Fuel tank additions causing jump in crew size

Crew Module size per person.

Taking the 45 crew module as example.
1.7 m radius by 22.6 m cylinder.
What would be in the inner volume?
4 cm thick armor is 0.004 m.
1.696 m inner radius and 22.596 inner length.

Volume

V = π×h×(R² − r²) = π × h × (D² − d²) ⁄ 4

204.23 m^3 inner volume.
Let's say 1/4 of that is for... six months of food
(there's a cook), water (there's a waste/water officer),
and HVAC (there's a Air Circulation officer). OR the means
to produce six months of it.

153.17 m^3, so 3.40 m^3 per person.
Each person would have about 3 of these,
plenty of room to "stand up", but not enough
room to spread out their arms.


In reality, there would be some kind of division into stations
and rooms, so no matter how you slice it, our living modules
would be pretty cramped.
Which is why I think the CIC would look like this..



Ha this is so funny to me. If you like scifi, find a copy of Dark Star.
it's dated, but entertaining.

I think if you grew up in space, living in cramped quarters would just be what you are used to.
Why you as a native spaceman might even prefer such cramped quarters.
It's not hard to imagine as babies prefer being held tightly and swaddled. With great design the space could be used very well in fact be quite confortable.

If I can't easily escape from where I am going I don't like that place, you have to be able to get into or out of your workstation easily

I am Not small deltav I think a 2x2x2M area is the msmallest possible volume for a human and thats pushing it.

Made a "drawing" showing what 3.4 m^2 per person of space COULD look like.
Edit: I realized you don't need much head room, would have to talk to psychologist,
of what is more important to not feel cramped, head room or room around...
but this is just a rough idea anyway.

The green man and the blue man are the same person in two different positions.
I think it's quite livable for people who grew up in space I think.


You can fully stretch each limb, "stand up", and have "personal space"
above 1.2 m in front, which is needed psychologically to feel not encroached upon.
en.wikipedia.org/wiki/Proxemics
But no head room.
Because most of the crew works in shift. At least 1/3 of the crew would be sleeping
at any one time. So practically, you might get at least 25% more space than 
this in your waking hours anyway.

Edit: I don't know if people would really be happy like this. But this is what we 
have in COADE, and I think it makes sense to really think through how it would be
and the way our ships are crewed, etc.

I'm with you, it'd be pretty cramped for me or you. I'm just trying to think this out as if it were real and see what it would really be like.
Your questions make me think into it more.

Well we know that without some miracle drug or genetic engineering, people can't live long term (more than 6 months or so) in zero g.
Their eyesight fails, they become very weak, etc, and most alarming, these changes are PERMANENT.

So I don't think anyone will "grow up" in zero g, but inside space stations
or "nursery stations" with 1 g or even better.

A person who grows up from age 0-15 or so in 1.5 g or even 2 g will do a lot 
better in zero g as an adult, than someone who grows up in zero g and 
has to be subjected to 1 g acceleration in a space warship.

The guy who grows up in 1.5 or 2 g in O'neill type cylinders, will be healthy, 
robust, compact, strong and be better able to deal with high g
acceleration in space warfare than the weak spindly unhealthy guy who grows
up in zero or low g.

Conclusion
So I don't think anyone will grow up in zero g. They'd be useless as adults in space warships,
at the very least they would be at a huge disadvantage.
They would need crash couches just to deal with 1g of acceleration, maybe even less.
They would be very tall and weak, taking up alot of room in habitat modules at no benefit.
They would have permanently weak eyesight, and many other health problems.
They would have very weak hearts and lungs, making them more likely to suddenly die
from even light trauma.

O'neill Cylinders or other spin gravity space stations spun up to 1g or even better are affordable and capable with current tech, and they would be essential for any long term habitat in space.
Children who grow up in this spin gravity would have distinct advantages over even those who grow up in low g environments like Mars.
They would be stronger, more robust, better able to deal with 1 g or lower acceleration in space warships, and would have stronger hearts, lungs,
and eyesight. They would be a better Space Warfare Navy Man, and would give a distinct advantage to whomever employed them vs those raised on
low g planets or even worse in zero g.