Revisit The DC Helicopter Event — Kinematics

stock here: remember the initial lie / line that an airplane flew into a helicopter?

What has been really odd to me, from the get go, was the way the Plane seemed to lose all forward momentum, and immediately tumbled into the water. Also, the flash was huge. I have reviewed other in air plane crashes and the fire ball / flash is no where that instantaneous or huge. The Helo impacted primarily from the side, so the mass of the Helo impacting the plane would not reduce the forward momentum of the Plane.

So this has been bugging me for quite some time…the weird Airplane “tumble” into the river, a near complete exhaustion of forward momentum.

Energy must have been added in order to reduce the Momentum of the Plane, and to destroy it’s Kinetic Energy of significant 42,327,084 ft-lbf. 42 Million Foot Lbs.

Also, the much lighter Helo “continues” on through, although of course, taken to river pretty quick by gravity

Riddle me this folks, I did the calcs, took a shower and pondered the possibilities that produced these kinematics.

Who can chime in with the answer. Bear in mind the aircraft was split in half and the Helicopter “went through” in one piece.

There is only one answer I can come up with in the span of a shower.

————————————— Kinetic Energy Calc

Kinetic Energy Calculations for CRJ-700 and UH-60 Black Hawk

Given Data

CRJ-700

• Weight: 64,600 lbs
• Estimated Landing Speed at 300 feet: 140 MPH (converted to 205.33 feet per second)

UH-60 Black Hawk

• Weight: 16,120 lbs
• Speed: 150 MPH (converted to 220 feet per second)

Conversions and Calculations

• Conversion Factor: 1 slug = 32.174 lbs
• Mass Calculation:
• CRJ-700 Mass: ( 64600 \div 32.174 = 2009.69 ) slugs
• UH-60 Mass: ( 16120 \div 32.174 = 501.2 ) slugs
• Kinetic Energy Formula: [ KE = rac{1}{2} m v^2 ]
• Kinetic Energy for CRJ-700:
• [ KE = 0.5 imes 2009.69 imes (205.33)^2 ]
• Result: 42,327,084 ft-lbf
• Kinetic Energy for UH-60 Black Hawk:
• [ KE = 0.5 imes 501.2 imes (220)^2 ]
• Result: 12,124,876 ft-lbf

Conclusion

• The CRJ-700, due to its significantly higher weight, has about 3.5 times more kinetic energy than the UH-60 Black Hawk at these speeds.
• This highlights the much greater energy involved in a landing or impact scenario for a commercial jet versus a military helicopter.