One Punch Man: How Powerful Were Metal Knight’s Missiles?

One Punch Man chapter 21

During the Dragon-level meteor crisis, S-Class heroes such as Genos and Metal Knight attempt to stop the incoming meteor. One of the most impressive efforts comes from Metal Knight’s missiles, which display a remarkable level of destructive power. This raises an important question: how powerful were those missiles?

To answer this, we estimate their yield by analyzing the size of the explosion shown in the manga, comparing it directly to the meteor’s size.

One Punch Man chapter 21

To determine the explosion’s scale, we compare it to the meteor’s diameter, previously analyzed. The meteor has an ellipsoidal shape with a width of 140 meters, which corresponds to 30 scale units. The explosion’s width measures 785 units, about 26 times larger.

This gives the explosion a diameter of approximately 3,640 meters, and a radius of 1,820 meters.

One Punch Man chapter 21

Next, we estimate the expansion velocity of the explosion. This value can vary widely depending on the explosive material. High explosives typically have detonation velocities between 1,800 and 3,000 m/s. For example, ANFO, an industrial explosive, can reach close to 3,000 m/s under certain confinement conditions.

Military-grade explosives like TNT range from about 4,700 m/s to over 7,000 m/s. To remain conservative, we use a value of 3,000 m/s. At this speed, the explosion would take roughly 0.6 seconds to expand across a radius of 1,820 meters.

With the size and time determined, we can now apply the Sedov–Taylor scaling law, which describes how a powerful explosion expands through a medium:

$$R = \left(\frac{E\,t^2}{\rho}\right)^{1/5}$$

Where:

• R = radius of the explosion (meters)

• E = energy released by the explosion (joules)

• t = time since detonation (seconds)

• ρ = density of the surrounding medium (kg/m³), for air ≈ 1.2 kg/m³

To find the explosion’s energy, we rearrange the formula:

$$E = \frac{\rho\,R^5}{t^2}$$

Using the values obtained earlier:

• R = 1,820 m

• t = 0.6 s

• ρ = 1.2 kg/m³

Substituting:

$$E \approx \frac{1.2 \cdot (1{,}820)^5}{(0.6)^2} \approx 4.3 \times 10^{16}\ \text{joules}$$

This corresponds to roughly 10 megatons of TNT.

This gives a total yield of approximately 4.29 × 10¹⁶ joules, or about 10 megatons of TNT.
Since 16 missiles were fired, this corresponds to roughly 625 kilotons of TNT per missile.

As Metal Knight himself states, this clearly qualifies as a highly powerful experimental weapon, and one of the most destructive conventional arsenals shown during the meteor crisis.

Even with conservative assumptions for expansion speed and air density, this result shows that Metal Knight’s missiles operate at multi-megaton yields, explaining why their detonation briefly overwhelms the meteor’s surface and stands out as one of the most powerful conventional attacks shown during the crisis.