Debunking Lift Theories Still Taught

[turboplanner]

Oh no, I will not give up trying to educate people.

In post #163 Guernsey made an attempt at humour using an aviation term

 

In post #164 Eightyknots joined in with another one

 

In post #165 I joined in with another one

 

I just want to reassure you that were were feeding off each other's jokes rather than baiting you to keep up your dialogue.

 

Having done some checking, I already knew from the 'repetitive' tag that it was going to be continuing regardless of what I said, probably until the last man standing was disposed of.

 

Mr Turbo has been materially incorrect I every statement he has made

I'm happy to summarise my comments by recommending people buy the book "Aerodynamics for Naval Aviators" NAVWEPS 00-80T-80, Naval Air Systems Command, United States Navy - available now on www.amazon.com for $20.67

 

 

[Bruce Tuncks]

Well Complete, your statement that " the plane is moving and the air is not".. is at best irrelevant and at worst means you have an incorrect understanding of the physics of motion. I could continue like this but have a better idea...

 

How about this to settle the argument about my Jabiru...we can be real scientists and run an experiment.

 

I will run a tube from the rear of my fuselage to the door and put in a sensitive pressure meter or a flow-meter. ( I can make use of a variometer which is a very sensitive flow-meter and is already in my panel).

 

If the pressure is MORE at the door or the flow is AWAY from the door then I will donate $100 on your behalf to the site. But if, as I say from my understanding of Bernoulli, the pressure is LESS at the door or the flow is TOWARDS the door then you will make the donation for me.

 

Be aware that the fuselage at the doors is over 100cm in diameter, and the fuselage near the tail is about 25cm in diameter. Slipstream from the propeller adds to the speed of the airflow over both points. You can see a bit of the actual fuselage in my photo.

 

Lots of details to work out, like how to agree on a trusted observer, and who will hold the money, but are you game?...I am.

 

 

[robinsm]

to much for me, I just fly the damn thing and it stays in the air. Why is fairly irrelevant to the average pilot. Accept the fact that if lift didn't happen we wouldn't be flying. Now how does a flapping wing on a duck create lift as well as staying in the sky. I don't care whether some one went to Uni or not, who they were taught by or what degree they had. Thats your business and not the subject for a p..ssing comp. Posulate all the theories you like, I am more concerned about fuel usage, navigation and keeping the thing flying so I dont hit the ground. I dont think you will ever agree, and frankly, who cares...!!!

 

 

[Guest ozzie]

I could never understand why they teach this 'why it flies stuff' that can never really be explained completely and fully to the student pilot when the teachers should be feeding the poor beggar with the skills needed to prevent them from creating smoking craters.

 

Bit like when being back at school being taught algebra and the like (that i have never used in real life) when they should have taught me how to get a home loan or deal with the taxman.

 

 

[metalman]

I could never understand why they teach this 'why it flies stuff' that can never really be explained completely and fully to the student pilot when the teachers should be feeding the poor beggar with the skills needed to prevent them from creating smoking craters.Bit like when being back at school being taught algebra and the like (that i have never used in real life) when they should have taught me how to get a home loan or deal with the taxman.

That's why explaining lift using newtons law is the simplest correct way to explain a complex issue, newtons law explains why it flies, the other stuff explains some peripheral forces as a result the wing moving through the air

 

 

[bexrbetter]

When you crack the window of your car does the air go out or in?

It goes in because it has been displaced by the solid form of the car just like a boat displaces water.

Of course initially it "goes in" momentarily due to both wanting to seek a lower pressure area and simple inertia, but the moment it finds pressure balance and then continues to come in raising pressure, it then tries to go back out again. I have done tufting tests on race cars to prove to the owners that their cooling system problem's are due to airflow actually going forward against the direction of travel much to their disbelief's. They also are somewhat distrusting when I greatly reduce the size of the cooling openings.

 

You will not duplicate this result with water.

 

.... and his nasty little insults.

When you strut around treating others to be of inferior intellect, it's no surprise to end up with a few insults.

 

 

[completeaerogeek]

In post #163 Guernsey made an attempt at humour using an aviation termIn post #164 Eightyknots joined in with another one

In post #165 I joined in with another one

 

I just want to reassure you that were were feeding off each other's jokes rather than baiting you to keep up your dialogue.

 

Having done some checking, I already knew from the 'repetitive' tag that it was going to be continuing regardless of what I said, probably until the last man standing was disposed of.

 

I'm happy to summarise my comments by recommending people buy the book "Aerodynamics for Naval Aviators" NAVWEPS 00-80T-80, Naval Air Systems Command, United States Navy - available now on www.amazon.com for $20.67

Mr Turbo, my purpose is to inform and help people be better aviators not to have arguments. The information I have give is correct and in accordance with NASA and other aviation institutions.

 

You may take it or leave it. Entirely up to you.

 

 

[Dafydd Llewellyn]

Quote: "When you crack the window of your car does the air go out or in?

 

It goes in because it has been displaced by the solid form of the car just like a boat displaces water.

 

If the 'faster air' outside, moving past your window was at a lower pressure as you suggest, the air would go out not in would it not?"

 

With all due respect: Horse s***t. What you describe would happen if you were trying to float a car upside down in water - i.e. it's a hydrostatics answer. Not relevant to the issue in question.

 

Bruce Tuncks has correctly described what happens in an unpressurised streamlined fuselage that has openings around the maximum cross-section and at the tail, such that flow can occur between the tail opening and the cabin. Whether flow goes into or out of such an opening (in the absence of anything that acts as a deflector or a scoop) depends on the difference between the static pressure on the outside of the fuselage and the static pressure in the cabin. The static pressure in the cabin depends on the aggregate effect of all the leakage points, but it will generally be somewhere between the free stream static pressure and the local pressure at the point of maximum local velocity; so it usually comes in at the tail and goes out at the cabin window or door leakage point - and this is well known as a source of carbon monoxide contamination of cockpits.

 

You may be surprised to learn that open cockpit aircraft are notorious for CO contamination of the cockpit air; but if you think about what I have said above, the reason will be obvious.

 

 

[johnm]

ozzie

 

if you had of been dealt house loans you would of been a banker

 

if if you had of been dealt kill the taxman, you would of been an accountant

 

there'd probably be similar forums for the above 2 subjects ........................ but they'd be dry and boring

 

we are all just basking in completeaerogeeks dealing of aerodynamics (I think that's the name of the subject)

 

 

[completeaerogeek]

Of course initially it "goes in" momentarily due to both wanting to seek a lower pressure area and simple inertia, but the moment it finds pressure balance and then continues to come in raising pressure, it then tries to go back out again. I have done tufting tests on race cars to prove to the owners that their cooling system problem's are due to airflow actually going forward against the direction of travel much to their disbelief's. They also are somewhat distrusting when I greatly reduce the size of the cooling openings.You will not duplicate this result with water.

 

When you strut around treating others to be of inferior intellect, it's no surprise to end up with a few insults.

____________________-

Well Complete, your statement that " the plane is moving and the air is not".. is at best irrelevant and at worst means you have an incorrect understanding of the physics of motion

 

Bruce, I am afraid you have a shovel and you keep digging yourself a bigger hole.

 

I have used this example in a conceptual (not mathematical) context every time I have mentioned it. Conceptually it is important as people ascribe all kinds of properties to the air that it does not have. Still air does not have momentum or kinetic energy. It has inertia and potential energy. Is that irrelevant?

 

Your statements are a perfect reason why this perspective is important. You seem to be unable to visualise flow.

 

To understand the concept of lift or flow it is important to visualise it in the way that it occurs not the way you think it does.

 

Now to your statement:

 

Of course initially it "goes in" momentarily due to both wanting to seek a lower pressure area and simple inertia, but the moment it finds pressure balance and then continues to come in raising pressure, it then tries to go back out again. I have done tufting tests on race cars to prove to the owners that their cooling system problem's are due to airflow actually going forward against the direction of travel much to their disbelief's

 

Now on to some other glaring conceptual errors:

 

First I think you mean momentum not inertia. Inertia is resistance to change or motion. (Newton’s 1st Law)

 

Secondly, what you are describing is ram effect. Ram effect occurs when the volumetric capacity of an intake is reached and the pressure in the intake equals or exceeds static.

 

Our Nene Vampires had this problem with the elephant ear intakes. The usual solution to this is spill doors. (I don't think it is me with the problem with the physics of motion...)

 

Also your racing car analogy is not valid here because you have not mentioned a key aspect-heat.

 

You can reduce the size of the intake while enlarging the exit and actually increase the velocity of the air because as the air is heated by the engine it expands. This principle was applied to the Spitfire and Mustang in their radiators by having a variable exit. It actually gave a thrust boost. This is called the Meredith effect after the RAE engineer who discovered it

 

Now on to your challenge. I would think carefully if I were you. I am happy to take your money and donate it.

 

Let me use an analogy:You see I have a nice Porsche and when I crack the window driving down the freeway it gives me a nice breeze for as long as the window is open...

 

It doesn't fill up and magically reverse flow.

 

Again what you are describing is ram effect not parallel flow.

 

The pressure at the point where the windscreen rises from the bonnet is higher than static. It creates a bow wave (pressure wave) that forces air up and over and round the side of the pillar.

 

At that point the air comes in if I choose. Your plane is no different. Aircraft are solid objects immersed in a viscous gaseous fluid. They behave in exactly the same way.

 

Aircraft are subject to the laws of displacement just like a submarine.

 

Now if your door apertures are parallel to the airflow and the air comes in it entirely defeats your Bernoulli explanation because if the streamline flow along the fuselage (which is obviously at a higher relative speed to the air inside the cabin) causes a pressure reduction the air would go out not in.

 

Physics is simple you can't have it both ways. Simply put, if outside pressure is higher than inside, air comes in. F=Ma is not negotiable.

 

As for your fume problem: Your tailplane probably has a localised flow impinging somewhere that creates a pressure wave higher than static and it is this that is causing a pressure rise, pushing the fumes back into your cabin. Pressure rises like this occur where the vertical or horizontal stabs join the aircraft.

 

Now to your insult: I don't think there is evidence of me strutting or treating people as inferior. If giving correct information is strutting then the problem doesn't lie with me.

 

In fact your statement about me not knowing about the physics of motion when you are clearly incorrect in your assertions rather points to you doesn’t it?

 

Bruce, air is a fluid. Water and air act in the same way. Air is considered incompressible below M1.0.

 

That is why the study of aerodynamics comes under fluid dynamics. Air and water behave in exactly the a same way unless you have come across a law of physics I have not heard of.

 

 

[completeaerogeek]

Quote: "When you crack the window of your car does the air go out or in?It goes in because it has been displaced by the solid form of the car just like a boat displaces water.

If the 'faster air' outside, moving past your window was at a lower pressure as you suggest, the air would go out not in would it not?"

 

With all due respect: Horse s***t. What you describe would happen if you were trying to float a car upside down in water - i.e. it's a hydrostatics answer. Not relevant to the issue in question.

 

Bruce Tuncks has correctly described what happens in an unpressurised streamlined fuselage that has openings around the maximum cross-section and at the tail, such that flow can occur between the tail opening and the cabin. Whether flow goes into or out of such an opening (in the absence of anything that acts as a deflector or a scoop) depends on the difference between the static pressure on the outside of the fuselage and the static pressure in the cabin. The static pressure in the cabin depends on the aggregate effect of all the leakage points, but it will generally be somewhere between the free stream static pressure and the local pressure at the point of maximum local velocity; so it usually comes in at the tail and goes out at the cabin window or door leakage point - and this is well known as a source of carbon monoxide contamination of cockpits.

 

You may be surprised to learn that open cockpit aircraft are notorious for CO contamination of the cockpit air; but if you think about what I have said above, the reason will be obvious.

___________________-

No that would be a buoyancy problem.

 

Wow you guys really need to read what I am saying and think before you post...Could you please explain why if the relative air speed outside the aircraft was higher than inside (which of course it is) that by his explanation of Bernoulli the air would not go out? Air goes from high to low pressure.

 

Daffyd, in what way is air different to water? (apart from density) I am always happy to learn new things.

 

And I am sorry but you are incorrect. Again...The principle I was describing was a hydrodynamics one not a hydrostatic one.. Might be time for some reading.

 

If an aircraft is a solid form immersed in air it behaves exactly the same as a solid object immersed in water. That’s why aerodynamics is also called fluid dynamics. Air is considered incompressible below M1.0.

 

Also it is perfectly reasonable that an open cockpit aircraft is subject to fumes for the same reason. There is a pressure wave built up at the front of the aircraft. Combine this with slipstream (if the aircraft is accelerating, and you have a higher dynamic pressure forward of the cockpit. If the dynamic air pressure is higher than that in the cockpit- Fumes. Not difficult really.

 

In your last point you missed the dynamic pressure rise where the air is impinging on the vertical and horizontal stabilisers at the root. This is a higher pressure point as at the leading edge of a wing so if the air is ingressing there of course it will be higher than in the cabin and push fumes in.

 

 

[Guest ozzie]

This guy works for CASA.

 

 

[M61A1]

I've been following this thread for a bit now...... is this some sort of "Human Factors" exercise on your (geek) part, so that you can write some sort of thesis?

 

If it's not, I'm quite sure that I wouldn't like to be one of your students. I was going to ask if you really taught in the defence force, but then I remembered most defence instructors (tech) that I ever had, most were ex-tradies, and often the worst. Usually people that hated what they did, so to get off the floor, did a Cert whatever, and became instructors.

 

If you really teach Human Factors, (amongst other things) I would expect a better grasp on how to interact and put the subject matter forward in a manner that people are more receptive to. You may well be 100% correct(or not) in what you say, but I am finding the way in which the material is presented somewhat inconsistent. I doubt that you intend to come across like Sheldon Cooper on hallucinogens, bit it's what I'm getting out of it.

 

 

[AVOCET]

They come in hot , and go out smoken !

 

 

[foxworker]

Hi all, it is amazing to me that there are still people out there teaching silly ideas about how lift works.Even CASA is still pushing things that aero professionals laugh at despite being told so many times that what they say is fiction.

 

As a 33 year aviation professional and University lecturer with an MSc in this stuff, it drives me nuts!

 

Here are several references that may embarrass your flying instructor (and a lot of professional pilots)

 

A clue: One if from NASA the other from Cambridge University so we can be pretty confident in what they say.

 

In reality there is NO DEBATE or 'alternate theories' about how lift works amongst aerodynamics specialists.

 

At the fringes in tiny percentages there is some weird stuff but for 99% of what is relevant this is the story...

 

If your flying instructor or aero guru tries to argue-tell them to write to NASA and explain themselves. Should get a laugh from the team at the Glenn Research Centre!

 

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

 

[foxworker]

completeaerogeek, great stuff, when I did my theory back in '91, I was pretty skeptical of the Bernoulli principle back then, as it made pretty much no sense at all., if they're still teaching this silly theory to explain lift. it needs to be stopped

 

 

[completeaerogeek]

I've been following this thread for a bit now...... is this some sort of "Human Factors" exercise on your (geek) part, so that you can write some sort of thesis?If it's not, I'm quite sure that I wouldn't like to be one of your students. I was going to ask if you really taught in the defence force, but then I remembered most defence instructors (tech) that I ever had, most were ex-tradies, and often the worst. Usually people that hated what they did, so to get off the floor, did a Cert whatever, and became instructors.

If you really teach Human Factors, (amongst other things) I would expect a better grasp on how to interact and put the subject matter forward in a manner that people are more receptive to. You may well be 100% correct(or not) in what you say, but I am finding the way in which the material is presented somewhat inconsistent. I doubt that you intend to come across like Sheldon Cooper on hallucinogens, bit it's what I'm getting out of it.

Ahhh M61. I see you have twigged. Thanks for your comments.

 

The first part of my purpose was to explain clearly that what may people think is correct is in fact nonsense and hopefully be of help. The second part was to see what sort of response I got.

 

The vociferous arguments based on fallacies are exactly what we in the industry need to fix. An authority figure (instructor or captain) using the cockpit or classroom power gradient consciously or unconsciously can teach new pilots or F/Os all kinds of bad habits or suppress their correct views and the junior pilot will often accept this just to 'get along'.

 

This is the 'Authority from Eminence' logical fallacy I mentioned earlier. (I am currently writing a book on this)

 

One of the posters said just this thing "it's just a hoop you have to jump through to get to the next stage". That is dangerous unprofessional thinking.

 

(As for being one of my students, I had the highest Student Satisfaction scores ever recorded in the department. Students still call me for advice and mentoring because they know I genuinely care about them knowing the right information and how to use it in the real world, not just the lecture room.

 

As for inconsistent- can you point it out please? The only thing I would ask is that you view the comments in context and start by reading my first post on Page 1.

 

It was concise, referenced and provided resources. If you are jumping in the middle no doubt it would look fragmented but you have to look at the whole subject in context.

 

Providing information with references that are unimpeachable and then watching people make emotional and inflammatory comments without having read them is quite interesting.

 

It is the kind of mentality that says 'I have always operated this way and I haven't had any problems in 30 years and you are not going to convince me otherwise' and then next thing you read about them in an ATSB report.

 

See Mr Turboplanner' comments. He is comprehensively wrong but will not see it. This is called 'Confirmation Bias' where someone only accepts information that fits with their pre-existing view. This has been a significant causal factor is quite a number of airline accidents.

 

The unwillingness to revise opinions or practices on the basis of new information is extremely dangerous and one of the contributing factors for the number of GA/RA accidents.

 

And no. Most of my facilitation has been in the corporate world-Airline and business and a corporate speaker here and overseas in Aviation where if you are crap, they don't ask you back.

 

No captive audiences there.

 

I hope that has made some sense to you.

 

Cheers.

 

 

[pmccarthy]

Wow, we have all been the subjects of a mind-bending experiment, and I didn't even post!

 

 

[M61A1]

Ahhh M61. I see you have twigged. Thanks for your comments.The first part of my purpose was to explain clearly that what may people think is correct is in fact nonsense and hopefully be of help. The second part was to see what sort of response I got.

 

The vociferous arguments based on fallacies are exactly what we in the industry need to fix. An authority figure (instructor or captain) using the cockpit or classroom power gradient consciously or unconsciously can teach new pilots or F/Os all kinds of bad habits or suppress their correct views and the junior pilot will often accept this just to 'get along'.

 

This is the 'Authority from Eminence' logical fallacy I mentioned earlier. (I am currently writing a book on this)

 

One of the posters said just this thing "it's just a hoop you have to jump through to get to the next stage". That is dangerous unprofessional thinking.

 

(As for being one of my students, I had the highest Student Satisfaction scores ever recorded in the department. Students still call me for advice and mentoring because they know I genuinely care about them knowing the right information and how to use it in the real world, not just the lecture room.

 

As for inconsistent- can you point it out please? The only thing I would ask is that you view the comments in context and start by reading my first post on Page 1.

 

It was concise, referenced and provided resources. If you are jumping in the middle no doubt it would look fragmented but you have to look at the whole subject in context.

 

Providing information with references that are unimpeachable and then watching people make emotional and inflammatory comments without having read them is quite interesting.

 

It is the kind of mentality that says 'I have always operated this way and I haven't had any problems in 30 years and you are not going to convince me otherwise' and then next thing you read about them in an ATSB report.

 

See Mr Turboplanner' comments. He is comprehensively wrong but will not see it. This is called 'Confirmation Bias' where someone only accepts information that fits with their pre-existing view. This has been a significant causal factor is quite a number of airline accidents.

 

The unwillingness to revise opinions or practices on the basis of new information is extremely dangerous and one of the contributing factors for the number of GA/RA accidents.

 

And no. Most of my facilitation has been in the corporate world-Airline and business and a corporate speaker here and overseas in Aviation where if you are crap, they don't ask you back.

 

No captive audiences there.

 

I hope that has made some sense to you.

 

Cheers.

No I have started at the start and my point was that although the material may or may not be correct, the way that it has been put forward has been in my opinion, dismal. If you were trying to prove that people get their back up because of confirmation bias, you have not, what you have proven is that people get their back up when called stupid, or told bluntly that what they believe (because that's what they were taught) is nonsense. No one asked the question, you essentially just marched on in and told everybody that if they didn't believe you that they were stupid.

I would personally rethink your satisfaction scores, many students I have been on courses with, just tell the instructor what they want to hear, because they don't want to be pinned down and grilled by someone who is just going to tell them how stupid they are. No it's not how course critiques are supposed to work, but frequently it's what happens.

 

On that note, you appear to have some confirmation bias of your own, inasmuch as you believe that it's your student's fault that they don't believe you, not your own instructional technique or condescending attitude.

 

A good instructor will find a way to help all of the students understand, not beat them into submission.

 

No captive audiences? Yes they are, their boss decides that in order to comply with their legally required SMS, that they should receive regular lectures about such stuff, he picks out something he thinks will comply, and there you are talking to a bunch of people who would rather just be out doing their job. Been there many times, enjoyed it once ( a well spoken funny doctor about DAMP).

 

 

[facthunter]

Well put M6. I was a trained secondary teacher and some of them did indulge in ridicule and put downs . I hope I avoided that. Students do not respond well to that technique. Input should be encouraged from all, and this won't happen if there is likely public embarrassment involved. Nev

 

 

[robinsm]

Ahhh M61. I see you have twigged. Thanks for your comments.The first part of my purpose was to explain clearly that what may people think is correct is in fact nonsense and hopefully be of help. The second part was to see what sort of response I got.

 

The vociferous arguments based on fallacies are exactly what we in the industry need to fix. An authority figure (instructor or captain) using the cockpit or classroom power gradient consciously or unconsciously can teach new pilots or F/Os all kinds of bad habits or suppress their correct views and the junior pilot will often accept this just to 'get along'.

 

This is the 'Authority from Eminence' logical fallacy I mentioned earlier. (I am currently writing a book on this)

 

One of the posters said just this thing "it's just a hoop you have to jump through to get to the next stage". That is dangerous unprofessional thinking.

 

(As for being one of my students, I had the highest Student Satisfaction scores ever recorded in the department. Students still call me for advice and mentoring because they know I genuinely care about them knowing the right information and how to use it in the real world, not just the lecture room.

 

As for inconsistent- can you point it out please? The only thing I would ask is that you view the comments in context and start by reading my first post on Page 1.

 

It was concise, referenced and provided resources. If you are jumping in the middle no doubt it would look fragmented but you have to look at the whole subject in context.

 

Providing information with references that are unimpeachable and then watching people make emotional and inflammatory comments without having read them is quite interesting.

 

It is the kind of mentality that says 'I have always operated this way and I haven't had any problems in 30 years and you are not going to convince me otherwise' and then next thing you read about them in an ATSB report.

 

See Mr Turboplanner' comments. He is comprehensively wrong but will not see it. This is called 'Confirmation Bias' where someone only accepts information that fits with their pre-existing view. This has been a significant causal factor is quite a number of airline accidents.

 

The unwillingness to revise opinions or practices on the basis of new information is extremely dangerous and one of the contributing factors for the number of GA/RA accidents.

 

And no. Most of my facilitation has been in the corporate world-Airline and business and a corporate speaker here and overseas in Aviation where if you are crap, they don't ask you back.

 

No captive audiences there.

 

I hope that has made some sense to you.

 

Cheers.

So have they asked you back after your arrogant, rude and downright"holier than thou" attitude...?

 

 

[rgmwa]

I'm reading all these very interesting posts but having trouble with some of the technical descriptions. My main problem is that I keep confusing `completeaerogeek' with `completelyarrogant'. Could somebody please explain the difference?

 

rgmwa

 

 

[completeaerogeek]

I'm reading all these very interesting posts but having trouble with some of the technical descriptions. My main problem is that I keep confusing `completeaerogeek' with `completelyarrogant'. Could somebody please explain the difference?rgmwa

Would you please specify why giving information that some clearly do not understand was arrogant?

 

 

[completeaerogeek]

This guy works for CASA.

Ahhh no...

 

 

[completeaerogeek]

Well put M6. I was a trained secondary teacher and some of them did indulge in ridicule and put downs . I hope I avoided that. Students do not respond well to that technique. Input should be encouraged from all, and this won't happen if there is likely public embarrassment involved. Nev

Ahh a retrospective qualification. How is providing information a negative experience? Making a correct statement and then having people abuse you for it is part of public discourse.

 

I don't mind it as long as the overall information and discussion of benefit.If your ego isn't in the way you can learn many new concepts. I have no problem being wrong. it is how we all learn. But if you care going to criticise me then you need to support it with facts and objective assessment. Otherwisse it is just your ego talking.

 

So my question to you is this: Is your statement and that of M61 an objective one?

 

Read my first post with all of the valid information and then see the hostile response it got from some. No-one was coerced into responding or commenting.

 

Their egos led them to lash out and insult me despite the fact that what I was saying was 100% correct.

 

This has been happening from time immemorial when anyone dismantled cultural myths. it is called shooting the messenger and it comes from insecurity and lack of intellectual courage.

 

If one person on this site now better understand basic aerodynamics then I have succeeded in my intent.