Flight Dynamics: The Swashplate and Phase-angle
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New simulation challenge
To be shure
fly 100 knots , push full left peddle and see what happens ...
I tried this at 40 knots and this was refreshing, but then again I am not a test pilot.
So after showing the wee-wa and fase shift stuff, the simulator starts flying quite well, so I ll try it in the virtual world and give you one of these egg-head graphs. For the time being I'll entertain the guys in the bar with an engineering plot that may have some esthetic appeal. (R44 drag curves in vertical autorotation)
Delta3
fly 100 knots , push full left peddle and see what happens ...
I tried this at 40 knots and this was refreshing, but then again I am not a test pilot.
So after showing the wee-wa and fase shift stuff, the simulator starts flying quite well, so I ll try it in the virtual world and give you one of these egg-head graphs. For the time being I'll entertain the guys in the bar with an engineering plot that may have some esthetic appeal. (R44 drag curves in vertical autorotation)
Delta3
Please, do not try some of these crazy manoeuvres that are being talked about on this thread. Fly the aircraft as per the Flight Manual and normal flying practice: this precludes flying at 40 or 100 kts and making a full pedal input.
In the test flying world we take cautious and progressive steps towards defining a flight envelope. It's there to protect.
'All Aircraft Bite Fools'. A good saying, remember?
We've had the same stupid comments, regarding amateur investigation of Handling Qualities, on earlier threads about the R22 rotorhead and I think I've made the same suggestion before. Just don't do it.
For the record, as an experienced test pilot, with quite a few hours teaching on the R22, I have every confidence in the rotor dynamics: provided due respect is given to the low inertia and flapping characterisitics. Just fly within the Envelope, be prepared and watchful: as you should be on any type that you fly.
But please, please, leave the test flying to the professionals.
In the test flying world we take cautious and progressive steps towards defining a flight envelope. It's there to protect.
'All Aircraft Bite Fools'. A good saying, remember?
We've had the same stupid comments, regarding amateur investigation of Handling Qualities, on earlier threads about the R22 rotorhead and I think I've made the same suggestion before. Just don't do it.
For the record, as an experienced test pilot, with quite a few hours teaching on the R22, I have every confidence in the rotor dynamics: provided due respect is given to the low inertia and flapping characterisitics. Just fly within the Envelope, be prepared and watchful: as you should be on any type that you fly.
But please, please, leave the test flying to the professionals.
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Yeah but.....
To: NickLappos
Using your position of the fount of knowledge on everything helicopter you accuse me of being wrong and in the process you use words that ridicule me as not knowing what I am talking about.
I quoted directly from the CFR 27-351 which states that at speeds of 0 to .6VNE the pilot must rapidly deflect the tail rotor pedals to attain a 90-degree sideslip both left and right. You expound on the fact saying that I am wrong and I reply with a direct quote from the CFR restating what it says and you still say I am wrong.
My argument stems from what it says in section 4 of the R-22 and R-44 POH which places restrictions on not performing sideslips or flying out of trim as it could result in mast bumping or rotor incursion.
Now we marry the certification requirements of CFR-27-351 with the statements in the POH and what is contained in the SFAR and most likely what is taught in the Robinson safety course.
If what the Georgia Tech report stated that these maneuvers were the root cause of some of the loss of control accidents incurred by the R-22 and R-44 then I reached two conclusions based on the Georgia Tech reports. (Conclusion #1) If the tests were performed during certification they would most likely incur mast bumping or rotor incursion. (Conclusion #2) The test was never performed. Remember that the R-22 was certificated by airplane people not helicopter people.
Here is a question. Supposing the FAA initiated a priority letter to Sikorsky outlining several points that require cautionary or warning status in the POH. And a page was entered into the S-92 POH and this page was not listed in the table of contents and the information on that page was watered down so as not to reflect the true nature of the information. Nor, did the FAA making it an official part of the POH ever sign it off. What is your opinion on this as this is what occurred on the R-22 and R-44 POHs.
The rigging procedure still sucks and yes an R-44 in the UK suffered loss of control caused mainly by flapping extremes on the blades. IMHO caused by the rotorhead design.
Using your position of the fount of knowledge on everything helicopter you accuse me of being wrong and in the process you use words that ridicule me as not knowing what I am talking about.
I quoted directly from the CFR 27-351 which states that at speeds of 0 to .6VNE the pilot must rapidly deflect the tail rotor pedals to attain a 90-degree sideslip both left and right. You expound on the fact saying that I am wrong and I reply with a direct quote from the CFR restating what it says and you still say I am wrong.
My argument stems from what it says in section 4 of the R-22 and R-44 POH which places restrictions on not performing sideslips or flying out of trim as it could result in mast bumping or rotor incursion.
Now we marry the certification requirements of CFR-27-351 with the statements in the POH and what is contained in the SFAR and most likely what is taught in the Robinson safety course.
If what the Georgia Tech report stated that these maneuvers were the root cause of some of the loss of control accidents incurred by the R-22 and R-44 then I reached two conclusions based on the Georgia Tech reports. (Conclusion #1) If the tests were performed during certification they would most likely incur mast bumping or rotor incursion. (Conclusion #2) The test was never performed. Remember that the R-22 was certificated by airplane people not helicopter people.
Here is a question. Supposing the FAA initiated a priority letter to Sikorsky outlining several points that require cautionary or warning status in the POH. And a page was entered into the S-92 POH and this page was not listed in the table of contents and the information on that page was watered down so as not to reflect the true nature of the information. Nor, did the FAA making it an official part of the POH ever sign it off. What is your opinion on this as this is what occurred on the R-22 and R-44 POHs.
The rigging procedure still sucks and yes an R-44 in the UK suffered loss of control caused mainly by flapping extremes on the blades. IMHO caused by the rotorhead design.
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I too had a full pedal incident - whilst doing my ppl... on my umpteenth pattern of the day I decided to push left pedal instead of turning left with the cyclic. I don't know why but I did!
What happened? Well as still here and still flying not a whole lot!
It woke up my instructor and me too - had it sorted as quick as it happended but we were flying at 60 knots, full left pedal and it continued to fly OK.. I know it wasn't prolonged but guess the disk made a fair few rotations before I reacted...
PW
What happened? Well as still here and still flying not a whole lot!
It woke up my instructor and me too - had it sorted as quick as it happended but we were flying at 60 knots, full left pedal and it continued to fly OK.. I know it wasn't prolonged but guess the disk made a fair few rotations before I reacted...
PW
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To idle stop
Fully agree,
(but I too did not the 40 knots experiment in one time, my instructor did give me the old bold pilot message)
delta3
Fully agree,
(but I too did not the 40 knots experiment in one time, my instructor did give me the old bold pilot message)
delta3
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But what about!!
Hi all
I have 2 questions,
1. Why will side-slipping increase flapping amplitude
2. Practising an approach and landing with "stuck pedals" requires flying out of trim, is this then a bad idear
Cheers, Eyesout.
I have 2 questions,
1. Why will side-slipping increase flapping amplitude
2. Practising an approach and landing with "stuck pedals" requires flying out of trim, is this then a bad idear
Cheers, Eyesout.
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So, in the real world in a 44, I have a man with a camera sat behind me pointing it out of the door.
He wants low level approx 50knots (0.38vne) sideways, so for an hour or more we are zipping through valleys etc with a 90deg offset.
taking LTE out of the equation, as this is about balance...
is this suicide?
Can I do it in a 206? (rather the 44 for the LTE thing)
Is it illegal?
He wants low level approx 50knots (0.38vne) sideways, so for an hour or more we are zipping through valleys etc with a 90deg offset.
taking LTE out of the equation, as this is about balance...
is this suicide?
Can I do it in a 206? (rather the 44 for the LTE thing)
Is it illegal?
Iconoclast
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It depends on which side of the looking glass you are standing.
To: 4ero
In the POH (Section 4 Last page) you are cautioned against out of trim and sideslipping flight maneuvers, as they would result in mast bumping and or loss of control. However there is no force behind these cautions since the information on this unnumbered page has never been officially included in the POH by virtue of an FAA signoff although it is based on an FAA priority letter sent to Robinson.
So from that standpoint you can do it.
However if you suffer loss of control Robinson helicopters can state that you were cautioned against doing this. In that case they have a strong case against pilot error.
These maneuvers are performed every day without serious consequences however there have been over 30 loss of control accidents in the R-22 and the R-44 and there must be some technical reason aside from pilot error. The Georgia Tech study pointed out that extreme flapping excursions were the result of Zero G or flying out of trim and sideslipping.
On many accidents it was determined that there was excessive flapping on the cone hinges resulting in the fracture of the blade tusk(s) when they contacted the droop stop(s). In a pure mast-bumping situation there is insufficient energy in the blades when they hit the teeter stops to fracture the blade tusk(s). There is however sufficient energy to contact the mast causing it to fracture.
What caused the blade flapping? You can refer to the Georgia Tech study or, make up your own reasons. It seems that no one wants to believe me.
taking LTE out of the equation, as this is about balance...
Is it illegal?
So from that standpoint you can do it.
However if you suffer loss of control Robinson helicopters can state that you were cautioned against doing this. In that case they have a strong case against pilot error.
These maneuvers are performed every day without serious consequences however there have been over 30 loss of control accidents in the R-22 and the R-44 and there must be some technical reason aside from pilot error. The Georgia Tech study pointed out that extreme flapping excursions were the result of Zero G or flying out of trim and sideslipping.
On many accidents it was determined that there was excessive flapping on the cone hinges resulting in the fracture of the blade tusk(s) when they contacted the droop stop(s). In a pure mast-bumping situation there is insufficient energy in the blades when they hit the teeter stops to fracture the blade tusk(s). There is however sufficient energy to contact the mast causing it to fracture.
What caused the blade flapping? You can refer to the Georgia Tech study or, make up your own reasons. It seems that no one wants to believe me.
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Lu you are wrong, the FAR does NOT call for "the pilot" to deflect anything. You are WRONG, Lu, WRONG. It is in the "strength" section, which, if you knew anything about FAR's, would signify that the structure must be analysed to withstand the loads imposed by that maneuver. YOU were WRONG when you said that Robinson does not meet the FAR ("there are several non-compliances").
That was your mistake, Lu, yours, not the FAR, yours. Admit it!
That was your mistake, Lu, yours, not the FAR, yours. Admit it!
Eyescout,
Why does sideslip increase flapping? Simple, but not intuitive unless explained:
Consider a Jet Ranger in forward flight;
The combination of the moment generated by the rotor with forward cyclic about the CG and the moment generated by the drag of the fuselage of the helicopter will tend to want the helicopter to adopt a nose down attitude. In forward flight we correct this with a horizontal stabiliser to push the tail back down and keep the fuselage level (amongst other things).
Now if we tried to fly sideway at the same speed, there is no stabiliser to correct the role attitude, so sideways flight results in quite a large role angle in steady flight.
If you are flying forwards and you allow the helicopter to be significantly out of trim, then due to the lateral effect just described the helicopter will tend to role. Assuming, that you have kept the same disc attitude to maintain the flight path, then this role causes an increase in lateral flapping, as the rotor is maintaining its attitude and the fuselage is rolling up towards it. When confronted with an aircraft that is rolling in forward flight, the instinctive response of a pilot is to apply corrective cyclic - so now he moves the disc down towards the fuselage....
At sufficiently high speed or sideslip angles or with sufficiently abrupt cyclic pitch inputs then yes, mast bumping can occur, on the Jet Ranger, B47, UH12, Huey, R22 an R44.
We all learnt to fly helicopters once and that will have involved plenty of sideslip on teetering rotor helicopters, but we are not all dead are we? All I will say is that if the sideslip is resulting in an 'abnormal' cabin attitude then the flight condition is potentially dangerous - so don't do it. Fly as per the hand book and you will be safe.
Furthermore, there is nothing fundamentally wrong with the Robinson tri-hinge rotor system. For those interested in why it has coning hinges - read the patent.
I have decided to post this for two reasons:
(1) Lu spreading incorrect slander about Robinson Helicopters is bad for everyone in the industry, our customers, pilots, operators and manufacturers...whether they fly Bell, Robinson, Sikorsky or whatever…to the media and the public a helicopter is a helicopter.
(2) For the inexperienced pilots that fly Robinson helicopters, I fear that Lu's 'Politics of Fear' do far more harm than good. If his malicious nonsense gets through to even a small percentage of low-time helicopter pilots then their resulting lack of trust in the machine will make them nervous and uncomfortable in the air - a sure-fire way to get yourself into trouble.
So i'll say it again:
THERE IS NOTHING FUNDEMENTALLY WRONG WITH THE DESIGN OF THE ROBINSON HUB AND PROVIDED YOU FLY AS PER THE MANUAL YOU WILL NOT MAST BUMP.
I do not intend to post anything else on this thread - it is pointless.
CRAN
NOTE: CRAN has a Degree in Mechanical Engineering & a Ph.D. in Helicopter Aerodynamics.
Why does sideslip increase flapping? Simple, but not intuitive unless explained:
Consider a Jet Ranger in forward flight;
The combination of the moment generated by the rotor with forward cyclic about the CG and the moment generated by the drag of the fuselage of the helicopter will tend to want the helicopter to adopt a nose down attitude. In forward flight we correct this with a horizontal stabiliser to push the tail back down and keep the fuselage level (amongst other things).
Now if we tried to fly sideway at the same speed, there is no stabiliser to correct the role attitude, so sideways flight results in quite a large role angle in steady flight.
If you are flying forwards and you allow the helicopter to be significantly out of trim, then due to the lateral effect just described the helicopter will tend to role. Assuming, that you have kept the same disc attitude to maintain the flight path, then this role causes an increase in lateral flapping, as the rotor is maintaining its attitude and the fuselage is rolling up towards it. When confronted with an aircraft that is rolling in forward flight, the instinctive response of a pilot is to apply corrective cyclic - so now he moves the disc down towards the fuselage....
At sufficiently high speed or sideslip angles or with sufficiently abrupt cyclic pitch inputs then yes, mast bumping can occur, on the Jet Ranger, B47, UH12, Huey, R22 an R44.
We all learnt to fly helicopters once and that will have involved plenty of sideslip on teetering rotor helicopters, but we are not all dead are we? All I will say is that if the sideslip is resulting in an 'abnormal' cabin attitude then the flight condition is potentially dangerous - so don't do it. Fly as per the hand book and you will be safe.
Furthermore, there is nothing fundamentally wrong with the Robinson tri-hinge rotor system. For those interested in why it has coning hinges - read the patent.
I have decided to post this for two reasons:
(1) Lu spreading incorrect slander about Robinson Helicopters is bad for everyone in the industry, our customers, pilots, operators and manufacturers...whether they fly Bell, Robinson, Sikorsky or whatever…to the media and the public a helicopter is a helicopter.
(2) For the inexperienced pilots that fly Robinson helicopters, I fear that Lu's 'Politics of Fear' do far more harm than good. If his malicious nonsense gets through to even a small percentage of low-time helicopter pilots then their resulting lack of trust in the machine will make them nervous and uncomfortable in the air - a sure-fire way to get yourself into trouble.
So i'll say it again:
THERE IS NOTHING FUNDEMENTALLY WRONG WITH THE DESIGN OF THE ROBINSON HUB AND PROVIDED YOU FLY AS PER THE MANUAL YOU WILL NOT MAST BUMP.
I do not intend to post anything else on this thread - it is pointless.
CRAN
NOTE: CRAN has a Degree in Mechanical Engineering & a Ph.D. in Helicopter Aerodynamics.
Last edited by CRAN; 29th Nov 2004 at 11:43.
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Thanks, Cran.
Folks, please take Lu's posts for what they are:
Unschooled ramblings that are essentially untrue.
Lu is not a graduate engineer, he is a retired technical rep with a great deal of maintenance experience, but no real knowledge of how helicopters are designed or certified. He has a strong dislike of Robinsons, and this makes him leave the Earth when it comes time to engage his thinking organs. The result is the drivel you see in this thread.
Frankly, his assertions are so baseless, they are arguably slanderous, and he could face action from the manufacturer for the complete flasehoods he spouts.
Folks, please take Lu's posts for what they are:
Unschooled ramblings that are essentially untrue.
Lu is not a graduate engineer, he is a retired technical rep with a great deal of maintenance experience, but no real knowledge of how helicopters are designed or certified. He has a strong dislike of Robinsons, and this makes him leave the Earth when it comes time to engage his thinking organs. The result is the drivel you see in this thread.
Frankly, his assertions are so baseless, they are arguably slanderous, and he could face action from the manufacturer for the complete flasehoods he spouts.
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To CRAN
(not asking for reply)
I fully agree with your statements.
As I did with the Wee-Wa and delta3 fases shift, I intend to demonstrate this with my scientific simulator, who is getting a better than 1% precision. Problem is that for the moment its only 2-dimensional. Intend to make it 3-dimensional in the next weeks, so I can simulate yaws.
I am no sure, but I sincerely hope that Lu believes the results of this scientific simulator that asserts the design is OK.
delta3
(not asking for reply)
I fully agree with your statements.
As I did with the Wee-Wa and delta3 fases shift, I intend to demonstrate this with my scientific simulator, who is getting a better than 1% precision. Problem is that for the moment its only 2-dimensional. Intend to make it 3-dimensional in the next weeks, so I can simulate yaws.
I am no sure, but I sincerely hope that Lu believes the results of this scientific simulator that asserts the design is OK.
delta3
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OK CRAN you know more than most about rotor systems and as I don't know you will have to accept what I read. However, as much as you defend the design of the rotor head used on the Robinson you surely have to admit that it has some unfortunate limitation when low time and even high time pilots come to grief due to their mishandling or getting caught out in flight conditioned that are not conducive to safe flight with that rotor head design. If certain manoeurves are likely to end in a failure then those manoeuvres must be clearly stated in the LIMITATION Section, Flight Restrictions of the Rotorcraft Flight Manual, not it seems by way of an arbituary warning some place in the flight manual.
Would this not be the correct way to inform potential pilots of the model what disasters lie ahead.
In my ignorance I do not believe that the rotor head design is suitable for the function that it was designed to deal with. Why do I think this? I just read the reports and think about 'why' and come to a decision based on my knowledge. I understand many others do a similar process in their minds and come to their own conclusions.
Would this not be the correct way to inform potential pilots of the model what disasters lie ahead.
In my ignorance I do not believe that the rotor head design is suitable for the function that it was designed to deal with. Why do I think this? I just read the reports and think about 'why' and come to a decision based on my knowledge. I understand many others do a similar process in their minds and come to their own conclusions.
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Head Turner,
This is the way Lu works. Now you are concerned about a "Robinson head problem"and the maneuver limits, and all afire.
The Robinson has no special problem that is not shared by thousands of helicopters with similar teetering rotor designs. Lu does not know what he is saying, but here we are all wrapped up!
If you fly your helicopter outside its envelope, you will either hurt yourself, or leave a flaw for some future guy to hurt himself. That is true of all helos. If you have been in a small bomb shelter for the last three decades, you might not know that teetering rotors have limits where a sideslip at forward speed causes large flapping ebvents, and can cause mast bumping. In that bomb shelter, you did not read about the 80+ Hueys that have had mast separation, and you therefore eat Lu's garbage with a spoon.
A reporter won the Pulitzer prize "exposing" these facts about 15 years ago, that's how old all this is! Here:
Fort Worth (Tex.) Star-Telegram
Pulitzer Prize Archives - 1985 - "For reporting by Mark J. Thompson which revealed that nearly 250 U.S. servicemen had lost their lives as a result of a design problem in helicopters built by Bell Helicopter -a revelation which ultimately led the Army to ground almost 600 Huey helicopters pending their modification."
The ability of internet wackos like Lu to start and spread this trash is one of the reasons why I no longer post at the other internet sites where they rule. Is pprune going that way too?
This is the way Lu works. Now you are concerned about a "Robinson head problem"and the maneuver limits, and all afire.
The Robinson has no special problem that is not shared by thousands of helicopters with similar teetering rotor designs. Lu does not know what he is saying, but here we are all wrapped up!
If you fly your helicopter outside its envelope, you will either hurt yourself, or leave a flaw for some future guy to hurt himself. That is true of all helos. If you have been in a small bomb shelter for the last three decades, you might not know that teetering rotors have limits where a sideslip at forward speed causes large flapping ebvents, and can cause mast bumping. In that bomb shelter, you did not read about the 80+ Hueys that have had mast separation, and you therefore eat Lu's garbage with a spoon.
A reporter won the Pulitzer prize "exposing" these facts about 15 years ago, that's how old all this is! Here:
Fort Worth (Tex.) Star-Telegram
Pulitzer Prize Archives - 1985 - "For reporting by Mark J. Thompson which revealed that nearly 250 U.S. servicemen had lost their lives as a result of a design problem in helicopters built by Bell Helicopter -a revelation which ultimately led the Army to ground almost 600 Huey helicopters pending their modification."
The ability of internet wackos like Lu to start and spread this trash is one of the reasons why I no longer post at the other internet sites where they rule. Is pprune going that way too?
Iconoclast
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This Breech stuff is getting a bit bad.
To: NickLappos
The non compliances are in the flight control system
In referencing the FARs I stated that the pilot had to perform certain maneuvers. I was not referencing why the maneuvers were being performed it was that they were being performed. I further stated that the Georgia Tech report identified several different flight regimes that would result in mast bumping or rotor incursion as a result if induced extreme flapping of the blades.
This same information was added to the POHs for both the R-22 and the R-44. I then added that if what the Georgia Tech report stated there was an excellent chance that in performing the maneuvers stated in the FARs that they would incur extreme flapping and possible loss of control.
Based on the above I ask four questions that I want you to answer:
Was the Gerogia Tech study correct?
If the report was correct would you agree that there was a possibility of loss of control when the FAR demonstration was made?
If there was a possibility of loss of control is there also a possibility that the test was not performed?
Based on your comments about the Bell helicopter and the many mast bumping incidents I again ask you if Robinson performed the test required in the FARs would they experience mast bumping and resultant loss of control?
I am not a retired Tech Rep so you are wrong there. I do have a lot of maintenance experience and I have an A&P license. It is true that I don’t have an engineering degree. In fact I don’t have any degree as I had to leave university because I had to support my wife and two sons.
Regarding my lack of knowledge of how helicopters and for that matter aircraft are designed I attended a fourteen month training program working in all of the firms shops building everything they made on three different models of helicopters. During that time I attended eight factory schools on the companies products. I ran a training program for the US Army on Sikorsky helicopters.
Fast forward after working on the Atlas missile as a field engineer and six and one half years as a design manager and project engineer on the Saturn Apollo program I got back on helicopters. I was a senior Maintainability engineer on the Cheyenne Helicopter working in direct contact with the design and production engineers. I set up the design for maintainability program on the Apache and worked as a senior Maintainability engineer again working in direct contact with the design engineers. I was the Manager of Technical Assistance (Product support) for Bell Helicopter International directing all product support activities on over 900 helicopters (Agusta Bell, Bell, Sikorsky and Boeing Vertol). I set up and managed the R&M program on the Agusta A129 and the EH-101 working with design engineering and the certification authorities. I also worked as a Maintainability engineer on the V-22 again working with the design engineers.
I set up and managed the RMS program on the Airbus A-310 wing working with the design offices of three major European Aerospace firms and worked directly with the certification authorities of the UK, Germany and France.
As a private consultant I have worked on the modification of DC-9s and 727s, I also worked on the recon pod for the F-16 and the electronics cooling system for the Apache. I worked as an R&M engineer on the A-330 and A-340 cargo systems and I worked as a Reliability Engineer on the Gulfstram G4X engine systems. I also worked as a Reliability Engineer for Fairchild Dornier on the design of the hydraulics systems used on their aircraft.
Nick you hold me in a low esteem and you want the other members of this forum to agree with you. Even though I do not have a degree it never got in my way. I worked with and for many companies who hired me for what I could do and for my past history. I worked for Douglas, Lockheed, Boeing, Hughes, Agusta, TRW, and many other aerospace firms. They never looked down their noses and said Lu Zuckerman doesn’t have a degree so why should you. I just retired from a job that paid $120,000 a year and when I worked in Europe I made $127,000 a year. I feel that it was pretty good for a fat kid from Cleveland that doesn’t have a university degree.
So get off my back.
The non compliances are in the flight control system The non compliances are in the flight control system.
Lu you are wrong, the FAR does NOT call for "the pilot" to deflect anything. You are WRONG, Lu, WRONG. It is in the "strength" section, which, if you knew anything about FAR's, would signify that the structure must be analysed to withstand the loads imposed by that maneuver. YOU were WRONG when you said that Robinson does not meet the FAR ("there are several non-compliances").
In referencing the FARs I stated that the pilot had to perform certain maneuvers. I was not referencing why the maneuvers were being performed it was that they were being performed. I further stated that the Georgia Tech report identified several different flight regimes that would result in mast bumping or rotor incursion as a result if induced extreme flapping of the blades.
This same information was added to the POHs for both the R-22 and the R-44. I then added that if what the Georgia Tech report stated there was an excellent chance that in performing the maneuvers stated in the FARs that they would incur extreme flapping and possible loss of control.
Based on the above I ask four questions that I want you to answer:
Was the Gerogia Tech study correct?
If the report was correct would you agree that there was a possibility of loss of control when the FAR demonstration was made?
If there was a possibility of loss of control is there also a possibility that the test was not performed?
Based on your comments about the Bell helicopter and the many mast bumping incidents I again ask you if Robinson performed the test required in the FARs would they experience mast bumping and resultant loss of control?
Lu is not a graduate engineer, he is a retired technical rep with a great deal of maintenance experience, but no real knowledge of how helicopters are designed or certified. He has a strong dislike of Robinsons, and this makes him leave the Earth when it comes time to engage his thinking organs. The result is the drivel you see in this thread.
Regarding my lack of knowledge of how helicopters and for that matter aircraft are designed I attended a fourteen month training program working in all of the firms shops building everything they made on three different models of helicopters. During that time I attended eight factory schools on the companies products. I ran a training program for the US Army on Sikorsky helicopters.
Fast forward after working on the Atlas missile as a field engineer and six and one half years as a design manager and project engineer on the Saturn Apollo program I got back on helicopters. I was a senior Maintainability engineer on the Cheyenne Helicopter working in direct contact with the design and production engineers. I set up the design for maintainability program on the Apache and worked as a senior Maintainability engineer again working in direct contact with the design engineers. I was the Manager of Technical Assistance (Product support) for Bell Helicopter International directing all product support activities on over 900 helicopters (Agusta Bell, Bell, Sikorsky and Boeing Vertol). I set up and managed the R&M program on the Agusta A129 and the EH-101 working with design engineering and the certification authorities. I also worked as a Maintainability engineer on the V-22 again working with the design engineers.
I set up and managed the RMS program on the Airbus A-310 wing working with the design offices of three major European Aerospace firms and worked directly with the certification authorities of the UK, Germany and France.
As a private consultant I have worked on the modification of DC-9s and 727s, I also worked on the recon pod for the F-16 and the electronics cooling system for the Apache. I worked as an R&M engineer on the A-330 and A-340 cargo systems and I worked as a Reliability Engineer on the Gulfstram G4X engine systems. I also worked as a Reliability Engineer for Fairchild Dornier on the design of the hydraulics systems used on their aircraft.
Nick you hold me in a low esteem and you want the other members of this forum to agree with you. Even though I do not have a degree it never got in my way. I worked with and for many companies who hired me for what I could do and for my past history. I worked for Douglas, Lockheed, Boeing, Hughes, Agusta, TRW, and many other aerospace firms. They never looked down their noses and said Lu Zuckerman doesn’t have a degree so why should you. I just retired from a job that paid $120,000 a year and when I worked in Europe I made $127,000 a year. I feel that it was pretty good for a fat kid from Cleveland that doesn’t have a university degree.
So get off my back.
The non compliances are in the flight control system The non compliances are in the flight control system.
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flapping
CRAN , (and others)
Flapping , in a teetering rotor, causes the rotor tip-path plane to tilt away(flap back) from the spin axis and is the result of differing airspeeds on adv/retreating blades.
I am having trouble seeing how "flapping loads" increase in a sideslip.
In sideways flight, the helicopter will roll, just as it will pitch in forward flight, but corrective cyclic is not needed in the "other" direction.
Actually, more cyclic has to added in the direction you are going, or you will slow down. The cg of the aircraft swings out behind and the rotor thrust then remains aligned with the cg, otherwise it would continue to roll.
In any case, the relationship of the rotor tilt to the fuselage has nothing to do with flapping. The ratio of forward speed to rotor speed is the only factor I am aware of that controls flapping angle for a given g loading.
What am I missing?
Flapping , in a teetering rotor, causes the rotor tip-path plane to tilt away(flap back) from the spin axis and is the result of differing airspeeds on adv/retreating blades.
I am having trouble seeing how "flapping loads" increase in a sideslip.
In sideways flight, the helicopter will roll, just as it will pitch in forward flight, but corrective cyclic is not needed in the "other" direction.
Actually, more cyclic has to added in the direction you are going, or you will slow down. The cg of the aircraft swings out behind and the rotor thrust then remains aligned with the cg, otherwise it would continue to roll.
In any case, the relationship of the rotor tilt to the fuselage has nothing to do with flapping. The ratio of forward speed to rotor speed is the only factor I am aware of that controls flapping angle for a given g loading.
What am I missing?
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Lu
So you've "worked on" Atlas missile, Saturn Apollo, Cheyenne, Agusta A129, EH-101, V-22, Airbus A-310, DC-9, 727, F-16, Apache, A-330, A-340, Gulfstram G4X and the Fairchild Dornier and you "worked for" a whole bunch of airplane and helo companies.
Sure that's a bit of everything but how can you claim to be an expert in anything except maintenance.
So you've "worked on" Atlas missile, Saturn Apollo, Cheyenne, Agusta A129, EH-101, V-22, Airbus A-310, DC-9, 727, F-16, Apache, A-330, A-340, Gulfstram G4X and the Fairchild Dornier and you "worked for" a whole bunch of airplane and helo companies.
Sure that's a bit of everything but how can you claim to be an expert in anything except maintenance.
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It has been mentioned many time on Rotorheads that piloting helicopters is one of the most dangerous professions there is. This is readily substantiated by looking at the percentage of threads that relate to accidents and fatalities.
Nick, Lu and others come from different backgrounds and have different perspectives on the helicopter, it's manufacturers and their motives. Lu's concern may be wrong, then again, it may not. He has not proven his base underlying concern, but conversely, has anyone proven him wrong? Lu may still question a subset of his base concern; the relationship between delta3 and phase-lag, but Nick I don't think that we even came to an agreement on this subject.
If Lu is able to cause current and future helicopter pilots to have a better respect for their craft, without libeling any company or person, is this a fault?
Frequently, when one side in a debate runs out of technical 'ammunition' that side will revert to personalizing the discussion. Personal attacks do little to advance knowledge, although they have been known to win elections.
On the previous thread [Topic: Is a second or so enough?] the discussion about the R-44's pitch cone coupling came up. It was assumed that the coupling was a conventional one and much information elaborating on the reasons for this were posted. Thanks to Lu persistence, it now appears that the R-44 coupling is the opposite of convention. This now creates a much more interesting and potentially informative discussion. It calls upon those with a practical or a theoretical knowledge of rotorcraft to discuss this phenomenon; yet, they have refrained from doing so.
Interesting!
Nick, Lu and others come from different backgrounds and have different perspectives on the helicopter, it's manufacturers and their motives. Lu's concern may be wrong, then again, it may not. He has not proven his base underlying concern, but conversely, has anyone proven him wrong? Lu may still question a subset of his base concern; the relationship between delta3 and phase-lag, but Nick I don't think that we even came to an agreement on this subject.
If Lu is able to cause current and future helicopter pilots to have a better respect for their craft, without libeling any company or person, is this a fault?
Frequently, when one side in a debate runs out of technical 'ammunition' that side will revert to personalizing the discussion. Personal attacks do little to advance knowledge, although they have been known to win elections.
On the previous thread [Topic: Is a second or so enough?] the discussion about the R-44's pitch cone coupling came up. It was assumed that the coupling was a conventional one and much information elaborating on the reasons for this were posted. Thanks to Lu persistence, it now appears that the R-44 coupling is the opposite of convention. This now creates a much more interesting and potentially informative discussion. It calls upon those with a practical or a theoretical knowledge of rotorcraft to discuss this phenomenon; yet, they have refrained from doing so.
Interesting!
Last edited by Dave_Jackson; 29th Nov 2004 at 20:52.
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Dave,
Just wait until Lu decides to hate the CarterCopter, then we'll watch you jump! His mindless diatribes are worthless, and his ability to worm away from what he posts makes him quite useless except as a gadfly.
This thread was hijacked by him when he asserted that a certain helo was not safe, and not properly certified, and he misquoted the regs to make his point. His string of unproven and unprovable slanders on that helo are a shame.
You can try to find good in that, because you seek good in all people, but such charity is unearned when Lu fails to learn anything from those who post facts. His kind of drivel is what makes the internet such a difficult place, and is the death knell of web sites.
Just because he confused you long enough to reverse your understanding of delta three (he has NEVER understood it, Dave!) does not mean he adds value.
Just wait until Lu decides to hate the CarterCopter, then we'll watch you jump! His mindless diatribes are worthless, and his ability to worm away from what he posts makes him quite useless except as a gadfly.
This thread was hijacked by him when he asserted that a certain helo was not safe, and not properly certified, and he misquoted the regs to make his point. His string of unproven and unprovable slanders on that helo are a shame.
You can try to find good in that, because you seek good in all people, but such charity is unearned when Lu fails to learn anything from those who post facts. His kind of drivel is what makes the internet such a difficult place, and is the death knell of web sites.
Just because he confused you long enough to reverse your understanding of delta three (he has NEVER understood it, Dave!) does not mean he adds value.
Iconoclast
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NYPD Blue Brooklyn version
To: Bronx
It was in response to Nicks’ claim that I do not have an understanding of how helicopters are designed. I do not claim to be able to design a helicopter or an airplane or even fly one but I do have a very strong understanding of the various design processes. I don’t claim to be a pilot but I fully understand the operation of various flight control systems and what happens when the pilot makes an input. Having a good understanding of maintenance requires that the maintainer fully understand the flight characteristics of the vehicle that is being maintained.
As far as claiming to be an expert I will never do that. An expert is a person that knows exactly how much Dynamite © to pack up a bulls ass in order to blow the bulls horns off without getting the bulls eyes bloodshot. I can’t do that and I doubt if anyone on this forum could do it.
So you've "worked on" Atlas missile, Saturn Apollo, Cheyenne, Agusta A129, EH-101, V-22, Airbus A-310, DC-9, 727, F-16, Apache, A-330, A-340, Gulfstram G4X and the Fairchild Dornier and you "worked for" a whole bunch of airplane and helo companies.
It was in response to Nicks’ claim that I do not have an understanding of how helicopters are designed. I do not claim to be able to design a helicopter or an airplane or even fly one but I do have a very strong understanding of the various design processes. I don’t claim to be a pilot but I fully understand the operation of various flight control systems and what happens when the pilot makes an input. Having a good understanding of maintenance requires that the maintainer fully understand the flight characteristics of the vehicle that is being maintained.
As far as claiming to be an expert I will never do that. An expert is a person that knows exactly how much Dynamite © to pack up a bulls ass in order to blow the bulls horns off without getting the bulls eyes bloodshot. I can’t do that and I doubt if anyone on this forum could do it.