Flying A Turbofan For Various Worlds...

[Spacescifi]

We make turbofans for flight on earth.

Scenario: Attempt to fly a turbofan jet plane on:

Mars: Nothing much happens right? No air. Jet engines need oxygen.

Neptune: Same?

Saturn: Same?

Jupiter: Same?

Conclusion: In theory you could bring liquid oxidizer but that just makes the plane weigh more and reduces flight range.

Which leads to the conclusion that ductfans and propeller craft powered by electric power are the ways we know could work for flight virtually anywhere. Since all you need is atmosphere to react with.

Anything requiring oxygen or any specific chemical is niche.

Yes you could design aircraft specifically FOR Neptune or Saturn to exploit their specific chemicals in the air, but they would not be craft good for flying almost on any other planet with atmosphere.

The foundation of modern industrial power began with mechanical power (pulleys, levers, etc), graduated with chemical power (gunpowder, dynamite, oil and gas, and rocketry), and has entered the age of electrical power, although we have not fully exploited it yet.

Chemical power has limits based on chemical reaction power released.

Electric only has limits based off heat and storage, and so far chemical beats it purely based on chemical storing more power.

EDIT: I did not mention nuclear, because although you could make a nuclear turbofan... the nuclear part is the danger. Specifically the radiation. Although if you had no better alternative it would be perhaps a good alternative in any atmosphere where free oxygen is rare or nonexistent.

 

Edited April 21 by Spacescifi

[kerbiloid]

A turbofun engine, turbofan just for fun.

As is doesn't need to compress the air up to fuel ignition point, but it would still need chemical reaction energy to power the generator..

[NFUN]

where is the turbo?

[Spacescifi]

https://medium.com/@marek.janda.eng/nuclear-powered-jet-engine-is-there-a-case-for-reviving-this-idea-34954e20e31a

 

Cool.

[kerbiloid]

14 hours ago, NFUN said:

where is the turbo?

It's rotated by electricity, to compress the air, heat it, and throw back with exhaust velocity.

[darthgently]

I still see a civ capable of controlling gravity, and the implied power available to do so, as playing with fans as being like grown ups using LEGOs for their custom car air intake or steering wheel.  Just doesn't click.  If I was reading a sci fi book I'd probably put it down at that point

[farmerben]

A turbofan on a gas giant might need to carry oxidizer but no fuel, since there is hydrogen to suck up.  On Titan there is methane.

[kerbiloid]

And the oxidizer:fuel mass ration is ~2.5:1, so an air-breathing plane has to carry about 30% of total propellant mass, while this one should carry ~70%, and that makes the fuel tank absence insignificant.

[Spacescifi]

12 hours ago, darthgently said:

I still see a civ capable of controlling gravity, and the implied power available to do so, as playing with fans as being like grown ups using LEGOs for their custom car air intake or steering wheel.  Just doesn't click.  If I was reading a sci fi book I'd probably put it down at that point

Does not bother me.

Possible solutions:

1. Access to unobtanium that specifically generates a zero gravity field when electric current is applied, which grows larger the more current is applied. Earth has none, or if it did once, was mined of all of it a long time ago by space aliens who use it. That's basically taken from Stargate, only a different function as opposed to naquadah. Can be found on select alien worlds. It also allows the excuse for not visiting Earth even though they know where it is (they have no unobtanium so nobody cares about Earth lol).

2. Bootstrapping alien tech so advanced you cannot retroengineer it (thus the turbofan). Yet claiming you made it to appear you're more technologically advanced than you really are (also from Stargate, Goauld loved doing this).

Edited April 22 by Spacescifi

[darthgently]

42 minutes ago, Spacescifi said:

Does not bother me.

Possible solutions:

1. Access to unobtanium that specifically generates a zero gravity field when electric current is applied, which grows larger the more current is applied. Earth has none, or if it did once, was mined of all of it a long time ago by space aliens who use it. That's basically taken from Stargate, only a different function as opposed to naquadah. Can be found on select alien worlds. It also allows the excuse for not visiting Earth even though they know where it is (they have no unobtanium so nobody cares about Earth lol).

2. Bootstrapping alien tech so advanced you cannot retroengineer it (thus the turbofan). Yet claiming you made it to appear you're more technologically advanced than you really are (also from Stargate, Goauld loved doing this).

This just makes my point.  These gymnastics make the premise a big yawn for me.  I'm weary of deus ex machina alien tech and such just to support a "cool idea". 

Good sci-fi runs at a deeper level for most readers and movie watchers.  The formula that goes "someone or group gets super powerful tech somehow  but to keep it from being too easy here are some arbitrary limitations on the tech" is worn out for me. 

I am admittedly a hard sci-fi fan where the tech is 99% believable or plausible in the nearer future and the main driver of the story is not the tech but rather what has always driven good stories from ancient times to the present.

I just don't find "can control gravity" and "turbo fans" a plausible combination.

But I'm operating from the premise that you pose these topics to get feedback for something you are working on and providing what I hope is useful feedback.  Maybe my premise is completely wrong in which case I'll tone it down

[Spacescifi]

47 minutes ago, darthgently said:

This just makes my point.  These gymnastics make the premise a big yawn for me.  I'm weary of deus ex machina alien tech and such just to support a "cool idea". 

Good sci-fi runs at a deeper level for most readers and movie watchers.  The formula that goes "someone or group gets super powerful tech somehow  but to keep it from being too easy here are some arbitrary limitations on the tech" is worn out for me. 

I am admittedly a hard sci-fi fan where the tech is 99% believable or plausible in the nearer future and the main driver of the story is not the tech but rather what has always driven good stories from ancient times to the present.

I just don't find "can control gravity" and "turbo fans" a plausible combination.

But I'm operating from the premise that you pose these topics to get feedback for something you are working on and providing what I hope is useful feedback.  Maybe my premise is completely wrong in which case I'll tone it down

I don't mind your feedback. Carry on or not as you wish.

Telling a good story is what matters in the end.

And there are different levels of SOFT scifi... theres Star Wars science fantasy that is soft as a marshmallow, and then there is Stargate SG1, which is like a jelly bean. A bit of thin candy hard science, but ultimately full of fiction in it's gòoey center.

Edited April 23 by Spacescifi

[Exploro]

On 4/21/2024 at 3:18 AM, Spacescifi said:

We make turbofans for flight on earth.

Scenario: Attempt to fly a turbofan jet plane on:

Mars: Nothing much happens right? No air. Jet engines need oxygen.

Neptune: Same?

Saturn: Same?

Jupiter: Same?

Conclusion: In theory you could bring liquid oxidizer but that just makes the plane weigh more and reduces flight range.

Which leads to the conclusion that ductfans and propeller craft powered by electric power are the ways we know could work for flight virtually anywhere. Since all you need is atmosphere to react with.

Anything requiring oxygen or any specific chemical is niche.

Yes you could design aircraft specifically FOR Neptune or Saturn to exploit their specific chemicals in the air, but they would not be craft good for flying almost on any other planet with atmosphere.

The foundation of modern industrial power began with mechanical power (pulleys, levers, etc), graduated with chemical power (gunpowder, dynamite, oil and gas, and rocketry), and has entered the age of electrical power, although we have not fully exploited it yet.

Chemical power has limits based on chemical reaction power released.

Electric only has limits based off heat and storage, and so far chemical beats it purely based on chemical storing more power.

EDIT: I did not mention nuclear, because although you could make a nuclear turbofan... the nuclear part is the danger. Specifically the radiation. Although if you had no better alternative it would be perhaps a good alternative in any atmosphere where free oxygen is rare or nonexistent.

 

Point of fact, jet engines do not need oxygen to operate. In fact, they don't even require combustion at all. Case in point, squids and octopus use jets. The means to accelerate reactant mass does not involve combustion.

With regards to turbojets, and by extension the cores of turbofans, as long as there is a source of heat and the engine operates as close to an ideal Brayton-cycle as possible, it should work in almost any gaseous medium. As you correctly identified, input heat to the core can be supplied from a nuclear reactor. As the diagram below shows, heat from the reactor is added to the fluid flow downstream of the compressor via a heat exchange.

Of course, why would you wish to use a turbojet, or turbofan, for powered flight within the atmospheres of other planets anyway?

[Spacescifi]

2 hours ago, Exploro said:

Point of fact, jet engines do not need oxygen to operate. In fact, they don't even require combustion at all. Case in point, squids and octopus use jets. The means to accelerate reactant mass does not involve combustion.

With regards to turbojets, and by extension the cores of turbofans, as long as there is a source of heat and the engine operates as close to an ideal Brayton-cycle as possible, it should work in almost any gaseous medium. As you correctly identified, input heat to the core can be supplied from a nuclear reactor. As the diagram below shows, heat from the reactor is added to the fluid flow downstream of the compressor via a heat exchange.

Of course, why would you wish to use a turbojet, or turbofan, for powered flight within the atmospheres of other planets anyway?

 

I wanted to design a scifi SSTO around the gimmick of being able to cancel the pull of gravity. I soon realized rocketry would be wastefull when I could just turbofan and coast into space.

Sure it will take longer but not unbearably so, maybe an hour more.

But it's worth it for not having to expend propellant.

For space travel they would use a special vacuum reaction drive that pushes off space vacuum itself for thrust and won't work within thick atmosphere.

Requires vacuum conditions to work.

[kerbiloid]

And a bipropellant second turbine to power the elctric generator.

[magnemoe]

On 4/23/2024 at 6:01 AM, Exploro said:

Point of fact, jet engines do not need oxygen to operate. In fact, they don't even require combustion at all. Case in point, squids and octopus use jets. The means to accelerate reactant mass does not involve combustion.

With regards to turbojets, and by extension the cores of turbofans, as long as there is a source of heat and the engine operates as close to an ideal Brayton-cycle as possible, it should work in almost any gaseous medium. As you correctly identified, input heat to the core can be supplied from a nuclear reactor. As the diagram below shows, heat from the reactor is added to the fluid flow downstream of the compressor via a heat exchange.

Of course, why would you wish to use a turbojet, or turbofan, for powered flight within the atmospheres of other planets anyway?

This, and it would probably work much better with good fusion. Or if you don't care about radiation as you are on Venus or Jupiter you skip the heat exchanger, look up project Pluto, nuclear ramjet 

[Nuke]

you just need to bring chemicals that have a highly exothermic reaction when combined with the alien atmosphere. we can call this fuel. eg for gas giants, its probably going to be oxygen you bring. it might not even be fire in the earthly sense though. not sure what kind of exothermic reactions you can cause with co2 atmos though. ive seem more than one video about ammonia engines.

[kerbiloid]

Liquid fluorine!

Together with liquid fluorine everything feels like fuel.

[JadeOfMaar]

On 4/21/2024 at 3:18 AM, Spacescifi said:

EDIT: I did not mention nuclear, because although you could make a nuclear turbofan... the nuclear part is the danger. Specifically the radiation.

If you're willing and able to sail through the radiation belts of Jupiter, of all places, you're not going to be afraid of onbord nuclear. And nothing less than onboard nuclear will keep your ship adequately powered in the time it takes to get to Jupiter and at any distance beyond Mars.

On 4/21/2024 at 3:18 AM, Spacescifi said:

Electric only has limits based off heat and storage, and so far chemical beats it purely based on chemical storing more power.

Someone correct me if I'm wrong. Electric is also limited in that it doesn't give heat to the air passing through it. Electric engines would have a hard time reaching transsonic speeds, meanwhile, any turbofan (nuclear or chemical afterburning) could do so and even go well into supersonic.

1 hour ago, Nuke said:

not sure what kind of exothermic reactions you can cause with co2 atmos though.

Magnesium. Some Mars jet engine concepts use that

[magnemoe]

34 minutes ago, JadeOfMaar said:

If you're willing and able to sail through the radiation belts of Jupiter, of all places, you're not going to be afraid of onbord nuclear. And nothing less than onboard nuclear will keep your ship adequately powered in the time it takes to get to Jupiter and at any distance beyond Mars.

Someone correct me if I'm wrong. Electric is also limited in that it doesn't give heat to the air passing through it. Electric engines would have a hard time reaching transsonic speeds, meanwhile, any turbofan (nuclear or chemical afterburning) could do so and even go well into supersonic.

Magnesium. Some Mars jet engine concepts use that

Yes nuclear also has practically unlimited range. Radiation shielding is an issue, would work better on an long plane. 
You could simply use electricity to make heat, way less efficient than propellers, however electrical propellers might be more effective than an an turboprop if you have to bring the oxidizer because the very high efficiency of electrical engines offset lots of the low power density of batteries. 
Electric cars is an bad comparison, they work well as your rarely use more than an faction of the engines power. 

Edited April 25 by magnemoe

[insert_name]

Maybe on a gas giant or other H2 atmosphere you could bring along oxidizer and source your fuel from the atmosphere, like the inverse of what is done on earth

[magnemoe]

1 minute ago, insert_name said:

Maybe on a gas giant or other H2 atmosphere you could bring along oxidizer and source your fuel from the atmosphere, like the inverse of what is done on earth

Yes, but you need much more oxidizer than fuel even if burning fuel rich. 

[JadeOfMaar]

34 minutes ago, insert_name said:

Maybe on a gas giant or other H2 atmosphere you could bring along oxidizer and source your fuel from the atmosphere, like the inverse of what is done on earth

Given the kinds of velocities involved with gas planets, leaning on chemical is easily the worst option by far. This is only practical at tiny worlds like Titan.

[magnemoe]

6 hours ago, JadeOfMaar said:

Given the kinds of velocities involved with gas planets, leaning on chemical is easily the worst option by far. This is only practical at tiny worlds like Titan.

Yes getting into orbit orbit after flying in the atmosphere of Saturn. An nuclear ramjet switching to liquid hydrogen then atmosphere get too thin even then hypersonic is the closest tech option.