coriolis effect & static droop
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Lu,
I am intrigued by your answer to my last post. Presumably we are merely using the same language in a different way?
How can a change in airflow over a rotor blade cause a gyroscopic force? In my understanding airflow over an aerofoil causes lift and drag, not gyroscopic forces.
I certainly agree that there are very large gyroscopic forces involved in a typical rotor system but occurring as a result of masses being rotated at speed and not as a result of blade pitch angle changes. Various (enormous!)figures have already been quoted.
My understanding (as a pilot with 22 years of rotary experience and much of that spent instructing) and that of the conventional British way of teaching is that the rotor disc is "steered" not "precessed" by using aerodynamic forces to overcome gyroscopic forces already acting. Aerodynamic and gyroscopic forces come to a compromise and what is left over gets fed back into the rotor head. If the resultant feedback of the two is too great for the pilot to handle then it is usual to design a hydraulic system to help him out.
My logic tells me that the relatively spindly pitch-change rods on a typical rotor head would be totally inadequate to apply sufficient precessional forces at an acceptable rate for purely gyroscopic control of a rotor disc, as would the pilot's own physical strength or the small hydraulic pump as typically used.
Maybe I am missing your drift due to us being from two different nations separated by a common language!
I am intrigued by your answer to my last post. Presumably we are merely using the same language in a different way?
How can a change in airflow over a rotor blade cause a gyroscopic force? In my understanding airflow over an aerofoil causes lift and drag, not gyroscopic forces.
I certainly agree that there are very large gyroscopic forces involved in a typical rotor system but occurring as a result of masses being rotated at speed and not as a result of blade pitch angle changes. Various (enormous!)figures have already been quoted.
My understanding (as a pilot with 22 years of rotary experience and much of that spent instructing) and that of the conventional British way of teaching is that the rotor disc is "steered" not "precessed" by using aerodynamic forces to overcome gyroscopic forces already acting. Aerodynamic and gyroscopic forces come to a compromise and what is left over gets fed back into the rotor head. If the resultant feedback of the two is too great for the pilot to handle then it is usual to design a hydraulic system to help him out.
My logic tells me that the relatively spindly pitch-change rods on a typical rotor head would be totally inadequate to apply sufficient precessional forces at an acceptable rate for purely gyroscopic control of a rotor disc, as would the pilot's own physical strength or the small hydraulic pump as typically used.
Maybe I am missing your drift due to us being from two different nations separated by a common language!
Guest
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As ever Lu you have failed to follow anyone elses logic but your own.
The reciprocating piston engine converts linear motion to rotary motion - the pistons move up and down accelerating then stopping because that is what they must do do rotate the crankshaft at a constant angular rate.
Even a schoolchild could understand the reverse of this process when a circular object rotating at constant angular rate converts this motion to vertical movement by accelerating then stopping a piston or a Pitch Operating Arm (back to the original point I think)
Yes the Lynx rolls to the left following the application of forward cyclic but only as a result of an acceleration cross couple and not the simple rigging error you attribute to the R22. The reason the Lynx fuselage reacts so quickly is due to the effective flapping hinge offset that gives it huge control power and is the secret of it's manoeuvrability (sorry, too many vowels in there for American readers).
The two helicopters you describe are different sizes but the important feature you fail to grasp is that of hinge offset. On a teetering head the flapping is allowed acroos the pivot of the rotor mast - on an articulated head the designers can put the flapping dragging and feathering hinges where they like. The hinge offset is where the flapping hinge is physically located expressed as a pecentage of the distance between the axis of rotation (rotor mast) and the blade tip. I suspect that despite the disparity in size, both your Sikorsky's have equivalent flapping hinge offsets that are probably quite small - therefore phase lag is very close to 90 degrees and the 45 + 45 combination of pitch horn lead and swashplate offset works well.
As hinge offset is increased the blades take less time to reach their high point approx 75 degrees in the case of the Lynx which has an effective (not physical because the flapping occurs in the titanium forging rather than an actual hinge) hinge offset of between 12 and 17% - the figure vary from book to book as there is more than one way to calculate effective hinge offset.
You could have left all that rubbish about rotary engines out as it proved exactly diddlysquat!
The reciprocating piston engine converts linear motion to rotary motion - the pistons move up and down accelerating then stopping because that is what they must do do rotate the crankshaft at a constant angular rate.
Even a schoolchild could understand the reverse of this process when a circular object rotating at constant angular rate converts this motion to vertical movement by accelerating then stopping a piston or a Pitch Operating Arm (back to the original point I think)
Yes the Lynx rolls to the left following the application of forward cyclic but only as a result of an acceleration cross couple and not the simple rigging error you attribute to the R22. The reason the Lynx fuselage reacts so quickly is due to the effective flapping hinge offset that gives it huge control power and is the secret of it's manoeuvrability (sorry, too many vowels in there for American readers).
The two helicopters you describe are different sizes but the important feature you fail to grasp is that of hinge offset. On a teetering head the flapping is allowed acroos the pivot of the rotor mast - on an articulated head the designers can put the flapping dragging and feathering hinges where they like. The hinge offset is where the flapping hinge is physically located expressed as a pecentage of the distance between the axis of rotation (rotor mast) and the blade tip. I suspect that despite the disparity in size, both your Sikorsky's have equivalent flapping hinge offsets that are probably quite small - therefore phase lag is very close to 90 degrees and the 45 + 45 combination of pitch horn lead and swashplate offset works well.
As hinge offset is increased the blades take less time to reach their high point approx 75 degrees in the case of the Lynx which has an effective (not physical because the flapping occurs in the titanium forging rather than an actual hinge) hinge offset of between 12 and 17% - the figure vary from book to book as there is more than one way to calculate effective hinge offset.
You could have left all that rubbish about rotary engines out as it proved exactly diddlysquat!
Guest
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Joe Pilot,
Just reread your post at top of this page - sorry I should have mentioned I was trying to keep things simple for Lu and only consider the effects of cyclic flapping without going into forward flight as the change in V2 would have complicated my argument. Very glad to see someone actually pays attention to my drivel!
Just reread your post at top of this page - sorry I should have mentioned I was trying to keep things simple for Lu and only consider the effects of cyclic flapping without going into forward flight as the change in V2 would have complicated my argument. Very glad to see someone actually pays attention to my drivel!
Guest
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>>(sorry, too many vowels in there for American readers).<<
I cannot help but feel hurt
Not all of us fall into that basket .... Some of us keep a dictionary in the loo just for reading
[This message has been edited by RW-1 (edited 28 January 2001).]
I cannot help but feel hurt
Not all of us fall into that basket .... Some of us keep a dictionary in the loo just for reading
[This message has been edited by RW-1 (edited 28 January 2001).]
Guest
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To: RW 1
I noticed that you pulled the plug on your 407 thread. Were you afraid if someone asked for my theory on why the tailrotor hit the fuselage and/or a theory on what would cause a blade to diverge from the plane of rotation and hit the fuselage that it would hijack you thread?
Regarding your comment about taking a dictionary to the loo it is obvious that you don’t avail yourself of its’ contents based on your spelling in your posts. Could it be that you use its' pages in place of toilet tissue. That was an attempt at humor/humour.
HeHeHe
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The Cat
[This message has been edited by Lu Zuckerman (edited 30 January 2001).]
I noticed that you pulled the plug on your 407 thread. Were you afraid if someone asked for my theory on why the tailrotor hit the fuselage and/or a theory on what would cause a blade to diverge from the plane of rotation and hit the fuselage that it would hijack you thread?
Regarding your comment about taking a dictionary to the loo it is obvious that you don’t avail yourself of its’ contents based on your spelling in your posts. Could it be that you use its' pages in place of toilet tissue. That was an attempt at humor/humour.
HeHeHe
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The Cat
[This message has been edited by Lu Zuckerman (edited 30 January 2001).]
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Lu Zuckerman: There should be a NOTAM for you, pilot wannabee.
I pulled the posts for reasons that are much too complex for your grey matter (based upon your history) to comprehend.
Your statement is yet another 6 year old goad, perhaps it will be pulled as well as the other crap you tried in another thread?
It is any wonder to you yet why my response stayed, but yours gets pulled?
Your going down your hole even further...
Dante himself now looks down upon you ...
And it is no suprise, your comments, I sent several members a likely response you would give when you found the thread gone, so far? I was right on.
No Lu, I pulled it because YOU failed to JUST give your theory on the tail strikes.
You wanted to banter about on whether one mishap was caused by it or the mains, instead of just addressing the AD, which was the purpose of MY thread.
A classic Hoverman example of you just posting to:
Hear yourself talk.
And start something with others.
There was no reason for it, and you have no excuse to account for it, again, your history preceeds you, and the others have already formed their opinions.
But as evident in your history here, you never just get to it, you strive to create ill will, illicit responses that you will no longer get from me.
Rather than subjecting this whole forum to yet another example of your driveling, I did everyone a favor and removed it.
If medals were given for letting others avoid you, I'd get the Congressional medal of honor for that move.
Your humor is as weak as your intellect, and you have already shown everyone the truth of that statement; all anyone has to do is read your priors.
I don't have to attack you any more LU, you do a better job of foiling yourself than I could ever dream of doing. I'm sure that irks you to no end, a lowly PPL seemingly getting better responses than the houty touty multi-degree engineer.
Truth is it's getting (or really gone past) the point where the real posters here just don't care what you have to say any more.
And the minority (would have been the majority 6 weeks ago, but not anymore)is getting smaller everyday.
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Marc
I pulled the posts for reasons that are much too complex for your grey matter (based upon your history) to comprehend.
Your statement is yet another 6 year old goad, perhaps it will be pulled as well as the other crap you tried in another thread?
It is any wonder to you yet why my response stayed, but yours gets pulled?
Your going down your hole even further...
Dante himself now looks down upon you ...
And it is no suprise, your comments, I sent several members a likely response you would give when you found the thread gone, so far? I was right on.
No Lu, I pulled it because YOU failed to JUST give your theory on the tail strikes.
You wanted to banter about on whether one mishap was caused by it or the mains, instead of just addressing the AD, which was the purpose of MY thread.
A classic Hoverman example of you just posting to:
Hear yourself talk.
And start something with others.
There was no reason for it, and you have no excuse to account for it, again, your history preceeds you, and the others have already formed their opinions.
But as evident in your history here, you never just get to it, you strive to create ill will, illicit responses that you will no longer get from me.
Rather than subjecting this whole forum to yet another example of your driveling, I did everyone a favor and removed it.
If medals were given for letting others avoid you, I'd get the Congressional medal of honor for that move.
Your humor is as weak as your intellect, and you have already shown everyone the truth of that statement; all anyone has to do is read your priors.
I don't have to attack you any more LU, you do a better job of foiling yourself than I could ever dream of doing. I'm sure that irks you to no end, a lowly PPL seemingly getting better responses than the houty touty multi-degree engineer.
Truth is it's getting (or really gone past) the point where the real posters here just don't care what you have to say any more.
And the minority (would have been the majority 6 weeks ago, but not anymore)is getting smaller everyday.
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Marc
Guest
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To: RW 1
“No Lu, I pulled it because YOU failed to JUST give your theory on the tail strikes”
Typical of your response to everything you obviously did not read what I stated in my post. I responded to your request for my theory on the tailboom strike and the possible main rotor strike. I ended my statement with, “any takers”. I expected to get a positive or a negative response. Some people may have been interested because of a vested interest in the 407. However before anybody could respond, you had pulled the thread.
“It is any wonder to you yet why my response stayed, but yours gets pulled”?
None of my responses were pulled. I removed them hoping to defuse the attacks on myself but nobody seemed to notice and the threads without my posts took on a life of their own where every body kept slagging me off as a person.
Now, I will ask you in the presence of all of the onlookers, do you want me to state my views and/or theories on what might have caused the tail boom strikes and the main rotor strike on the last 407 to crash? If you do, open a new thread, as I don’t want to be constantly reminded in my email that someone has responded on my thread. You can introduce the thread in your own inimitable fashion. You can even call it Lus’ Vues on the 407. The ball as they say, is in your court.
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The Cat
“No Lu, I pulled it because YOU failed to JUST give your theory on the tail strikes”
Typical of your response to everything you obviously did not read what I stated in my post. I responded to your request for my theory on the tailboom strike and the possible main rotor strike. I ended my statement with, “any takers”. I expected to get a positive or a negative response. Some people may have been interested because of a vested interest in the 407. However before anybody could respond, you had pulled the thread.
“It is any wonder to you yet why my response stayed, but yours gets pulled”?
None of my responses were pulled. I removed them hoping to defuse the attacks on myself but nobody seemed to notice and the threads without my posts took on a life of their own where every body kept slagging me off as a person.
Now, I will ask you in the presence of all of the onlookers, do you want me to state my views and/or theories on what might have caused the tail boom strikes and the main rotor strike on the last 407 to crash? If you do, open a new thread, as I don’t want to be constantly reminded in my email that someone has responded on my thread. You can introduce the thread in your own inimitable fashion. You can even call it Lus’ Vues on the 407. The ball as they say, is in your court.
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The Cat
Guest
Posts: n/a
>>. I responded to your request for my theory on the tailboom strike and the possible main rotor strike. <<
No, you did not. You offered to do so after 5-6 round and round semantic posts as to whether the latest mishap was related to the AD and whether the main rotor strike was the cause or secondary.
Are you so that wrapped up in yourself to believe that? My my, you truly are a piece of work.
Again, don't confuse yourself in your ongoing quest to hang yourself.
>>I removed them hoping to defuse the attacks on myself but nobody seemed to notice <<
And the reason is for the above, my posts on the top of page 4, 5 and above.
You figured out just how much that post weakened your already precarious position on the board, one step in the right direction, but don't expect anyone to believe you, as stated before and not by me, your credibility has lost a great deal.
There is no ball, if you had acted professionally to begin with, I wouldn't have had to pull the thread. Another 6 year old dare.
>>Typical of your response to everything you obviously did not read what I stated in my post. <<
This is yet anotheer LU' ism that hoverman failed to list in his imatation of you, you like to use that one way too much.
I believe you should use that on yourself anbd ask why you would continue to post here at all, ask why so many of your own supporters 6 weeeks ago are now as fed up with your posts as I?
Nothing more needs to be said, you don't get it, and never will unless someone put's it in a textbook for you.
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Marc
No, you did not. You offered to do so after 5-6 round and round semantic posts as to whether the latest mishap was related to the AD and whether the main rotor strike was the cause or secondary.
Are you so that wrapped up in yourself to believe that? My my, you truly are a piece of work.
Again, don't confuse yourself in your ongoing quest to hang yourself.
>>I removed them hoping to defuse the attacks on myself but nobody seemed to notice <<
And the reason is for the above, my posts on the top of page 4, 5 and above.
You figured out just how much that post weakened your already precarious position on the board, one step in the right direction, but don't expect anyone to believe you, as stated before and not by me, your credibility has lost a great deal.
There is no ball, if you had acted professionally to begin with, I wouldn't have had to pull the thread. Another 6 year old dare.
>>Typical of your response to everything you obviously did not read what I stated in my post. <<
This is yet anotheer LU' ism that hoverman failed to list in his imatation of you, you like to use that one way too much.
I believe you should use that on yourself anbd ask why you would continue to post here at all, ask why so many of your own supporters 6 weeeks ago are now as fed up with your posts as I?
Nothing more needs to be said, you don't get it, and never will unless someone put's it in a textbook for you.
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Marc
Guest
Posts: n/a
To: RW 1
I take that as a no. You don't want me to offer you my theories about what might have caused the latest accident. If you hadn’t pulled your thread you would be able to see that I did respond to your statements about the AD. It should have been obvious even for you that I could not tell you if the latest crash in the GOM related to the AD because they have not recovered the tail boom. I told you that the information letter offered the possibility that the AD did not go far enough and that the subject GOM crash could point out an entirely different problem that would be much greater than a tailboom strike.
[This message has been edited by Lu Zuckerman (edited 31 January 2001).]
[This message has been edited by Lu Zuckerman (edited 31 January 2001).]
I take that as a no. You don't want me to offer you my theories about what might have caused the latest accident. If you hadn’t pulled your thread you would be able to see that I did respond to your statements about the AD. It should have been obvious even for you that I could not tell you if the latest crash in the GOM related to the AD because they have not recovered the tail boom. I told you that the information letter offered the possibility that the AD did not go far enough and that the subject GOM crash could point out an entirely different problem that would be much greater than a tailboom strike.
[This message has been edited by Lu Zuckerman (edited 31 January 2001).]
[This message has been edited by Lu Zuckerman (edited 31 January 2001).]
Guest
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>>I take that as a no. You don't want me to offer you my theories about what might have caused the latest accident. <<
Is your middle name Gump? Damn, you are SLOW.
I wanted to discuss the AD, you wanted to banter, everyone who saw the thread knows it, but you seem to have forgotten.
Again, you admit it in your post above, you wanted to go beyond what the topic was about, and guess what? I didn't, nor to subject the forum to you rambling beyond the topis presented.
Get a clue before you post.
I won't have to edit this post, it says all.
(You can give yet another 6 year old answer, and have the last word if it makes you feel so important, I'm sure no one else cares to indulge you on this thread, have at it sparky!)
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Marc
Is your middle name Gump? Damn, you are SLOW.
I wanted to discuss the AD, you wanted to banter, everyone who saw the thread knows it, but you seem to have forgotten.
Again, you admit it in your post above, you wanted to go beyond what the topic was about, and guess what? I didn't, nor to subject the forum to you rambling beyond the topis presented.
Get a clue before you post.
I won't have to edit this post, it says all.
(You can give yet another 6 year old answer, and have the last word if it makes you feel so important, I'm sure no one else cares to indulge you on this thread, have at it sparky!)
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Marc
Guest
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To: RW 1
My comment, (I take that as a no) was not indicative of my brain capacity but it was a measure of yours. I take that as a no, is very often used in comedy routines and it past you in a flash. I put it in there as another means of pulling your chain. Now since you don’t want to hear my theories on what may have caused the previous and the latest 407 accidents then maybe some 407 drivers might be interested if only for a laugh. Lets see how you reply to this post and how many times you refer to me as 6 year old.
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The Cat
My comment, (I take that as a no) was not indicative of my brain capacity but it was a measure of yours. I take that as a no, is very often used in comedy routines and it past you in a flash. I put it in there as another means of pulling your chain. Now since you don’t want to hear my theories on what may have caused the previous and the latest 407 accidents then maybe some 407 drivers might be interested if only for a laugh. Lets see how you reply to this post and how many times you refer to me as 6 year old.
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The Cat
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Lu:
You are displaying the classic behaviour of a stalker. This thread is about coriolis effect and static droop, yet you seem to be following RW-1 from thread to thread hounding him about the 407.
Hmmm? is there a trend here?
Cheers, OffshoreIgor
You are displaying the classic behaviour of a stalker. This thread is about coriolis effect and static droop, yet you seem to be following RW-1 from thread to thread hounding him about the 407.
Hmmm? is there a trend here?
Cheers, OffshoreIgor
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To: Ofshoreigor
Short of starting a thread to get RW 1s attention I take advantage of this being an open forum and post where I know he is. Now, on the other hand why don’t you chastise him for doing the same thing? As they say, tit for tat whatever a tit and a tat are. Now that I have your attention can you please tell me what IMHO and its’ variants mean. This must either be a British contraction or, it started on these threads long before I joined.
Your response will be appreciated.
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The Cat
Short of starting a thread to get RW 1s attention I take advantage of this being an open forum and post where I know he is. Now, on the other hand why don’t you chastise him for doing the same thing? As they say, tit for tat whatever a tit and a tat are. Now that I have your attention can you please tell me what IMHO and its’ variants mean. This must either be a British contraction or, it started on these threads long before I joined.
Your response will be appreciated.
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The Cat
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For that matter there is a trend Lu Zuckerman fails to realize:
He has many people on all the threads he gets involved with on the open forum who end up hoping he would just leave.
>>I put it in there as another means of pulling your chain.<<
On ANY other open forum I have moderated or particapated in, that statement would be followed by your banishment.
Grow up already and realize no one enjoys your presence here anymore.
If a vote was taken for who to leave, you or I, I would abide by the results.
I seriously doubt you think could.
But I pity you, because obviously, if you left here you wouldn't have anywhere to go.
Other forums such as heli's only have thrown you off, engineer forums would throw you off within 2 weeks, etc. For someone who does analysis, you repetedly fail to recognize the "Lu be gone" pattern you bring upon yourself.
[This message has been edited by RW-1 (edited 31 January 2001).]
He has many people on all the threads he gets involved with on the open forum who end up hoping he would just leave.
>>I put it in there as another means of pulling your chain.<<
On ANY other open forum I have moderated or particapated in, that statement would be followed by your banishment.
Grow up already and realize no one enjoys your presence here anymore.
If a vote was taken for who to leave, you or I, I would abide by the results.
I seriously doubt you think could.
But I pity you, because obviously, if you left here you wouldn't have anywhere to go.
Other forums such as heli's only have thrown you off, engineer forums would throw you off within 2 weeks, etc. For someone who does analysis, you repetedly fail to recognize the "Lu be gone" pattern you bring upon yourself.
[This message has been edited by RW-1 (edited 31 January 2001).]
Guest
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If you don't know what IMHO is, it is because you lack the H.
Right now I'm ROTFLMAO, there will be others.
It's a standard internet acronym, easily available on any website that lists them, possibly why you can't find it.
"Run Forrest ... Run!"
[This message has been edited by RW-1 (edited 31 January 2001).]
Right now I'm ROTFLMAO, there will be others.
It's a standard internet acronym, easily available on any website that lists them, possibly why you can't find it.
"Run Forrest ... Run!"
[This message has been edited by RW-1 (edited 31 January 2001).]