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NASA Tests Flying Airbag
coondoggie writes "NASA is looking to reduce the deadly impact of helicopter crashes on their pilots and passengers with what the agency calls a high-tech honeycomb airbag known as a deployable energy absorber. So in order to test out its technology NASA dropped a small helicopter from a height of 35 feet to see whether its deployable energy absorber, made up of an expandable honeycomb cushion, could handle the stress. The test crash hit the ground at about 54MPH at a 33 degree angle, what NASA called a relatively severe helicopter crash."
The thing hit the ground, and what happened? Worst. summary. ever. From nasa: "Engineers say the MD-500 survived relatively intact as a result of the honeycomb cushion. "
Perhaps you need to go back and study some more physics. In earth gravity of 32ft/s^2 it would take about 2 seconds to hit the ground from 35 feet falling straight down. 2 seconds of earth acceleration has you moving at 64ft/s, which is just over 43mph. Even the lackluster summary states the impact was at 33 degrees, which implies the helicopter was guided in along a slope, rather than being dropped. So using a bit of trig, 35ft/Sine(33) = 64.26ft is the length of slope the helicopter descended, at 33 degrees to the ground, to impact at 54mph, which would then imply that it was actually falling slower than gravitational pull would account for, largely due to the friction of the guide cable. This is likely the same rig used to test reentry mechanisms for many other NASA vehicles, which has the ability to vary impact angle, while maintaining repeatability between each test in a given configuration.