Fart powered biological underwater propulsion

[Spacescifi]

 

I will preface this by saying that this a regarding a fictional consideration.

I was curious whether or not a humanoid lifeform could have the capacity to do their number 2 in the bathroom a bit different.

Namely... convert all of the solid waste we call poop.... into one mighty epic fart all at once. 

Granted the conversion would take time, and their inner stomach organs would need to be different to accomodate for that.

Yet I don't see anything where known physics gives this a hard no yet.

My main concerns are:

1. I suppose they would need a higher metabolic rate than us, since their bodies do more work than ours (actually converting all poop into gas to fart out all at once. Meaning they may need to eat more than us too. More work requires more energy. More energy requires more fuel (food).

2. The solid to gas process may or probably will cause them to sweat, since solids become gas through heat as far as I know. So they likely would want water. Bad. Or ar least find a place to cool down. Maybe a pool.

3. The main reason I came up with this is that I wanted the humanoids to have their own biological propulsion... kind of like this... minus the need for water as they as using bio-gas (waste converted gas). In orbit inside the spaceship it would be even more fun... albeit kinda a dangerous given the thrust and hitting bulkheads  it could even serve as an astronauts last ditch back up for thrust inside their spacesuit... provided it had a port to release the um... exhaust.

 

 

 

Did I get anything wrong physics or biology wise?

 

What do you think?

How much thrust would an average adult's waste er... provide?

Like the how many pounds or less of thrust? Since specific impulse is meaningless as they use all the thrust at once and spend all day building up for another fart from the foods eaten.

Edited October 15, 2020 by Spacescifi

[HebaruSan]

 

[Spacescifi]

19 minutes ago, HebaruSan said:

 

 

Well.... that is a bit overpowered for my setting... but it is gas exhaust nonetheless.

I mean if you had a match I am sure it would ignite... I don't reccomend it though.

[kerbiloid]

Immortal emotionless space-farting humanoids with antimatter for every case...

I start worrying for the Universe...

Upd.
Btw. Antimatter. It can effectivey vaporize everything. JUst in this case it's required in homeopatic dose.
So, if the humanoids can produce antimatter as a part of their metabolism...

Edited October 16, 2020 by kerbiloid

[lemon cup]

I don’t see any way this could be remotely feasible unless some sort of pusher-plate were involved.

[.50calBMG]

Also wouldn't be getting a 1G constant acceleration, not worth doing.

[sevenperforce]

Wow.

Uhm -- so, metabolic gas is produced as a byproduct of digestion by bacteria which are unable to fully metabolize certain food chemistry. The human gut does not produce any metabolic gas by itself, apart from the action of gut bacteria.

6 hours ago, lemon cup said:

I don’t see any way this could be remotely feasible unless some sort of pusher-plate were involved.

I burst out laughing.

[Spacescifi]

3 hours ago, sevenperforce said:

Wow.

Uhm -- so, metabolic gas is produced as a byproduct of digestion by bacteria which are unable to fully metabolize certain food chemistry. The human gut does not produce any metabolic gas by itself, apart from the action of gut bacteria.

I burst out laughing.

 

Well...

https://www.sciencedaily.com/releases/2010/04/100414083539.htm

https://www.scientificamerican.com/article/bacteria-used-to-create-fossil-fuel-alternative/

 

You may be on to something we can heavily exploit.

 

https://www.google.com/amp/s/futurism.com/purple-photosynthetic-bacteria-poop-power/amp

At any rate, it seems that bacteria that can do all that for a humanoid by converting raw excrement into gas would need some sturdy inner tank and a means of compression before letting it all loose.

They would have no need for toilets beyond urination.

With bodies this unique though, chances are not remote that they may be able to eat stuff we can't,  ans probably won't be able to eat some stuff we can without becoming ill.

[Clamp-o-Tron]

Spoiler

18 hours ago, HebaruSan said:

 

Whiskey Tango Foxtrot is the back of that rocket? Did they use archival footage of the back of a space shuttle and slap it on whatever that weird Saturn V INT-21 thing is?

So, let's do some actual math to see if farts are a reasonable means of propulsion.

The velocity of a fart at 1 atm pressure is ~3 m/s.

One day's fecal production is about 0.13 kilograms, for a human. (All figures will be for humans, since a "Humanoid"'s body shouldn't significantly be different. Sure, they might have 100 m/s farts, but that shouldn't really change our final answer as you'll see.

The average human is 62 kilos, for a mass ratio of fart/body of about 0.002. So very small. Into the rocket equation it goes!

dV = (3 m/s) 0.002

dV for one day's worth of feces = 0.006 m/s.

So no, human(oid) farts aren't a very good means of propulsion, simply because of the minuscule exhaust velocity (less than a brisk jog) and the relative mass of the fart to the body.

 

Sure, I could see a massive gas-bag creature floating in a dense atmosphere and propelling itself with bursts of air, but that wouldn't be remotely humanoid.

 

(If any of my math or figures are wrong or inaccurate, correct me, but the difference in dV shouldn't be significant enough to make it a form of propulsion.)

Edited October 16, 2020 by Clamp-o-Tron

[Gargamel]

24 minutes ago, Clamp-o-Tron said:

So, let's do some actual math to see if farts are a reasonable means of propulsion.

There was a thread some time ago on this very concept as a means of RCS.

[kerbiloid]

27 minutes ago, Gargamel said:

There was a thread some time ago on this very concept as a means of RCS.

There was at least three of them, apart from particular dedicated posts.
Looks like this future tech is perspective.

[Spacescifi]

4 hours ago, Clamp-o-Tron said:

  Reveal hidden contents

Whiskey Tango Foxtrot is the back of that rocket? Did they use archival footage of the back of a space shuttle and slap it on whatever that weird Saturn V INT-21 thing is?

So, let's do some actual math to see if farts are a reasonable means of propulsion.

The velocity of a fart at 1 atm pressure is ~3 m/s.

One day's fecal production is about 0.13 kilograms, for a human. (All figures will be for humans, since a "Humanoid"'s body shouldn't significantly be different. Sure, they might have 100 m/s farts, but that shouldn't really change our final answer as you'll see.

The average human is 62 kilos, for a mass ratio of fart/body of about 0.002. So very small. Into the rocket equation it goes!

dV = (3 m/s) 0.002

dV for one day's worth of feces = 0.006 m/s.

So no, human(oid) farts aren't a very good means of propulsion, simply because of the minuscule exhaust velocity (less than a brisk jog) and the relative mass of the fart to the body.

 

Sure, I could see a massive gas-bag creature floating in a dense atmosphere and propelling itself with bursts of air, but that wouldn't be remotely humanoid.

 

(If any of my math or figures are wrong or inaccurate, correct me, but the difference in dV shouldn't be significant enough to make it a form of propulsion.)

 

It's not for propulsion... more for a quick escape boost if swimming underwater.

 

What if the 'waste' was a whole 7 days worth converted into gas thrust?

If that is not enough.... I could always rely on different chemistries that allow for higher thrust using reactive chemicals that the humanouds produce that... combust kind of like a water baking soda rocket... only powerful enough to blow exhaust as gas only.

 

Off subject but poop nuclear thermal rockets are viable propulsion.

 

All you need is a renewable food source (plants), energy (sunlight or light lamps) and soil.

 

Plant keeps on giving. Crew keeps on pooping.

 

Viable alternative once the LH runs out.

Or RCS if nothing else.

Edited October 16, 2020 by Spacescifi

[Clamp-o-Tron]

32 minutes ago, Spacescifi said:

It's not for propulsion... more for a quick escape boost if swimming underwater.

Well, the rocket equation still applies, and underwater, pressure increases, making fart velocity decrease. So even more useless.

32 minutes ago, Spacescifi said:

What if the 'waste' was a whole 7 days worth converted into gas thrust?

0.006 * 7 = 0.042

That would be the wettest uhhh... cart? Crap+fart? Trying to not use the word sometimes considered obscene for it, but you know what I mean.

32 minutes ago, Spacescifi said:

If that is not enough.... I could always rely on different chemistries that allow for higher thrust using reactive chemicals that the humanouds produce that... combust kind of like a water baking soda rocket... only powerful enough to blow exhaust as gas only.

If using low-exhaust-velocity reactions like farts or coke and mentos, the organism would have to be almost entirely composed of reaction mass to be useful.

Higher-energy reactions would rip an organism to shreds with pressures at least in the dozens of bars and temperatures in the thousands of celsius. So no, those wouldn’t work.

32 minutes ago, Spacescifi said:

Off subject but poop nuclear thermal rockets are viable propulsion.

 

All you need is a renewable food source (plants), energy (sunlight or light lamps) and soil.

 

Plant keeps on giving. Crew keeps on pooping.

 

Viable alternative once the LH runs out.

Or RCS if nothing else.

You can find better stuff to throw through the reactor. I sup’ose it’s kinda renewable, but you’d be better using it as a fertilizer for aforementioned plants.

Doesn’t help that the Isp would be abysmal.

Edited October 16, 2020 by Clamp-o-Tron

[Spacescifi]

30 minutes ago, Clamp-o-Tron said:

Well, the rocket equation still applies, and underwater, pressure increases, making fart velocity decrease. So even more useless.

0.006 * 7 = 0.042

That would be the wettest uhhh... cart? Crap+fart? Trying to not use the word sometimes considered obscene for it, but you know what I mean.

If using low-exhaust-velocity reactions like farts or coke and mentos, the organism would have to be almost entirely composed of reaction mass to be useful.

Higher-energy reactions would rip an organism to shreds with pressures at least in the dozens of bars and temperatures in the thousands of celsius. So no, those wouldn’t work.

You can find better stuff to throw through the reactor. I sup’ose it’s kinda renewable, but you’d be better using it as a fertilizer for aforementioned plants.

Doesn’t help that the Isp would be abysmal.

 

I know the ISP is poor... yet warp drive merely gets a ship closer to it's location.

No worry about tech mismatch. We use what we know. STand SW were are outdated the moment written, and are still even by modern tech (they never utilize drones hardly ever).

So one could have the poorest of ISP's and all would be ok merely by using gravity assist for high velocity change by warping back and forth near any body with gravity to achieve any trajectory/speed desired.

The nuclear thermal poo rockets are mainly for rendezvous and landing.

Once landed better propellant should be sourced locally.

Come to think of it, that's something KSP2 should implement.

Resource fuel utilization. From asteroid laser. ablation to propellant cracking from rock to poop nuclear thermal... it's all so useful rather than constraining oneself as if there is no more propellant to be had when one can use both astronautand animal poo (provided there are useful low g animals wirh high poo content LOL).

With warp of. Course

Edited October 16, 2020 by Spacescifi

[kerbiloid]

For fast underwater escape jumps they should better follow the cuttlefish way with pumping and pushing water.

[Spacescifi]

15 minutes ago, kerbiloid said:

For fast underwater escape jumps they should better follow the cuttlefish way with pumping and pushing water.

 

I already considered that.

Yet I I am not sure the humanoid shape has the room for that without addons to the mark I body plan.

In other words, likely some exterior pumping pushing organ, since an inner one may crowd out already vital inner organs for life.

 

I think the human body does not have much in the way of spare space for inner additional pumpinh pushing organs (essentially a secondary heart on steroids). Not without deformation... which I know you will find a way to snark on.