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Gigantic Air Gun To Blast Cargo Into Orbit
Hugh Pickens writes: "The New Scientist reports that with a hat tip to Jules Verne's From the Earth to the Moon , physicist John Hunter has outlined the design of a gigantic gun that could slash the cost of putting cargo into orbit. At the Space Investment Summit in Boston last week, Hunter described the design for a 1.1-kilometer-long gun that he says could launch 450-kilogram payloads at 6 kilometers per second. A small rocket engine would then boost the projectile into low-Earth orbit. The gun would cost $500 million to build, says Hunter, but individual launch costs would be lower than current methods. 'We think it's at least a factor of 10 cheaper than anything else,' Hunter says. The gun is based on the SHARP (Super High Altitude Research Project) light gas gun Hunter helped to build in the 1990s while at the Lawrence Livermore National Laboratory (LLNL) in California. With a barrel 47 meters long, it used compressed hydrogen gas to fire projectiles weighing a few kilograms at speeds of up to 3 kilometers per second."
The real question on all of our minds though: "How far will it launch a pumpkin?"
Just wondering how they plan to address the problem of controlling the G-forces and prevent damages to the cargo.
The cannon idea was tried before ...... not a test single cargo survived the trip (or made it to orbit).
At 450 kilos you can launch three people with breathing gear and parachutes. Think of it as the "Econo" version of space tourism.
Is that a gigantic air gun with a 1km barrel in your classified launch facility, or are you just happy to see me?
~dijjnn
Gerald Bull was Canadian engineer who died (bullet in the head) trying to build such a cannon.
See http://en.wikipedia.org/wiki/Project_HARP
You can't take the sky from me...
$500 million is what BART wants to spend to build a 3.2 mile stretch of elevated rail to connect the Oakland Coliseum to the Oakland Airport, and this boondoggle of a project is already funded. Imagine the progress we would make towards space travel if we spent the same amount of money on technology that will move cargo into space as opposed to moving people too lazy to take the already existing BART Shuttle to the airport?
-- This sig is only a test. If this were a real sig it would say something witty. --
I may be wrong in this calculation but running the numbers I get a weird result.
The gun is 1.1K long with a final velocity of 3km/s.
So the payload would be in the gun for 1.1/(3/2) = 0.73 seconds.
In that 0.73 seconds the payload would accelerate to 3 kms/sec The continuous acceleration would be 3000/9.8/0.73= 417 Gs. That is sure a lot of Gs. Much more than the 3.2 the shuttle produces.
All you need is a booster rocket (and a cargo) which can stand 1670 g of acceleration (possibly higher, if the gun does not provide uniform acceleration.)
v^2 = u^2 + 2*a*S
u=0, v=6000, S=1100 => a=16,364 m/s^2 = 1670g
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Bullshit. Several weapon systems do just that, including the rocket assisted howitzer shells used in the M109 Paladin.
With enough duct tape over any likely orifices, I don't see why not. I still don't think they would survive launch though.
A bullet may have your name on it but splash damage is addressed "To whom it may concern."
Search for Gerald Bull and read abut his super-gun project.
> Cargo it seems would have a better chance but any sensitive equipment (like
> 99% of anything used in space) or explosive materials (fuel) wouldn't be able
> to be shot up in a gun.
Nonsense. Guns have been firing projectiles filled with explosives for centuries. The US Army has had shells filled not only with explosives but optics, electronics, and actuators for terminal guidance for dacades. In WWII they had anti-aircraft guns that fired shells with vacuum tube proximity detonators in them. In WWI they used shells with self-winding mechanical timers. Fuel would be easy.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
With discrete component electronics you just pot the whole thing in epoxy. I don't know how well that works with integrated circuits -- the point of failure is likely to be the fine wires that connect the chip to the package leads, although those may be light enough that the real concern is vibration rather than steady G force. Even vacuum tubes can be built tough, if they're built small.
But ~400 Gs (per calculations by a poster above) is nothing. The radio proximity fuzes in WW II antiaircraft projectiles didn't use transistors, and had to withstand ~20,000 Gs when fired and ~5,000 Gs of shell spin.
-- Alastair
He died in an earlier post.
It saves a great deal of fuel by getting the rocket needed to achieve the remaining velocity going 3km/sec and above the atmosphere.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Ah I love the smell of terrified redneck racist in the morning it smells like victory!
Still I pity your need to overcompensate for your inadequacies.
Matterafact, the proximity-fuzed antiaircraft shells of WW2 had a vacuum tube in them.
rj
You work with what you have.
Hey wait this guy might be on to something, this lattice reminds me of something.
"It's an energy field created by all living things. It surrounds us, penetrates us, and binds the galaxy together."
Yes that sounds similar!
We need to master the lattice and soon we will be able to jump really high, move shit with our minds, and battle each other with laser swords.
Extreme heat and magnetic forces would make it harder on the payload. Ultra high energy railguns usually need to have thier rails replaced everyfiring. Add in the complexity of, no doubt, hundreds of massive capicitors, it would be like the LHC.
As a tax-payer, I refuse to fund it unless it makes a cool "FffffummmppPPP" sound.
Table-ized A.I.
1. In round numbers:
. ~9.5 km/sec to LEO (given, approximate)
. ~6.0 km/sec from gas gun (FTA)
. ~0.5 km/sec atmospheric drag (FTA)
= ~4.0 km/sec needed from projectile rocket
. 350s ISP for projectile rocket (assumed, optimistic)
= 0.69 propellant fraction
. 450Kg projectile (FTA)
= 310Kg projectile rocket propellant
= 140Kg projectile non-propellant
. ???Kg projectile structure, motor, etc.
= ???Kg net cargo to LEO (in any case, 140Kg)
2. Assuming you want to rondezvous with something in an established orbit (e.g., the ISS), any significant orbital maneuvering is out of the question; in paticular an orbital plane change--whether by the projectile or the target--as it's too expensive.
That limits the number of launch windows. You can't simply launch projectiles into orbit as fast as the gun can fire, otherwise you'll end up with them scattered in various orbits that you have to chase down (again, very expensive).
E.g., there are nominally 2 launch windows/day for Shuttle flights from KSC to the ISS. (Due to various rules, in practice it's limited to 1/day, but we'll ignore that.)
3. Even with optimal launch parameters, orbital rondezvous is still non-trivial, and one reason why even unmanned ISS resuplly vehicles are much more than simply a dumb ballistic container, and have, e.g., OMS and RCS motors, propellant and the weight/complexity/cost penalties that come with them.
Which is why larger, more infrequent and expensive missions will remain the norm for the foreseeable future--with or without a space gun or its ilk.
4. In short, we need an orbital infrastructure that can handle smaller/dumber vehicles. That doesn't exist, and few if any of these proposals account for it. With, e.g., a group of ion/electric tugs it may make more sense. That is, something that can cost-effectively collect those smaller/dumber vehicles and bring them to where they're needed.
Send up consumables, for sure. Fuel, water, compressed air, freeze-dried food, etc. Even if just used for that, this is not a bad plan. There's no rule that says you have to use only ONE method to get stuff off-planet.
One good criticism would be that this is a short-term project. You'll need conventional lift to get the tools up into space to build an orbital mining facility. This air-gun can be used to lift all the materials that those tools will use to build the mining facility and fuel for the crafts that will go get the asteroids and coax them back. But once that's done, we ought not need the air gun nearly as much or at all.
Still, compared to the costs of things like shuttles or ISS, this is pocket change.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
I don't know about the GP but I only needed one look. Do you realise you have reinvented Luminiferous ether?
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
You using that euphemism for shit or corpses? Because if it's corpses sign me up.
-The world would be a better place if everyone had a hoverboard
Since it would be used only for eco-friendly recycling, it could not possibly be considered a weapon of any sort.
I'm sure this is what medieval siege engineers shouted at the unhappy garrisons of besieged castles they were bombarding with decaying horse corpses: "That's no weapon, we're just recycling!"
Ezekiel 23:20
Back when I was doing giant space gun work at Boeing :-). Feel free to ask questions. I'm not about to type in several volumes of technical data, but it's nice to see he's converged on the same muzzle velocity we came up with (5.7km/s).
Our desigh: particle-bed heater with Aluminum-oxide heat storage (it's actually #20 sandpaper grit). It's much easier to store hydrogen at room temperature, then heat it just before it hits the barrel. Using small particles, you get lots of area for heat transfer. The particle bed gets warmed up with heaters of your choice over a period of hours, then you fire the gun and in a second or so transfer a good chunk of that heat to the hydrogen.
Why heat the hydrogen? The speed of sound of a gas depends on the molecular weight and temperature, and hot hydrogen works best. The efficiency of a gun drops dramatically as you reach the speed of sound of the working gas. Think of it this way, speed of sound is how fast pressure waves travel.
If the projectile outruns that speed, there is no way for the gas at the back end to send push to the projectile further up the barrel. It's a bit more complicated than that since you are constantly feeding gas from the back end, and the gas right near the projectile is moving almost as fast, so pressure waves can catch up, but on the whole as you get near Mach 1 of the gas, your ability to push drops way down.
Depending on size of the gun, and where you are launching to, the west slope of Hawaii and the Andes are good locations. The first has *long* even slopes, courtesy of lava flows. The second are shorter, steeper slopes, but somewhat higher altitude (less air to fly through), and closer to the equator.