Project Orion: A discussion of Science and Science Fiction

[kerbiloid]

The designers had various ideas about the Orion.

[Gargamel]

57 minutes ago, Spacescifi said:

 

Are you sure?

Did not the designers intend the Orion to detonate bombs in atmosphere part way to space?

Everything I’ve read said orbital construction.  It was never intended to be used in atmosphere, let alone it being a violation of international law.   
 

Just because somebody somewhere said “you know, it might work…” doesn’t mean somebody more intelligent didn’t come along later and said it won’t, and showed them why.    But yet, their initial guess is still out there on the books, but that doesn’t make it true.  

[Spacescifi]

11 minutes ago, Gargamel said:

Everything I’ve read said orbital construction.  It was never intended to be used in atmosphere, let alone it being a violation of international law.   
 

Just because somebody somewhere said “you know, it might work…” doesn’t mean somebody more intelligent didn’t come along later and said it won’t, and showed them why.    But yet, their initial guess is still out there on the books, but that doesn’t make it true.  

 

Understood... this changes things for me.

 

Alright... I am beginning to see a picture.

 

Space only rockets for space, and chemical or air breathing rockets for air flight.

 

By space only I mean mini-mag with fusion.

 

I am going to have ditch some cherished scifi ideas and go places I never considered.

 

Will be fun though. There is an awful lot you can do with modern tech if you can suspend the flow of gravity from effecting anywhere near your spacecraft before launch.

Ha... you could even make zeppelins SSTO's so long they ride a grav-suspending rocket to space.

And reusable chemical rockets would be popular for first staging as well.

 

Chemical rockets with grav-suspension could save a lot of fuel, since all they have to do is burn and drift into space. Takes longer but there is no need to rush.

 

What is an hour vs 8 minutes if you are saving tons upon tons of fuel?

[kerbiloid]

A Nexus-like design with toroidal heating/combustion chamber with 24 throats around, blowing at the conical central nozzle of exterenal expansion.
The cut cone bottom is flat and open.

Tier 1. The toroidal chamber is a methane+hydrogen+oxygen chemical combustion chamber. A Nexus classics (just with additional methane for thrust).
The cone bottom is closed with a shield.

Tier 2. A microwave beam, powering the vertical lift-off stage.
The cone bottom is open.
A "transparent lamp" inside it (like in a gas-core reactor), with dusticles/gasicles receiving the microwave beam from ground.
The received heat is heating the toroidal chamber with hydrogen and air.
Works same way but the propellant is not its energy source source

Lifts vertically at up to 3 g up to the 200 km altitude, releases the payload with hydrogen engines which accelerate it and put in LEO.
The first stage reaches 600 km, vertically falls down, and reenters.

The on-ground power source is a pure-deuterium thermonuclear powerplant.

Tier 3: The same but with a hydroboron fusion reactor onboard. Gets  in LEO, then separates the payload.

[SunlitZelkova]

1 hour ago, Gargamel said:

Everything I’ve read said orbital construction.  It was never intended to be used in atmosphere, let alone it being a violation of international law.   
 

Just because somebody somewhere said “you know, it might work…” doesn’t mean somebody more intelligent didn’t come along later and said it won’t, and showed them why.    But yet, their initial guess is still out there on the books, but that doesn’t make it true.  

@Spacescifi The early concepts involved launching from the surface, while the Soviet counterparts, PK-3000 and PK-5000, were lofted into the upper atmosphere by conventional boosters before then switching to NPP.

A cursory look was given at the damage that could be done to the environment, but it was the 1950s, so I don’t know if their conclusions are valid.

Orion was perfectly legal up until the signing of the Partial Test Ban Treaty in 1963. After this and the simultaneous appearance of the Saturn C-5 as a vehicle for orbital assembly, studies switched to assembly in orbit- but then the Outer Space Treaty came along in 1967 and completely killed the concept for good.

Edit- To be clear, regardless of what is actually physically possible, this is what was considered at the time.

Edited June 16, 2022 by SunlitZelkova

[Gargamel]

6 minutes ago, SunlitZelkova said:

@Spacescifi The early concepts involved launching from the surface, while the Soviet counterparts, PK-3000 and PK-5000, were lofted into the upper atmosphere by conventional boosters before then switching to NPP.

A cursory look was given at the damage that could be done to the environment, but it was the 1950s, so I don’t know if their conclusions are valid.

Orion was perfectly legal up until the signing of the Partial Test Ban Treaty in 1963. After this and the simultaneous appearance of the Saturn C-5 as a vehicle for orbital assembly, studies switched to assembly in orbit- but then the Outer Space Treaty came along in 1967 and completely killed the concept for good.

Edit- To be clear, regardless of what is actually physically possible, this is what was considered at the time.

I’m not sure if you meant to quote me or not, but if you did, you missed my  point completely.  
 

Earlier designer says I want to do this.   Shortly after somebody comes along and says no, this is very very bad.  So it’s not done.     
 

Just because something was an idea at one point does not make it a good idea.  

[kerbiloid]

http://www.astronautix.com/o/orionsaturnv.html

Quote

American nuclear pulse orbital launch vehicle. The final iteration of the Orion design was a nuclear pulse propulsion module launched into earth orbit by a Saturn V. The 100 metric ton unit would have had a diameter of 10 m to match that of the booster. This would limit specific impulse to 1800 to 2500 seconds, still two to three times that of a nuclear thermal system.

(Pictures from that site aren't embedded.)

***

Also about the fizzix itself.

https://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html

[SunlitZelkova]

12 hours ago, Gargamel said:

I’m not sure if you meant to quote me or not, but if you did, you missed my  point completely.  
 

Earlier designer says I want to do this.   Shortly after somebody comes along and says no, this is very very bad.  So it’s not done.     
 

Just because something was an idea at one point does not make it a good idea.  

Agreed. All I was saying was that “it was never intended” to be used in-atmosphere is incorrect.

9 hours ago, kerbiloid said:

http://www.astronautix.com/o/orionsaturnv.html

(Pictures from that site aren't embedded.)

***

Also about the fizzix itself.

https://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html

As you can see, that dates from 1965, after the PTBT but before the OST.

Here is the surface launched Orion from prior to 1963- http://www.astronautix.com/o/orionplanetary.html

Again, to be clear, I am not saying it actually could have worked- just that it existed, and “Orion was never intended to be launched from the surface” is incorrect.

For the purposes of a sci-fi story/world if one really wants to they can probably make Orion fly from the surface if they really want to. Of course, this would mean abandoning a “hard sci-fi” intention.

[kerbiloid]

Just now, SunlitZelkova said:

Again, to be clear, I am not saying it actually could have worked- just that it existed, and “Orion was never intended to be launched from the surface” is incorrect.

Orion is an unexpected by-product of a two-stage thermonuke reduced to a tactical nuke with direct blast.

Of course they were taking into account all hypothetically possible variants of its usage, like in a brainstorm. This doesn't mean they were going to implement all of them, ever mentioned.

[Gargamel]

I also intended to be lord emperor of the planet.   Doesn’t mean it would be a good thing. 

[sevenperforce]

The concepts which had Orion providing a portion of the launch dV typically used massive disposable boosters (notionally a ring of 12-16 Shuttle-sized SRBs) to loft Orion out of the atmosphere first.

There were some concepts which lit that candle on the ground but it never would have worked.

Regardless, make the story about your story, not about the minutiae of your ship. Like Firefly. 

[KSK]

This is going from one secondary source, so if anyone has any good primary sources, hit me with ‘em. With that said, I’m pretty sure that Orion was always intended to be ground launched. The various chemically boosted proposals were an attempt to mitigate the fallout problem (less radioactive dirt kicked up with a midair start) once that became an actual political issue. 

Also, at the risk of appealing to authority, the guys working on Orion were bomb designers. They’d have been well versed in weapon effects, so if they thought atmospheric flight was viable…? *shrug*.

Of course whatever models they were using to figure out pusher plate dynamics may not have been up to the job.

None of which makes ground launched Orion a good thing of course.
 

 

[Spacescifi]

I think ground launch is totally possible.

 

Yes you would lose the launch platform but that is all... the launch center itself would be farther away.

 

My idea of an Orion belly lander with a rear pusher plate ship is T-shaped with a pusher plate at the tail end.

I think using a disposable first stage series of rockets for initial launch is great idea.

Yes the boosters would be huge but it's the price that has to be paid.

 

The idea of a belly lander would work best for low gravity places like the moon and asteroids and comets.

 

Returning to earth. Could be done with a bunch of second stage boosters sent to connect with the Orion in LEO before it does reentry maneuvers, the last of which would be reusuable since the ship would belly land with them.

 

So in actuality, a heavy belly lander is not a an SSTO to anywhere, bit rather mostly to moons and preferably asteroids or comets with lots of ice.

 

The main advantage one gains with pure fusion bombs is the ability to 'throttle down' the blast potential of the bomb.

 

Which means you can in theory launch lighter weight orion vessels than possible with traditional fission triggered nukes.

Which also means that onboard chemical rockets could lift it without the help of a disposable first stage array of rockets.

 

Yet it all ends with optimization.

 

A lighter orion belly lander that could VTOL with it's own chemical rockets would have slim margins for non-fuel payload compared to an orion that relied on disposable first stage rocketry.

You can get more utility out of the second stage orion, at the expense of needing 'help' from ground control to ever return to an earth world.

Any ship that is an SSTO however large is a glorified shuttle and nothing more. Anything extra makes it worse at it's job of shuttling.

A large SSTO orion serving as a shuttle only needs seats for the crew and BARE minimum life support. Since the shuttle orion will link up with the second stage orion for crew transfer anyway in orbit.

Then it can land using it's onboard rockets and remaining chemical propellant reserves.

Edited June 17, 2022 by Spacescifi

[SunlitZelkova]

1 hour ago, Spacescifi said:

I think ground launch is totally possible.

It would not.

From kerbiloid's link ( https://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html )-

Quote

This is wasteful, as most of the expensive fissile material does not get used properly. It would also require very large individual pulse units to produce sufficient acceleration, likely in the megaton range. Megaton-level nuclear detonations produce a lot of fallout, produce enough thermal radiation to damage the spaceship, and most importantly, generate electromagnetic pulses in the upper atmosphere that would disrupt electronic devices. [Emphasis added]

That would include the Orion spacecraft itself. And I'm certain there are even more important reasons others can go into.

You can still make a story about it though, just don't worry about the technical details. I myself have two separate worlds in the works involving the PK-3000/5000 and some of the atmospheric Orions.

[Spacescifi]

12 minutes ago, SunlitZelkova said:

It would not.

From kerbiloid's link ( https://toughsf.blogspot.com/2016/06/the-nuclear-spear-casaba-howitzer.html )-

That would include the Orion spacecraft itself. And I'm certain there are even more important reasons others can go into.

You can still make a story about it though, just don't worry about the technical details. I myself have two separate worlds in the works involving the PK-3000/5000 and some of the atmospheric Orions.

 

Pure fusion  bombs would not produce the fallout nukes do... in theory it may even be possible to create small fusion bombs as powerful as nukes or less.

 

Pure fusion does not even produce an EMP does it?

 

It's the bomb a manned Orion deserves!

Edited June 18, 2022 by Spacescifi

[Terwin]

1 hour ago, Spacescifi said:

Pure fusion  bombs would not produce the fallout nukes do... in theory it may even be possible to create small fusion bombs as powerful as nukes or less.

Fission does not scale down below critical mass, while fusion can scale all the way down to 17.6 MeV (2.8 x 10^-12 joules).

The only reason to use a pusher-plate is if you have no materials that can contain/redirect the blast out of a nozzle.

As a thin layer of balsa-wood is plenty strong enough to contain the 'blast' from a single pair of hydrogens fusing into a helium, you would need some serious handwavium going on for a fusion powered pusher-plate vessel to make any sense.

1 hour ago, Spacescifi said:

It's the bomb a manned Orion deserves!

Because anything less than 42 gigajoules(10 tons of TNT, aka smallest fission bomb yield and roughly 2x10^13 times the size of the smallest workable fusion yield) will attract the giant space-beavers that will eat your crew-cabin, then use the rest of the rocket to build their space-dams. 

[Spacescifi]

53 minutes ago, Terwin said:

Fission does not scale down below critical mass, while fusion can scale all the way down to 17.6 MeV (2.8 x 10^-12 joules).

The only reason to use a pusher-plate is if you have no materials that can contain/redirect the blast out of a nozzle.

As a thin layer of balsa-wood is plenty strong enough to contain the 'blast' from a single pair of hydrogens fusing into a helium, you would need some serious handwavium going on for a fusion powered pusher-plate vessel to make any sense.

Because anything less than 42 gigajoules(10 tons of TNT, aka smallest fission bomb yield and roughly 2x10^13 times the size of the smallest workable fusion yield) will attract the giant space-beavers that will eat your crew-cabin, then use the rest of the rocket to build their space-dams. 

 

I was unaware fusion reactions could be scaled that far down.

 

So basically I have one more question.

Matterbeam's pure fusion idea called for pure fusion bombs.

Could such bombs be used with chemical propellant if scaled down enough?

 

I am envisioning a reaction chamber full of propellant, and mini-pure fusion bomb going off inside a magneticaly lined vacuum chamber behind it

 

The idea would be to channel the fusion plasma blast to the propellant and out the nozzle.

 

So I guess the real question is what is the max heat a nozzle can take because that decides how energetic our fusion reactions are allowed to be.

 

I would like to think some tricks like coating the throat with thin layer of oil between pulses could prevent vaporization of the nozzle.

 

Which is more or less the same trick the pusher plate employs but the who really knows until such is tested?

 

I actually think a nozzle could survive a nuke level plume from a pure fusion plasma blast.

 

According to nuke testing I read about, metal balls suspended in the air above ground zero for nuke testing were coated with thin layer of oil.

And the balls were fine when found, even though they had been lauched far away.

So apparently the oil coating thing works!

Edited June 18, 2022 by Spacescifi

[kerbiloid]

The Orion Planetary design was to be launched from ground.

http://www.astronautix.com/o/orionplanetary.html

It "was" 41 m in diameter and 50 m high, and as we can see, not even close to a real project state, just a conceptual design.

Orion appeared with no purpose, and was officially developed and funded from budget as a pure orbital craft.
Various temporary early ideas were in between.

***

6 hours ago, KSK said:

With that said, I’m pretty sure that Orion was always intended to be ground launched. The various chemically boosted proposals were an attempt to mitigate the fallout problem (less radioactive dirt kicked up with a midair start) once that became an actual political issue. 

It became a political issue on the Treaty signing, when the whole project was closed.

And as we can see
http://www.astronautix.com/o/orionsaturnv.html
the really funded engineering project was 10 m in diameter to match Saturn V, which became its launch booster when the project got enough mature to think about that.

6 hours ago, KSK said:

Also, at the risk of appealing to authority, the guys working on Orion were bomb designers. They’d have been well versed in weapon effects, so if they thought atmospheric flight was viable…?

And they had to cut their dreams from 41..130 m down to 10 m actually designed.

Because expectations vs reality.

4 hours ago, Spacescifi said:

Pure fusion does not even produce an EMP does it?

Every asymmetric ion distribution does, and the Orion charge is designed to be as extremely asymmetric as possible (because of direct blast).

It's the most EMP nuke among the nukes.

Pure fission plays no role, as it also must be asymmetric for the Orion-like propulsion.

1 hour ago, Terwin said:

Fission does not scale down below critical mass

It does, but is a waste of fissile materials.

[Terwin]

45 minutes ago, Spacescifi said:

Matterbeam's pure fusion idea called for pure fusion bombs.

Could such bombs be used with chemical propellant if scaled down enough?

Sort of replacing the combustion of a chemical rocket with little bits of fusion?  If you have sufficiently rapid small-scale fusion events, that sounds a bit like a fuel-rich fusion torch set-up when running.

 

45 minutes ago, Spacescifi said:

So I guess the real question is what is the max heat a nozzle can take because that decides how energetic our fusion reactions are allowed to be.

 

I would like to think some tricks like coating the throat with thin layer of oil between pulses could prevent vaporization of the nozzle.

 

Which is more or less the same trick the pusher plate employs but the who really knows until such is tested?

When using an actively cooled chamber/nozzle, I do not think that the heat is the greatest problem, but the pressure-wave caused by the fusion blast would very much be a limiting factor, as the stronger the blast, the thicker everything needs to be to contain it without popping like an over-filled balloon.

 

45 minutes ago, Spacescifi said:

I actually think a nozzle could survive a nuke level plume from a pure fusion plasma blast.

 

According to nuke testing I read about, metal balls suspended in the air above ground zero for nuke testing were coated with thin layer of oil.

And the balls were fine when found, even though they had been lauched far away.

So apparently the oil coating thing works!

Ablative cooling works, so long as you have ablative left, but it does not help much against pressure waves.  I think pressure waves would be a bigger issue than straight-up heating.

[Spacescifi]

21 minutes ago, Terwin said:

Sort of replacing the combustion of a chemical rocket with little bits of fusion?  If you have sufficiently rapid small-scale fusion events, that sounds a bit like a fuel-rich fusion torch set-up when running.

 

When using an actively cooled chamber/nozzle, I do not think that the heat is the greatest problem, but the pressure-wave caused by the fusion blast would very much be a limiting factor, as the stronger the blast, the thicker everything needs to be to contain it without popping like an over-filled balloon.

 

Ablative cooling works, so long as you have ablative left, but it does not help much against pressure waves.  I think pressure waves would be a bigger issue than straight-up heating.

 

I see... so instead of a big heavy pusher plate we get s thick and heavy nozzle to handle the fusion pressure wave.

 

It's quite interesting that at high power scales you MUST scale up the engine components or they WILL fail.

 

Guess a pulsed fusion nozzle had better be large, heavy, and reinforced to handle the nuke level pressure waves. May as well add active cooling and ablative cooling from oil as well.

 

We need the fusion plumes to be nearly as energetic as possible for propelling as heavy SSTO's as possible.

 

 

Edited June 18, 2022 by Spacescifi

[sevenperforce]

14 hours ago, Spacescifi said:

Guess a pulsed fusion nozzle had better be large, heavy, and reinforced to handle the nuke level pressure waves. May as well add active cooling and ablative cooling from oil as well.

Why does it need to be pulsed? Why does it need to be pulsed at all? There is no reason to use pulsed propulsion if you can simply do the same thing with continuous thrust.

What is the obsession with using pulse propulsion? Does your story need a pulsed propulsion system as a plot point? If so, then just propose a mechanism for creating pure fusion which has some minimum size associated with it, smaller than nukes.

You will never need both ablative and active cooling. One is plenty. And if you are talking about using a film of oil as your ablator, then really that is just another form of active cooling since the oil will need to be replenished. Instead of using oil, just use the propellant that you already have. That’s what active cooling is, fundamentally.

Are you familiar with the Firefly universe? In the series, the Serenity is a cargo ship which bears a lot of resemblance to what you have described. It is a single stage spaceship which takes off and lands vertically as a belly lander, and it has two airbreathing chemical engines in rotating nacelles which allow it to transition between horizontal and vertical flight.  Not unlike the proposals you’ve made, the ship has an internal gravity cancellation field which reduces the effect of gravity and thus the amount of thrust that the chemical engines need to produce to get off the ground and into orbit. The main engine is powered by fusion and releases a controlled plasma explosion which, along with an inertial dampener, is enough to propel the ship between planets with a single pulse. The main engine cannot be used in the atmosphere or the plasma will ignite with the oxygen in the air and produce a nuclear-level explosion.

14 hours ago, Spacescifi said:

We need the fusion plumes to be nearly as energetic as possible for propelling as heavy SSTO's as possible.

Or you could just use multiple engines. Wouldn’t that be easier?

[kerbiloid]

I thought that Firefly is just a space western...

P.S.
And use the jets of chemical engines, assisted by the gravity canceller, as a plasmatic pusher plate to catch the orionish nuke shot.

[sevenperforce]

4 minutes ago, kerbiloid said:

I thought that Firefly is just a space western...

P.S.
And use the jets of chemical engines, assisted by the gravity canceller, as a plasmatic pusher plate to catch the orionish nuke shot.

The Firefly design is ridiculously cool, but unfortunately it does not actually work. To get off the ground on two engines, the engines need to be located at the center of mass, but that means they have no actual pitch authority. Maybe the inertial/gravitational dampeners provide pitch authority? I don’t know.

Also, if you have a super awesome fusion plasma rocket which produces a massive explosion upon reaction with oxygen, then do that at smaller thrust levels inside a simple duct and boom, air breather. Otherwise you’re leaving energy on the table. Then again, maybe that’s precisely how the rotating engines operate. 

15 hours ago, Spacescifi said:

It's quite interesting that at high power scales you MUST scale up the engine components or they WILL fail.

I mean, this is tautological.

If you decide to use giant explosion pulses in your engine for no reason then your engine will have giant explosion pulses in it. That seems implied.

[Spacescifi]

10 minutes ago, sevenperforce said:

Why does it need to be pulsed? Why does it need to be pulsed at all? There is no reason to use pulsed propulsion if you can simply do the same thing with continuous thrust.

What is the obsession with using pulse propulsion? Does your story need a pulsed propulsion system as a plot point? If so, then just propose a mechanism for creating pure fusion which has some minimum size associated with it, smaller than nukes.

You will never need both ablative and active cooling. One is plenty. And if you are talking about using a film of oil as your ablator, then really that is just another form of active cooling since the oil will need to be replenished. Instead of using oil, just use the propellant that you already have. That’s what active cooling is, fundamentally.

Are you familiar with the Firefly universe? In the series, the Serenity is a cargo ship which bears a lot of resemblance to what you have described. It is a single stage spaceship which takes off and lands vertically as a belly lander, and it has two airbreathing chemical engines in rotating nacelles which allow it to transition between horizontal and vertical flight.  Not unlike the proposals you’ve made, the ship has an internal gravity cancellation field which reduces the effect of gravity and thus the amount of thrust that the chemical engines need to produce to get off the ground and into orbit. The main engine is powered by fusion and releases a controlled plasma explosion which, along with an inertial dampener, is enough to propel the ship between planets with a single pulse. The main engine cannot be used in the atmosphere or the plasma will ignite with the oxygen in the air and produce a nuclear-level explosion.

Or you could just use multiple engines. Wouldn’t that be easier?

 

As far as I know (very much feel to correct me if wrong), external pulse propulsion using pure fusion is far simpler to make compared to a pure fusion continous plume rocket, and pulsed pure fusion rocket would be midway difficulty between the two.

 

Just how a continous fusion rocket would work is beyond me, since I am aware of the problems associated with trying to sustain a fusion reaction. It's hard. It is far easier to just get pulses of fusion and utilize that.

 

Now how one does that with an SSTO is a bit of a process.

 

You propose using small fusion pellets at a fast enough pulsed rate to make the ship fly like a continous plume.

But how do intend to do that.... in atmosphere?

Detonating a fusion reaction inside the throat of a nozzle seems like a bad idea, which is why I proposed using an inner magnetized vacuum chamber to focus the blast out the nozzle. The expansion will mainly be leaving the nozzle instead of all over.

 

Trying to do this rapidly would make active cooling arguably harder.

 

So ultimately my fascination with pulsed pure fusion is threefold

1. Safer than 'garden variety' nukes.

2. Fusion reactions can be both scaled below a nuke or scaled up to one.

3. Pulsed fusion is less complex than continous fusion reactions. I would also argue less maintenance too.

 

 

[Spacescifi]

19 minutes ago, sevenperforce said:

The Firefly design is ridiculously cool, but unfortunately it does not actually work. To get off the ground on two engines, the engines need to be located at the center of mass, but that means they have no actual pitch authority. Maybe the inertial/gravitational dampeners provide pitch authority? I don’t know.

Also, if you have a super awesome fusion plasma rocket which produces a massive explosion upon reaction with oxygen, then do that at smaller thrust levels inside a simple duct and boom, air breather. Otherwise you’re leaving energy on the table. Then again, maybe that’s precisely how the rotating engines operate. 

I mean, this is tautological.

If you decide to use giant explosion pulses in your engine for no reason then your engine will have giant explosion pulses in it. That seems implied.

 

I can beat the firefly design.... without grav cancelers.

 

A pair of flank rocket engines along the sides of the midsection.

The shape I prefer for the ship is that of a letter T made with thick cylinders, with either the pusher plate or the nozzle at the tail end.

 

For pitch control I would have some high thrust RCS under the belly of the frontal broadway cylinder near it's tips, and also some RCS above on the top.

Lift off is obviously less hazardous to the environment witha pulsed pure fusion rocker than a pure fusion external propulsion system but the EPP is far easier as you need no uber magnetic field to channel the fusion plasma into the chemical reaction chamber.

 

Also I honestly think you get a higher thrust with the EPP per pulse no matter what anyway.

Simply because you can get away with fusion reactions so powerful that they would destroy a rocket's reaction chamber anyway.

 

 

 

 

 

 

 

Edited June 18, 2022 by Spacescifi