The OSCAR-B Fuel Tank needs a little love.

[Starwhip]

#VOLUME FINDER
import math

#1 mL = 1 cm^3
#1 L = 1000 cm^3
#1 m^3 = 100cm * 100cm *100cm = 1,000,000 cm^3
#1 L = 0.001 m^3

#1 OTE = 2 Rockomax X200-32's = 4 X200-16's = 8 X200-8's (2.5 m by 1 m)
#Thus, OTE = 2.5 m by 8 m
#One OTE = ~78500 L
#One OTE = 2,880 LF + 3520 OX = 6400 LFO Units

OTE = (78539.81633974484 / 6400)  #Exact volume of tank / LFO units

while True:
    radius = float(input("Diameter (m): "))/2    #in METERS
    height = input("Height (m): ")               #in METERS
    volumeM = float(height) * (2*math.pi*(radius**2))
    volumeL = volumeM / 0.001

    volumeBase = volumeL / (2*OTE)
    OXIDIZER = volumeBase * 1.1
    LIQUIDFUEL = volumeBase * 0.9
    print("Volume (m^3): "+str(volumeM))
    print("Volume (L): "+str(volumeL))
    print("Oxidizer: "+str(OXIDIZER))
    print("Liquid Fuel: "+str(LIQUIDFUEL))

This program, tuned for the Orange Tank and tested on several other parts, gives me this value for the Oscar-B tank:

Diameter (m): 0.625                            <--- This is an input
Height (m): 0.5                                  <--- So is this one. Everything that follows is generated by the program (an output)
Volume (m^3): 0.30679615757712825
Volume (L): 306.79615757712827
Oxidizer: 13.750000000000002
Liquid Fuel: 11.25

The Oxidizer and Liquid Fuel levels currently in-game are as follows:

Liquid fuel 5.735 L

Oxidizer 7.000 L

I wrote a .cfg for it, but I would like to see it fixed in the stock game. Still working on checking consistency for the other parts as well.

EDIT:

Also, this:

The Oscar-B Fuel Tank provides fuel to attached liquid fuel engines.

It is currently the smallest liquid fuel tank in the game, containing enough fuel to run the tiny LV-1 at full throttle for just over 15 seconds. It only carries 70% of the capacity of the next largest fuel tank (the ROUND-8 Toroidal Fuel Tank) and less than 7% of the capacity of the FL-T200 Fuel Tank.

The Oscar-B's mass ratio (5.245) is slightly worse than that of the Round-8 (5.44), and significantly worse than an FL-T or Rockomaxx tank (9). Additionally the oxidizer volume is 0.0094 l short thus the ratio between oxidizer and liquid fuel is not exactly matched. Also, it cannot be attached radially.

So please, don't come after me by stating that "The devs know that it is not balanced". (<----- was not intended to sound as vicious as it does)

Edited October 1, 2014 by Starwhip

[klgraham1013]

It's sad that I've used the Oscar-B more for aesthetics purposes than as a fuel supply. Even the smallest engines wipe it out in no time.

[Wanderfound]

It's sad that I've used the Oscar-B more for aesthetics purposes than as a fuel supply. Even the smallest engines wipe it out in no time.

OB's do have plenty of practical uses, though.

* Junction boxes for mating, splitting and routing fuel lines.

* Microprobes; there's plenty of delta-V in an OB when the probe only weighs a few hundred kg.

* Ultra-narrow base segments for making skinny landers to fit inside SP+ cargo bays:

[Starwhip]

Something I realized just now: The diameter is 0.625 meters, but what is the height? I don't think that it's 0.5 meters.

[Jouni]

The Oscar-B is fine as it is. I've always understood that it's too small for Kerbal technology, and as a result structural overhead takes a larger fraction of total size and mass than in bigger fuel tanks. In a similar way, the 3.75 m fuel tanks are too large for Kerbal technology, requiring extra reinforcements.

[stupid_chris]

Don't try to attribute volumes to tanks in KSP. Really, ask NathanKell and Taniwha from MFT how complex this stuff is. Nothing in stock makes sense regarding volumes.

[Tweeker]

They really need to be radial mountable, I hate having to stick a monoprop tank on and then stack Oscar-b tanks on it when building landers. It is a crude work around that is unnecessary.

It would also be nice to see some taller tanks in this parts range.

[John FX]

Some tanks just have thick walls is how I see it.

[Helix935]

OB's do have plenty of practical uses, though.

* Junction boxes for mating, splitting and routing fuel lines.

* Microprobes; there's plenty of delta-V in an OB when the probe only weighs a few hundred kg.

* Ultra-narrow base segments for making skinny landers to fit inside SP+ cargo bays:

[snip]

i personally prefer using it to make small skycranes for rovers