completeaerogeek

_________________ MR Turbo Planner I am going to quote you here because again you have made a pejorative statement about me justified by nonsense. You a really are quite a dab hand at embarrassing yourself: A very good example that a little knowledge (very little in your case) is a dangerous thing. CAG "Well SC wings were a real change maker. Curved on the bottom and flat on top. Messes with some people's heads! Turbo planner: "This describes the wings used on Sprint Cars which do such a great job of clamping 850 horsepower cars DOWN on to the track surface, so the geek has some studying to do. Supercritical wings were introduced originally to help break the sound barrier and are irrelevant to RA and GA flying and irrelevant to supersonic flying, and seem to have been used just as distraction by the geek." There are so many things wrong with this statement it is hard to know. This is the kind of thing that prove 'a little knowledge is dangerous thing) Firstly: Spoilers used on sprint and F1 Cars for that matter are curved plate aerofoils. The turn flow upwards to create downforce. Nothing contradictory there. Simple Newtonian Physics. Secondly, SC aerofoils were NOT introduced to ‘try to break the sound barrier. The X-1 had a thing symmetrical aerofoil and exceeded M 1.0 in 1947. You have misinterpreted the WIKI article you read to make this statement. The next transonic aircraft- the F-86 had a symmetrical aerofoil. (as did most military aircraft at the time and for many years) SC wings in fact were designed in the 1960s by NASA scientist Richard Whitcomb (who also gave us winglets). The SC wing is designed to minimise the angular change of flow over the upper surface of the wing thus reducing density changes that happen when the air ‘turns the corner’ of the leading edge. Density is directly related to the speed of sound so when density drops, the local speed of sound drops causing standing shock waves. This is the basis of MMO and MCrit. As all airliners cruise in the transonic range (above M 0.8) this reduces drag and much improves efficiency. In terms of light aircraft using wings with SC characteristics again Mr Planner you are quite wrong. Attached is the wing profile of a Piper Tomahawk (not even a new aircraft) Many performance LSA aircraft are now using symmetrical or SC style aerofoils as a drag reduction measure just as the P-51 (close to symmetrical did many years. The Canberra has a symmetrical wing so when you try to explain bogus theories about wings flying because they curved upper surfaces and flat undersides, they are proven to be nonsense. Either a physical principle fits all of the criteria in all normal examples or it is bunk. Lastly- you seem not to be able to interpret academic language as you have misinterpreted what the Naval Aviator text is saying. Friction (form drag) is indeed confined to the boundary layer but viscosity is not. If it was the streamlines above the boundary layer would not be affected by the change in velocity (speed and direction) of the boundary layer. Watch the video again or see attached. What the text is saying is: that in order to study the flow field 'attached to the wing surface' you can ‘neglect’ - not invalidate) the friction in order to make it simpler. Now given that most student pilots want to fly for airlines where they will be sitting on top of an SC wing, and that the factual and accurate understanding of flow around an aerofoil is the same whether you are flying an A380 or a J-170 – and that I introduced the SC aerofoil discussion to debunk the idea that wings have to have a 'curved upper surface‘ and that lift created by the curved upper surface ‘sucks the plane into the sky’ What part of this discussion is a ‘distraction’?

Gentlemen thank you for your thoughtful comments. As I mentioned (and NASA does too) Bernoulli's theorem does give an approximation of the pressure differences on top of the wing. based as it is on Newton's second Law however, the statement that Bernoulli is irrelevant is not to say that there is not some value, just that it c an be dispensed with as an explanation for pilots because it caused more problems than it solves.. The mathematical solving for Bernoulli is somewhat inaccurate as it assumes air is inviscid but that was never my point. Just as in many things, most people cannot solve the mathematical equation not is it necessary for pilots but most Flying Instructors (and pilots) cannot explain it, they invent all kinds of silly theories about how Bernoulli applies and this is what has brought me here. In PART 61 CASA mentions Bernoulli and Venturi in the same sentence. This is untenable and I have written to CLARC to say so. As I have said and you know, a wing is not venturi which relies on a closed system to operate. A wing is an open system. In other parts of the DAY VFR CPL syllabus they ask students to explain why the upper surface of the wing generates most of the lift. Again this is a very silly thing to say and reinforces the myths. A SC wing (that most pilots will spend most of their careers sitting on top of) particularly at cruising speed is generating a large proportion of its lift from the underside of the wing. Even the new LSA aircraft are using Symmetrical or SC aerofoils as a drag reduction measure and CASA's statement is barely adequate for high camber conventional wings. The essential thing is this: The pressure differentials that Bernoulli and Newton refer to are a result of AOA (and camber if relevant) not the cause of lift. as such they are a side conversation not the explanation we should be using otherwise you get silly statements like the plane sucks itself up into the air. Moving a solid object through a fluid causes disturbances that result in forces Newton explains without formulas and that anyone can understand. It is not necessary for pilots to solve for lift. it is necessary that they be able to correctly visualise what is happening around a wing as a matter of understanding what is happening and an essential piece of knowledge. to jot do so is to say just because GP dispenses 99.0% of the treatments based on their best guess and without any verifying tests, they shouldn't have to learn biochemistry or anything about pathogens. Just play match the symptom to the drug.. If you are designing a wings then calculus is your tool. if you are flying air aircraft, a competent and accurate conceptual understanding of what is happening is essential particularly at low airspeeds. For the last 3 years I have been teaching lift to BSc students without any detail on Bernoulli and it is clear that they have a much better understanding of the flow around their aircraft, how it changes and what it means for practical performance than when they came in believing ETT or Venturi myths both of which are perpetuated by having to explain Bernoulli without understanding it.o say that a correct understanding of lift in a practical sense 'doesn't matter a jot' is just irresponsible. Cheers

________________________________ Perhaps you should hold your tears of mirth for a minute and stop being to bombastic. You embarrass yourself. Your behaviour demonstrates is exactly why we need to educate our pilots because your s is clearly lacking. Next before you get too narky - almost everything you have expressed here is your opinion. You have demonstrated confirmation bias, one of the most problematic characteristics for pilots. You are open only to your own opinion. Here is you misquoting me: Allow me to quote you " You're saying that the outer wing of a turning aircraft has more induced drag than the inner. That can only be because of the difference in speed of the two wings, right? A faster (outside) wing is producing more lift so it's producing more drag, that's your premise isn't it? Have you ever thought about how much the difference in speed (and therefore drag) actually is? Actually I said no such thing. That is you quoting you... Here is what I actually said: Now as to adverse yaw-the tendency for the wing on the outside of the turn to have increased induced drag and pull the nose towards the outside of the turn which is then balanced with rudder into the turn... Would you explain which part of this is incorrect? It appears that you like listening to yourself so much you repeat things no-one has said. Here is a little something from Princeton Universty for you: An unwanted side effect of aileron operation is adverse yaw—a yawing moment in the opposite direction to the roll. Using the ailerons to roll an aircraft to the right produces a yawing motion to the left. As the aircraft rolls, adverse yaw is caused primarily by the change in drag on the left and right wing. The rising wing generates increased lift which causes increased induced drag. The descending wing generates reduced lift which causes reduced induced drag. The difference in drag on each wing produces the adverse yaw. There is also often an additional adverse yaw contribution from a difference in profile drag between the up-aileron and down-aileron. So the statement in my notes is correct (as it should be because if you had bothered to read my posts you would have seen that it is credited to the FAA PHAK. We need to educate our pilots so that we don't end up with a generation of cowboys who only listen to themselves. All you have done here is demonstrate hubris and arrogance. You have not been able to factually challenge anything I have said. You seem to be saying to young pilots- don't worry about how it all works, just program the FMC and ask for a coffee. Given that virtually ALL airline accidents these days are caused by pilot mishandling- often caused by a lack of systems knowledge your statement is stunning. My BSc ATPL/CPL students are actually keen to know as much as they can about their aircraft, They are acting professionally as all responsible pilots should. Instead of encouraging people to be professional aviators you attack people like me who are trying to educate them. Again you have not been able to factually counter anything I have stated- rather you have perpetuated ad hominen attacks to disguise you ignorance. Arrogance and hubris are real dangers in aviation. You should be ashamed.

________________________________ Perhaps you should hold your tears of mirth for a minute and stop being to bombastic. You embarrass yourself. Your behaviour demonstrates exactly why we need to educate our pilots because yours is clearly lacking. Hubris is unprofessional and dangerous. You have demonstrated confirmation bias, one of the most problematic characteristics for pilots. You are open only to your own opinion. Here is you misquoting me: Allow me to quote you " You're saying that the outer wing of a turning aircraft has more induced drag than the inner. That can only be because of the difference in speed of the two wings, right? A faster (outside) wing is producing more lift so it's producing more drag, that's your premise isn't it? Have you ever thought about how much the difference in speed (and therefore drag) actually is? Actually I said no such thing. This is you quoting you...It is clear that you like the sound of your own voice. Here is what I said: Now as to adverse yaw-the tendency for the wing on the outside of the turn to have increased induced drag and pull the nose towards the outside of the turn which is then balanced with rudder into the turn... Would you explain which part of this is incorrect? Here is a little something from Princeton University for you: An unwanted side effect of aileron operation is adverse yaw—a yawing moment in the opposite direction to the roll. Using the ailerons to roll an aircraft to the right produces a yawing motion to the left. As the aircraft rolls, adverse yaw is caused primarily by the change in drag on the left and right wing. The rising wing generates increased lift which causes increased induced drag. The descending wing generates reduced lift which causes reduced induced drag. The difference in drag on each wing produces the adverse yaw. There is also often an additional adverse yaw contribution from a difference in profile drag between the up-aileron and down-aileron. So the statement in my notes is correct -as it should be because if you had bothered to read my posts you would have seen that it is credited to the FAA PHAK. All of this ad hominem attack that you seem to enjoy only exposes you as a buffoon. You have not been able to factually challenge anything I have said. All you have done is spout bluster and nonsense. Your kind of behaviour is dangerous because it says to young pilots, you don't need to understand what it gong on, just program the FMC and ask for a coffee. Being that almost all airline accident are due to pilot mishandling these days, a responsible person would be encouraging young pilots to be professional aviators not cowboys as you seem to be. My young BSc ATPL students are very keen to understand how their aircraft works as they should be. You do them a huge disservice.

You have hit the nail on the head. There is no constriction above a wing which is why the venturi explanation is rubbish. To use an analogy, cut a bucket in half vertically and see if it still holds water. Neither does the venturi explanation. Look at the NASA post on the page one of this thread. Also the air actually slows down over a cambered wing surface-it doesn't speed up as in a venturi. Watch the Cambridge University Wind Tunnel video on page 1. Have fun!

Yes you You are correct but at the level we need to know it, it is quite simple. The two principles are intimately connected but it is a fact that turning flow causes lift. The pressure fields are a RESULT of changing the direction of flow. Use a flat wing in NASA's FoilSim to prove it to yourself. Flat wing-Zero AOA=no lift. Flat wing 7 degrees AOA L:D ratio of 9:1. In research it is always best to go to the simplest example of what proves your explanation. Some aspects of Bernoulli's theorem can be used but only as an approximate because air is not Inviscid as he assumes. Also Bernoulli is derived from Newton's second law so why not make it simple and use Newton. The problem is not Bernoulli's theorem per se, it is the kooky explanations people use when they don't actually understand what Bernoulli's theorem demonstrates.. That is why people use a Venturi as an explanation and this is What Bernoulli's theorem was designed to explain but a wing is not and never will be a venturi If you read the explanation of Conservation of momentum/flow it can only occur in a closed system like a venturi.. A wing is an open system. Also Bernoulli's calculations only apply along a single streamline not across the whole flow field around a wing. The last an most dangerous part for pilots is that it is easy to imagine air being acted on by a ceiling fan or a kite or a hang glider. The two flows across the surfaces are easy to interpret and give an accurate picture. If you mention Bernoulli, most people don't understand it and make up all kind s of weird stories Like Equal Transit Time or the 'Venturi' effect to explain what happens a there we go astray. if you like you can do an experiment with your fellow pilots. Ask them if the air speeds up across the upper half of a wing. I am willing to bet most say yes. But if you look at the Cambridge video, you find that relative to the static air it actually slows down. Really messes with the explanation doesn't it? I hope this was helpful.

Thank you I will.

If you want to discuss another dangerous idea, how about Power + Attitude = Control? Ask the Asiana 214 crew how well that worked for them or the AF 447 guys (oh you can't)

Yeah the old bumble bee chestnut was funny until they used high speed cameras and found that it used its wing in a figure 8 to create to create lift on both parts of the rotation. Kind of like a biplane!

Yep they are in my first post as is the Cambridge University video. Now why can't CASA get this through their heads?????

You bet. That is kind of my whole mission here. How in the world did the guts on AF447 not notice that there was too much blue and not enough brown on all 5 ADIs? Why did the pilot of the Colgan Air Dash 8 (and the PF of AF447) pull back on the stick when he got a stall warning? Boggles the mind...

______________________ Hi Gnarly, thanks for your feedback but if you go back to my first post, and read on, I have been fairly very restrained with people making incorrect statements and misquoting me snidely. You may also better understand my comments in context. When someone says that pitch changes do not affect AOA I have to wonder if they should be near an aeroplane. All I am trying to do is to help young pilots understand that what they most likely have been taught is rubbish. It was not my intention to insult anyone and I did pass my respects to HIC but his facts were simply incorrect. Should I ignore that because he is an experience flyer? I very much admire anyone with lots of experience. Pilots and anyone in aviation should be expanding their knowledge and challenging their assumptions. It is critical. Actions by the most experience and venerated pilot of the two crews involved at Teneriffe were the primary cause of the worst accident in aviation history... Confirmation bias is deadly. I love this business that is why I am trying to clear up these myths... Aerodynamicists have never promoted these silly explanation mainly because they are so easily disprovable.. They have been cobbled together by people who don't understand how thing work. And I have to respectfully disagree with you. Science is not in 'flux'. Science moves ahead because of investigation, logic and challenge by peer review. It is only by this process that we have moved from caves to the moon. Challenging established thought is the very basis of science (and in this respect, the antithesis of religion) but to do so, you have to be able to prove what you assert because everyone else will be climbing over you to prove you wrong. That's how scientists make their careers. I don't want to start a religious argument -my point was about empirical evidence. However - as an analogy it is pertinent: Which principles were figured out by the religious (supernatural) aspect of religion (unquestioning faith) as opposed to religious scholars who were practical scientists.? Perhaps we should ask Keppler and Gallileo... :) And to be fair which science is in flux? Science (certainly the physical sciences) are long established. Newton wrote Pricipia in the 1600s and we still send satellites into space using his formulas. Nothing has changed unless you get into the weird world of Quantum Mechanics I don't mind where evidence comes from and you can believe whatever you like but don't confuse scientific facts with unsupported assertions. They are very different. My analogy was talking to the fact that even our institutions (CASA) are teaching that a wing is a venturi. It boggles the mind...

In any case the point of my posts was to make young pilots aware that the way many people are taught that lift works is rubbish. As in my first post on page 1. It amazes me that these myths are still around... Have a nice day...

Yes but that can be a bit confusing for a new pilot can't it? Elevator up and down and all that? Of course you are correct once the turn has been initiated by rolling but the elevator cannot initiate a turn... Unless you are in a 90 degree bank already!

nQUOTE="bexrbetter, post: 447929, member: 8594"]In your aloofness you have failed to complete a critical strategy in a debate, know thy enemy. Many of us here are aware of Head in the Clouds long distinguished flying history and plane design/building history and you are looking rather less than clever. Theory is great and thanks goodness for Mathematicians and other scientists who have got us where we are today, but theory without knowledge of how to practically apply it is as useless as big tits on a Nun. The problem here is that you are falling into a Logical Fallacy called authority by eminence. Reputation and experience mean nothing if you are factually incorrect. The classic example of this is religion which is long on 'reputation and authority' but bankrupt on verifiable facts. Science always wins... Forgive me if I don't bow down before factually incorrect statements. The eminent A.A. Griffiths also told Whittle that his engine was impractical and would not be of use. OOPS... The problem is that applying actions without understanding the principles at work is a recipe for disaster... Happy to be corrected factually on anything I have said... My respects to 'Head in the Clouds' for his achievements but how many 20,000hour captains have driven perfectly serviceable aircraft into the ground because they would not listen to their crew stating obvious facts. Want me to list them??? I'm sorry but when it comes to Physics vs Reputation, I will take Physics every time...

I am a waiting Mr Turbo? Anything? Anything at all????? Anything to contribute? Facts maybe? Well reasoned arguments? Or just galley chat... I do enjoy a good discussion.

As I said, if you don't read what you are commenting on, you may be embarrassed. I have been teaching BSC CPL/ATPL Aerodynamics at University. I teach cadets in my spare time as a way of contributing to the future of aviation. how about you? Now if you have a specific fact to challenge please do so. Anything else is trolling...

Yes, I was suspecting another Troll so did a quick Google before heading off to the ignore list. I think I found out the reason for the apparent need to offer denigrating remarks and make it personal rather than accept and address the comment. It seems Prof geek is mainly used to lecturing ab-initio kids in the cadets and no doubt they're supposed to sit up and pay attention. Are you suggesting that I am trolling? The only person I have made tongue in cheek comments to was the person saying that pitching an aircraft doesn't cause AOA changes. If you would like to please demonstrate where I am factually incorrect in any statement I have made,I would be pleased to take it on board. Before you do, please read my comments in context starting from the first post. Then I will be happy for feedback. And no, I have been lecturing to BSc CPL/ATPL students at University as I clearly stated. If you are going to be critical, at least be correct. Prof aerogeek - I came across another set of your cadets lecture notes and although I see they mainly consist of diagrams lifted from various publications (with appropriate credits) I am interested in what I think is your own statement on Page 36 about the purpose of rudder where it states - Ahh no: that is from the FAA PHAK . feel free to tell, them they are wrong. Here the aircraft is rolling and turning to the left. Ailerons work opposite to each other to roll the aircraft. Rudder is used to assist the turn and prevent skidding. My friend-am I to assume that you have never heard of adverse yaw? ? I must have the whole idea of use of rudder during rolling and turning quite wrong. Can you explain how we are supposed to use it to assist the turn please? You probably do...

You are really dancing all over the place to extract your foot from your mouth. Perhaps a slow down and a cup of tea might do some good... The above was my statement to someone being unpleasant...You may have interpreted it as someone else's... Have a nice day...

Oh and I would be happy to know in which way I am unravelling. Any factual statements will do. I have all day...:)

You probably do...

This is not looking good, people are speaking nonsense in attempt to support unsupportable views. I am having fun! Read my original post please, Aviation works on facts, evidence and science not opinions. When someone says that pitching an aircraft up doesn't change it's AOA you have to laugh... Here are some educational documents I prepared earlier. Enjoy! Let me know if you have something factual to say. I'll be waiting!

QF actually... and I ALWAYS encourage my students to challenge me. It is the basis of Human Factors CRM. I was not impugning the reputation of the pilot in question but instead, pointing out that it is a simple truth that if people (including CASA) are promoting myths like Equal Transit Time and Venturi theory even in their syllabus (CSA) how can they possibly understand a supercritical aerofoil which by definition invalidates their claims? You are really dancing all over the place to extract your foot from your mouth. Perhaps a slow down and a cup of tea might do some good...

Who was it once that said the law is an ass? What kind of credibility does CASA have left anyway?More so when they are promoting myths. See the NASA image attached. The venturi myth is simple rubbish because once you cut the top off a venturi it is not a closed system any more, so the conservation of energy is invalid... As soon as they appoint a new director I will be writing to them. CLARC doesn't listen. This is just embarrassing...