BlackHawk Crash
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BlackHawk Crash
Ran across this one today....don't know if it has been posted before...but interesting shot of a crash.
http://media.putfile.com/Accident---...litary-Helicop
http://media.putfile.com/Accident---...litary-Helicop
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Never saw that, ouch! Looks like a main rotor problem, causing a massive ilateral vibration, shaking the tail off. Do you see the first two wiggles of the fuselage back and forth before it fails?
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Yes.....she wiggled....but you also notice the second bird spins right and crashes as well. I would bet it was downed by shrapnel from the bird in trail that loses the tail boom.
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If you watch the tail of the second aircraft coming into shot, you can see the contact between the first's main rotors and the second's tail section.
It appears number two came in too tight and spun his tail into the other rotor.
It appears number two came in too tight and spun his tail into the other rotor.
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I think you will find it was a US Army accident whilst on Ex Purple Star in the mid ninties. The Aussie one you refer to was a very similar accident but at night.
US Army collision
Aussie Blackhawk collision
Spookily, the accidents were 6 days apart.
US Army collision
Aussie Blackhawk collision
Spookily, the accidents were 6 days apart.
Last edited by wg13_dummy; 18th Dec 2005 at 15:03.
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UwantME2landWHERE!
Its tricky to tell cause from effect. The second aircraft (on the left of the video) also underwent exactly what the other did. Both had main rotor strikes, and the tails wiggle the same way.
When a few feet of the main blade is lost the massive imbalance shakes the wole aircraft (and can't be seen on this video.) The massive vibration is close enough to the main rotor 1/revolution frequency that it literally shakes the aircraft apart. That tail wiggle is the first lateral bending mode of the fuselage, and is the effect of the blade strike. I don't believe the tail was struck by anything.
Your dog knows how to find the first bending mode of a captured creature, that's why he has the instinctive lateral head shake. This shake excites the creature's natural frequency, and breaks its neck, so the dog doesn't have to do as much work to get lunch. Notice how the dog's shake frequency changes with the weight of the toy, he finds the natural frequency, and dwells there. You do that too when you pick up a long stick and snap it by shaking it from one end.
Its tricky to tell cause from effect. The second aircraft (on the left of the video) also underwent exactly what the other did. Both had main rotor strikes, and the tails wiggle the same way.
When a few feet of the main blade is lost the massive imbalance shakes the wole aircraft (and can't be seen on this video.) The massive vibration is close enough to the main rotor 1/revolution frequency that it literally shakes the aircraft apart. That tail wiggle is the first lateral bending mode of the fuselage, and is the effect of the blade strike. I don't believe the tail was struck by anything.
Your dog knows how to find the first bending mode of a captured creature, that's why he has the instinctive lateral head shake. This shake excites the creature's natural frequency, and breaks its neck, so the dog doesn't have to do as much work to get lunch. Notice how the dog's shake frequency changes with the weight of the toy, he finds the natural frequency, and dwells there. You do that too when you pick up a long stick and snap it by shaking it from one end.
96 Crash
I think one of the factors involved in the 96 Ft Campbell crash was a change in the lz at the last minute.
The crews had practised previously but some strap hangar decided to make a change to the program. Not the cause but certainly a contributing factor.
The crews had practised previously but some strap hangar decided to make a change to the program. Not the cause but certainly a contributing factor.
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Nick I stand corrected.
Initially when viewing the video, it appeared, to me, that the second aircraft was yawing in the opposite direction. However, I now see that both aircraft were on the same profile.
I see what you’re saying, determining ‘cause from effect’, tricky!
Although I will continue my propensity for rash decision and snap judgments!
'Never let it be said that I allowed cold, hard fact or logic get in the way of considered opinion!'
Initially when viewing the video, it appeared, to me, that the second aircraft was yawing in the opposite direction. However, I now see that both aircraft were on the same profile.
I see what you’re saying, determining ‘cause from effect’, tricky!
Although I will continue my propensity for rash decision and snap judgments!
'Never let it be said that I allowed cold, hard fact or logic get in the way of considered opinion!'
