If Loroi Rocket Drives Were Real This Is How Exhaust Plumes Would Look
Posted: Sat Jun 05, 2021 11:44 pm
Arioch takes great pains to use real science where it does not conflict with the fiction.
One of the things I like most about scifi is when it answers 'what if'. What if this were real? What would it be like?
So it is no surprise that I wonder the same about the long glowy rocket plumes I see so common in scifi media, not just here. Also in Elite Dangerous and just about every popular space sim nowadays.
Loroi rockets are so efficient they are arguably TOO efficient to justify the long glowy plumes seen behind them.
Why? Mass flow decides how glowy and visible out the nozzle an exhaust plume looks. With low mass (hydrogen for example or H2O) you won't see much of anything but a nozzle glow and perhaps a wispy transparent plume near the nozzle. Higher mass flow out the nozzle does tend to glow more.
Here is a video demonstration:
https://youtu.be/aB8knRvUywo
For example, let's say we use the uber-efficient Loroi engines....how much glow you really see depends on mass flow, annd in order to have high mass flow enough to see it then you need a LOT of propellant to burn at 30g in 100 hours.
Let's say you have a thousand tons of this super propellant (same as IRL Spacex starship) that would take up a lot more space inside vessels than depicted, unless the stuff is dense as liquid uranium or perhaps even more dense than liquid uranium.
Even then, if one does the math and divides a thousand tons by 100 hours one will see that these super engines only burn ten tons of this super fuel every hour.
Which means when looking at the nozzle anything you see coming out would be a lot less than ten tons. The answer I received from a calculator after dividing ten tons by sixty minutes was 0.1666666667.....whatever that means per minute is coming out the exhaust. If you viewed it from nearby you would see the mass flow per second, which would be even less.
Even the shuttles have the long glowy plumes, and I would like to think they lack the super-efficiency of the ships but I doubt that since torpedoes also use the same drives as ships to hit them.
Pointy rocket plumes in space seem strange due to a lack of atmosphere to pinch them, but then again I suppose with thrust this insane that may not matter, you can get pointy plumes even in vacuum if exhaust is going out high enough. Same reason plasma beams are a thing.....exhaust would just be much shorter range than the weaponized ones that focus plasma more.
At best. I think....wispy blue plumes may be in order, barely visible and throughly transparent.
No...maybe purple since it's fuel must be superdense, but still transparent.
I thought ironically that Babylon 5 did torchdrive plumes correct when Sheridan says 'ramming speed' during the battle for Earth. The nozzle glows but the plume itself is wispy and short. Looks more like a flashlight glow actually...only the barely visible plume indicates otherwise.
https://youtu.be/MXkIuVLnsFE
Missiles and shuttles both would look akin to flashlight glow out the nozzle due to high efficiency but low mass flow....no visible plume to speak of.
What if you are like, shut up Bamax! This could still look as it does in the story!
Well...yes, there are exceptions that physics WOULD allow for, but it would require other modications to the story like:
1. Loroi vessels and any other blowing long glowy plumes with uber efficiency must be much larger. You need a high mass flow rate to get the long plume glow, and since Loroi ships are too efficient as is, the only way to increase mass flow is to increase the amount of mass going out, which you do by increasing the size of the ship's fuel/propellant tanks and therefore it's overall size/mass. In other words, if they had a lot more than a thousand tons of superfuel, then likewise more mass flow would go through the nozzle and be visible as a long glowy plume. Something as massive as the Star Wars Deathstar would unquestionably generate a glowy and obvious plume if propelled via rocketry....even if Loroi rocketry.
2. Missiles and shuttlecraft are a hopeless case for long glowy plumes due to to low mass to begin with if they are using the torchship drive. Lightbulb look is the best they can do.
3. Still want long glowy rocket plumes on everything? There may be a possible exception that physics could allow for! Assuming superdense liquids are possible anyway. You would need super dense liquid fuel, denser than any known to man....even liquid uranium. Likewise you would need metal stronger than any known to man material to hold such a superdense material without breaking or leaking. Such a superdense fuel would allow for the way everything looks in Outsider without changing the appearance of anything as is. Only performance would be effected UNLESS RCS thrusters also use the same drive, because otherwise ships and missiles would be too mass heavy and take too long to thrust to justify using traditional cold gas thrusters or any comparatively weak IRL thrusters used IRL. You would need the same uber drive to run the RCS to keep all as seen in the comic.
Disclaimer: I am not suggesting Arioch change his illustrations, as I still like his comic since it actually does answer 'what if' in other ways...notably with Loroi culture.
I simply like to answer 'what if it were real'!
One of the things I like most about scifi is when it answers 'what if'. What if this were real? What would it be like?
So it is no surprise that I wonder the same about the long glowy rocket plumes I see so common in scifi media, not just here. Also in Elite Dangerous and just about every popular space sim nowadays.
Loroi rockets are so efficient they are arguably TOO efficient to justify the long glowy plumes seen behind them.
Why? Mass flow decides how glowy and visible out the nozzle an exhaust plume looks. With low mass (hydrogen for example or H2O) you won't see much of anything but a nozzle glow and perhaps a wispy transparent plume near the nozzle. Higher mass flow out the nozzle does tend to glow more.
Here is a video demonstration:
https://youtu.be/aB8knRvUywo
For example, let's say we use the uber-efficient Loroi engines....how much glow you really see depends on mass flow, annd in order to have high mass flow enough to see it then you need a LOT of propellant to burn at 30g in 100 hours.
Let's say you have a thousand tons of this super propellant (same as IRL Spacex starship) that would take up a lot more space inside vessels than depicted, unless the stuff is dense as liquid uranium or perhaps even more dense than liquid uranium.
Even then, if one does the math and divides a thousand tons by 100 hours one will see that these super engines only burn ten tons of this super fuel every hour.
Which means when looking at the nozzle anything you see coming out would be a lot less than ten tons. The answer I received from a calculator after dividing ten tons by sixty minutes was 0.1666666667.....whatever that means per minute is coming out the exhaust. If you viewed it from nearby you would see the mass flow per second, which would be even less.
Even the shuttles have the long glowy plumes, and I would like to think they lack the super-efficiency of the ships but I doubt that since torpedoes also use the same drives as ships to hit them.
Pointy rocket plumes in space seem strange due to a lack of atmosphere to pinch them, but then again I suppose with thrust this insane that may not matter, you can get pointy plumes even in vacuum if exhaust is going out high enough. Same reason plasma beams are a thing.....exhaust would just be much shorter range than the weaponized ones that focus plasma more.
At best. I think....wispy blue plumes may be in order, barely visible and throughly transparent.
No...maybe purple since it's fuel must be superdense, but still transparent.
I thought ironically that Babylon 5 did torchdrive plumes correct when Sheridan says 'ramming speed' during the battle for Earth. The nozzle glows but the plume itself is wispy and short. Looks more like a flashlight glow actually...only the barely visible plume indicates otherwise.
https://youtu.be/MXkIuVLnsFE
Missiles and shuttles both would look akin to flashlight glow out the nozzle due to high efficiency but low mass flow....no visible plume to speak of.
What if you are like, shut up Bamax! This could still look as it does in the story!
Well...yes, there are exceptions that physics WOULD allow for, but it would require other modications to the story like:
1. Loroi vessels and any other blowing long glowy plumes with uber efficiency must be much larger. You need a high mass flow rate to get the long plume glow, and since Loroi ships are too efficient as is, the only way to increase mass flow is to increase the amount of mass going out, which you do by increasing the size of the ship's fuel/propellant tanks and therefore it's overall size/mass. In other words, if they had a lot more than a thousand tons of superfuel, then likewise more mass flow would go through the nozzle and be visible as a long glowy plume. Something as massive as the Star Wars Deathstar would unquestionably generate a glowy and obvious plume if propelled via rocketry....even if Loroi rocketry.
2. Missiles and shuttlecraft are a hopeless case for long glowy plumes due to to low mass to begin with if they are using the torchship drive. Lightbulb look is the best they can do.
3. Still want long glowy rocket plumes on everything? There may be a possible exception that physics could allow for! Assuming superdense liquids are possible anyway. You would need super dense liquid fuel, denser than any known to man....even liquid uranium. Likewise you would need metal stronger than any known to man material to hold such a superdense material without breaking or leaking. Such a superdense fuel would allow for the way everything looks in Outsider without changing the appearance of anything as is. Only performance would be effected UNLESS RCS thrusters also use the same drive, because otherwise ships and missiles would be too mass heavy and take too long to thrust to justify using traditional cold gas thrusters or any comparatively weak IRL thrusters used IRL. You would need the same uber drive to run the RCS to keep all as seen in the comic.
Disclaimer: I am not suggesting Arioch change his illustrations, as I still like his comic since it actually does answer 'what if' in other ways...notably with Loroi culture.
I simply like to answer 'what if it were real'!