Radial size
The radial size is the diameter or mounting position for most parts. If the mounting position is not radial, then the part is either round or one of two special forms. Such rectangular parts as the M-1x1 Structural Panel lack a radial size or it's a size to the next bigger diameter like the Probodobodyne QBE. Four radial sizes exist with varying names. The size scale looks like the internal definition as the Mk2 to size 1 Adapter uses this term and starts with 0 and many values in computer programming are starting from 0 rather than 1.
Any stackable part can be connected to any other stackable part. Matching radial sizes only serves to give a rocket a cleaner visual appearance, and several adapter parts exist to allow transitions between radial sizes while maintaining an unbroken surface.
Contents
Sizes
We will use the FL-T100 Fuel Tank as the baseline length unit.
| Radial size | Fuel per length | Typical crash tolerance | Typical maximum temperature | ||
|---|---|---|---|---|---|
| Rocket fuel | Liquid fuel | Monopropellant | |||
| Tiny / 0.625m | 6 m/s | 2000° | |||
| Small / 1.25m | 6 m/s | 2000° | |||
| Large / 2.5m / Rockomax | 6 m/s | 2000° | |||
| Extra Large / 3.125m / Kerbodyne | 6 m/s | 2000° | |||
| Mk1 | 20 m/s | 2000° | |||
| Mk2 | 40 m/s | 2200° | |||
| Mk3 | 50 m/s | 2300° | |||
Rocket
The typical mass ratio for rocket fuel is 9.
Tiny / 0.625m
Typically used for probes and nose electronics.
Small / 1.25m
The most common size, and the primary size available at the beginning of the game.
Large / 2.5m / Rockomax
Extra Large / 3.75m / Kerbodyne
Only rocket fuel is available at this size.
Spaceplane
Spaceplane parts may carry either rocket fuel or liquid fuel. Compared to rocket parts they tend to have a poorer mass ratio (usually about 8), but better crash tolerance and maximum temperature.
Mk1
Like the 1.25m rocket size, this size is a cylinder. All inline air intakes are of this size, but there are no rocket fuel tanks. Crash tolerance is typically 20 m/s and maximum temperature is typically .
Mk2
With its side chines, this spaceplane size is reminiscent of the real-world Lockheed SR-71 Blackbird. It is between the 1.25m and 2.5m sizes in cross-sectional area. These parts feature a small amount of lift.
Mk3
Reminiscent of the real-world Space Shuttle. The cross-sectional area is similar to the 3.75m rocket size.
Assets
When creating assets, the correct diameter for a desired model can be found in the table below. The "meter scale" refers to the actual model's diameter, which is then typically scaled up via the default rescaleFactor of 1.25, to give the "actual" in-game diameter. Size scale is used to denote the standard when selecting a node size.
| Name | Size scale | Meter scale | Actual size | Example |
|---|---|---|---|---|
| Tiny | 0 | 0.5 m | 0.625 m | Rockomax 48-7S |
| Small | 1 | 1 m | 1.25 m | LV-T30 Liquid Fuel Engine |
| Large | 2 | 2 m | 2.5 m | Rockomax "Mainsail" Liquid Engine |
| Extra large | 3 | 3 m | 3.75 m | Kerbodyne KR-2L Advanced Engine |
As a special radial size Radial mounted appears. Parts like Rockomax 24-77 so lack general metric counterparts as to eliminate confusion.
Non-cylindrical sizes named “Mk2”, and “Mk3” exist and are used by fuselage parts intended for spaceplanes.
Additional sizes
Several addons add additional, usually larger, radial sizes which are roughly following the stock size scale. There are up to 9 meter parts in the B9 Aerospace mod and mods like Tweakscale can scale parts more freely.
