Aerodynamics ~ Coriolis
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dave, coriolis affect happends when the blade tip moves closer to the centre of rotation. coning blades both spin up together but flaping blades accellerate individualy therefore neading lead/lag dampers
Iconoclast
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To: Sling Load
In my original call to Ray Prouty regarding the R-22 18-degre offset we discussed gyroscopic precession and whether the Robbie had a 72-degree phase angle due to pitch flap coupling. He indicated that there was gyroscopic precession and I was going to call him later about the 18-degree offset and whether it would effect recovery from zero G. I never made the second call because of all of the S**T I got when I stated in this forum that I had contacted Ray Prouty. And because of that S**T barrage I decided to have the Robbie test performed. Please do not judge me by the comments made by those individuals that really don’t know or those that use their position of prominence to attack me personally.
In my original call to Ray Prouty regarding the R-22 18-degre offset we discussed gyroscopic precession and whether the Robbie had a 72-degree phase angle due to pitch flap coupling. He indicated that there was gyroscopic precession and I was going to call him later about the 18-degree offset and whether it would effect recovery from zero G. I never made the second call because of all of the S**T I got when I stated in this forum that I had contacted Ray Prouty. And because of that S**T barrage I decided to have the Robbie test performed. Please do not judge me by the comments made by those individuals that really don’t know or those that use their position of prominence to attack me personally.
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Lu,
I don't beleive youve quite got the jist of the comments made by myself and others. You are making comments about things that you think you know something about, thats the problem.
If you stay in your area of expertise, I doubt anyone would question your experience on the projects you have undertaken. You rely on your memory and stories which, may make nice fireside reading, are full of flawed theories. Concepts of understanding are another thing, if you beleive it works that way, fine, but don't tell professionals in their field they are wrong, you simply stray off course.
I don't beleive anyone attacks you personally, youve just gotta accept when youre wrong, aerodynamics and physics just get in your way, and when it suits you, they are your ally.
You can't have it both ways.
I don't beleive youve quite got the jist of the comments made by myself and others. You are making comments about things that you think you know something about, thats the problem.
If you stay in your area of expertise, I doubt anyone would question your experience on the projects you have undertaken. You rely on your memory and stories which, may make nice fireside reading, are full of flawed theories. Concepts of understanding are another thing, if you beleive it works that way, fine, but don't tell professionals in their field they are wrong, you simply stray off course.
I don't beleive anyone attacks you personally, youve just gotta accept when youre wrong, aerodynamics and physics just get in your way, and when it suits you, they are your ally.
You can't have it both ways.
Iconoclast
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To: All and Nick if you are monitoring the thread
I contacted the Sikorsky service department (203-386-3407) and asked them about centrifugal forces were more important than centripetal forces in the design of the rotorhead. He told me that there was a very good explanation in the Blue Bible of centrifugal forces and how these forces effected the operation of the rotorhead.. I laughed and told him that Nick Lappos indicated that I was technically unsophisticated in referencing the Blue Bible when discussing an engineering problem and then he laughed. He suggested that I send an email to the department and they would get an answer.
Here is the email message:
Gentlemen:
I have a technical question. I participate in a technical forum dealing with helicopters and on several occasions I referenced the Sikorsky Helicopter Flight Theory for Pilots and Mechanics and the subject matter dealt with gyroscopic precession and the use of the term centrifugal force. One of your test pilots also participates on this forum and he chided me saying that I was technically unsophisticated for using this book in a discussion of engineering principles. I spoke with Mr. Robert McFarland of your organization and he suggested I send the request via email.
My question is, when Sikorsky engineers design a rotorhead are they more concerned with centripetal forces in calculating stress levels on the head or, are they more concerned with centrifugal forces?
I would appreciate a rapid response if possible, as this is an ongoing discussion on the forum.
I contacted the Sikorsky service department (203-386-3407) and asked them about centrifugal forces were more important than centripetal forces in the design of the rotorhead. He told me that there was a very good explanation in the Blue Bible of centrifugal forces and how these forces effected the operation of the rotorhead.. I laughed and told him that Nick Lappos indicated that I was technically unsophisticated in referencing the Blue Bible when discussing an engineering problem and then he laughed. He suggested that I send an email to the department and they would get an answer.
Here is the email message:
Gentlemen:
I have a technical question. I participate in a technical forum dealing with helicopters and on several occasions I referenced the Sikorsky Helicopter Flight Theory for Pilots and Mechanics and the subject matter dealt with gyroscopic precession and the use of the term centrifugal force. One of your test pilots also participates on this forum and he chided me saying that I was technically unsophisticated for using this book in a discussion of engineering principles. I spoke with Mr. Robert McFarland of your organization and he suggested I send the request via email.
My question is, when Sikorsky engineers design a rotorhead are they more concerned with centripetal forces in calculating stress levels on the head or, are they more concerned with centrifugal forces?
I would appreciate a rapid response if possible, as this is an ongoing discussion on the forum.
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Lu, to be fair I think you should have included either a link to PPRuNe, or a sense of the level of the discussion.
We weren't discussing basics, or fudged over details, or "it's close enough to be able to fix or fly the helicopter". We were all being excessively meticulous, concerned with some of the finer details.
In that sense, Nick was right. The "Blue Book" (I've never read it) is quite likely technically unsophisticated. Doesn't mean there's anything inherently wrong with that book. It's just analogous to quoting "Budgie, the Helicopter" in this discussion.
_____________
Nick, I'm sure we'd all be interested to eavesdrop in the coffee room when this gets passed around Sikorsky. Try and write down some of the better ones, for our amusement.
We weren't discussing basics, or fudged over details, or "it's close enough to be able to fix or fly the helicopter". We were all being excessively meticulous, concerned with some of the finer details.
In that sense, Nick was right. The "Blue Book" (I've never read it) is quite likely technically unsophisticated. Doesn't mean there's anything inherently wrong with that book. It's just analogous to quoting "Budgie, the Helicopter" in this discussion.
_____________
Nick, I'm sure we'd all be interested to eavesdrop in the coffee room when this gets passed around Sikorsky. Try and write down some of the better ones, for our amusement.
Iconoclast
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To: heedm
No matter how technical this thread is and who is quoting from an engineering text or from the Blue Book it all boils down to this. In the real world what do rotorhead designers work with (centripetal or centrifugal forces) That’s it, bottom line.
I’ll say it again if centrifugal force is a non force and centripetal force is a real force then which one does the designer use in calculating the stress on the rotorhead. Centripetal force would not exist if there were no centrifugal force. Centripetal force is the reaction to centrifugal force. The work performed by centripetal force on the rotorhead is to restrain the blades (of course the rotorhead attachments are in this equation as well). The work performed by centrifugal force is to balance out the lifting forces so that the blades don’t fly up. So both forces are real but in the case of centripetal force it is calculated based on the centrifugal force and it is the rotorhead that is doing the work. To sum it all up, centripetal force is not a force it is like a scale measuring the forces imposed on the rotorhead by the centrifugal force generated by the blades.
No matter how technical this thread is and who is quoting from an engineering text or from the Blue Book it all boils down to this. In the real world what do rotorhead designers work with (centripetal or centrifugal forces) That’s it, bottom line.
I’ll say it again if centrifugal force is a non force and centripetal force is a real force then which one does the designer use in calculating the stress on the rotorhead. Centripetal force would not exist if there were no centrifugal force. Centripetal force is the reaction to centrifugal force. The work performed by centripetal force on the rotorhead is to restrain the blades (of course the rotorhead attachments are in this equation as well). The work performed by centrifugal force is to balance out the lifting forces so that the blades don’t fly up. So both forces are real but in the case of centripetal force it is calculated based on the centrifugal force and it is the rotorhead that is doing the work. To sum it all up, centripetal force is not a force it is like a scale measuring the forces imposed on the rotorhead by the centrifugal force generated by the blades.
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Lu, you're so utterly wrong you're humiliating yourself.
_______________
If there is both then the forces would cancel and nothing is holding the blades on or balancing the lift.
IF you think the blade isn't moving you have to put in a centrifugal force to make things work.
IF you realize the blade is turning, then you don't need to add imaginary forces to make things work.
I don't mind if you want to keep this up. The more you stay stuck on your line of thinking the more others imagine you to be a fool.
Matthew.
_______________
If there is both then the forces would cancel and nothing is holding the blades on or balancing the lift.
IF you think the blade isn't moving you have to put in a centrifugal force to make things work.
IF you realize the blade is turning, then you don't need to add imaginary forces to make things work.
I don't mind if you want to keep this up. The more you stay stuck on your line of thinking the more others imagine you to be a fool.
Matthew.
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To vorticey :
I agree with all you say. This thread was done as a mind game to provoke thought about the concept of a cyclical type of Coriolis.
Perhaps my earlier description was not clear enough. For the fun of it, envision the situation of helicopter flying at night. Every one of the blades has a light at its tip. There is a camera mounted 50 feet below the craft and pointed straight up at the rotor disk. Looking at the camera monitor during level flight will show a circular ring of light.
If this helicopter was then to be put in a sustained roll for a few seconds, the circular ring will now appear as an ellipse. To me, this could be an example of a temporary or cyclical Coriolis.
In a teetering rotor, the knuckle joint is handling the rotational acceleration/deceleration between the blades and the mast. In a flapping rotor, the lead-lag is handling it.
[ 01 December 2001: Message edited by: Dave Jackson ]
I agree with all you say. This thread was done as a mind game to provoke thought about the concept of a cyclical type of Coriolis.
Perhaps my earlier description was not clear enough. For the fun of it, envision the situation of helicopter flying at night. Every one of the blades has a light at its tip. There is a camera mounted 50 feet below the craft and pointed straight up at the rotor disk. Looking at the camera monitor during level flight will show a circular ring of light.
If this helicopter was then to be put in a sustained roll for a few seconds, the circular ring will now appear as an ellipse. To me, this could be an example of a temporary or cyclical Coriolis.
In a teetering rotor, the knuckle joint is handling the rotational acceleration/deceleration between the blades and the mast. In a flapping rotor, the lead-lag is handling it.
[ 01 December 2001: Message edited by: Dave Jackson ]
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heedm,
I find Leishman's book to be excellent--it's my personal favorite. It is a bit expensive, but no more so than some of the others ($US95 from B&N I think). It doesn't cover _all_ the intricacies of some of our discussions though, but it's still great.
Lu,
"...He indicated that there was gyroscopic precession and I was going to call him later about the 18-degree offset and whether it would effect recovery from zero G."
I still have the feeling that he wasn't familiar with the head and assumed it to be like that on the 206 (link-horn connection in-line with teetering hinge). Some of your descriptions make it seem like the swashplate input links are phased wrong, and that this is the sole cause of all the problems.
"I never made the second call because of all of the S**T I got when I stated in this forum that I had contacted Ray Prouty. And because of that S**T barrage I decided to have the Robbie test performed."
So are you really interested in learning any of this, or do you just like to b!tch on this forum?? If you'd have called and spoken with him again, perhaps he could have explained it to you. Instead, you continue to argue your point with no new knowledge. If you call him, you don't have to tell us about it--you can just use it to educate yourself. As I've said before, a simple test as you describe will not prove your point, regardless of what the results may _appear_ to show.
"Please do not judge me by the comments made by those individuals that really don’t know or those that use their position of prominence to attack me personally."
I think 'your' comments alone are what most people use to judge your lack of understanding.
I find Leishman's book to be excellent--it's my personal favorite. It is a bit expensive, but no more so than some of the others ($US95 from B&N I think). It doesn't cover _all_ the intricacies of some of our discussions though, but it's still great.
Lu,
"...He indicated that there was gyroscopic precession and I was going to call him later about the 18-degree offset and whether it would effect recovery from zero G."
I still have the feeling that he wasn't familiar with the head and assumed it to be like that on the 206 (link-horn connection in-line with teetering hinge). Some of your descriptions make it seem like the swashplate input links are phased wrong, and that this is the sole cause of all the problems.
"I never made the second call because of all of the S**T I got when I stated in this forum that I had contacted Ray Prouty. And because of that S**T barrage I decided to have the Robbie test performed."
So are you really interested in learning any of this, or do you just like to b!tch on this forum?? If you'd have called and spoken with him again, perhaps he could have explained it to you. Instead, you continue to argue your point with no new knowledge. If you call him, you don't have to tell us about it--you can just use it to educate yourself. As I've said before, a simple test as you describe will not prove your point, regardless of what the results may _appear_ to show.
"Please do not judge me by the comments made by those individuals that really don’t know or those that use their position of prominence to attack me personally."
I think 'your' comments alone are what most people use to judge your lack of understanding.
Iconoclast
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To: Kyrillian
“I still have the feeling that he wasn't familiar with the head and assumed it to be like that on the 206 (link-horn connection in-line with teetering hinge). Some of your descriptions make it seem like the swashplate input links are phased wrong, and that this is the sole cause of all the problems”.
Regarding Ray Proutys’ understanding of the Robinson head he wrote an article on it in the AHS technical forum. I also believe he had some involvement in the early design.
Regarding the swashplate input links I have no problem as they cause the swashplate to operate just like on a two blade Bell. Push the cyclic forward and the front end goes down over the nose and the back end goes up over the tail. The similarities between the Robinson and the Bell stop at that point.
On the Bell when the blade is disposed over the lateral axis and cyclic is pushed forward the pitch horn which is 90-degrees ahead of the blade causes the blade angle to be at its’ lowest point. Conversely the other blade is at the highest pitch. Precession causes the blades to flap down over the nose and up over the tail.
On the Robinson with the blades disposed in the same manner and forward cyclic is pushed the front of the swashplate will move down just like the Bell. The Robinson blade will not be at its’ lowest pitch like the Bell. The blade will have to travel another 18-degrees until it is at its’ lowest pitch. The Bell is rigged for forward cyclic with the blades disposed as above over the lateral axis. The Robinson blade is advance 18-degrees from that position in order to establish forward cyclic settings but I’m sure you were well aware of that fact. I’m also sure that Ray Prouty is also aware of it as well.
On the infamous Robinson (Cantrell) web site they show a Robinson head and address gyroscopic precession. When you get to the explanation they have an illustration addressing precession on the Robinson but the illustration is for a Bell swashplate. Now if you look above at the positioning of the blades on both helicopters the inputs are wrong for the Robinson because it implys that the Robinson has a 90-degree phase angle. If it does the blade will dip down and to the left with forward cyclic. However Nick sez that pitch flap coupling will cause the blade to respond in 72-degrees as opposed to 90-degrees.
Now I think If I am correct about the offset the test will prove it, contrary to what you might think.
You have access to a 206 and a Robinson. Perform this test. On both helicopters place the blade over the longitudinal axis. Move the cyclic forward from the rigged neutral position. The Bell blades will not move but the Robinson blades will. Now advance the Robinson blades until the pitch horns are directly above the lateral axis. Move the stick forward and backward from the rigged neutral position and the blades will not move.
Now I don’t have your educational background but I have always been told that with maximum change in cyclic pitch the blades will respond 90-degrees later. If what Nick said and Frank Robinson alluded to by saying it was too technical to explain to non engineers and pilots then I am wrong and all of my instructors and engineers that I have worked with are also wrong.
“I still have the feeling that he wasn't familiar with the head and assumed it to be like that on the 206 (link-horn connection in-line with teetering hinge). Some of your descriptions make it seem like the swashplate input links are phased wrong, and that this is the sole cause of all the problems”.
Regarding Ray Proutys’ understanding of the Robinson head he wrote an article on it in the AHS technical forum. I also believe he had some involvement in the early design.
Regarding the swashplate input links I have no problem as they cause the swashplate to operate just like on a two blade Bell. Push the cyclic forward and the front end goes down over the nose and the back end goes up over the tail. The similarities between the Robinson and the Bell stop at that point.
On the Bell when the blade is disposed over the lateral axis and cyclic is pushed forward the pitch horn which is 90-degrees ahead of the blade causes the blade angle to be at its’ lowest point. Conversely the other blade is at the highest pitch. Precession causes the blades to flap down over the nose and up over the tail.
On the Robinson with the blades disposed in the same manner and forward cyclic is pushed the front of the swashplate will move down just like the Bell. The Robinson blade will not be at its’ lowest pitch like the Bell. The blade will have to travel another 18-degrees until it is at its’ lowest pitch. The Bell is rigged for forward cyclic with the blades disposed as above over the lateral axis. The Robinson blade is advance 18-degrees from that position in order to establish forward cyclic settings but I’m sure you were well aware of that fact. I’m also sure that Ray Prouty is also aware of it as well.
On the infamous Robinson (Cantrell) web site they show a Robinson head and address gyroscopic precession. When you get to the explanation they have an illustration addressing precession on the Robinson but the illustration is for a Bell swashplate. Now if you look above at the positioning of the blades on both helicopters the inputs are wrong for the Robinson because it implys that the Robinson has a 90-degree phase angle. If it does the blade will dip down and to the left with forward cyclic. However Nick sez that pitch flap coupling will cause the blade to respond in 72-degrees as opposed to 90-degrees.
Now I think If I am correct about the offset the test will prove it, contrary to what you might think.
You have access to a 206 and a Robinson. Perform this test. On both helicopters place the blade over the longitudinal axis. Move the cyclic forward from the rigged neutral position. The Bell blades will not move but the Robinson blades will. Now advance the Robinson blades until the pitch horns are directly above the lateral axis. Move the stick forward and backward from the rigged neutral position and the blades will not move.
Now I don’t have your educational background but I have always been told that with maximum change in cyclic pitch the blades will respond 90-degrees later. If what Nick said and Frank Robinson alluded to by saying it was too technical to explain to non engineers and pilots then I am wrong and all of my instructors and engineers that I have worked with are also wrong.
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Lu,
Why not contact you "friend" Ray Prouty and ask him to explain phase lag. While you're on the phone why not ask himw to explain why it is that one particularly well known book "Helicopter Performance Stability and Control" ISBN 0-89464-929-9 in the chapter "Rotor flapping characteristics" discusses phase lags less than 90 degrees for rotor with hinge offset. Better still contact the writer - Ray Prouty.
Why not contact you "friend" Ray Prouty and ask him to explain phase lag. While you're on the phone why not ask himw to explain why it is that one particularly well known book "Helicopter Performance Stability and Control" ISBN 0-89464-929-9 in the chapter "Rotor flapping characteristics" discusses phase lags less than 90 degrees for rotor with hinge offset. Better still contact the writer - Ray Prouty.
Iconoclast
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To: Grey Area
That is what Mr. Prouty said in an engineering text. Now let’s look at real life. On the Sikorsky heads (other than the S-76) the pitch horn leads the blade by 45-degrees. The maximum deflection of the swash plate is 45-degrees ahead of the commanded direction. That is, if the pilot pushes forward cyclic the swashplate will deflect downward 45-degrees ahead of the longitudinal axis. That means that when a blade is disposed over the right side and in alignment with the lateral axis the blade will have the greatest amount of pitch removed from it. The blade on the opposite side assuming a 4-blade system has the greatest amount of pitch added to it. With precession the blades will move downward over the nose and up over the tail. Now in my book 45 + 45 = 90. Other helicopters (Aerospatial) have a similar phase lag (angle) of 90-degrees but the numbers are 60 + 30 = 90. Now from an aerodynamic point of view the blades may not respond in 90-degrees and this is allowed in the certification documents, which state that the blades should move in the same sense as cyclic input. However they allow a deviation of several degrees as a result of coupling. This deviation can be compensated for by cyclic input. Maybe this is what Mr. Prouty was alluding to in his book. The only helicopter that I know of that has an offset hinge (cone hinge) that does not have a phase angle of 90-degrees is the Robinson. That is if you accept that pitch flap coupling will effect the 72-degree phase angle and make it respond like a 90-degree phase angle.
That is what Mr. Prouty said in an engineering text. Now let’s look at real life. On the Sikorsky heads (other than the S-76) the pitch horn leads the blade by 45-degrees. The maximum deflection of the swash plate is 45-degrees ahead of the commanded direction. That is, if the pilot pushes forward cyclic the swashplate will deflect downward 45-degrees ahead of the longitudinal axis. That means that when a blade is disposed over the right side and in alignment with the lateral axis the blade will have the greatest amount of pitch removed from it. The blade on the opposite side assuming a 4-blade system has the greatest amount of pitch added to it. With precession the blades will move downward over the nose and up over the tail. Now in my book 45 + 45 = 90. Other helicopters (Aerospatial) have a similar phase lag (angle) of 90-degrees but the numbers are 60 + 30 = 90. Now from an aerodynamic point of view the blades may not respond in 90-degrees and this is allowed in the certification documents, which state that the blades should move in the same sense as cyclic input. However they allow a deviation of several degrees as a result of coupling. This deviation can be compensated for by cyclic input. Maybe this is what Mr. Prouty was alluding to in his book. The only helicopter that I know of that has an offset hinge (cone hinge) that does not have a phase angle of 90-degrees is the Robinson. That is if you accept that pitch flap coupling will effect the 72-degree phase angle and make it respond like a 90-degree phase angle.
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dave
>If this helicopter was then to be put in a sustained roll for a few seconds, the circular ring will now appear as an ellipse. To me, this could be an example of a temporary or cyclical Coriolis.
teetering head, no, the camera must be moved with the spining axes therefore the light would be a circle still.
rigid, mmmmm, i think it would be almost the same, the camera must be moved perpendicular to the spinning axes not just 50ft below the air craft.
>If this helicopter was then to be put in a sustained roll for a few seconds, the circular ring will now appear as an ellipse. To me, this could be an example of a temporary or cyclical Coriolis.
teetering head, no, the camera must be moved with the spining axes therefore the light would be a circle still.
rigid, mmmmm, i think it would be almost the same, the camera must be moved perpendicular to the spinning axes not just 50ft below the air craft.
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To vorticey:
> teetering head, no, the camera must be moved with the spinning axes therefore the light would be a circle still. <
The camera is rigidly attached to the fuselage and is located directly below the mast. It is therefor on the mast axis (i.e. 'rotor hub plane'). The tip lights are on the circumference of the 'tip path plane'. When the 'tip path plane' tilts in respect to the 'rotor hub plane' the circle will appear as an ellipse. To take this to a ludicrous extreme, if the disk was tilted 90-degrees then the camera would see a straight line. (i.e. the edge of the disk.)
This 'narrowing' of the circle can be equated, in a cyclical context, with a reduction in the diameter of the circle due to increased coning.
I think.
> teetering head, no, the camera must be moved with the spinning axes therefore the light would be a circle still. <
The camera is rigidly attached to the fuselage and is located directly below the mast. It is therefor on the mast axis (i.e. 'rotor hub plane'). The tip lights are on the circumference of the 'tip path plane'. When the 'tip path plane' tilts in respect to the 'rotor hub plane' the circle will appear as an ellipse. To take this to a ludicrous extreme, if the disk was tilted 90-degrees then the camera would see a straight line. (i.e. the edge of the disk.)
This 'narrowing' of the circle can be equated, in a cyclical context, with a reduction in the diameter of the circle due to increased coning.
I think.
I love these big Lu calls. Here it is:
From a man whom quotes Ray Prouty in an alledged conversation as entirely backing up his arguements, a man whom continually uses selective (basic) publications to justify scientific arguement, a man whom has just been disproven by Ray Prouty in a book:
Lu says: >>That is what Mr. Prouty said in an engineering text. Now let’s look at real life.<<
I LOVE THE INTERNET. This is why I keep reading pprune. Any efforts to have Lu removed should bear in mind that this place will be far less humourous.
Go Lu.
From a man whom quotes Ray Prouty in an alledged conversation as entirely backing up his arguements, a man whom continually uses selective (basic) publications to justify scientific arguement, a man whom has just been disproven by Ray Prouty in a book:
Lu says: >>That is what Mr. Prouty said in an engineering text. Now let’s look at real life.<<
I LOVE THE INTERNET. This is why I keep reading pprune. Any efforts to have Lu removed should bear in mind that this place will be far less humourous.
Go Lu.
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Lu would be fine if he just occasionally qualified his outrageous accusations with the 'IMHO' or sometimes said : "I have learnt so much about a topic which I now realise I knew so little about - thanks for the education" or some such.
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That is what Mr. Prouty said in an engineering text. Now let’s look at real life.
The above quoted statement seems to only apply in "Lu Land" ...
The expected follow up will be coming;
"You misunderstood what I said..."
or
"What I meant to say was..."
Unfortunately while very funny, there is no room for error on that gaff.
Man, this is fun watching just what he'll say next...
[ 03 December 2001: Message edited by: RW-1 ]
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No need to bash Lu. He stuck to his theories for a long time, but did ultimately admit that what we were describing made sense.
Taking a small bit of knowledge and satisfying yourself with it is not unprecedented.
I, for one, enjoy being challenged to explain something clearly. The questions he posed did challenge me and did inspire a lot of postings on these threads.
Taking a small bit of knowledge and satisfying yourself with it is not unprecedented.
"I know not how I seem to others, but to myself I am but a small child wandering upon the vast shores of knowledge, every now and then finding a small bright pebble to content myself with while the vast ocean of undiscovered truth lay before me" -- Isaac Newton
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Lu,
The phase lag can be easily calculated, here are some approximations I did earlier (couldn't get accurate Lock numbers for the blades so assumed 8, thus the margin of error is 3 deg).
AS332 - 83 deg
SA365 - 83 deg
UH60 - 82 deg
S76 - 84 deg
WG30 - 63 deg
BO105 - 59 deg
Not a 90 deg among them! Now as to your comment about Mr Prouty and the real world - why not ask some pilots? You could always listen to the answers as well!
The phase lag can be easily calculated, here are some approximations I did earlier (couldn't get accurate Lock numbers for the blades so assumed 8, thus the margin of error is 3 deg).
AS332 - 83 deg
SA365 - 83 deg
UH60 - 82 deg
S76 - 84 deg
WG30 - 63 deg
BO105 - 59 deg
Not a 90 deg among them! Now as to your comment about Mr Prouty and the real world - why not ask some pilots?
You could always listen to the answers as well!
Join Date: Jan 2001
Location: AB, Canada
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Grey Area, could you post the hinge offsets for each of those types? Where do those numbers come from? Flight test? Are they specific to a certain flight regime? If so how much do they change?
A lot of questions. If you have the data for the first, I'd really appreciate it. Thanks.
A lot of questions. If you have the data for the first, I'd really appreciate it. Thanks.