What you could and could'nt do with unlimited fuel in real life?

[Spacescifi]

 

I am not discussing the unlimited fuel mod.

Rather what we could do and not do if we found a way to generate more liquid fuel from existing fuels? Liquid fuels only?

My conclusions: Space planes are now viable. Jet airliners aren't obsolete, but for the rich they are. Rocketliners become popular with the wealthy. Virtually any scifi ship shape desired is possible as long as either enough nozzles are added or big enough ones are included.

Missiles become so lethal that jet fighters become obsolete. Since the missile can keep flying till it hits something.

The solar system is explored by man personally within only a decade. Because of unlimited fuel.

What we could'nt do? Lifting some objects would be possible unless one had either an army of rockets or a few massive ones.

 

Edited June 30, 2019 by Spacescifi
Mass

[kerbiloid]

We can sell "ever-rotating wheel" souvenirs.

And make non-stop golems rotating hamsterwheels in powerplants.

Edited June 30, 2019 by kerbiloid

[KSK]

1. The renewable energy sector takes a huge hit because they can’t compete with free and unlimited fossil fuel. Environmentalism no longer comports with economic reality.

2.  Various regimes around the world that are economically dependent on their oil reserves go into severe economic depression, not to mention suffering a huge loss of global influence. The political ramifications of this are severe.

3.  The logistics of warfare - and guerrilla warfare become alarmingly simple. The same technology that makes airliners obsolete, also means that anyone with a spare light aircraft and an axe to grind can reenact 9/11 with impunity.

The combination of points 2 and 3 kicks off World War 3, amidst the mass flooding and environmental damage caused by point 1.

The lucky few escape to Musk City on Mars. 

[Spacescifi]

17 minutes ago, KSK said:

1. The renewable energy sector takes a huge hit because they can’t compete with free and unlimited fossil fuel. Environmentalism no longer comports with economic reality.

2.  Various regimes around the world that are economically dependent on their oil reserves go into severe economic depression, not to mention suffering a huge loss of global influence. The political ramifications of this are severe.

3.  The logistics of warfare - and guerrilla warfare become alarmingly simple. The same technology that makes airliners obsolete, also means that anyone with a spare light aircraft and an axe to grind can reenact 9/11 with impunity.

The combination of points 2 and 3 kicks off World War 3, amidst the mass flooding and environmental damage caused by point 1.

The lucky few escape to Musk City on Mars. 

 

Wow. What chemical fuels would be popular now that we don't worry about running out? Hydrogen/oxygen stiil reign supreme in rocket fuel?

Or will heavier chemical fuels dominate?

Edited June 30, 2019 by Spacescifi

[KSK]

Kerolox would be the fuel of choice I would think. With unlimited fuel, ISP becomes far less important, so the added expense and logistics of dealing with liquid hydrogen are no longer worth it.

Plus, if you’ve tuned your infinite fuel provider to produce RP1 (rocket grade kerosene) then you also have an extremely high quality fuel source for aircraft engines. Not totally sure about that - there may be subtleties in the chemistries of current jet fuels  that would still make them  better for jet engines. 

Methane might be another choice for highly reusable spacecraft as it’s cleaner burning and won’t gunk up your engines so much.

Either way, I’d expect hydrocarbon fuels to dominate for rocketry.

 

[Nuke]

let me know when you design a spacecraft that runs on wood. delta-v would suck so it would be like flying a redwood to space. you could always john denver more rockets. 

Edited June 30, 2019 by Nuke

[Spacescifi]

11 hours ago, KSK said:

Kerolox would be the fuel of choice I would think. With unlimited fuel, ISP becomes far less important, so the added expense and logistics of dealing with liquid hydrogen are no longer worth it.

Plus, if you’ve tuned your infinite fuel provider to produce RP1 (rocket grade kerosene) then you also have an extremely high quality fuel source for aircraft engines. Not totally sure about that - there may be subtleties in the chemistries of current jet fuels  that would still make them  better for jet engines. 

Methane might be another choice for highly reusable spacecraft as it’s cleaner burning and won’t gunk up your engines so much.

Either way, I’d expect hydrocarbon fuels to dominate for rocketry.

 

 

Does methane generate a lot of exhaust steam in atmosphere? Like typical booster and chem rockets?

Methane seems pretty clean. Does not even leave a lot of smoke. Pretty flame too.

 

[Guest]

You could probably prevent the heat death of the universe o_o

You probably couldn’t bring back the dead?

Edited June 30, 2019 by Guest

[kerbiloid]

Spoiler

49 minutes ago, Dale Christopher said:

You could probably prevent the heat death of the universe o_o

You probably couldn’t bring back the dead?

Soon:
Undead Universe: Resurrection of Heat.

 

[KSK]

1 hour ago, Spacescifi said:

 

Does methane generate a lot of exhaust steam in atmosphere? Like typical booster and chem rockets?

Methane seems pretty clean. Does not even leave a lot of smoke. Pretty flame too.

 

Theoretically, completely burning a given quantity of methane will give you slightly less water than burning any other straight chain alkane. With apologies if you already know this, an alkane is a saturated hydrocarbon (molecule containing only hydrogen and carbon) where all the carbon atoms are linked by single bonds and each carbon atom then bonds to as many hydrogen atoms as it can.

For comparing rocket exhausts though, this is a gross simplification. It assumes that your rocket fuel is 100% straight chain alkanes - which it won’t be. It’s assuming that you’re burning your rocket fuel in just the exact amount of oxidiser to completely burn it - which tends not to be the case for various reasons.

Most importantly,  rocket exhaust is complicated stuff, even for a methalox engine. Its probably fairer to say that the glowing stuff you see is a stew of ionised bits and pieces that may become carbon dioxide and steam once they’ve cooled down a bit. Any ‘steam’ you see is more likely to be smoke or water vapour in the atmosphere condensing out on the particles making up that smoke.

Methane burns cleanly because it contains one carbon atom per molecule. Any other hydrocarbon will have two or more carbon atoms per molecule, linked by carbon-carbon bonds. Those take quite a lot of energy to break - and to completely burn your hydrocarbon you gotta break them all. Long story short - the bigger your hydrocarbon molecule, the less chance that you’ll completely burn it, giving you a sooty exhaust full of tiny particles of unburned carbon.

Some SRBs are hugely smoky because they burn a mix of ammonium perchlorate and aluminium, giving you an exhaust full of alumina particles - think finely powdered ceramic.

Inportant caveat - all the above is pulled out of my head with no fact checking. There are other folks on this forum who know a lot more about this than me - I’m relying on chemistry that I learned a couple of decades ago.

Edited June 30, 2019 by KSK

[wumpus]

On 6/29/2019 at 9:10 PM, Spacescifi said:

 

I am not discussing the unlimited fuel mod.

Rather what we could do and not do if we found a way to generate more liquid fuel from existing fuels? Liquid fuels only?

My conclusions: Space planes are now viable. Jet airliners aren't obsolete, but for the rich they are. Rocketliners become popular with the wealthy. Virtually any scifi ship shape desired is possible as long as either enough nozzles are added or big enough ones are included.

Missiles become so lethal that jet fighters become obsolete. Since the missile can keep flying till it hits something.

The solar system is explored by man personally within only a decade. Because of unlimited fuel.

What we could'nt do? Lifting some objects would be possible unless one had either an army of rockets or a few massive ones.

 

What do you mean "fuel from fuel"?

If you mean "more heat/energy from current fuels" then you wind up much higher Isp on your rockets and spaceplanes and SSTO become viable.  It also doesn't count as "hard science fiction" as the hard limits were known since Carnot's work in 1824 (modern electric plans often are "close enough" to that number that increasing it wouldn't cause many changes: maybe somebody gets a bigger bonus.  That's it).

"The renewable energy sector takes a huge hit because they can’t compete with free and unlimited fossil fuel. Environmentalism no longer comports with economic reality. " Note: most of the environmental issues are due to fuel binding with oxygen, using less fuel means less CO₂.  Of course if you had the same heat engine (and atmosphere), you would likely generate more NO_x compounds (and more smog and likely more global warming).  Designing engines for reduced NO_x might get VW-style hacks to cash in the the "cheap gas gold rush".

Note that "manned solar exploration is harder than it sounds.  If you have the "infinite fuel mod", then yes, burn at 1g and get to Pluto in a week or so.  If you only have superior fuel and need full oxidizer, you don't have the "infinite fuel mod", but instead something more like LV-N.  This will get you just about anywhere in space, but not quite in a week.

Interstellar issues might still be painfully slow (outside of places like Alpha Centauri and Proxima Centauri), but at least you won't be fighting the rocket equation every step of the way (even the mighty Orion needs a high portion of nuclear explosions before getting to relativistic speed).

One thing that shouldn't be ignore if fuel became suddenly cheap (not just light) is that aluminum would be dirt cheap.  Cheaper than iron, and would not only replace steel, but claw back much of the gains carbon fiber is making.  Aluminum is sometime called "frozen electricity".

There would be a certain performance gain in all the datacenters of the world as electricity dropped in price and they would be clocked for max performance ignoring efficiency.  Probably nothing major, but it would require a certain shift in design (but not that much, modern chips are so tiny that efficiency is required simply to allow them to survive at all (although peltier heat sinks would suddenly make sense)).

Note that it is important to decide if this "magic fairy dust" only decreases fuel mass (perhaps it is metalic hydrogen: this might even be a real thing and could be considered [assuming you wrote fast enough that it isn't "proven impossible"] significantly hard scifi), then you only get the rocket bonuses (including spaceplanes, but spaceplane flights aren't much cheaper than previous jet flights).  Not environmentalism issues and the cheap aluminum.

[ARS]

Take your fuel and...

You can skip the middle part

Edited July 1, 2019 by ARS

[Cheif Operations Director]

Free Energy

[kerbiloid]

Merlin: kerolox, mixture ratio ~ 2.34
(CH₂)_n: O ~= 2.34
O = (12 + 2 * 1) * 2.34 / 16 ~= 2
CH₂ + 2O → H₂O + CO.

Raptor: methalox, mixture ratio (3:8) ~ 2.67
CH₄: O ~= 2.67
O = (12 + 4 * 1) * 2.67 / 16 ~= 2.67
CH2 + 2.67 O → H₂O + CO_1.67 = H₂O + CO_5/3 = xH₂O + 3 C + 5 O = xH₂O + 3 CO + 2 O = xH₂O + CO + 2 CO₂

So, kerolox → CO, methalox → CO + 2 CO₂.

Methane gets burnt more completely.

Edited July 1, 2019 by kerbiloid

[Spacescifi]

2 hours ago, wumpus said:

What do you mean "fuel from fuel"?

If you mean "more heat/energy from current fuels" then you wind up much higher Isp on your rockets and spaceplanes and SSTO become viable.  It also doesn't count as "hard science fiction" as the hard limits were known since Carnot's work in 1824 (modern electric plans often are "close enough" to that number that increasing it wouldn't cause many changes: maybe somebody gets a bigger bonus.  That's it).

"The renewable energy sector takes a huge hit because they can’t compete with free and unlimited fossil fuel. Environmentalism no longer comports with economic reality. " Note: most of the environmental issues are due to fuel binding with oxygen, using less fuel means less CO₂.  Of course if you had the same heat engine (and atmosphere), you would likely generate more NO_x compounds (and more smog and likely more global warming).  Designing engines for reduced NO_x might get VW-style hacks to cash in the the "cheap gas gold rush".

Note that "manned solar exploration is harder than it sounds.  If you have the "infinite fuel mod", then yes, burn at 1g and get to Pluto in a week or so.  If you only have superior fuel and need full oxidizer, you don't have the "infinite fuel mod", but instead something more like LV-N.  This will get you just about anywhere in space, but not quite in a week.

Interstellar issues might still be painfully slow (outside of places like Alpha Centauri and Proxima Centauri), but at least you won't be fighting the rocket equation every step of the way (even the mighty Orion needs a high portion of nuclear explosions before getting to relativistic speed).

One thing that shouldn't be ignore if fuel became suddenly cheap (not just light) is that aluminum would be dirt cheap.  Cheaper than iron, and would not only replace steel, but claw back much of the gains carbon fiber is making.  Aluminum is sometime called "frozen electricity".

There would be a certain performance gain in all the datacenters of the world as electricity dropped in price and they would be clocked for max performance ignoring efficiency.  Probably nothing major, but it would require a certain shift in design (but not that much, modern chips are so tiny that efficiency is required simply to allow them to survive at all (although peltier heat sinks would suddenly make sense)).

Note that it is important to decide if this "magic fairy dust" only decreases fuel mass (perhaps it is metalic hydrogen: this might even be a real thing and could be considered [assuming you wrote fast enough that it isn't "proven impossible"] significantly hard scifi), then you only get the rocket bonuses (including spaceplanes, but spaceplane flights aren't much cheaper than previous jet flights).  Not environmentalism issues and the cheap aluminum.

 

I meant reproduction of liquid fuels only. So assuming you had molten alluminum, then yeah, you could... no.

 

I was thinking of a scifi way of reproducing like simple (just one element) fuels. So of you had liquid methane, you could make more by inserting a scifi fuel matrix core.

 

Based off human bones in concept, which actually help generate more blood cells, so the fuel matrix would replicate more of the chemical fuel ot is inserted into.

Of course, molten fuels would destroy the matrix, so room temp or cooler fuels are desired.

 

How to still get good thrust? Use a separate matrix with an oxider and combine the oxider with the other fuel.

Or just run the fuel over a nuclear reactor. You're not running out.

[Guest]

Ah, not really unlimited if based of human bones. (Unless you have an unlimited source of human bones D:) Oh wait... you mean the process of fuel generation being similar to bone marrow producing blood cells... hmmm blood cells dont just get produced by some unlimited means though, the functions of the body require an input of materials. Perhaps what you want is a process of turning a low energy density substance into a higher energy density substance by adding energy collected by some means? You need some kind of input whatever the case. 

What you describe actually sounds a bit like a catalytic converter. Maybe call your device a catalytic regenerator? 

The best all-round fuel imo for your purpose is Methane. If you want a lot of energy from it maybe go the "Species" route (remember that movie?) in it the thing that convinced the researchers that the aliens were friendly is that the aliens transmitted instructions that would enable humans to produce "a superior catalyst for methane"  the guy then elaborated saying "we now have the ability to produce a nearly infinite amount of energy from this clean burning fuel" 

but in reality methane is pretty cool! it's also what the dudes who lived in that Mad Max thunderdome town used to power their dune buggies XD (they got it from pig poo)

Edited July 1, 2019 by Guest

[mikegarrison]

18 hours ago, KSK said:

Theoretically, completely burning a given quantity of methane will give you slightly less water than burning any other straight chain alkane.

Inportant caveat - all the above is pulled out of my head with no fact checking. There are other folks on this forum who know a lot more about this than me - I’m relying on chemistry that I learned a couple of decades ago.

Close, except that actually methane will give you more water than any other hydrocarbon. The ratio of water to CO2 depends only on the ratio of H to C atoms in the fuel, and methane at 4:1 has the highest possible ratio of H:C of any pure hydrocarbon.

[KSK]

1 minute ago, mikegarrison said:

Close, except that actually methane will give you more water than any other hydrocarbon. The ratio of water to CO2 depends only on the ratio of H to C atoms in the fuel, and methane at 4:1 has the highest possible ratio of H:C of any pure hydrocarbon.

Hmm, I thought I had this figured out. Thinking aloud:

CH₄ + 2O₂ ------------>  2H₂O + CO₂   -  so two moles of water per mole of methane. Or 36g of water from 16g of hydrocarbon (2.25:1)

C₂H₆ + 7/2O₂ ------------> 3H₂O + 2CO₂  -  so three moles of water per mole of ethane. Or 54g of water from 30g of hydrocarbon (1.8:1)

 

Ahhh - I appear to have made a schoolboy error and stand corrected. I must have been thinking in terms of moles of water produced per mole of fuel, rather than mass of water per mass of fuel. 

Remember kids - always define your units!

 

[cantab]

"Friends don't let friends use reactionless drives in their universes."

If your spaceships can bypass the normal rocket equation, then all you need is one ship and a long runup and you can smash to smithereens anything you can hit. The Earth, say. Unless the engine TWR is tiny enough that the runup would be unreasonably long.

Edited July 2, 2019 by cantab

[Spacescifi]

On 7/2/2019 at 10:35 AM, cantab said:

"Friends don't let friends use reactionless drives in their universes."

 

"Friends let friends use reactionless drives in their universes because they already have FTL, which allows anyone with it to catch up to or outrun a reactionless drive."

-Me

Besides, there are numerous scifi ways to neutralize the threat.

Easy ones that come to mind are:

1. FTL sensors that reach 7 lightyears out.

2. A warp drive that ONLY drops your ship out at the same speed and orbital heading as the target object, regardless of past speed or orbital heading.

 

Why? You could detect a relativistic object long before it reached you. And if a ship was moving at dangerous velocities, the velocity and orbit matching warp drive would allow for easy intercept.

 

Edited July 4, 2019 by Spacescifi
Friends