Fantasy Flight Games has provided the below image (which is Canon) of an Imperial-era Onager-class star destroyer bombarding a planet with her axial superheavy composite beam turbolasers (wow, that's a mouthful).

The image

Onager-class firepower

At first, it looks like simple enough artwork depicting fireball only. However, on opening it in a new tab and zooming in, you can make out two distinct blast waves progressing away from the main fireball.

Playing around in MS Paint

I made a copy of the above image, increased the brightness & contrast to make the blast waves stand out a little more, then played around a bit in MS Paint.

Onager-class firepower - Copy
Onager-class firepower - Copy 00
Onager-class firepower - Copy 02

Red circle = 1809 px

Purple circle = 250 px

Green circle = 140 px


Assuming planetary diameter of 12,240 km (which is the diameter of Coruscant and the standard to which planets are compared in Star Wars), then we make the following conclusions:

  • The fireball and inner shockwave around it have devastated an area 947.26 km in diameter. This is an area over a fifth the size of India, which is the world's seventh largest country.
  • The outer shockwave has travelled a distance of 845.77 km from the blast centre, devastating an area 1,691.54 km in diameter. This is an area over two-thirds the size of India.

I haven't yet gotten to calculating the yield of that explosion. I know that I should use the Surface Destruction formula:

R^3*[(27136*P + 8649)^(1/2)/13568 - 93/13568]^2

However, I'm stumped as to what pressure value I should use for the outer shockwave.

I could try making a calculation using the inner shockwave and go with the 40 to 50 psi overpressure values that are possible with nuclear explosions. Refer these links:

Link 1

Link 2

And before anyone asks: Yes, there is abundant evidence in Canon that turbolaser blasts are nuclear.

By my guesstimates, this should be a 6-B (Country level) feat.


ByAsura suggested that I use 10 psi and 20 psi as low-balls.

Surface Destruction formula:

R^3*[(27136*P + 8649)^(1/2)/13568 - 93/13568]^2

R = 845771 metres

P1 = 10 psi = 0.689476 bar

P2 = 20 psi = 1.37895 bar

Yield 1: = 17.23 Teratons = 6-B (Country level)

Yield 2: = 48.62 Teratons = 6-B (Country level)

Note: This would not scale to the heavy turbolasers of other Star Wars capital ships. It's abundantly clear that these turbolasers are a step up from them. However, the orbital autocannons of the Mandator IV-class Siege Dreadnought (which actually have a calc'ed 6-B feat here) would likely scale. It is quite possible that the superheavy composite beam turbolaser is a precursor to the orbital autocannon.

Community content is available under CC-BY-SA unless otherwise noted.