Can a falling bullet go through a roof?

Can a falling bullet go through a roof?

When a bullet is falling from the sky, one might wonder whether it could potentially penetrate and go through a roof. This phenomenon has sparked both curiosity and concern among those who wonder about the feasibility and potential harm it could cause. So, can a falling bullet go through a roof, and what determines its fate?

Hypersonic and Subsonic Behavior

To tackle this conundrum, it is essential to differentiate between high-speed (hypersonic) and low-speed (subsonic) bullets, as their penetration capabilities exhibit distinct characteristics:

• Hypersonic bullets:

• Travel at high speeds of over Mach 1 (> 660 ft/s / 202 mph)
• Can sustain a sufficient amount of energy to consistently penetrate most standard building roofs
• Are mostly associated with projectile systems deployed from aircraft (e.g., missiles)

• Subsonic bullets:

• Travel at low speeds of less than Mach 1 (<660 ft/s / 202 mph)
• Would typically stall or ricochet upon engaging a roof

Properties of a Building Roof and Bullet

It is fundamental to understand that the potential for a bullet to perforate a building roof highly depends on three key attributes:

• Material: Diverse materials create varying susceptibility to penetration: wood-based, steel-supported, slate, tile, and fabric-based roofs pose distinct chal-

lengers for bullets.

• Thickness: Buildings often are constructed with varying roof thickness (average – 3 ft /.9 m or less to 12 in /.3 m in thickness range). Additionally, obstacles like roof edges, rafter spaces, or valleys can significantly impair bullet migration.

• Sharpness/Gauge: Ballistic parameters like bullet angle, hardness, and precision are considerable factors influencing how easily projectiles can pierce and create holes in specific roof styles.

Piercability of Varying Roof Materials and Thicknesses

Table: Experimental Results for Selected Roof Conditions

• Subsonic ballistics tests were conducted: refers to no damage observed: signifies visible penetration/migration.
  Some examples help illustrate the variability of penetrability:
  o Asphalted wood roof surfaces can effectively absorb hypersonic bullets by dissipating shockwaves efficiently.
  o Modern, ridged steel-framed composite roofs can sustain significant impac-
  tes but present a barrier too tough to breach.
  Concrete or fiberglass-based structures could, even at supersonic speeds (Mach
  1).