Sikorsky S-92: [Archive Copy]
Join Date: May 2004
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The 2CV is a top car!
Interestingly enough, the original design spec for that car required it to be able to drive across a ploughed field with a cargo of eggs without breaking them.
Stick with me here because there is a point to this.
When helicopters were first trailed by the Admiralty in the UK (Scapa Floe, Orkney during WWII) the best use they could put them to was guess what...............?
Transporting eggs from all the poultry farms because they didn't break as many as the lorry drivers did!
One of the pilots was called BristowBTW.
Just a little bit of rotary wing trivia for all you spotters out there.
MM
Interestingly enough, the original design spec for that car required it to be able to drive across a ploughed field with a cargo of eggs without breaking them.
Stick with me here because there is a point to this.
When helicopters were first trailed by the Admiralty in the UK (Scapa Floe, Orkney during WWII) the best use they could put them to was guess what...............?
Transporting eggs from all the poultry farms because they didn't break as many as the lorry drivers did!
One of the pilots was called BristowBTW.
Just a little bit of rotary wing trivia for all you spotters out there.
MM
See here for all you ever wanted to know about fuel tank crashworthiness!
http://aar400.tc.faa.gov/aar-430/reports/01-76.pdf
http://aar400.tc.faa.gov/aar-430/reports/01-76.pdf
Join Date: Jul 2005
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The anti vibration generator broke loose from the fuselage and made a big hole trough the skin and started to eat into the sponson(with the fuel tank..)
5-10 cm below the hole there are 4000psi hydraulic lines....
5-10 cm below the hole there are 4000psi hydraulic lines....
Join Date: Jul 2005
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Zebedee- The information you got suggesting that the crew were about to ditch is not true.
The loose anti vibration generator was found by mech`s after trouble-shooting due to a "AVC degrade" warning on eicas.
But after seeing the damage done you start to wonder what this could lead to...
The loose anti vibration generator was found by mech`s after trouble-shooting due to a "AVC degrade" warning on eicas.
But after seeing the damage done you start to wonder what this could lead to...
Join Date: Nov 2004
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I don't know a great deal about the technology, but i gather that fuel tanks in F1 cars are rubber based (i assume silicon rubber to stop oil corrosion). I imagine they are pretty light, as well as being extremely damage tolerant. I'm guessing that the rubber is used as a resin for composite contruction. The likelyhood of tank leakage/puncture, and all the unpleasant consequenses, would thus be much reduced...
What is the latest in heli rotor vibration damping? I promise not to do any controversial calcs!
Mart
What is the latest in heli rotor vibration damping? I promise not to do any controversial calcs!
Mart
Join Date: Nov 2000
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zebedee
I'll bite..
You say that I fly 92`s has given credence to what you said, including your suggestions that the crew was about to ditch and that things could have been catastrophic. Where do you get this????
In fact, he said,
You also said
This force generator is mounted in the cabin wall near the floor as S92 Mech has written. How do you figure it drove itself through the roof?
What's your agenda? Why should anyone on this list feel compelled to give you details, when it seems you enjoy such unbridled exaggeration?
I'll bite..
You say that I fly 92`s has given credence to what you said, including your suggestions that the crew was about to ditch and that things could have been catastrophic. Where do you get this????
In fact, he said,
But "potentially catastropic" and "on the verge of ditching" is out of the blue..
Yep, "it fell off" then (because it was still being powered) drove itself through the roof, some wiring and, eventually, the top of the fuel tank.
What's your agenda? Why should anyone on this list feel compelled to give you details, when it seems you enjoy such unbridled exaggeration?
Join Date: Dec 2004
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Zebedee, I do have some detail of what happened with the failure of the force generator mount. I have no information on what happened during the flight or what the flight crew did. I've read reports from Sikorsky and seen detailed pictures of the failure. While the mount and skin near the force generator were badly damaged, the inboard wall of the fuel sponson appeared to have very little damage.
If the active vibration control worked as it should, the force generator would have been disabled by the AVC computer very soon after it fell from it's mount. The AVC system has feedback from the force generators and accelerometers mounted nearby. If the generated force does not match the phase and/or amplitude that the computer is looking for, the computer will disable the system. While the generator would have knocked on the floor a few times after it fell, it should not have been but a few seconds.
If the active vibration control worked as it should, the force generator would have been disabled by the AVC computer very soon after it fell from it's mount. The AVC system has feedback from the force generators and accelerometers mounted nearby. If the generated force does not match the phase and/or amplitude that the computer is looking for, the computer will disable the system. While the generator would have knocked on the floor a few times after it fell, it should not have been but a few seconds.
Errrm, Graviman, helicopters have been using rubber tanks for about oh 40 odd years, and still use them today. Not sure about the S-92, but the AB139 uses rubber bladder tanks.
noooby
noooby
Join Date: Nov 2004
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Doh! 
Didn't realise this, since the smaller machines seemed to be conventional construction.
Any good links on the Sikorsky active vibration control? I take it this is basically just a servo driven mass?
Mart
Didn't realise this, since the smaller machines seemed to be conventional construction.Any good links on the Sikorsky active vibration control? I take it this is basically just a servo driven mass?
Mart
Join Date: Apr 2003
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Graviman,
The vibe system on the S-92 (and the EC225) Use "force generators" which are solid state electric motors with extreme precision rpm control. They also have a built in counter weight system that can be driven off center so they can change the force the put out. They can also change the phase of the spinning so that they can determine the direction that the force is exerted. Thus, they control the frequecny, amplitude and phase of the vibratory force. A set of vibration pickups in the cabin floor read what each seat is experiencing, and send their readings to a computer that then compares the readings, remembers the best way to juggle the forces, and then adjusts the several force generators to get the best ride for all.
The vibe system on the S-92 (and the EC225) Use "force generators" which are solid state electric motors with extreme precision rpm control. They also have a built in counter weight system that can be driven off center so they can change the force the put out. They can also change the phase of the spinning so that they can determine the direction that the force is exerted. Thus, they control the frequecny, amplitude and phase of the vibratory force. A set of vibration pickups in the cabin floor read what each seat is experiencing, and send their readings to a computer that then compares the readings, remembers the best way to juggle the forces, and then adjusts the several force generators to get the best ride for all.
Nick
Just a minor correction - the EC225 doesn't use the electric motor / spinning weight type force generator, instead its more like a loudspeaker voicecoil, ie using electromagnetic forces to move a weight around. The out come is pretty much the same though.
HC
Just a minor correction - the EC225 doesn't use the electric motor / spinning weight type force generator, instead its more like a loudspeaker voicecoil, ie using electromagnetic forces to move a weight around. The out come is pretty much the same though.
HC
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Cdn driver,
The facts about the S-92 blowing the flotation gears are as follows;
On approach to a rig, the floats inflated when they armed the system. It was not finger trouble by the pilots. It was probably caused by a defect in one of the immersion switches. I know Sikorsky have had quite a few problems with those switches
The facts about the S-92 blowing the flotation gears are as follows;
On approach to a rig, the floats inflated when they armed the system. It was not finger trouble by the pilots. It was probably caused by a defect in one of the immersion switches. I know Sikorsky have had quite a few problems with those switches
Crosswind limitations
What is this I am hearing, that the S92 has a very limited crosswind capability?
I understand they had to stop flying the other day due to too much crosswind.
It would be interesting to know if this is a real controllabilty issue or if it is just due to the fact that the a/c has not been fully tested to the edges of the envelope (yet?).
I understand they had to stop flying the other day due to too much crosswind.
It would be interesting to know if this is a real controllabilty issue or if it is just due to the fact that the a/c has not been fully tested to the edges of the envelope (yet?).