That ain’t even a HARD landing!
Really? F=MA, 15 feet is a long way to accelerate when its 32.2 ft/sec^2. Falling from 15 feet is more than enough to kill ya man.
No aircraft can withstand a "drop test" from much more than 15 feet. Keep in mind this is a pure "drop" test, not cushioned by ground effect or any aerodynamics whatsoever. I know NASA did testing on GA fuselages several years ago that were swung on a trapeze rig from only about 75 feet so they hit at an angle, and in most cases the internal seat structures failed and would have killed the pax, even though the fuselage was basically in one piece afterward. A pure drop from 15 feet onto a solid surface, with no suspension, no human leg bending, nothing to gradually slow the stop at the end is extremely severe.