completeaerogeek

Hey again Aro - the 'lift is pressure thing' while true in principle can be misleading. AOA which creates angular change creates the pressure differences. NO AOA (or camber) no lift. The pressure diffs are a result of turning flow caused primarily by AOA. That's why a turning flow explanation is easier to understand.

Agree - Sprintcar wings have nothing to do with an airliner, and I only introduced it because of this quote from the geek: "Well SC wings were a real change maker. Curved on the bottom and flat on top. Messes with some people's heads!" That's what he said, and a sprint car wing is curved on the bottom and flat on the top, so the resulting force is down, not up. _____ Ahhh Turbo- at no point did I say that Bernoulli was incorrect. As I have repeatedly said, it is derived from Newton's second Law. However, you can explain lift accurately and effectively without ever hearing of Bernoulli. What I have said is that Newton provides a much clearer explanation and does not require mathematical interpretation. Also people do no understand what Bernoulli is saying, as you clearly do not, and so make up stories like Equal Transit Time and Venturi Theory.

Agree - Sprintcar wings have nothing to do with an airliner, and I only introduced it because of this quote from the geek: "Well SC wings were a real change maker. Curved on the bottom and flat on top. Messes with some people's heads!" That's what he said, and a sprint car wing is curved on the bottom and flat on the top, so the resulting force is down, not up. _____________- Oh Turbo, sprint car wings and aircraft wings use exactly the same laws of physics and fluid flow principles. The aerodynamic forces create resultant forces in exactly the same way. The only variation is the direction of the resultant force...

____________________ Hi Aro, If we use flow turning as the explanation, it is easy to understand that as the wing approaches the stall the upper surface flow cannot make such a rapid angular change and breaks away. I I use teh example of a jet boat or car taking a sharp bend and spinning out. The physics is very similar. Also the reason why this is useful conceptually, is that the same illustration works when we are increasing load factor and therefor stall speed. Most people have seen bow waves from a boat so they have a visual conceptual reference. I think it is important to keep mathematics away because many pilots do not have the skills or knowledge to understand them-and it is not necessary. The physical properties of their aircraft are determined at the design and flight test stage.. The fact that fluid flow is consistent in water and air means that most of us have a ready frame of reference.

Hi Bruce- who was saying Bernoulli is nonsense? Bernoulli's equation is derived from Newton's 2nd law. It has some problems as it assumes air is inviscid but it can be used by aerodynamicists and people who understand it's proper use. The problem is when people don't understand it they make up stories to explain how it works and that is where we get equal Transit Time and venturi theory Life would be much easier for pilots if we stuck to Newton and turning flow. It is a physical principle that anyone can understand..

You are really grasping at straws not. A small amount of camber on top. It is much flatter on top than underneath which kind of blows up convention explanations of lift now doesn't it?

I don't think so. Please find attached the A380 wing plot. SC wings are designed to reduce the density change above the wing as air approached M1.0. The do this by minimising upper surface camber and therefore the angular change as the air changes direction at the leading edge, the reduction in density drop means that the local speed of sound is not lowered as much as on a conventional wing and this reduces standing shock wave size.

My apologies. Must have been lazy fingers. The diagrams I have supplied clearly show flatter and that is what I have said in the remainder of my posts.

Ahh yes they do. Please provide the physical laws under which the sprintcar wings work differently? Be specific now. Might have some trouble there as the rules for fluid dynamics apply to ALL solid objects... Oh and aircraft fly in 3D not 1D

My apologies. It was intended to Mr Turbo only was the end of a long and very silly series of statements he made including numerous statements attacking me when I am just trying to help. If you follow his statements you will see what I mean. I too was taught the these silly theories in the RAAF many years ago and when I found out I was wrong I delved into it a bit deeper. Teaching undergraduates aiming to be airline pilots for the last 3 years has made me se how widespread this nonsense it so I just trying to offer information so people can be better informed. I began this thread-(see the first post) to help people understand what is actually happening because the more we know as pilots, the better we will be and the safer we will stay. The experts have known these stories were rubbish for years. If you see my first post, I uploaded a video from Cambridge University and references from NASA. The problem has been that there have never been any alternate theories accepted by the experts. These stories have been made up by people who don't understand how tings work. If you believe things that are entirely wrong it can cause problems particularly at low airspeed/altitude. When we see accidents like AF447, Asiana 214 and Colgan 3407 where the primary cause for the accident was pilots mishandling the aircraft, it does make me wonder if they understand what they are actually doing. Anyway apologies and thanks for your feedback. Cheers

How can I make this any clearer. IT IS EXACTLY THE SAME PHYSICAL PRINCIPLE AND THE CURVED SHAPES PERFORM EXACTLY THE SAME FUNCTION. They change the direction of the air to suit whatever purpose is intended...

MR Turbo- a physical reaction is not dependent on orientation of reaction. Are you really that obtuse or are you trying to upset people? For your information- SC aerofoils ARE what you would erroneously call 'upside down' aerofoils. All that matters is the direction of the total reaction force. By your reasoning a plane that aileron rolled upside down would fall out of the sky.... I don't think you should be around aircraft...

Hi Aro - -Apologies - that was not was not aimed at you but at Mr Turbo

There are lots of instructors still teaching this. I have seen it personally and encountered it while teaching. It is very prevalent. I have met airline pilots who believe it and it is still included in TV shows about flying. and by flying schools who put videos on the web. Search for yourself. They are easy to find.

I would stay away from pressure explanations. pressure is a result of lift not the cause. Always start with the simplest example-in tis case a flat plate wing. Increase AOA from a=zero and you have lift as a reaction force to turning the air. pressure is a result of AOA not wing shape.

CASA is talking about the Venturi Myth not ETT. I am in conversation with CLARC at the moment about changing this to a more clear explanation using Turning Flow and deleting reference to a venturi. See the first post in this thread for references.

ETT never was an explanation. See wind tunnel pic attached. In all of my statements (please correct me) I have said 'flatter' not flat. See the A380 profile attached. Distance has nothing to do with anything.

_______________- How can I make this any clearer. IT IS EXACTLY THE SAME PHYSICAL PRINCIPLE AND THE CURVED SHAPES PERFORM EXACTLY THE SAME FUNCTION. They change the direction of the air to suit whatever purpose is intended...

_______________- Geez you really are scrambling now aren't you? It s a long time since I have seen someone backpedalling that fast. They work EXACTLY the same way. It is irrelevant which way the flow is turned. They perform the SAME FUNCTION using the same principles. Time to quit while you are behind.....

Sorry didn't mean to overstate my point but if you see his latest clanger he says that sprint car wings have nothing to do with airliners... Absolute classic! Apart from using exactly the same principle of turning flow, being able to calculate their relative 'downforce' in exactly the same way and the fact that they are just an aerofoil turning the airflow to create a reaction force... Well nothing at all I suppose...

Agree - Sprintcar wings have nothing to do with an airliner, and I only introduced it because of this quote from the geek: "Well SC wings were a real change maker. Curved on the bottom and flat on top. Messes with some people's heads!" That's what he said, and a sprint car wing is curved on the bottom and flat on the top, so the resulting force is down, not up. Sprint car wings have nothing to do with an airliner? That is priceless!!!!! IS there some alternate physics theory from your Universe you would like to share?

SC wings produce lift by turning flow. Just like all other wings from from kites to A380s. By using the erroneous 'wing is curved on top so air speeds up to create a low pressure and lift' nonsense everyone just gets confused. The deep convex curve under an SC wing helps push the air forwards and downwards under the wing and this creates a large part of the lift component. Towards the trailing edge there is a reflex curved which redirect the air downwards increasing the turning flow. Outboard of the root twist the wing on top is fairly flat and the 2-4 degrees deck angle in cruising flight couples with the angle of incidence provides all the lift necessary. At lower speeds flaps and slats increase the angle of the turning flow, moving a larger mass of air nwards to compensate for decreasing air speed and energy.

________________ Remind me not to visit your home village they seem to be missing their idiot. Perhaps its time to go home. I note that you have not addressed the many errors you made in your statements. My flat plate reference was directly aimed at your nonsense about military aircraft. It is fairly apparent that you have no idea what you are talking about and every time you are caught out you ignore your past sins and try to insult me. You were wrong about the development of SC wings. Your point about the sprint cars was moot. F1 cars have spoilers not 'deflectors and they work on exactly the same principle as sprint cars. And it is clear despite you blathering that you still don't understand what the Aero book was saying. A bit sad really. I didn't say Tobago I said Tomahawk The point is that even RA aircraft are using non-traditional aerofoils and to perpetuate nonsense serves no-one. Powered hang gliders, parafoils another recreational aircraft use single surface aerofoils which debunk ETT and venturi theory. I have never claimed Bernoulli is wrong, just that we don't need it to understand lift (it is after all derived from Newton's 2nd law and incorrect explanations offered to 'prove' Bernoulli leads pilots to have a totally false idea of what is holding them up. That Mr Turbo, Was the point of my original post.. And it is your assertion that no pilot flying recreationally will every go onto the airlines? And who are the two or three? All modern airliners (and most business jets) use SC wings. Do I have to post the wing profiles so you can get this through your head? If you understand in concept how SC (and all other) aerofoils create lift you will have no problems with any other type. Nevertheless: You are welcome to keep making silly non factual and unsupportable statements if you like. it is quite amusing.

__________________________________ Practical aerodynamics is not very complex at all.. The first sailors learned the principles thousands of years ago. Modern sailors (I have been sailing for over 30 years) need so 'see the flow in order to trim their sails and make them as efficient as possible. Please look at the video from Cambridge at the beginning of this thread and the slides I just posted. Your statement about Newton’s Laws and turning flow is correct and that is my whole point here. I have deliberately not introduced mathematics because this is a conceptual discussion at the level that pilots need to know. Calculus is not necessary but a correct conceptual picture is. Again, it is not that Bernoulli is incorrect, it is that it is explained incorrectly with ETT and ‘Venturi’ theory. Saying that pilots don’t need to understand how a wing works is dangerous. Too many pilots turn back towards the airfield in low airspeed/ engine failure situations and stall/spin in exactly because they do not understand what is happening with their wings.. If you want to watch people doing silly things and injuring themselves because they don’t understand the principles of motion watch ‘The Science of Stupid’. It is enlightening.

In high power to weight aircraft, and military aircraft a lot of power creates enough force to a virtually flat surface to overcome gravty. The same applies with RC aircraft where the power to weight ratio can be enough to overcome gravity on the prop alone. This is my favourite bit. It shows a stunning lack of understanding. How lift works has nothing to do with how much 'power' you have. 100,000LB of thrust at 0 AOA with a flat plate wing will not create ANY lift. Lift only required energy create movement.That energy can come from gravity (a glider) or an engine. A paper plane is the most basic form of a flat wing. It has no thrust (other than your hand) and flies very well. You have completely missed the point that a flat plate is the simplest kind of aerofoil and works by exactly the same laws as any other aerofoil. If turns the air creating a reaction force. A kite does not require any thrust, just the relative motion of the air. I think for the sake of what little credibility you have left, you should retire and ponder what we have discussed. You are just digging a bigger hole…