Originally Posted by
Phil77
How come that the gearbox on that EC135 (it rolled over after clipping a trailer on (forced) landing) moved a mere 5 inches towards the side of impact?!?
Last time I checked dirt is a lot harder than water - or was the crew just lucky not beeing beheaded by a flying gearbox? (pardon my sarkasm).
Phil77,
I am by no means a physicist but wouldn't the fact that dirt is much harder than water be a contributory factor?
When a blade hits the ground, isn't it more likely to shatter or break in some way? (See the photo of the Philly EC135 - all of the blades are sheared at the root.) This will dissipate most of the remaining kinetic energy.
However, when a blade hits the water, isn't it just as likely to decelerate rapidly? This means that a lot of the energy will be transferred along the blade until it gets to the end ie the gearbox.
Although saying that, maybe it comes down to the more modern design of the EC135? I remember from the video of that ENG AS350 which came down on a New York roof that the pax were very lucky not to get clobbered by the gearbox when it came away from the aircraft.