Icing + other wx nasties
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
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To: Nick Lappos
“Grounding straps connect (electrically) the blades to the rest of the airframe, and are of little use to protect against static build-up, because the airframe is not grounded”!
Response: The primary purpose of the bonding straps, whether they be on the rotorhead or on a black box or transmission, is to ensure that the entire airframe is at the same electrical potential with this potential being primarily the result of precipitation static. If elements of the airframe to include all of the appliances contained within the airframe are not properly bonded they will create sparking due to the potential difference with this sparking having an effect on the electronic system. It can also cause electrical shocks if a person acts as the bonding between two un-bonded elements. Now these are not my words they are contained in the FAA certification documents for aircraft of all sizes.
“The grounding straps Lu keeps driveling about are used to protect the rotor from lightening strikes, where the charge will arc and cause local damage”.
If you have metal blades or composite blades that are designed to conduct the charge of a lightning strike the bonding straps must also be able to conduct the current developed during a lightning attachment to the blades. Conventional braided bonding straps cannot conduct these high current levels and when the lightning strike occurs the braided strap will most likely melt. If the primary purpose of the bonding straps is to conduct the high current then they will be much larger than the common braided strap. If you have composite blades and depend upon the graphite in the composite to conduct the charge then you have problems as with high current the composite ceases to be a conductor and it becomes an insulator and as such the blade will explode. I brought this to the attention of Agusta on the A-129. Most helicopters us common braided bonding straps on the rotor system to conduct static charges off the rotor system to the transmission and then to the airframe.
“On the S-76 family, we tried small static wicks on the tail to wick off the charge, but they did not seem to work and were removed”.
Response:
Perchance your engineering department should have contacted Dayton-Granger and they would have designed a proper system. According to their handbook it is necessary to determine the best location for the wicks as well as which wick is best for the application. Speaking of Dayton-Granger they designed four static dissipating antennas for the Blackhawk and they may be represented on the Comanche.
“For the dreaded Lu-Zuckerman-mythological-corona-that-can-be-seen-for-miles, grounding straps would have to extend to the earth to ground the static charge. I'll bet Lu has a friend's cousin's best man who used to sell this grounding strap”.
Response:
Once again, I must correct you, as I did not say the helicopters could be seen for miles so I can only assume this is your attempt at continuing sarcasm. Regarding the miles long grounding strap it is not needed as most wheeled helicopters (at least those that I am familiar with) have a stiff cable attached to the landing gear. This cable has a metal ferrule attached to it and this ferrule makes contact just before the wheels hit the ground. Go out to your helicopters and see if they have one. You addressed this problem in another thread saying that if the static charge is not dissipated with a grounded wand during cargo hook operations the man on the ground could get knocked on his ass. I responded that it is also true when making a hoist over water where the hook is dragged through the water so as not to render the man in the water unconscious. Now, I ask you, where do you think this high voltage charge comes from? The answer is the rotor. Now I ask you how this charge is drained from the rotor through the transmission on most helicopters? The answer is bonding straps. One more question. What if there is no means of draining the static charge off of the rotor and the charge keeps building? The answer is when it reaches the threshold of maximum charge for the conducting surface the charge will dissipate in the form of corona discharge.
“This thread and the one where Lu waxes about angles and 45 degree horns are both reduced to absurdity by Lu's ability to confuse himself”.
Response:
Discounting the S-76, where somebody screwed up in the design of the transmission casting, I suggest that you go out and look at every other Sikorsky on the parking lot. If Sikorsky design philosophy remained true, the servos will be offset by 45-degrees from the control axis and the pitch horns will have 45-degree lead ahead of the blade. What pray tell is wrong with me having said that in a previous post? Or, is this just another sarcastic remark to make you look good and me look bad?
[ 02 December 2001: Message edited by: Lu Zuckerman ]
“Grounding straps connect (electrically) the blades to the rest of the airframe, and are of little use to protect against static build-up, because the airframe is not grounded”!
Response: The primary purpose of the bonding straps, whether they be on the rotorhead or on a black box or transmission, is to ensure that the entire airframe is at the same electrical potential with this potential being primarily the result of precipitation static. If elements of the airframe to include all of the appliances contained within the airframe are not properly bonded they will create sparking due to the potential difference with this sparking having an effect on the electronic system. It can also cause electrical shocks if a person acts as the bonding between two un-bonded elements. Now these are not my words they are contained in the FAA certification documents for aircraft of all sizes.
“The grounding straps Lu keeps driveling about are used to protect the rotor from lightening strikes, where the charge will arc and cause local damage”.
If you have metal blades or composite blades that are designed to conduct the charge of a lightning strike the bonding straps must also be able to conduct the current developed during a lightning attachment to the blades. Conventional braided bonding straps cannot conduct these high current levels and when the lightning strike occurs the braided strap will most likely melt. If the primary purpose of the bonding straps is to conduct the high current then they will be much larger than the common braided strap. If you have composite blades and depend upon the graphite in the composite to conduct the charge then you have problems as with high current the composite ceases to be a conductor and it becomes an insulator and as such the blade will explode. I brought this to the attention of Agusta on the A-129. Most helicopters us common braided bonding straps on the rotor system to conduct static charges off the rotor system to the transmission and then to the airframe.
“On the S-76 family, we tried small static wicks on the tail to wick off the charge, but they did not seem to work and were removed”.
Response:
Perchance your engineering department should have contacted Dayton-Granger and they would have designed a proper system. According to their handbook it is necessary to determine the best location for the wicks as well as which wick is best for the application. Speaking of Dayton-Granger they designed four static dissipating antennas for the Blackhawk and they may be represented on the Comanche.
“For the dreaded Lu-Zuckerman-mythological-corona-that-can-be-seen-for-miles, grounding straps would have to extend to the earth to ground the static charge. I'll bet Lu has a friend's cousin's best man who used to sell this grounding strap”.
Response:
Once again, I must correct you, as I did not say the helicopters could be seen for miles so I can only assume this is your attempt at continuing sarcasm. Regarding the miles long grounding strap it is not needed as most wheeled helicopters (at least those that I am familiar with) have a stiff cable attached to the landing gear. This cable has a metal ferrule attached to it and this ferrule makes contact just before the wheels hit the ground. Go out to your helicopters and see if they have one. You addressed this problem in another thread saying that if the static charge is not dissipated with a grounded wand during cargo hook operations the man on the ground could get knocked on his ass. I responded that it is also true when making a hoist over water where the hook is dragged through the water so as not to render the man in the water unconscious. Now, I ask you, where do you think this high voltage charge comes from? The answer is the rotor. Now I ask you how this charge is drained from the rotor through the transmission on most helicopters? The answer is bonding straps. One more question. What if there is no means of draining the static charge off of the rotor and the charge keeps building? The answer is when it reaches the threshold of maximum charge for the conducting surface the charge will dissipate in the form of corona discharge.
“This thread and the one where Lu waxes about angles and 45 degree horns are both reduced to absurdity by Lu's ability to confuse himself”.
Response:
Discounting the S-76, where somebody screwed up in the design of the transmission casting, I suggest that you go out and look at every other Sikorsky on the parking lot. If Sikorsky design philosophy remained true, the servos will be offset by 45-degrees from the control axis and the pitch horns will have 45-degree lead ahead of the blade. What pray tell is wrong with me having said that in a previous post? Or, is this just another sarcastic remark to make you look good and me look bad?
[ 02 December 2001: Message edited by: Lu Zuckerman ]
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Lu,
You wormed around again! You used the bonding straps as a cure for the mythological-Lu-Zuckerman-glows-in-the-dark problem, now you completely forget about that.
The bonding straps are quite necessary, but unlike your original (now forgotten) thought, they have nothing to do with corona effects.
If you ever, ever stayed on the point, you'd have to admit you are wrong, so it is easier to change the argumant and keep it live.
You are a waste of electrons.
BTW, you easily say "screw up" about the S-76 transmission, because you are an ignoramous about that too. If any ppruner except you would like to know why that is not a screw-up,I will post it. You don't get the time of day.
You wormed around again! You used the bonding straps as a cure for the mythological-Lu-Zuckerman-glows-in-the-dark problem, now you completely forget about that.
The bonding straps are quite necessary, but unlike your original (now forgotten) thought, they have nothing to do with corona effects.
If you ever, ever stayed on the point, you'd have to admit you are wrong, so it is easier to change the argumant and keep it live.
You are a waste of electrons.
BTW, you easily say "screw up" about the S-76 transmission, because you are an ignoramous about that too. If any ppruner except you would like to know why that is not a screw-up,I will post it. You don't get the time of day.
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
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To: Nick Lappos
While you are at it, include the reasons why Sikorsky and you had to test three different sets of linkages in the mixing unit to compensate for the “Non Screw Up”. You told us about the testing of the various linkage set-ups in one of your posts but never told us why and someone else alluded to the screw-up in the casting and it was never denied.
The casting problem came out in a thread where a poster asked why there were the lumps in the fine lines of the S-76. One person indicated that the lumps were to accommodate the servos. Whether that is true or not, I can’t say however it was in that thread that the casting problem arose and it went back and forth and was never denied by you or any one else.
[ 02 December 2001: Message edited by: Lu Zuckerman ]
While you are at it, include the reasons why Sikorsky and you had to test three different sets of linkages in the mixing unit to compensate for the “Non Screw Up”. You told us about the testing of the various linkage set-ups in one of your posts but never told us why and someone else alluded to the screw-up in the casting and it was never denied.
The casting problem came out in a thread where a poster asked why there were the lumps in the fine lines of the S-76. One person indicated that the lumps were to accommodate the servos. Whether that is true or not, I can’t say however it was in that thread that the casting problem arose and it went back and forth and was never denied by you or any one else.
[ 02 December 2001: Message edited by: Lu Zuckerman ]
Join Date: May 2001
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Lu,
You want me to ask him where he worked, and in either example you gave, neither place either
1.Did not fly at night and..
2.Their helicopter type the Shar flew did not exhibit the effect.
So his response either way will be met by your "I told you so"
I don't get your question, it predicts the answer before asking the question.
You want me to ask him where he worked, and in either example you gave, neither place either
1.Did not fly at night and..
2.Their helicopter type the Shar flew did not exhibit the effect.
So his response either way will be met by your "I told you so"
I don't get your question, it predicts the answer before asking the question.
At the risk of feeding the troll, look up the dictionary for 'iconoclast'. 'Destroyer' and 'image breaker' are a couple of definitions, which should leave little or no doubt as to the reasoning behind the argumentative nature of most of the replies here.
Retreating to the "do not feed the troll" bunker
Retreating to the "do not feed the troll" bunker
Join Date: May 2001
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John, once again your'e right.
This is what i found on the www.helis.com/debate/2000.htm
[*]
Old Lu just can't help himself.... here comes the troll!!
Lu, Lu, Lu
[ 03 December 2001: Message edited by: sling load ]
[ 04 December 2001: Message edited by: sling load ]
This is what i found on the www.helis.com/debate/2000.htm
27 July 2000 19:39;38 from Lu Zuckerman
It is my contention that there is no such thing as retreating blade stall. what is your opinion
It is my contention that there is no such thing as retreating blade stall. what is your opinion
Old Lu just can't help himself.... here comes the troll!!
Lu, Lu, Lu
[ 03 December 2001: Message edited by: sling load ]
[ 04 December 2001: Message edited by: sling load ]
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
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To: John Eacott
I used the term Iconoclast as a joke as a result of all of the sarcastic s**t I have received on these threads.
To: sling load:
You can stop gloating. I put that on the web site in conjunction with a thread on Just Helicopters. It is still my contention that retreating blade stall can best be described as a differential of lift across the disc, which results in the disc flapping back. I have even made these comments on these threads. You can use this description and apply aerodynamic precession or gyroscopic precession but in my mind that is what is happening. The blades are not stalling, they are just generating less lift. If you want to call it retreating blade stall that’s OK with me as that is the accepted term but it still ends up being a differential of lift that causes the flapback / blowback.
I’ll use this illustration which I have used on these threads as well as on Just Helicopters.
If you believe that the retreating blade has stalled and further believe that individual blades stall and drop out of orbit and fall due to the stall then try to visualize this. Once the blade has stalled and dropped down over the tail (90-degrees later) it still is attached to a spinning rotorhead and must then immediately get back to the commanded tip path. That means that that blade when it is down over the tail it must fly up until it is now the advancing blade and, will end up being down over the nose, as this is the commanded tip path. If you were to look at the disc from the side of the helicopter the disc would scribe an inverted V or be just the opposite of the cone angle. Can you imagine the vibratory forces that would ensue if the blades had to change their position so radically at anywhere from 250 to 500 times per minute?
Now this may be difficult to comprehend but try to visualize the disc as a single entity. The basic premise in helicopter design is to have an equal distribution of lift across the disc. When the pilot moves his cyclic he alters the lift distribution across the disc and the disc tilts in the direction of cyclic movement. You can visualize this as aerodynamic precession and I think of it as gyroscopic precession. In either case there is a differential of lift across the disc.
In the case of retreating blade stall, the retreating side is generating less lift than the advancing side. This causes either a perturbation of the disc if you accept gyroscopic precession or it is a direct aerodynamic lift that responds 90-degrees later and the result is the disc blows back / flaps back.
I put the comment on the web to find out what other people thought on the subject.
I used the term Iconoclast as a joke as a result of all of the sarcastic s**t I have received on these threads.
To: sling load:
You can stop gloating. I put that on the web site in conjunction with a thread on Just Helicopters. It is still my contention that retreating blade stall can best be described as a differential of lift across the disc, which results in the disc flapping back. I have even made these comments on these threads. You can use this description and apply aerodynamic precession or gyroscopic precession but in my mind that is what is happening. The blades are not stalling, they are just generating less lift. If you want to call it retreating blade stall that’s OK with me as that is the accepted term but it still ends up being a differential of lift that causes the flapback / blowback.
I’ll use this illustration which I have used on these threads as well as on Just Helicopters.
If you believe that the retreating blade has stalled and further believe that individual blades stall and drop out of orbit and fall due to the stall then try to visualize this. Once the blade has stalled and dropped down over the tail (90-degrees later) it still is attached to a spinning rotorhead and must then immediately get back to the commanded tip path. That means that that blade when it is down over the tail it must fly up until it is now the advancing blade and, will end up being down over the nose, as this is the commanded tip path. If you were to look at the disc from the side of the helicopter the disc would scribe an inverted V or be just the opposite of the cone angle. Can you imagine the vibratory forces that would ensue if the blades had to change their position so radically at anywhere from 250 to 500 times per minute?
Now this may be difficult to comprehend but try to visualize the disc as a single entity. The basic premise in helicopter design is to have an equal distribution of lift across the disc. When the pilot moves his cyclic he alters the lift distribution across the disc and the disc tilts in the direction of cyclic movement. You can visualize this as aerodynamic precession and I think of it as gyroscopic precession. In either case there is a differential of lift across the disc.
In the case of retreating blade stall, the retreating side is generating less lift than the advancing side. This causes either a perturbation of the disc if you accept gyroscopic precession or it is a direct aerodynamic lift that responds 90-degrees later and the result is the disc blows back / flaps back.
I put the comment on the web to find out what other people thought on the subject.
Lu,
As this thread has turned into a protracted discussion on glowing helicopters, I have started a SEPERATE thread for Retreating Blade Stall (again!) and have transferred your comments there, so as not to obscurate the topic at hand.
Can we argue RBS on that thread, and leave this one to your glowing helicopter theory???
As this thread has turned into a protracted discussion on glowing helicopters, I have started a SEPERATE thread for Retreating Blade Stall (again!) and have transferred your comments there, so as not to obscurate the topic at hand.
Can we argue RBS on that thread, and leave this one to your glowing helicopter theory???
