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#1
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number of rotor blades
Just a theoretical question that someone may be able to help with.
Alot of helicopters have only two rotor blades, ie:Robinsons, Bells, etc. Others have multiples, ie:dauphins with 4, Hughes etc. If a blade is thrown on a two blade, bend over and kiss your rear bye bye. What would happen if you had a 4, 5, or even 6 blade?Would you still be able to autorotate? I know the airframe would probably vibrate violently, but would it be survivable in an autorotate, or even low power to at least get to the ground. Have there been instances in the past where this has happened with a 2 blade. Thanks in advance. Rob Fonhof |
#2
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If a blade is thrown on a two blade, bend over and kiss your rear bye bye.
What would happen if you had a 4, 5, or even 6 blade?Would you still be able to autorotate? The only thing I've ever heard about a survivable "blade loss incident" was on an early autogiro (Pitcairn, I think) The test pilot lost one of the four main rotorblades. The story has it that the opposing blade departed soon after the first and he was able to sucessfully land. I also remember that he never flew again. Tom |
#3
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"Rob Fonhof" wrote in
: Just a theoretical question that someone may be able to help with. Alot of helicopters have only two rotor blades, ie:Robinsons, Bells, etc. Others have multiples, ie:dauphins with 4, Hughes etc. If a blade is thrown on a two blade, bend over and kiss your rear bye bye. What would happen if you had a 4, 5, or even 6 blade?Would you still be able to autorotate? I know the airframe would probably vibrate violently, but would it be survivable in an autorotate, or even low power to at least get to the ground. Have there been instances in the past where this has happened with a 2 blade. If you lose a blade, the imbalance will be so large as to take the transmission and everything attached to it out of the aircraft, most likely. It isn't survivable, just as losing a wing on an airplane isn't survivable, except in the most unusual of circumstances. -- Regards, Stan |
#4
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Stan Gosnell wrote:
It isn't survivable, just as losing a wing on an airplane isn't survivable, except in the most unusual of circumstances. Stan..... Do you have any idea as to how often a blade has been thrown since the invention of the helicopter, gyro, etc. How about in the last decade. |
#5
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Curious Question wrote in
: Stan Gosnell wrote: It isn't survivable, just as losing a wing on an airplane isn't survivable, except in the most unusual of circumstances. Stan..... Do you have any idea as to how often a blade has been thrown since the invention of the helicopter, gyro, etc. How about in the last decade. It's pretty seldom, I suspect about the same frequency as airplanes losing wings. The only one I've heard of recently is a Sikorsky S76 which lost a blade (actually the blade broke off relatively close to the head) over the North Sea last year. All aboard were lost. The blade had been previously hit by lightning, and this coupled with a manufacturing defect caused it to fail. Losing a main rotor blade on a certificated helicopter is very rare, unless it's in conjunction with a collision, where the blades hit something and subsequently fail. I fly them for a living, and losing a MR blade is something I just don't worry about. The NTSB, and perhaps other national aviation safety agencies, publishes summaries of all aviation accidents in the US, going back to 1962, and it's searchable. You should be able to find what you're looking for there, at least for the USA. http://www.ntsb.gov/aviation/aviation.htm -- Regards, Stan |
#6
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About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a M/R
blade loss. They were on approach, I seem to recall about 100 ft AGL, and broke a TT strap (badly corroded). The M/R gearbox left the aircraft and all 3 souls were lost. This was the first time a blade had slung in the BO105 (same head) or BK117 history. Then I remember years ago Donald Trumps Agusta A109 lost a blade up in NY with several of his VP's aboard. All were killed. Then there were the M/R spindle problems with the S76 when it first came out. Your right though, a M/R separation is very, very rare. JC "Stan Gosnell" wrote in message ... Curious Question wrote in : Stan Gosnell wrote: It isn't survivable, just as losing a wing on an airplane isn't survivable, except in the most unusual of circumstances. Stan..... Do you have any idea as to how often a blade has been thrown since the invention of the helicopter, gyro, etc. How about in the last decade. It's pretty seldom, I suspect about the same frequency as airplanes losing wings. The only one I've heard of recently is a Sikorsky S76 which lost a blade (actually the blade broke off relatively close to the head) over the North Sea last year. All aboard were lost. The blade had been previously hit by lightning, and this coupled with a manufacturing defect caused it to fail. Losing a main rotor blade on a certificated helicopter is very rare, unless it's in conjunction with a collision, where the blades hit something and subsequently fail. I fly them for a living, and losing a MR blade is something I just don't worry about. The NTSB, and perhaps other national aviation safety agencies, publishes summaries of all aviation accidents in the US, going back to 1962, and it's searchable. You should be able to find what you're looking for there, at least for the USA. http://www.ntsb.gov/aviation/aviation.htm -- Regards, Stan |
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"Helimech" wrote in
: About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a M/R blade loss. They were on approach, I seem to recall about 100 ft AGL, and broke a TT strap (badly corroded). The M/R gearbox left the aircraft and all 3 souls were lost. This was the first time a blade had slung in the BO105 (same head) or BK117 history. Then I remember years ago Donald Trumps Agusta A109 lost a blade up in NY with several of his VP's aboard. All were killed. Then there were the M/R spindle problems with the S76 when it first came out. Your right though, a M/R separation is very, very rare. JC I had forgotten about the Hermann ship. The BH206 also had TT strap problems when it was new, and shucked a few blades, IIRC. -- Regards, Stan |
#8
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IN CLARIFICATION TO THE ABOVE:
THAT WAS NOT "DONALD TRUMP'S AGUSTA THAT WAS LOST IN THE ACCIDENT UP IN NEW JERSEY. THAT AIRCRAFT WAS LEASED THAT DAY FROM PARAMOUNT AVIATION. TRUMP HAD FIVE (5) OF HIS L A R G E HELICOPTERS SITTING IN THE HANGAR ON THE DAY THAT THE LEASED AIRCRAFT WAS LOST. I WAS THE CHIEF INSPECTOR FOR TRUMPS HELICOPTER OPERATIONS AT THE TIME SO YOU CAN TAKE THIS INFO TO THE BANK. HIS AGUSTA 109 WAS IN MAINTENANCE THAT DAY AND WAS UNAVAILABLE. THE BLADE THAT FAILED HAD A "FORGING LAP": LEFT IN THE M/R/B SPAR SINCE MANUFACTURE WHICH CREATED A "STRESS RAISER", EVENTUALLY A CRACK, AND THE REST IS HISTORY. For the rest of the commenters, now with many composite blades out there a better record can probably be expected although no great inspection methods have yet been developed for composites. Metal blades departed aircraft many many times, hence Sikorsky's "BIM" indicators on the blade roots. Hundreds of thousands od pounds of centrifugal force and cracked blades will always present a problem, huh? |
#9
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"Helimech" wrote:
About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a M/R blade loss. They were on approach, I seem to recall about 100 ft AGL, and broke a TT strap (badly corroded). The M/R gearbox left the aircraft and all 3 souls were lost. Ok another question. What is a TT strap? Dennis. Dennis Hawkins n4mwd AT amsat DOT org (humans know what to do) "A RECESSION is when you know somebody who is out of work. A DEPRESSION is when YOU are out of work. A RECOVERY is when all the H-1B's are out of work." To find out what an H-1B is and how Congress is using them to put Americans out of work, visit the following web site and click on the "Exporting America" CNN news video: http://zazona.com/ShameH1B/MediaClips.htm |
#10
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Subject: number of rotor blades
From: Stan Gosnell It isn't survivable, just as losing a wing on an airplane isn't survivable, except in the most unusual of circumstances. -- Regards, Stan I do know a an accident with a glider where the pilot lost a wing, spin down into a marsh with big fluffy trees and survied. It happened in Florida a few years ago and the glider was a 1-26. Craig |
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