Spacesuit Manuvering WITHOUT RCS

[Spacescifi]

 

Just curious what is possible. If you are in a spacesuit floating in space, to what extent can you control your pitch, yaw, and roll?

I imagine you can some....but I think it will be very drifty...like on ice...

 

Like this well known scene....is it physically possible to bring yourself OUT of a roll without RCS even if you are spinning violently?

 

 

My guess?

Difficult...hopefully not impossible.

 

What do you know of this?

 

[cubinator]

In order to cancel any of your rotation you'd have to do something like rotate your arms rapidly, which would be really tough in a spacesuit. If you had a heavy toolbag you could swing on a tether, you might be able to use that instead. But I don't think you'd be able to cancel any really significant rotation, you'd be better off just being aware of how you're spinning and living with it.

[SpaceFace545]

Maybe throw something opposite of your spin, probably wouldn’t help much but would help.

[Spacescifi]

16 minutes ago, cubinator said:

In order to cancel any of your rotation you'd have to do something like rotate your arms rapidly, which would be really tough in a spacesuit. If you had a heavy toolbag you could swing on a tether, you might be able to use that instead. But I don't think you'd be able to cancel any really significant rotation, you'd be better off just being aware of how you're spinning and living with it.

 

Wow....so RCS is life in space.

 

Maybe they should install some CMG's inside spacesuits...although even those can get saturated I know.

 

I reckon inside a spacecraft with air you could 'swim' through air. Albeit slowly. And inefficiently.

 

 

Edited May 18, 2021 by Spacescifi

[cubinator]

Just now, Spacescifi said:

 

Wow....so RCS is life in space.

 

Maybe they should install some CMG's inside spacesuits...although even those can get saturated I know.

I think small thrusters are the simplest solution. They are included in the current NASA spacesuits and are what astronauts are trained to use in the event they end up free-flying from the space station.

That's if you're in an uncontrolled spin. But if you're free floating and NOT rotating to start with, you could swing your arms or spin a tethered mass to slowly get yourself into a different orientation.

[Spacescifi]

1 minute ago, cubinator said:

I think small thrusters are the simplest solution. They are included in the current NASA spacesuits and are what astronauts are trained to use in the event they end up free-flying from the space station.

That's if you're in an uncontrolled spin. But if you're free floating and NOT rotating to start with, you could swing your arms or spin a tethered mass to slowly get yourself into a different orientation.

 

I know 

 

A few CMG's would be the backup...of a backup.

The last resort.

[Spica]

Conservation of angular momentum prevents you from strictly stopping your own rotation purely with internal processes.

You can redistribute any angular momentum within your own body by whirling your arms or using a gyroscope, but you can't ever get rid of it by yourself.

Of course if you can throw things away from you or react against some external object or field you have more options, like RCS or a magnetorquer.

[Starman4308]

You could ameliorate the spin by stretching out your arms and legs, but as mentioned by @Spica, angular momentum is conserved: you have to push/pull on something to actually get rid of said angular momentum.

Reaction wheels/CMGs typically don't store that much angular momentum: they're mostly used for fine stability control on telescopes and other devices which need to maintain a very constant orientation. Even then, they occasionally have to use RCS to get rid of angular momentum before the wheels get saturated and cannot store any more angular momentum.

IRL, spacecraft are either spin-stabilized, RCS stabilized, or stabilized by both RCS and reaction wheels (EDIT: Or stabilized by more esoteric methods like magnetorquers and solar pressure vanes) . This contrasts with KSP, where spacecraft are largely stabilized by magic torque machines misleadingly called reaction wheels.

 

Edited May 18, 2021 by Starman4308

[kerbiloid]

You can even propel without RCS.

Just strangle the wrist, take off the glove and throw it in opposite direction.

(From a short sci-fi movie).

***

Btw, a new alien species idea.
They spend their body to propel in space, then eat and regenerate.

Edited May 18, 2021 by kerbiloid

[SpaceFace545]

29 minutes ago, kerbiloid said:

You can even propel without RCS.

Just strangle the wrist, take off the glove and throw it in opposite direction.

(From a short sci-fi movie).

***

Btw, a new alien species idea.
They spend their body to propel in space, then eat and regenerate.

Hmm, love death and robots.

[kerbiloid]

1 hour ago, SpaceFace545 said:

Hmm, love death and robots.

Season 2 is just released.

[magnemoe]

7 hours ago, cubinator said:

In order to cancel any of your rotation you'd have to do something like rotate your arms rapidly, which would be really tough in a spacesuit. If you had a heavy toolbag you could swing on a tether, you might be able to use that instead. But I don't think you'd be able to cancel any really significant rotation, you'd be better off just being aware of how you're spinning and living with it.

Yes you can change your orientation but you can not cancel out a spin, now you could add reaction wheels to an space suit but don't think this is very efficient as spacewalks are pretty short duration. 

[kerbiloid]

Blowing air from the mouth is an equivalent of ion engines.

[YNM]

50 minutes ago, kerbiloid said:

Blowing air from the mouth is an equivalent of ion engines.

Yeah but you need to suck it in first.

 

Edited May 18, 2021 by YNM

[kerbiloid]

14 minutes ago, YNM said:

Yeah but you need to suck it in first.

 

In that video he can.

Also a spacesuit can have a vent.

[SpaceFace545]

1 hour ago, kerbiloid said:

In that video he can.

Also a spacesuit can have a vent.

Usually those vents are on the torso so that wouldn’t do much 

[tomf]

Looking at the video I can't believe that is the most efficient air swimming stroke. I would have thought something like breast stroke would be best.

I have also had to do some experiments in blowing. I reckon I can blow 5l (I have unusually large lungs) through a 4.5mm diameter straw in 3.5 seconds for a velocity of 90 m/s¶ and 0.5 kgm/s momentum. I could do that about once every 10 second without getting to dizzy giving me an acceleration of 0.0006m/s^2

The intake is going to be pretty directionless so should have minimum momentum.

¶ 90m/s is about double what an internet search suggests is an upper bound.

[Spaceman.Spiff]

8 hours ago, kerbiloid said:

take off the glove and throw it in opposite direction.

Why throw it? The suit is pressurized and the release of gas would create more movement than the glove would.

[kerbiloid]

58 minutes ago, Spaceman.Spiff said:

Why throw it? The suit is pressurized and the release of gas would create more movement than the glove would.

First strangle the wirst, to prevent the leakage.

Then through the glove to be pushed in the opposite direction by Newton.

[SpaceFace545]

26 minutes ago, kerbiloid said:

First strangle the wirst, to prevent the leakage.

Then through the glove to be pushed in the opposite direction by Newton.

that would be a nasty amputation but i guess it would work. Not properly strangling your wrist could result in an unfortunate depressurization.

[Spacescifi]

3 hours ago, tomf said:

Looking at the video I can't believe that is the most efficient air swimming stroke. I would have thought something like breast stroke would be best.

I have also had to do some experiments in blowing. I reckon I can blow 5l (I have unusually large lungs) through a 4.5mm diameter straw in 3.5 seconds for a velocity of 90 m/s¶ and 0.5 kgm/s momentum. I could do that about once every 10 second without getting to dizzy giving me an acceleration of 0.0006m/s^2

The intake is going to be pretty directionless so should have minimum momentum.

¶ 90m/s is about double what an internet search suggests is an upper bound.

 

Air is a lot less dense than water so you need more kinetic energy to apply to it to get it to do work for you.

What he is doing with his arms is not unlike what tiny insect wings do...only insects do it in a more complex figure eight type of flapping 

[sh1pman]

1) install a nozzle at the rear end of your digestive system

2) eat a spicy shawarma or burrito, preferably with expired meat

3) wait 2-4 hours

4) pressure-fed rocket engine complete. 

[Spacescifi]

1 hour ago, sh1pman said:

1) install a nozzle at the rear end of your digestive system

2) eat a spicy shawarma or burrito, preferably with expired meat

3) wait 2-4 hours

4) pressure-fed rocket engine complete. 

 

That is a rather tasty solution. May not be ready when you need it though. Unless your suit has mechanical means to feed you that whole you're inside it LOL.

[kerbiloid]

Just work in pairs. The fellow worker is not just a 30+ cm thick radiation shield, but also more  than a quintal of chemically inert and storable propellant.

[mikegarrison]

Cats have a well-studied reflex for orienting themselves in freefall, so that they land feet-down. But this partially relies on them having a much more flexible spine than humans have.

They can change their orientation, but not their angular momentum.

Edited May 18, 2021 by mikegarrison