The Tragic Tale of Saddam Hussein's “Supergun”
bbc.com
bbc.com
Now I'm not saying nothin' bout RT in general, but this particular story isn't exactly non-problematic...
Actually, the TV show was released before the events you mention, so the details don't match exactly, but it's close enough for government work, so to speak.
I couldn't understand from the article how the hydrogen was being used in a "gas gun". Since pure hydrogen doesn't ignite, wouldn't we care about the molecular weight of the oxidizer as well?
It turns out the "light gas" is important just for it's low molecular molecular weight. It's never ignited, and one could substitute Helium for Hydrogen if one wanted. The gas is a second stage in addition to, rather than instead of the gunpowder. It's like a spring-air gun, but instead of spring you use an explosive charge.
Here's Wikipedia: https://en.wikipedia.org/wiki/Light-gas_gun
And here's some PVC experimentation: http://www.chrisfenton.com/2-stage-light-gas-gun/
...As it were.
At its 2013 launch price and at full LEO payload capacity, the Falcon 9 v1.1 cost $1,864 per pound ($4,109/kg).
Ref: https://en.wikipedia.org/wiki/Falcon_9#Launch_prices
From TFA:
The cost was roughly $1,727 per kilogram, adjusting for inflation. By comparison, Nasa estimates that it costs $22,000 per kilogram to launch a modern satellite into orbit using conventional rockets.
Look up the rocket equation to see what a huge difference this makes.
There's at least two super-guns in them, both launching to space as described (one of them "and beyond", it's a Moon shot).
Even though this wouldn't be appropriate for use for delicate satellites, I wonder if this would be a critical piece of equipment for industrialized space - raw materials like fuel and oxygen and structural materials. Unfortunately full satellites would be a challenge since googling reveals that experiments involving these things included 10,000 gees of acceleration.
In reference to the second graph on the page, mach 1 is apparently 1125.33 fps
Do we know if the space guns are rifled or smooth bore?
The problem with those graphs is that they are not optimizing propellant quantity for each barrel length. Adding an axis for quantity of propellant shows that you get diminishing returns to increasing barrel length and propellant, but there is a limit to how much you can increase both without increasing the barrel's thickness (as well as the firing mechanism's strength).
You also have to remember that a gun will require > Mach 25 to get to orbit, and air acts differently at that kind of speed (, and once past ~Mach 3).
Is there a reason the space gun would be at a 45 degree angle and not pointed vertically? I know the reason rocket launches happen as close to the equator as possible, but they still go straight upwards...
I should also mention that unless the projectile was fired at or above escape velocity (intended to leave the Earth's gravity well), it would require some onboard propulsion to 'circularize' its orbit (and avoid crashing back into the Earth on its first time around).
[1] https://en.wikipedia.org/wiki/Rocket-assisted_projectile
(As nickff points out, modern tank cannons are generally smoothbore; the current fashion for armor-piercing is solid kinetic darts that need to go very, very fast to punch through their target, and rely on stabilizing fins for accuracy.)
Probably second biggest down sides of rifling is that it weakens the barrel. How much depends a lot on how the rifling is done. But anyhow this has to be compensated with thicker/stronger barrel.
But that gets problematic at extreme pressures. You wan't to use pressure vessel steel, because such steels 1. have good fatigue strength and 2. they tend to send around little less shrapnel when they fail. Problem is that such steels are typically low alloy steels with somewhat low yield strengths. So you would like to make thicker barrel, but the problem here is that you quickly hit diminishing returns. There is usually very little point making barrel thicker if the outer diameter is twice the inner diameter. (Except if you need more rigidity to improve accuracy. But that's whole another subject.)
Anyhow, the brits still use rifled tank gun.
The gun can be built somewhere in the Andes, at 4 km altitude. It can be pretty long there. Plus using either ablative head - like new Russian-Indian air missiles - or small forward jets - similar to Russian 200miles/h torpedo - will help to decrease atmospheric speed losses.
The 6.5 Mach gets you to 180km altitude from powerful regular gun - https://en.wikipedia.org/wiki/Project_HARP :
"On November 18, 1966 the Yuma gun fired a 400 lb (180 kg) Martlet 2 projectile at 7,000 ft/s (2,100 m/s)[1] sending it briefly into space and setting an altitude record of 180 km (590,000 ft; 110 mi);"
That means that it was going at least 5 Mach after reaching 30km altitude. Doesn't looks like such a big loss of speed in the atmosphere - only about 1 Mach due to atmosphere as the other 0.5 Mach - due to gravitation.
You would have to be pretty naive to think the Iraqi's, who always wanted to be the dominant Persian Gulf state in the region, would actually use this for its intended purpose and not weaponize it to intimidate its neighbors in the region.
I mean, of course the Iraqi military (like everyone else) thought about it as a weapon first, but if I were Bull I'd have been happy to con them out of spending the same money on more effective weapons.
That sounds so weird. Could you post a reference?
(Just google "saddam hussein sci-fi cover art")
With a mostly static target region (London, Regions of Iran), steering capable projectiles and lots of resources to build multiple of these that immobility is not really an issue.