Command modules vs passenger modules + probe

[ineon]

I am optimising a spaceplane that I successfully got to orbit, docked and de-orbited. It flies really nicely, has great manoeuvrability, can land really gently but could do with a bit of work getting it to dock nicely. It has 2 Mk1 Inline Cockpits, and I think that I want to change it for a Mk1 Crew Cabin. I am going to use it for crew rotations - no cargo.

Detailed analysis if you really want it:

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Original

Part	Mass	Cost	Electricity	Monoprop	Torque
Mk1 Cockpit	1.03	1600	50	7.5	10
Mk1 Cockpit	1.03	1600	50	7.5	10
Total	2.06	3200	100	15	20

New

Part	Mass	Cost	Electricity	Monoprop	Torque
Mk1 Crew cabin	1	550
Probodyne HECS	0.1	650	10		0.5
1.25 Service bay	0.1	500
Z100 battery	0.01	80	100
FL R10 RCS tank	0.37	200		80
Advance Stabiliser	0.1	1200			15
Total	1.67	3180	110	80	15.5

The advantages that I see are that it does not require a pilot to be one of the crew that is rotating, as well as being marginally lighter and cheaper (20Kerbucks saved - woo) and the other specs are about the same. I could also use it for tourists too. Having a cargo bay has the small advantage that I can put other radially attached parts in there too to avoid drag (mechjeb is the main one).

The big disadvantage is that if I loose power then I am completely dead in the water space, whereas if I had a command module I could at least manoeuvre using RCS or control surfaces, or fire the engine when I am pointing in approximately in the right direction. Another small disadvantage is that there are 3 things in the plane instead of 2, this makes it slightly longer and has more places for it going spaghetti on me (it does have enough lift to tear itself apart at mach3 under 10km altitude).

I guess that I have a few more options in placing components wrt getting the CoM in the right place, but equally more complexity.

Any more advantages or disadvantages that I have missed?

[WhiteKnuckle]

Are you docking, or just EVAing Kerbals across? If not then just skip the whole RCS system.

Take a small battery and right-click it, you can then lock it out the same way you would a fuel tank, that way if you run out of power you have an emergency backup supply, at least enough to turn you towards the sun.

[ineon]

  On 1/21/2016 at 6:26 PM, WhiteKnuckle said:

Are you docking, or just EVAing Kerbals across? If not then just skip the whole RCS system.

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Hmmm... If I am only doing crew rotations, then you are right, and I can get rid of all that drag from RCS thrusters.

  On 1/21/2016 at 6:26 PM, WhiteKnuckle said:

Take a small battery and right-click it, you can then lock it out the same way you would a fuel tank

Expand  

I completely forgot about that. Well remembered.