Spin gravity in SF spaceships.

[Astro Pen]

I didn't realise that the semicircular canals still know that you are spinning and you can get motion sickness.
That is a bit of a spanner in the works of an otherwise great idea.

 

[Ursa major]

I didn't realise that the semicircular canals still know that you are spinning and you can get motion sickness.

The aliens in my WiPs use ships with rings that are, in most cases, no less than 400 metres** in diameter and, for civilian use, usually much larger. Note that: 1) the whole ship rotates; 2) such ships are usually much longer than (7-8 times) their diameters.

My aliens are not just prone to motion sickness; they're none too happy about high accelerations, so it's just as well that their means of interstellar travel depends more on reducing the effective distances between star systems than it does on increasing the speeds (and their associated accelerations) of their spacecraft.

A very long time ago, I did the calculations*** to find out how fast the rings could rotate without producing significant motion sickness problems, but can't find the spreadsheet that contains the numbers (assuming that I didn't work it out on paper). However, I think it was 27 or 28 seconds per revolution... which, happily, matches the 27.1 seconds per revolution that I set in the PowerPoint animation in the series of slides and presentations that contain ship designs ).


** - The metre is not a unit that the aliens themselves use.

*** - I think it was based on something I read, a long time ago, on Wikipedia about rotation-based artificial gravity. The appropriate section of the current article is here.

 

[Swank]

• The Coriolis effect gives an apparent force that acts on objects that are moving relative to a rotating reference frame. This apparent force acts at right angles to the motion and the rotation axis and tends to curve the motion in the opposite sense to the habitat's spin. If an astronaut inside a rotating artificial gravity environment moves towards or away from the axis of rotation, they will feel a force pushing them in or against the direction of spin. These forces act on the semicircular canals of the inner ear and can cause dizziness.[8] Lengthening the period of rotation (lower spin rate) reduces the Coriolis force and its effects. It is generally believed that at 2 rpm or less, no adverse effects from the Coriolis forces will occur, although humans have been shown to adapt to rates as high as 23 rpm.[9]

One G at 2 rpm is a diameter of 448 meters.

I think people could deal with much less with time and/or drugs.

 

[Ursa major]

One G at 2 rpm is a diameter of 448 meters.

I think people could deal with much less with time and/or drugs.

Clearly:

although humans have been shown to adapt to rates as high as 23 rpm.

 

[Swank]

Clearly:

No one lived for 3 months in a 23 rpm centrifuge, so the "adaptation" the article mentions was something short term showing that people could perform tasks under those difficult conditions. Like fighter pilots do.

I was offering my opinion that people might be able to live for years at something greater than 2 rpm because the inner ear senses do adapt over longer periods - like how people adapt to weightlessness, which takes several days to over a month.


Otherwise, thanks for quoting me twice to try to make me sound stupid, mod.

 

[Ursa major]

Otherwise, thanks for quoting me twice to try to make me sound stupid, mod.

Being a bit defensive, aren't we?

I was agreeing with you, and was highlighting what had prompted me to do so, i.e. that a very much higher rate (23 rpm) had been achieved, at least for a limited (though, unfortunately, unquantified) period**.


** - I would assume that the testing (whether conducted in one study or in a series of, possibly independent, studies) had involved a combination of: 1) gradually increasing the rate to be achieved; 2) increasing the period during which any given maximum rate was being applied; 3) gradually decreasing the time taken to get to the maximum rate), in order to build up a picture of how rates higher than 2 rpm could be used in practive.