Reply #109: A 767 packs a whopping lot of kinetic energy, that's for sure

[AZCat]

I was curious how much kinetic energy a 767 travelling at 400 kts had, so I did a quick calculation.

Assumptions:
1) Weight of 767 drawn from this site. I used the lightest gross weight and chopped off 10% for fuel use, giving 143,000 kg as the estimated weight

2) Speed of 400 kts

Formulas and conversions:
Kinetic energy = 0.5*weight*(velocity^2)
1 kt = 0.514 m/s
1 lb TNT = 2.1 MJ

Calculations:
KE = 0.5*(143,000)*(400*0.514)^2 = 3.02*10^9 Joules

This is equivalent to: (3.02*10^9)/(2.1*10^6) = 1440 lbs TNT

That's a pretty big explosion just right there, although I don't think all the kinetic energy would be released at once.

This is about 14 cubic feet of explosive (TNT is about 100 lbs/ft^3) for reference.

As a comparison to missiles, the AGM-84 Harpoon packs 215 pounds of high explosive (DESTEX) for a warhead. I was unable to find the specific combustion energy for DESTEX, but I suspect it is higher than TNT.