Orion drive and related physics

[Bill Phil]

1 hour ago, SomeGuy123 said:

What about landing?  I know the basic idea of Orion for launches from Earth is to make gigantic vessels, crammed full of supplies and equipment, and get them into orbit all in one go.  They might be unmanned, which would mean you wouldn't have to worry about injuries to the crew from the gamma rays of each blast.  

But suppose you did want to land.  Is it possible?

You should probably use chemical ships for landing. An Orion needs a certain altitude of "propping up", like the Saturn IB's milk stool, so it can release a bomb.

[PB666]

1 hour ago, Nothalogh said:

In atmo, it produces more thrust than in vac.

The design of the shock absorption system was to moderate the acceleration per pulse to 2 G, with if I recall correctly, 2 to 3 pulses per second 

So to get to 0.2c they are going to 2 g at 2 to 3 pulses per second. Hmmm lets see c ~ 1 yr at 1 g so 0.2 c would take 70 days at 2 g thats 35 days at 86400 seconds per day that comes out to 7.5 million hydrogen bombs.

This is not rational, its insane to think you could eject weapons every half second get complete noninterfering clearance and eject again, the ejection port is going to get pressurized at several atmospheres full of radioactive material which will end up being the bane of crewmembers involved in the plant. 

 

[Nothalogh]

13 minutes ago, PB666 said:

0.2c

I'm talking about the "small" 40m Orions, for earth liftoff and intra system work

[magnemoe]

8 minutes ago, PB666 said:

So to get to 0.2c they are going to 2 g at 2 to 3 pulses per second. Hmmm lets see c ~ 1 yr at 1 g so 0.2 c would take 70 days at 2 g thats 35 days at 86400 seconds per day that comes out to 7.5 million hydrogen bombs.

This is not rational, its insane to think you could eject weapons every half second get complete noninterfering clearance and eject again, the ejection port is going to get pressurized at several atmospheres full of radioactive material which will end up being the bane of crewmembers involved in the plant. 

 

Pulse rate depend on ship size, for an large ship you use larger bombs and longer between each, this is far more effective as you can use fusion bombs, for something interstellar you would use bombs in the megaton class, benefit is that you could take an small generation ship with you, radiation protection is by distance, the bomb magazine gives some shielding, during burn the original orion idea was to use an storm cellar during burn, acceleration courses and water to protect. 
For longer trips replace water with beer. 
One benefit with orion is that added massis rather an benefit, you build it like an ship not like an airplane. 

[magnemoe]

22 minutes ago, Nothalogh said:

I'm talking about the "small" 40m Orions, for earth liftoff and intra system work

Or the even smaller 12 meter one.

Edited February 21, 2016 by magnemoe

[Nothalogh]

12 minutes ago, magnemoe said:

Or the even smaller 12 meter one.

Mother of dog, where are you going with that thing?

[magnemoe]

Just now, Nothalogh said:

Mother of dog, where are you going with that thing?

Note, this breakes the game in an fun way 

Standard trajectory, launch windows still applies but only as in its take longer and don't hit the sun, its no other rules 

[Nothalogh]

3 minutes ago, magnemoe said:

Note, this breakes the game in an fun way 

Standard trajectory, launch windows still applies but only as in its take longer and don't hit the sun, its no other rules 

Ah, a full on brachistochrone transfer.

Old man Heinlein approves

[magnemoe]

1 minute ago, Nothalogh said:

Ah, a full on brachistochrone transfer.

Old man Heinlein approves

Why travel any other ways
We and the kerbals would probably be equal shocked in how the other part applied nuclear technology
Made sense in the setting, on return burn I had to catch up with Kerbin a bit. Cargo was an Ike base capable of operating on Duna and an lander capable of going from Ike surface to Duna surface and back. Various probes too. 

[SomeGuy123]

3 hours ago, Nothalogh said:

In atmo, it produces more thrust than in vac.

The design of the shock absorption system was to moderate the acceleration per pulse to 2 G, with if I recall correctly, 2 to 3 pulses per second 

So you need 9300 m/s to reach orbit.  At 2 Gs, that's 20 m/s gained per second.  At an average of 2.5 blasts per second (you might adjust the number used depending on altitude), it's 1163 nuclear explosions.  Per launch.  

It's kind of ironic that instead of being crazy, this is one of the most level headed, practical methods of reaching space with a lot of stuff anyone can actually build...

Let's see : the W48 supposedly cost 1.25 million each, with 1 million of that being the plutonium.  Let's say that is 1970 dollars.  So 6 million today.  And call it 12 million per pulse unit.    So 14 billion per launch in fuel.

Which sounds like a lot, but you're lifting thousands of times the mass of a falcon heavy all the way to orbit every launch...

Edited February 22, 2016 by SomeGuy123

[fredinno]

On 2/21/2016 at 6:22 PM, Nothalogh said:

It is in light of that overwhelming potential of Orion that I have come to regard the various policies that brought about its demise, as nothing short of treason against the human species

Like the Nuclear test Ban Treaty?

On 2/21/2016 at 10:51 PM, Buster Charlie said:

• 
  Artificial Radiation Belt Lifetime
  From Aerospace Projects Review Volume 1, Number 4
• 
  Artificial Radiation Belt
  Do not launch Orion from anywhere within the "Trapping Region"
  From Aerospace Projects Review Volume 1, Number 4

Detonating pulse units in space near Terra can create nasty artificial radiation belts. The explosion can pump electrons into the magnetosphere, creating the belt.

There are two factors: detonation altitude from Terra's surface, and magnetic latitude in Terra's magnetic field. If the detonation is within 6,700 kilometers of Terra's surface (i.e., further than 2 Terran radii from Terra's center) and at a magnetic latitude from 0° to 40°, the radiation belt can last for years. Above 2 Terran radii the radiation belt will last for only weeks, and from latitude 80° to 90°, the radiation belt will last for only a few minutes.

The military discovered this the hard way with the Starfish Prime nuclear test. The instant auroras were very pretty. The instant EMP was very scary, larger than expected (but the test was using a 1.4 megaton nuke, not a 0.001 megaton pulse unit). The artificial radiation belt that showed up a few days later was a very rude surprise. About one-third of all low orbiting satellites were eventually destroyed by the radiation belt.

The radiation belts are harmless to people on Terra, but astronauts in orbit and satellites are at risk.

 

Looking at the info I quote above, I'd like to also point out that as I've mentioned before there is such a ridiculous efficiency of this system in the atmosphere (because you can get away with even smaller bombs for the same amount of thrust) that it would be worth it to give up the traditional launch site requirements (Equatorial launches, near infrastructure). I don't know if you can launch nuclear rockets from the south pole, but certainly it'd probably avoid killing that many civilians.  On the other hand I think the north end of Alaska might be nice. We could really liquid off the russians and launch them from that tiny island in the berring sea that is right off their coast.

 

Yeah, you need to launch from the poles to avoid the magnetosphere, and burn straight up until earth escape velocity- the most kerbal way.

[Nothalogh]

4 hours ago, fredinno said:

Like the Nuclear test Ban Treaty?

Among several other things, yes.

[Bill Phil]

Even with the risk of 10 people dying due to an Orion launch, it's nearly nothing compared to the amount of people killed in car crashes, or war, or cancer. It's not like killing 10 people right there, even if Orion was responsible they would die decades later.

[fredinno]

12 hours ago, Bill Phil said:

Even with the risk of 10 people dying due to an Orion launch, it's nearly nothing compared to the amount of people killed in car crashes, or war, or cancer. It's not like killing 10 people right there, even if Orion was responsible they would die decades later.

People would still lose their s**t though, unlike nuclear bomb tests, these bomb launches would be highly publicised.

Edited February 29, 2016 by fredinno

[Bill Phil]

7 minutes ago, fredinno said:

People would still lose their s**t though, unlike nuclear bomb tests, these bomb launches would be highly publicised.

But they would then need to show them that the Auto industry has been at least partly responsible for millions of deaths over the last century.

[fredinno]

23 minutes ago, Bill Phil said:

But they would then need to show them that the Auto industry has been at least partly responsible for millions of deaths over the last century.

Yeah, noone cares because they're so used to it. You're combining the fact that people are deathly afraid of deaths realting to space exploration, then combining that with radiophobia, you WILL have a bad day no matter what you do.

[Nothalogh]

1 hour ago, fredinno said:

People would still lose their s**t though, unlike nuclear bomb tests, these bomb launches would be highly publicised.

Thus it would require an operator with zero possibility of being swayed by "public opinion"

[fredinno]

3 minutes ago, Nothalogh said:

Thus it would require an operator with zero possibility of being swayed by "public opinion"

basically nooone, unless it is a dictatorship.

[Nothalogh]

2 minutes ago, fredinno said:

basically nooone, unless it is a dictatorship.

It's the brass ring of history though, he who grows the stones to grab it is the undisputed winner 

[Bill Phil]

46 minutes ago, fredinno said:

Yeah, noone cares because they're so used to it. You're combining the fact that people are deathly afraid of deaths realting to space exploration, then combining that with radiophobia, you WILL have a bad day no matter what you do.

Exactly.

The cost to benefit ratio is bigger than cars, and yet we're afraid of it?!! This can open up the solar system, the STARS to exploration. And yet, radiation, a simple fact of life anyways, is what people are afraid of? Propaganda really works, I guess.

[StrandedonEarth]

18 minutes ago, Bill Phil said:

The cost to benefit ratio is bigger than cars, and yet we're afraid of it?!! This can open up the solar system, the STARS to exploration. And yet, radiation, a simple fact of life anyways, is what people are afraid of? Propaganda really works, I guess.

Take away their bombs, and it doesn't really affect them, except in an abstract way. Take away their cars, and they're affected in a very concrete way, and will scream blue murder about it.

Now if for some reason the only way to generate more power to charge their iPhones without raising taxes was to build nuclear power plants, they'd be all for it.

[Bill Phil]

1 minute ago, StrandedonEarth said:

Take away their bombs, and it doesn't really affect them, except in an abstract way. Take away their cars, and they're affected in a very concrete way, and will scream blue murder about it.

Now if for some reason the only way to generate more power to charge their iPhones without raising taxes was to build nuclear power plants, they'd be all for it.

But here's the thing:

If cars were projected to kill millions from the outset, would they have ever been used? Probably. They're very useful. But enormously dangerous.

[sal_vager]

Nice thread @lobe, I'm pinning this for March

[Nothalogh]

On 2/21/2016 at 6:39 PM, magnemoe said:

Why travel any other ways
We and the kerbals would probably be equal shocked in how the other part applied nuclear technology
Made sense in the setting, on return burn I had to catch up with Kerbin a bit. Cargo was an Ike base capable of operating on Duna and an lander capable of going from Ike surface to Duna surface and back. Various probes too. 

Now if only we could automate a skew flip maneuver, to pull the ultimate Heinlein

[Aghanim]

May I hijack this thread for a while? I want to talk about all pulse drive, including Orion drive and inertial confinement fusion drive. How can I calculate the parameters of an pulse drive, including thrust, ISP and waste heat? I'm assuming sufficiently advanced technology to be able to induce a laser driven inertial confinement fusion inside a helium-3 gas flow inside the magnetic nozzle, so that the firing frequency isn't limited to how fast can the pellet gun can fire. If my drive can fire in 1 kHz frequency, how much thrust and heat will be produced? Please point me to the right direction so I can calculate this myself

 

PS: Do they implement Latex support yet?