A Sea Launched/landing Super Heavy SSTO?

[SOXBLOX]

So, you have ditched the Project Orion submarine part? Oh, good.

On 8/7/2020 at 7:45 PM, Spacescifi said:

 

Let me let you in on a little secret... I don't argue merely for the sake of 'winning'. I don't even care about 'winning' online arguments.

OK. Do I care whether you care? And frankly, wouldn't you consider it a win to come out with more knowledge than before, regardless of the fate of your idea? Just wondering...

[Spacescifi]

8 hours ago, SOXBLOX said:

So, you have ditched the Project Orion submarine part? Oh, good.

OK. Do I care whether you care? And frankly, wouldn't you consider it a win to come out with more knowledge than before, regardless of the fate of your idea? Just wondering...

I have not totally ditched the sub orion idea..  lets just say it would be illogical to have entire fleets of them, and maybe just build one ... for science, as GLADOS often says, (although GLADOS is a sociopath who does expsriments more because she has a programmed 'itch'  to do so).

I do not know if you care, I do know that it it takes two to argue or debate, since one cannot debate themselves... not without looking foolish. My point being solely that I am not treating this as a debate.... it is not worth the energy.

As for the SSTO nuclear seaplane, it is one thing to explain logical reasons for why it would be an engineering nightmare (like KSK did with the the sub Orion). But to flatly dismiss it does not show why you believe so nor the proofs.

The SSTO seaplane, or 'spacebird' as I call it, would utilize air augmented nuclear thermal water rocketry for takeoff. After surviving reentry it would use the wings to glide around in circles to bleed off speed until it chooses to land on the ocean. It seems SSTO's should have wings and land like airplanes, purely to save on propellant mass.

I do prefer knowledge above all here. And friendly discussions... which KSP seems to be one of the last places online that has that.

Go anywhere else just about and what have you to expect?

Hostile debates. About words at that! I have seen that often times, if friendly discussions stayed exactly that, forums would not need moderators as they would self-moderate.

Moderators exist partly to inhibit hostile debates... here at least.

Other places not so much... mods even join the 'fun'.

 

 

Edited August 9, 2020 by Spacescifi

[magnemoe]

On 8/8/2020 at 2:45 AM, Spacescifi said:

 

Let me let you in on a little secret... I don't argue merely for the sake of 'winning'. I don't even care about 'winning' online arguments.

In this case, I wonder if the extra large LH tanks and the complicated setup of LOX/LH would be worth the trouble as opposed to water tanks which can afford to be smaller without the complications required when piping LOX and LH?

Less tank... more payload to orbit... sound fair?

Piping water is easier. And nuclear reactors are compact and robust.

It just seems that not only does the LH/LOX setup take longer, it has arguably more parts and is more susceptible to combustion failure (BOOM).

Water does not have that problem, as nuclear reactors provide the energy for water propulsion, not chemical combustion.

Also nuclear exhaust can be designed to be fairly safe too.

Now if you can convince me that a nuclear SSTO seawater NTR will likely always be necessarily heavier than an LH/LOX incarnation SSTO... then you might persuade me.

I doubt that is the case though....

Now this could be an practical shuttle to have on an manned interstellar mission. 
Here your payload has to be minimized and its obviously an extremely dangerous mission in the first place. 
Even if it was stone age intelligent life on the planet the ship would not add much danger to their dangerous life unless they go Florida man on you  

Having the thing launch 10 times a day on earth I say no. Have no issues with an NTR upper stage but an nuclear SSTO just no. 
Pro nuclear but you will have landing fails. 
 

[SOXBLOX]

If it's gas core, you'll have no problems SSTO-ing the thing. Even liquid core can work, but you may want LH anyways, the lighter exhaust increases ISp compared to water.

No comment on the safety or engineering feasibility of any designs using these.

[tater]

SSTO vehicles when TSTO is so very much easier (even with complete reuse) makes little sense for large payloads.

Crew? Sure, particularly lower g loading concepts (Skylon, etc) to make for more routine/comfortable operations for people.

 

[Guest]

TSTO is not much easier when using advanced engines such as GCNR, though. You've either have to figure out staging with two GCNRs (a nontrivial matter), or forgo using your best engine for a large part of the flight. Now, if you can't stop uranium from getting out of the exhaust, staging might be used to keep a GCNR away from things you don't want contaminated. In fact, TSTO is a crutch for when you really, really can't use a drive with exhaust velocity around 10km/s, which would be the optimal engine for Earth liftoff, and would give you a mass ratio of e. Airliners don't use drop tanks, much less drop engines (military aircraft do both, but it's situational). A reusable cargo or passenger spaceship shouldn't have to, either.

In particular, a GCNR gives you between 15-30km/s depending on how you set it up. That's more than 10km/s optimum, so cold propellant injection could be used to increase thrust, should it be lacking. Even with a nuclear lightbulb, you're pretty much free from the need for staging.

Edited August 9, 2020 by Guest

[Spacescifi]

40 minutes ago, Dragon01 said:

TSTO is not much easier when using advanced engines such as GCNR, though. You've either have to figure out staging with two GCNRs (a nontrivial matter), or forgo using your best engine for a large part of the flight. Now, if you can't stop uranium from getting out of the exhaust, staging might be used to keep a GCNR away from things you don't want contaminated. In fact, TSTO is a crutch for when you really, really can't use a drive with exhaust velocity around 10km/s, which would be the optimal engine for Earth liftoff, and would give you a mass ratio of e. Airliners don't use drop tanks, much less drop engines (military aircraft do both, but it's situational). A reusable cargo or passenger spaceship shouldn't have to, either.

In particular, a GCNR gives you between 15-30km/s depending on how you set it up. That's more than 10km/s optimum, so cold propellant injection could be used to increase thrust, should it be lacking. Even with a nuclear lightbulb, you're pretty much free from the need for staging.

 

Is not the exhaust not safe with nuclear gas core?

The idea is a single stage for travel to the surface and back of an Earth world?

Then again... perhaps we can forget safety?

 

We are landing in the middle of the ocean for crying out loud!

If crew is concerned about radiation wait a few days before you open the hatches!

In the mean time use the ship's propellers to drive it near a beach.

 

Funnily enough, such a vessel would be a literal ship AND a spaceship.

 

Hahaha... forget safety... full radiation equals less complex but robust design and less engine heating! Full open cycle! The ocean can take it!

 

Edited August 9, 2020 by Spacescifi

[Guest]

Generally, it is. However, low-tech open cycle designs might have their exhaust contaminated with traces of uranium. This is a highly problematic effect, as it decreases exhaust velocity, makes the exhaust radioactive and causes the engine to use up uranium fuel faster than it should. It can probably be eliminated (although nobody ever built such an engine, so we don't know for sure), at the cost of additional complexity.

Nuclear lightbulb (closed cycle gas core) is free of this problem, but it has a lower exhaust velocity. However, it would still be enough to optimize for a launch from Earth.

Edited August 9, 2020 by Guest

[Spacescifi]

8 minutes ago, Dragon01 said:

Generally, it is. However, low-tech open cycle designs might have their exhaust contaminated with traces of uranium. This is a highly problematic effect, as it decreases exhaust velocity, makes the exhaust radioactive and causes the engine to use up uranium fuel faster than it should. It can probably be eliminated (although nobody ever built such an engine, so we don't know for sure), at the cost of additional complexity.

Nuclear lightbulb (closed cycle gas core) is free of this problem, but it has a lower exhaust velocity. However, it would still be enough to optimize for a launch from Earth.

 

Nice! So that means that it is physically possible to build a 'spacebird' that launches from the ocean and lands like a seaplane.

If we want max payload to orbit without staging gas core is the way?

But you mentioned uranium loss... forgive me for saying what I am about to say... but in scifi, that is a problem easily solved by antimatter triggered nuclear reaction mass.

So the higher your energy imparted to the propellant, the less propellant you need to lift high mass payloads to orbit.

Higher energy increases both ISP and thrust no?

Or is it just the propellant choice that effects thrust?

Edited August 9, 2020 by Spacescifi

[kerbiloid]

If attach stteam engines to the pistons of the pusher plates, it can swim breaststroke using them as flippers.

Spoiler

 

[KSK]

9 hours ago, Spacescifi said:

Nice! So that means that it is physically possible to build a 'spacebird' that launches from the ocean and lands like a seaplane.

If we want max payload to orbit without staging gas core is the way?

But you mentioned uranium loss... forgive me for saying what I am about to say... but in scifi, that is a problem easily solved by antimatter triggered nuclear reaction mass.

I'm not sure it does. From a very quick read on Wikipedia (so treat this with the requisite pinch of salt and feel free to come back with better sources) a gas core engine uses the propellant to shield the reactor walls from the gaseous nuclear fuel at the engine core. Which means there's going to be some mixing between the fuel and the propellant and, since you're using an open-core design, that mixing means that some of your nuclear fuel is ejected with the propellant.

I'm not sure how boosted fission gets around that problem. It might mean that the gas core is smaller because it needs less fissionable mass to remain self-sustaining but that mass still needs to be in contact with the shielding propellant, so suffers from the same loss-of-fuel problem.

As an aside, I'm not even sure how antimatter boosted fission would work, although I'm happy for more knowledgeable folks to weigh in here.

A fission reactor is all about maintaining and controlling a chain reaction. Naturally radioactive atom (lets go with uranium here for convenience) splits, spitting out multiple neutrons which can then be absorbed by other uranium atoms, causing them to split, which then releases more neutrons... 

There's only a certain probability of a neutron causing a uranium atom to undergo fission. Leaving out any complicated nuclear physics, most of a uranium atom is empty space with a very small nucleus in the middle. Chances are that the neutron is just going to sail right through it without ever hitting the nucleus. Therefore, there's a so-called mean-free-path at work which is the distance that a given neutron has to travel before splitting another uranium atom and continuing the chain reaction. If the mean-free path is too long, the neutron escapes. If too many neutrons escape, the chain reaction stops.

So boosting fission yield is all about reducing that mean free path and there are a few ways to do it:

1. Use more fissile material. Equivalently, for uranium, use enriched fuel (higher proportion of fissile U235 to non-fissile U238). 
2. Use slower neutrons
3. Use more neutrons. If your neutrons from the fission reaction aren't enough to keep a chain reaction going, use an external source of neutrons as well.
4. Compress your fissile material.

Or in other words, use more targets, use slower bullets so that your targets have time to wobble into their way before they go speeding past (remember that atoms aren't stationary even in a solid), use more bullets, or put your targets closer together so that your bullets have more chance of hitting a target.

Options 1 and 2 are the nuclear power plant options. Use enough nuclear material (exact amount will depend on enrichment level) and use a moderator to slow the neutrons down*. Option 4  is (I believe) how nuclear weapons work. Set off a carefully shaped set of explosive charges around your fissile core and if you've calculated everything just right and gotten your timing exactly so, then you squash a sub-critical lump of nuclear material to a sufficient density that it goes critical. The timers for such things used to be (and probably still are) beyond top secret. 

The only way I can see antimatter helping with any of the above is if annihilation produces neutrons. So far as I'm aware it doesn't but I could well be wrong.

 

* I recommend not using a KSP forum moderator - they're too darn good at containing runaway chain reactions.  
 

Edited August 10, 2020 by KSK

[Guest]

8 hours ago, Spacescifi said:

But you mentioned uranium loss... forgive me for saying what I am about to say... but in scifi, that is a problem easily solved by antimatter triggered nuclear reaction mass.

Not really. Antimatter won't help you one bit, unless you ditch "nuclear" part entirely and just build a gas core antimatter thermal engine. This bypasses the problem by heating the reaction mass with antimatter directly. In an open-cycle gas core, you're running your propellant through reacting uranium gas. Unless you take precautions, such as spinning the chamber to make uranium stick to the sides, or a magnetic separator of some kind, the propellant stream will blow some of the uranium gas out with it. That, or just use closed-cycle.

8 hours ago, Spacescifi said:

Nice! So that means that it is physically possible to build a 'spacebird' that launches from the ocean and lands like a seaplane.

Certainly, though unless it's really, really large, it's better to make it land on the runway. In fact, someone already thought of it (with air augmentation, even!):

It was supposed to use some sort of nuclear, such as a GCNR. In fact, it's probably the only practical engine choice (as much as there's anything practical about the Aldebaran).

Edited August 10, 2020 by Guest

[kerbiloid]

The fact that antimatter usage looks rather simple ("just put and warm") and does not make someone to dig into the nuclear fizzix-schmizzix voodoo and learn various headcrunching designs of nuclear reactors and engines still does not make antimatter a silver bullet for any case of propulsion or power source.

[Guest]

No, but a GCAR does not have uranium contamination problems of a GCNR, and that's what I was addressing. These are very different engines, and GCAR is a much harder tech because it uses antimatter, but there's no use combining them unless you have a complexity addiction.

Quite frankly, a closed cycle GCNR works just fine for liftoff and most other non-interstellar uses, too. The one from a NASA report has 18km/s exhaust velocity, meaning a ship with a mass ratio of e will be able to fly to Mars on a single stage. 
http://www.projectrho.com/public_html/rocket/enginelist2.php#id--Nuclear_Thermal--Gas_Core
It's not a torchship, but it's the next best thing.

[Spacescifi]

7 hours ago, Dragon01 said:

No, but a GCAR does not have uranium contamination problems of a GCNR, and that's what I was addressing. These are very different engines, and GCAR is a much harder tech because it uses antimatter, but there's no use combining them unless you have a complexity addiction.

Quite frankly, a closed cycle GCNR works just fine for liftoff and most other non-interstellar uses, too. The one from a NASA report has 18km/s exhaust velocity, meaning a ship with a mass ratio of e will be able to fly to Mars on a single stage. 
http://www.projectrho.com/public_html/rocket/enginelist2.php#id--Nuclear_Thermal--Gas_Core
It's not a torchship, but it's the next best thing.

 

It is very ironic that antimatter, although not possible to produce efficiently yet, is a simpler rocket compared to any nuclear or fusion variant that tries to gwt similar performance.

Yet when creating scifi, I have thought for some time that having fantastic plot device tech kind of implies that the said civilization can do everything we wish we could AND the other thing that is total plot device.

Basically, if I were an ancient Roman writing scifi I might have gear driven boats powered by some freak design of an aeolipile using sea water and heating it via fire for steam.

The total plot device would be flapping aircraft, also powered by steam, but not for long before gliding back down.

Ridiculous approximation of the future I know... but man is not supposed to know all the details of the future.

I suppose it is for thr best... since if we did... half the scifi stories... probably 99% would be considered more fantasy than reality to future readers LOL.

Sometimes... ignorance IS for the best. It is not always a negative.

Like... little children DO NOT need to be told where babies come from!

Edited August 11, 2020 by Spacescifi

[SOXBLOX]

Storing AM is much more difficult than storing uranium. Antimatter engines will be more complicated than nuclear ones.

[Spacescifi]

23 minutes ago, SOXBLOX said:

Storing AM is much more difficult than storing uranium. Antimatter engines will be more complicated than nuclear ones.

 

AM is considered exotic matter is it not? As in rare.

My scifi method would be synthesize exotic matter of our own that won't react with the AM.

Will it ever be possible? I wish!

I think at least one poster long ago suggested that there ARE some normal forms of matter that won't blow up antihydrogen on contact.

But that matters not either way.

I'm a scifi writer.

Not a prophet.

 

Edited August 11, 2020 by Spacescifi

[K^2]

14 minutes ago, Spacescifi said:

AM is considered exotic matter is it not?

There isn't a strict definition for "exotic," and it tends to vary over time what people mean by it, but currently the standard usage is matter with negative energy. So no, AM is not exotic matter in modern usage of the word.

As for rarity, depends on what kind. Anti-neutrinos are very common. Positrons (anti-electrons) can be found in upper atmosphere, produced by energetic solar radiation. But as you get to more and more massive particles, natural abundance drops. The more massive anti-particle is, the less rarely it will be produced in some reaction, and any that are produced will find something to annihilate with relatively quickly even in the interstellar space.

[kerbiloid]

4 hours ago, Spacescifi said:

It is very ironic that antimatter, although not possible to produce efficiently yet, is a simpler rocket compared to any nuclear or fusion variant that tries to gwt similar performance.

That's exactly what I said.
By using antimatter you don't simplify a ship..
Vice versa, you make it more complex by an order of magnitude because you still need all nuclear stuff to support the antimatter storage, and you have to duplicate this stuff 2-3 times because if a reactor fails, the AM will not be just lying and sleeping, it will inevitably burst.
Also you have to care about the transporting of the antimatter from the storage to the engine, If it touches the pipe, it bursts.

AM is not something you can throw with a shovel into the oven under boiler like coke.

4 hours ago, Spacescifi said:

Basically, if I were an ancient Roman writing scifi I might have gear driven boats powered by some freak design of an aeolipile using sea water and heating it via fire for steam.

The aeolipile is nothing but a funny toy. It's many times less efficient than even the worst of steam engines,

And if you were an Ancient Roman writing scifi, you would unlikely care about those mad ideas from Greece, because it's enough to get a score of slaves of any origin moar to replace a whole plant of aeolipiles, and they can be easily replaced at any moment, rather than a moody Greek mechanician.

Irl the known A.Roman sci-fi was about flying carriages with a pack of eagles. Because they were realists.

Edited August 11, 2020 by kerbiloid

[SOXBLOX]

Just remember that that unless you find a natural source of AM, any AM you use will be an energy transport mechanism, not a fuel. Putting it in a ship would be equivalent to buying batteries from the dollar store and putting them in a kid's toy. It's just that AM is even touchier to contain than, say, liquid nitroglycerin. Instant boom if it comes into contact with anything besides AM. Like atmosphere, the ship hull, or your face. So you need magnetic fields, which need constant power, which needs a nuclear reactor. So AM needs a lot more stuff in the ship to work. As you surely know, "Every gram counts"!

[Guest]

Quote

It is very ironic that antimatter, although not possible to produce efficiently yet, is a simpler rocket compared to any nuclear or fusion variant that tries to gwt similar performance.

It doesn't really simplify anything. At best, you move complexity around. A GCAR will be about as complex an a GCNR, but you will have antimatter storage to deal with. A lateral move at best, and storing antimatter is harder. It does have other benefits (like cleaner exhaust and lighter fuel), so in the end, both of those engines can have their uses.

20 hours ago, Spacescifi said:

Sometimes... ignorance IS for the best. It is not always a negative.

Like... little children DO NOT need to be told where babies come from!

This is wrong. Ignorance is never good. In practice, you're never better off not knowing something, though incomplete knowledge regularly trips up those who aren't aware of their limitations. Bereft of knowledge, the ignorant rely purely on luck, and more often than not, suffer for it. It doesn't make for better stories, and the only ones who can "benefit" from it are those whose psyche is too weak to handle the harsh truths of reality (and even then, this seldom lasts long in practice).

There's nothing wrong with teaching little children basic facts of human biology, either. In fact, it's very important to teach them that as soon as possible. This can save them a lot of headaches later on. You wouldn't believe how much damage the old paradigms of thinking about these matters can cause.

[Spacescifi]

22 minutes ago, Dragon01 said:

It doesn't really simplify anything. At best, you move complexity around. A GCAR will be about as complex an a GCNR, but you will have antimatter storage to deal with. A lateral move at best, and storing antimatter is harder. It does have other benefits (like cleaner exhaust and lighter fuel), so in the end, both of those engines can have their uses.

This is wrong. Ignorance is never good. In practice, you're never better off not knowing something, though incomplete knowledge regularly trips up those who aren't aware of their limitations. Bereft of knowledge, the ignorant rely purely on luck, and more often than not, suffer for it. It doesn't make for better stories, and the only ones who can "benefit" from it are those whose psyche is too weak to handle the harsh truths of reality (and even then, this seldom lasts long in practice).

There's nothing wrong with teaching little children basic facts of human biology, either. In fact, it's very important to teach them that as soon as possible. This can save them a lot of headaches later on. You wouldn't believe how much damage the old paradigms of thinking about these matters can cause.

 

Regarding children I agree they should be taught as soon as they are able to understand... yet not a moment before.

I was raised to know that my... 'stuff' was not for anyone else to touch, and to scream and tell any other adult if such ever happened.

This was long before I knew where babies come from.

In fact, when I did learn from my parents (from a medical brochure no less), I was grossed out, since at that young age I simply did not care about sex.

To some degree I think the family values matters, since other boys my age were (middle school) already into... a well known vice. While I was virtually a stranger to it 

 

Edited August 11, 2020 by Spacescifi

[K^2]

9 hours ago, SOXBLOX said:

Just remember that that unless you find a natural source of AM, any AM you use will be an energy transport mechanism, not a fuel.

So is hydrogen/oxygen in LH2 rockets by that measure. This isn't a useful distinction. Rocket fuel is just a way to store a lot of energy in one place, and whether that fuel was found naturally or had to be made hardly makes a difference, so long as there's efficient method for production. Yes, we aren't there with AM yet, but we'd have to be to be buildings ships powered by it. So distinguishing between natural fuel and "energy transportation mechanism" isn't really necessary.

[Codraroll]

2 hours ago, K^2 said:

So is hydrogen/oxygen in LH2 rockets by that measure. This isn't a useful distinction. Rocket fuel is just a way to store a lot of energy in one place, and whether that fuel was found naturally or had to be made hardly makes a difference, so long as there's efficient method for production. Yes, we aren't there with AM yet, but we'd have to be to be buildings ships powered by it. So distinguishing between natural fuel and "energy transportation mechanism" isn't really necessary.

If you look at things in a very broad perspective, all we have is "energy transportation mechanisms". There are no such things as energy sources, after all.

[magnemoe]

6 hours ago, Codraroll said:

If you look at things in a very broad perspective, all we have is "energy transportation mechanisms". There are no such things as energy sources, after all.

Solar is one, in practice nuclear is too, yes you run the reactor down but that takes years.
Now nuclear can be used for engines. 
Yes you have radiation hazards as you can not bury the reactor or put in on an very long boom on an shuttle.