Project Uranus: By Gun To Orbit

[Lunar_Lander]

We had some discussions about Gerald Bull's High Altitude Research Program on the IRC channel last week. I have read quite a few accounts on HARP (Wikipedia articles, the two astronautix.com articles for which you'll find the links below, as well as some scientific magazine articles).

I have the opinion that there will be no problem as to pick up HARP again. As mentioned in the first astronautix article, people at Ottawa tried to stop Canadian funding of the project and were finally successful, and Bull was deprived of his chance of launching a minimum satellite by gun.

If we would get funding for a new project of such a kind, what would be the next logical step?
Constructing new projectiles and the rocket for the satellite launch?
Contacting US Army for a potential support and for getting a new gun?
Contacting equatorial countries for a possible launch range?
(Of course only three of a whole lot of things to be done, but these were the ones that came to my mind most immediately)

Articles at astronautix.com:
http://www.astronautix.com/articles/abroject.htm
http://www.astronautix.com/lvs/martlet.htm

 

[T.Neo]

I don't know much about HARP or the Martlet rocket, but what I do know about projectiles being launched out of large bore cannons as would be used to launch satellites makes me skeptical.

Launching anything out of a gun (especially with a high velocity) incurs a high acceleration of 1000's of Gs. While copper-jacketed lead slugs and cannon shells can survive this, most if not all spacecraft built in the history of space exploration would probably fall apart when subjected to less then 100 Gs.

However, certain systems have shown that electronic systems can be launched out of a gun-like system, for example airbursting munitions and certain russian tank guns that can fire antitank missles. This would be extremely useful to anyone trying to destroy orbiting tanks, but not very useful to someone wanting to launch cameras and other highly sensitive equipment.

I am sure some heating would also occur from launching at or around sealevel at more then 1000 m/s. While this would be no problem to a protected projectile, it would mean that any sensitive materials and/or components be shielded, causing the complexity and cost of the system to go up.

The payload would now have to be constructed out of more robust (and thus heavier) materials. More mass in the frame and supporting structure will leave less space for power generation and instrumentation. I doubt you'd be able to cram any meaningful attitude control system into the package as well and expect it to survive.

Not to mention that you would have to accomodate what is essentially a launch vehicle, which would also have to be made to withstand the rigors of a gun launch as well.

At best you'd only get 2000 m/s out of a gun launch anyway, AFAIK.

I think a far more viable option to launching minisats would be to have some sort of super-cheap small launcher, or piggyback on larger government launches. You'd be able to accomodate far more in terms of useful payload mass and versatility.

I'm basically repeating what I said on the IRC the other day here, for the benefit of anyone who is interested. I think that a gun launch is a cool idea, but I don't really see it as being legitimate, at least not for orbital minisat launches.

 

[RisingFury]

I'd say the technical aspects of the gun could be overcome... but I'd guess that such a gun would violate international treaties, preventing militarization of space.

 

[TSPenguin]

I don't think that this treaty would be violated through this. The gun stays on the ground after all.
For all intents and purposes, this is just a fancy launchpad.

 

[T.Neo]

Indeed.

It's a launch platform. I'd imagine it would be pretty useless as a weapon.

Numerous rockets are operating right now which are more then capable of putting a kinetic impactor into orbit.

 

[Sky Captain]

I think an electromagnetic cannon would be better for space launch because of much higher velocity attainable requiring only small apogee kick to establish stable orbit. An electromagnetic accelerator track could be made several kilometers long making the acceleration less of a concern. Also it would be a great way how to cheaply resupply space stations and interplanetary spacecraft with dumb payloads such as water, food, and fuel

 

[Wolfer]

Something along these lines? http://en.wikipedia.org/wiki/Launch_loop
The big engineering problem seems to be the length and the height of the device. But, afaik, if you're going to launch people on something like this it's going to have be long, unless you want your passengers to look like pancakes.

 

[Ark]

Excuse my largely sci-fi based physics knowledge, but couldn't you get around the excessive Gs by completely flooding the payload bay with water? Since water isn't compressible, wouldn't replacing all the air/vacuum with water support every part of the spacecraft and prevent damage?

 

[Sky Captain]

Something along these lines? http://en.wikipedia.org/wiki/Launch_loop
The big engineering problem seems to be the length and the height of the device. But, afaik, if you're going to launch people on something like this it's going to have be long, unless you want your passengers to look like pancakes.

I had a simpler system in mind - basically a large railgun or coilgun running up the side of an equatorial mountain. Obviously not useful for launching people, but then again mass of people are minority compared to mass of other stuff required to start large scale space exploration.

 

[TSPenguin]

The advantage of a cannon over a rail system is that a cannon can be relatively easy mounted so that it can point anywhere.
A quite more impressive task to achieve with a long rail system.

 

[RisingFury]

Excuse my largely sci-fi based physics knowledge, but couldn't you get around the excessive Gs by completely flooding the payload bay with water? Since water isn't compressible, wouldn't replacing all the air/vacuum with water support every part of the spacecraft and prevent damage?

The G forces would still be there, however, if you filled the spacecraft with water and made sure it doesn't leak, you'd effectivelly produce a "pillar" that would hold up against the load. You do have to keep in mind, though, that now all of this water pushes on the wall where acceleration is pointing, so make sure that wall is strong.

However, given the mass of water required for that, I'm sure there'd be easier ways to reinforce the spacecraft, without making it weigh a lot...

 

[Wolfer]

The advantage of a cannon over a rail system is that a cannon can be relatively easy mounted so that it can point anywhere.
A quite more impressive task to achieve with a long rail system.

Not if you want to launch people or fragile stuff in space. Then you would still need a freakishly long barrel so the acceleration can be gradual and you would also need to use a series of successive explosions, a bit like in the V3. But for simpler payloads I totally agree with you.

 

[Notebook]

Not a gun, but an old favourite:

http://www.slingatron.com/spacelaunch.htm

http://www.slingatron.com/index.html

N.

 

[T.Neo]

It would need to be some very powerful and large coil/railgun.

You are also launching at a high velocity from sealevel, which means you will encounter large amounts of atmospheric drag and heating.

You will also need a seperate propulsion system onboard the payload to circularize it's orbit.

You will only be able to launch to a single inclination, so it would be a dedicated system. But moving the system around shouldn't be an issue, since launch pads don't move anyway.

 

[Lunar_Lander]

I just finished a fascinating book on the project called Paris Kanonen - The Paris Guns (Wilhelmgeschütze) and Project HARP, in which there was a quite detailed description on the HARP firings and associated equipment. I would even go as far as stating that the HARP system could be easily replicated from these descriptions.

It is also said in there that probably every scientific instrument could be modified to work on a gun launch, and I would believe that. They show a photo of one of the two probes carrying a Langmuir probe (which measures electron densities and temperatures), saying that the full space of the Martlet 2 the apparatus took in 1966 would have been shrunk to a fraction of the size of the nose cone in 1988.

I received a message in which it was criticized that such probes traverse the atmosphere very fast, and how one could possibly get the fine structure of the winds and so on. That is quite easy to solve by the used method to eject balloons or instrumented parachutes from the projectiles. Tracking the metalized parachutes by radar was a very reliable method they developed.

As for Launch Sites I would propose an equatorial Pacific Island, as they give more than ample downrange water to conduct launches safely. One suggestion would be Nauru, being at 1° South latitude, or even better Aranuka of the Gilbert Islands, Kiribati, being only 0°9' North. There also the other islands of Kiribati would be available for needed instrumentation, like triangulating cameras.