anyone willing to do the math?
You are aware that there is no such thing as "escape velocity" when you are bouyant, right? A more apt question is more can they reach orbital velocity.
Your question begs multiple misconceptions.
First, escape velocity is about getting you permantly out of earths gravity well. Not something you want if your destination is a stable orbit around the earth.
Second, escape velicity is a ballistic value, ie. the speed required to kick your butt off the planet from ground level going straight up.
Third, pushing "a big inflated condom" around in the upper atmosphere is not really a problem since there isn't much air to create drag.
Further, the higher you go, the less drag you feel, hence the "launch" of the orbiter from a platform already 20 miles up.
-- The morphemes of your disquisition are ascertainable, but they have eschewed an ambit of transpicuous exposition.
That is what the ion engine is for. They calculate it will take 9 days to acclerate the craft to 8km/s.
Incorrect. The blimp expands until the pressure inside is the same as the pressure outside, so any change in air density will be reflected as a proportional change in helium/hydrogen density. See my other post for a longer explanation of that.
"Studies have shown that people who eat peanuts live longer than those who do not eat."
Even regular blimps use multiple gas cells so that a problem with one doesn't bring the whole thing down. Granted, debris is a concern but it needn't be a deal breaker.
People have a misconception that if you put a hole in a blimp, that it crashes. If properly designed it will not.
It all comes down to the pressure difference between the insides and the outsides of the blimp.
Reading their promotional literature, they do not maintain much of a pressure difference between the insides of the blimp and the outsides. Thus, a hole will not really result in the helium being replaced with the heavier atmospheric gases.
Most blimps can manage a safe emergency landing if even significantly damaged.
Last but not least, I suspect that their choice of helium was more due to the dramatic reduction in safety precautions they have to take with the stuff on the ground. There are real advantages to using diatomic gases over monotomic gases (for example, they leak much more slowly through micro-pores). But the advantages do not make up for the disadvantage of the risk of explosion on the ground or at low altitudes.
Thank you. The stupid Hindenburg was the begining of bad science in the media. Due to the radio reports and the worldwide viewing of the recorded images of the disaster no formal inqury into the cause of the disaster was done. As we know now the skin of the Hindenburg was painted with what was essentially ROCKET FUEL. A small static discharge along a seam is the most likely cause of the disaster, the skin almost exploded and it wasn't until much later in the disaster when the envelopes tore open due to loss of internal structure that the Hydrogen had any affect on the fire. Not only that but no people were hurt by the hydrogen fire because due to hydrogens boyancy it would have risen to the top of the structure and burnt there.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
http://www.jpaerospace.com/atohandout.pdf
Here are the details:
Atmospheric airship with crew of three takes payload to 140,000 ft. Airship uses lift and buoyancy, and driven by propellers designed to operate in near vacuum.
Dark Sky Station (DSS) at 140,000 ft. Permanent, crewed facility.
Airship that flies from DSS to orbit. Over a mile long. Uses buoyancy to climb to 200,000 ft. From there uses solar/electric propulsion to reach orbital velocity over several days.
Continuing to use solar/electic propulsion, it can keep on going to anywhere in the solar system.
Several "DSS" platforms have been flown. All equipment has been flown at 100,000 ft. and tested in the environment. Ion engine tests of the orbital airship at 120,000 ft. will occur in the next five months.
Every segment of the plan has funding. DoD is funding the atmospheric airship for reconnaissance. Telecom companies are funding DSS.
Yes. Atomic oxygen (O1), standard diatomic oxygen (O2, the kind we breathe), and ozone (O3, the kind the blocks UV and gets eaten by fluorocarbons). O1 and O3 are very reactive, but nothing that a hydrogen balloon should have to worry about, so long as it contains most of its hydrogen.
Of course, one of the other great benefits of helium over hydrogen is that helium is MUCH more containable - He stays inside Mylar envelopes a lot longer than H, which has been known to burrow its way out of multi-layer metal/ceramic containers thanks to its small atomic size.
I love vegetarians - some of my favorite foods are vegetarians.
One variation possibility they have not covered possibly is the use as a platform for more conventional launches.
You mean, like the The Da Vinci Project's X Prize attempt?
To quote from their site, "A reusable helium balloon will lift our spacecraft, "Wild Fire" to an altitude of 80,000 feet. This is where Wild Fire's rocket engines will fire and propel the crew to the 100 km altitude goal -- space."
--This is a self-referential sig--
It's much worse than that. In order to make it look better, they covered the skin with a mixture of iron oxide and aluminum powder. That's right, boys and girls, they covered it with thermite! No wonder it burned so fast!
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Actually it is. Any Nuclear reactor can be tuned to produce Helium. I think they did this briefly at the Laurence Livermoor reactor for a short time before decomissioning it.
"Curiosity killed the cat, but for a while I was a suspect."- Steven Wright
This is stupid, I swear noone has any vision.
First, they're talking about 20 miles up for this two-mile 'lily-pad'. At 20 miles, we still have atmosphere, so we still have buoyant(sp) forces acting. Since there's a buyoant(sp) force at work, orbital mechanics can be damned. Your airship doesn't fall back to Earth because it's lighter than air.
Are you with me, then? You have a lovely two-mile long launch platform. From here, you launch another, smaller balloon with even less density and a few ion engines. This smaller balloon floats up as high as the remaining atmosphere allows. At this point, we'll say that the balloon is 'floating' on the very top of the Earth's atmosphere. It won't go down (buyoant[sp] force) and it won't go up (gravity). At this point, as long as the ion engines can beat the force of gravity, you have acceleration.
Acceleration, even small amounts of it, mean a lot in a vaccum. Give it a couple weeks and you'll find yourself speeding along at 8 km/s. Let go of the object you want in orbit and use the same ion engines to slow down. Physics being what they are, you should wind up back where you started with the same amount of velocity as when you left. At which point, you'll be 'floating' on the top of the Earth's atmosphere and you can manipulate your airship to get back down to the 20-mile-high 'lily-pad'.
Just to quibble: Helium is a noble gas, so it won't be diatomic above ~4K. (Diatomic gasses are gasses with molecules formed by two atoms joined by chemical bonds.)
I see your point, though. Helium has a nucleus that is four times as heavy (two protons and two neutrons versus a lone proton for most hydrogen), and has another electron in its orbitals. These factors greatly reduce the diffusion rate. Diatomic gasses would have some added advantages of greater size per unit weight but would have some disadvantages such as pressure buildup upon decomposition and less buoyancy due to greater weight.
No sir, they didn't do it to look good, they did it for passive thermal regulation. If the gas gets too hot, the blimp rises too fast, where it gets more sun, etc...
Hindenburg, anyone?
No oxygen to burn?
Helium, not hydrogen?
In the Hindenburg it was the blimp material and not the hydrogen that caused the flames?
Ignorant Comment Of The Week, anyone?
--- Ban humanity.
This blimp needs air for bouyant lift, so you are inevitably going to be in the atmosphere. Ion engines, unfortunately, only work in a vacuum. And even if they did work at that altitude, the drag would so high that they wouldn't accelerate the ship at all.
.01, then the drag force at 5000 fps, 1/5 of orbital velocity, is: .5 rho Cd V^2 A
.01
If the ship was, say, 50 ft wide and had a rediculously low drag coefficient of
where
rho is density (about 1.7x10^-5 slugs/ft^3)
Cd is
V^2 is velocity squared. At 5000 fps, that's 2.5x10^7
A is area, 50 ft
This yeilds a drag of a little more than 100 lbf.
The most powerful ion engine is Nasa's new HiPEP that has a thrust of about 1/10th of a pound.
Now, I'm a big fan of JP Aerospace, and wish them all the luck in the world. Their program of launching sounding rockets from high-altitude balloon platforms was quite exciting. Hypersonic blimps, though, are just not going to happen.
Thad
I love Mondays. On a Monday, anything is possible.
Good analysis. In reality, the drag coefficient is going to be more like .2 due to the "dirty" truss structure that supports the engine and keeps the v-shape - even that's giving them some leeway. So, at 100,000 ft, the average wind velocity is 40-knots (take my word for it). This produces a drag force on the balloon of:
.5 * rho * Cd * A * V^2
.5 * 1.7E-5 * .2 * 50 * (40kt * 1.69(ft/sec)/kt)^2 = 0.4lb.
.
This means that they would need four ion engines just to keep station over a geographic point. It also means that 40-knots is their terminal air-velocity with said engines. Ya ain't gonna to get to orbit that way! Plus, their actual "orbital" craft has a MUCH bigger planform. .
This sig is a test. If this had been an actual sig, you would be reading something quite a bit wittier than this now.
Escape velocity is what you need to get infinitely far from earth. In other words, if you went at or above escape velocity (and assuming no drag and not crashing into things and no weird influences by other objects and probably a couple other things) you would never return to earth. For low earth orbit you need much less, about 9000 mi/h.
a/c
No matter how far *vertically* you lift something, you still need significant *horizontal* velocity in order to reach, and stay, in orbit. Blimps get you high, but not fast. Airbreathers get you fast, but nowhere near fast enough, and nowhere near high enough. In the end you don't save all that much because the size of the actual booster required isn't reduced all that much. (Something like 75% of the fuel in an orbital launch is used to generate that horizontal velocity.)
You're right that "thrust" should be "acceleration", but you're wrong about g. G is the gravitational constant; g is the acceleration due to gravity at the Earth's surface.
The shareholder is always right.
Yes, I know you won't get aerodynamic lift without air, so there will be some drag, but your back-of-envelope calculation doesn't tell enough of the story to know if it's a showstopper.
My question is how the heat gets dumped on the way back. I guess it has so much surface are the heat load at any given point is small, but we're not talking about titanium here.
You forgot about lift. If you shape yoru baloon in such a way that it produces lift if it has forward momentum, you can get around the drag. You start at say 100,000 feet with zero velocity. You turn on your ion engine, and accelerate to a few fps. Yes you have a big drag area, but you also have a big lift area. You use the lift to move higher than the buoyant force can move you. As lift brings you higher, you accelerate, because dynamic pressure will remain a constant (so that drag cancels out thrust and you still have net lift) The only problem I can see is that at very high altitudes you have rarefied gas dynamics and effective temperatures of the air is very high, so you need to have some sort of TPS even if youre moving very slowly. Its worth a shot to try it though.
So, yeah, you're right it's leaving, but it's also being replaced by natural radioactivity so that even after all the hydrocarbons are used up, natural gas wells will still be producing helium for millions of years.
According to Praxair, fifty percent of current natural gas consists of helium. So, it's not all that rare which helps to explain why it's not all that expensive.
Quid festinatio swallonis est aetherfuga unonusti?
That's Latin in dactylic hexameter, by the way.
The 5th foot seems a bit of a stretch as a dactyl to me. (Though so do some of Vergil's verses, so what do I know?) And the Romans didn't have the letter "w" so I take that word as an English retrofit (as well as the prefix un- rather than the Latinate in-).
You're allowed to use spondees here & there y'know. How aboutQuid festin|atio | swallonis | est aether | fuga un|onusti?
What haste of the unburdened swallows is air-flight?
Quid festin|atio | fugae | avis | liberae | est idem?
What haste of the free bird's flight is this?
Sounds more like Vergil to me.
Does this post make me fascetor grammaticalis?
Actually we've been around for 25 years. We have just over 80 test flights on the program so far.
JP
John Powell
President
JP Aerospace, America's OTHER Space Program
The problem with getting to orbit isn't altitude, it's velocity. From your handy-dandy high-school physics book: E_altitude = mgh (mass times gravity times altitude) = 1 kg * 9.8 m/s2 * 100 km = 9.8*10^5 J. Whereas kinetic energy is E_kinetic = 0.5*m*v^2 = 0.5 * 1kg *(7.6 km/s)^2 = 2.8*10^7 J.
So getting to altitude takes only 3% of the energy required to reach orbital velocity. This is again why all these schemes that have you starting on a balloon, or a tall tree or whatever just won't work. Saying I lack vision is idiotic; I just happen to know some physics.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
At this point, we'll say that the balloon is 'floating' on the very top of the Earth's atmosphere. It won't go down (buyoant[sp] force) and it won't go up (gravity). At this point, as long as the ion engines can beat the force of gravity, you have acceleration.
Wrong! As long as the ion engines can beat drag, you have acceleration. But they won't, and you can show that in a few lines - though I wish it were easier to write equations here...
At 50 km altitude the atmospheric denisty is something like 1 gram per cubic meter. So to lift 1 kg of mass with a balloon you need something like 1000 cubic meters of volume (actually more since you're using hydrogen and not vacuum, but whatever). That will mean a balloon with a radius of 6 meters. It will have a frontal area of 120 square meters. Now, the drag equation is: F_drag = Cd * Area * density * velocity^2, where Cd = 0.2, Area = 120 m2, denisty = 0.001 kg/m3, velocity = 8 km/s. So, F_d = 1.5 million Newton. The ion engine on DS-1 produced 0.09 N of thrust, and massed about 10 kg.
So this idea is cracked by a factor of 10 million or so. I'm sure I'll get lots of indignant, anonymous replies saying how it's actually at 60 km, not 50 etc etc. But the point remains, this is an idea anyone who passed high school physics should be able to see through. Sorry, but that's life. Don't moderate down the messenger....
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
Two gold stars for you!
We will be using dynamic lift. That is an absolute must. We will also be bringing the truss structures inside the envelope, so the drag coefficients should become more comparable to regular flying wings.
The heat loading issue on the way back down is no worse than it is on the way up. We can go into a high drag profile at a very high altitude and spread the loss of kinetic energy over a very long time frame. Skin heating is proportional to the power dissipation rate, so a long time frame keeps that number low.
--Be The Alien.