Online Flight School

[mariosabogal]

Hey, just wanted to update everybody.

 

Our online flight school, “Mario’s Flight School” is making some good progress in developing more aviation tutorial videos. Please be sure to check out our stuff, linked below. If you like what you see please spread the word. If you don’t like what you see please message me ideas to make it better, if you have any.

 

Thanks! Mario.

 

Website : http://www.mariosflightschool.net/

 

Youtube Channel: http://goo.gl/MIiXSQ

 

https://www.youtube.com/watch?v=MA5VJdsIfxg

 

 

[farri]

Hey, just wanted to update everybody.]

• A common explanation using Bernoulli's principle asserts that the air must traverse both the top and bottom in the same amount of time and that this explains the increased speed on the (longer) top side of the wing. But this assertion is false; it is typically the case that the air parcels traveling over the upper surface will reach the trailing edge before those traveling over the bottom.[48]
   
   
  

 

 

 

Hi Mario! I`ve taken a look at your video clip, 'Why an Airplane Flies' and you are using the Bernoulli principal, to explain why the aircraft flies.

 

I`m not an aeronautical engineer but I did teach the Bernoulli principal when I was instructing, as an AUF CFI, however, there are now those who don`t accept the Bernoulli principal, being the reason the aircraft flies.

 

I can imagine the confusion a student would experience after having learnt that the Bernoulli principal, keeps the AC in the air, only to be told later, that it is not correct.

 

If it is not correct,why is it still taught?

 

Frank.

 

 

[Happyflyer]

• A common explanation using Bernoulli's principle asserts that the air must traverse both the top and bottom in the same amount of time and that this explains the increased speed on the (longer) top side of the wing. But this assertion is false; it is typically the case that the air parcels traveling over the upper surface will reach the trailing edge before those traveling over the bottom.[48]
   
   
  

 

 

Hi Mario! I`ve taken a look at your video clip, 'Why an Airplane Flies' and you are using the Bernoulli principal, to explain why the aircraft flies.

 

I`m not an aeronautical engineer but I did teach the Bernoulli principal when I was instructing, as an AUF CFI, however, there are now those who don`t accept the Bernoulli principal, being the reason the aircraft flies.

 

I can imagine the confusion a student would experience after having learnt that the Bernoulli principal, keeps the AC in the air, only to be told later, that it is not correct.

 

If it is not correct,why is it still taught?

 

Frank.

Frank, I believe it is out of favour because it only tells part of the story, most of the lift force is developed because the wing forces the air down, resulting in an equal and opposite force up (Newton's third law). The Benoulli theory has trouble explaining why a wing on an aerobic aeroplane can fly upside down.

 

 

[farri]

Frank, I believe it is out of favour because it only tells part of the story.

So I think that should be explained when instructing, on what creates lift.

 

Frank.

 

 

[Happyflyer]

Yes I agree. Refer to https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html

 

 

[Ultralights]

the Bernoulli's principle is correct, though used in the incorrect context, Bernoullis principle is that air moving at a higher speed, or accelerated to a higher speed, loses static pressure.. and it is correct. and provable, hence the invention of the venturi.

 

as for how a wing flies, its still correct, air accelerated over the upper curve of a wing, will lose pressure, and can be proven using pressure sensitive instruments and water filled tubes, so, yes, its still correct, what has changed is the amount of lift this provides, and how it does it,

 

Modern causes of life are now that the downward deflection of air, results in an upward, or equal and opposite reaction force imposed on the structure that is forcing the air downwards. yes, Bernoullis Principle plays a part, but so does direct air deflection on the lower surface of the wing, all effects combined produce the downward air movement required to generate lift from the wing.

 

 

[farri]

Guys, don`t get me wrong, I`m not arguing one way or the other. This issue first came to my attention, a while back, in Sport Pilot magazine.( Can`t recall which edition). In one of the articles, it claimed that the Bernoulli theory, was a myth.... I thought it odd that Sport Pilot, which is a monthly magazine, paid for and distributed to RA-Aus members, (me being one of them), would come out and publicly state that it is a Myth, while RA-Aus, FTF`s, are teaching it....... Well,I assume they are teaching it.

 

Wikipedia.

 

Basic or popular sources often describe the "Equal Transit-Time" theory of lift, which incorrectly assumes that the parcels of air that divide at the leading edge of an airfoil must rejoin at the trailing edge, forcing the air traveling along the longer upper surface to go faster. Bernoulli's Principle is then cited to conclude that since the air moves slower along the bottom of the wing, the air pressure must be higher, pushing the wing up.[125] However, there is no physical principle that requires equal transit time and experimental results show that this assumption is false.

 

Frank.

 

 

[shags_j]

Wow please lets not get into this one again. There is much discussion on this already here (http://recreationalflying.com/threads/bernoulis-irrelevant.5961/)

 

 

[mariosabogal]

@farri sorry for the delayed response, i'll ask our Aerodynamic Engineer on staff and he will shed some light on this.

However, I highly recommend you watch both Bernoulli and Newton tutorial videos, as I understand they are both speaking to the same thing.

 

But i'll see what our expert says, stand by.

 

https://www.youtube.com/watch?v=yZ88xGrRDgI

 

https://www.youtube.com/watch?v=_hNDWXle3xs

[old man emu]

[mariosabogal]

Hey, so I asked Steve Pomroy... and he offered a fantastic explanation.

 

------ [insert] ------

 

Hey Mario.

 

If you recall, I talked previously about the importance of distinguishing between the *reason* the air travels faster over the top of the wing, and the *result* of the air traveling faster. Frank's misunderstanding is the result of people not making this distinction. He referenced the "equal transit time" principle, which is indeed garbage. But this is distinct from Bernoulli.REASON: The air travels faster over the top of the wing because of continuity (or circulation if you prefer).

 

RESULT: Once the increase in speed is a given, Bernoulli dictates a drop in pressure.

 

The effects of continuity (or circulation) can be both calculated and measured -- and indeed the calculations match the measurements. Ditto for Bernoulli.

 

Also, Bernoulli's equation can be formally derived from Newton's 2nd Law. It's not possible for one of them to be right while the other is wrong. I won't torture you with the details (calculus), but here's the general process:

 

1) Select a small element of fluid (air) travelling along a defined streamline.

 

2) Apply a force balance (Newton's 2nd Law, F=ma) to the fluid element.

 

3) Integrate (add up) the pressure and velocity changes along the streamline.

 

4) Result: Bernoulli's Equation (Ps + Pd = C).

 

For more details:

 

- http://www.flightwriter.com/2010/12/straw-man-of-equal-transit-time-lift.html

 

- http://www.flightwriter.com/2010/12/wherefore-art-thou-lift-lift-part-2.html

 

- http://www.flightwriter.com/2010/12/going-in-circles-lift-part-3.html

 

Cheers,

 

Steve Pomroy

 

President: SkyWriters Publishing

 

http://www.SkyWriters.aero

 

http://www.FlightWriter.com

 

------ [end insert] ------

 

And for even more of of Steve's Knowledge goodness be sure to check out http://www.mariosflightschool.net/

 

Steve writes all the scripts for all the tutorial videos! :)

 

Happy Flying! Mario.

 

 

[fly_tornado]

I've always found Bernoulli very interesting, the idea that your wing is just sucked up into space by an invisible vacuum. Surely whoever decided wings created lift with Bernoulli must have been a practising Catholic, it fits in very nicely?

 

http://en.wikipedia.org/wiki/Firmament

 

 

[Roundsounds]

Aside from pilots knowing about the relationship of angle of attack, airspeed, surface area and the effects of ice / damage on lift - the theorems of Bernoulli, Newton or the hangar cat are neither here nor there. I'm sure there are way more important things we could fill our / student's brains with.

 

 

[ben87r]

I always think of it like this (maybe incorrectly!) newtons does not explain why a wing with zero AoA can generate lift and, old mate Bernies theory dosnt explain why a surface (and a wing) with zero camber generates lift but, the two together can explain all in my opinion anyway

 

 

[fly_tornado]

so what plane flies with 0 AoA?

 

 

[ben87r]

Most cambered wings will be in the negative region before creating no lift hence, at zero AoA lift is still created. Zero camber wings should create zero lift at zero AoA.

 

 

[Roundsounds]

It's all just magic....

 

 

[Roundsounds]

FT - try entering this into your web browser:

 

grc.nasa.gov/www/k-12/WindTunnel/Activities/lift_formula.html

 

 

[Ultralights]

A Savannah at high speed will have a 0 AOA in cruise.

 

 

[frank marriott]

A Savannah at high speed will have a 0 AOA in cruise.

I didn't realise Savannah and "high speed" went together:roflmao:

 

 

[facthunter]

You beat me to it frank.

 

More seriously...There is a zero lift AoA for these things. A flat wing will have some pretty critical boundary layer problems, but seem to work very well on small models.

 

There are plenty of wind tunnel tests showing manometer tubes connected to various parts of the wing section which illustrate what sort of pressures are happening when air flows over.

 

Smoke (Layered) will also show what happens before the wing and after. Downwash effect at positive AoA's.

 

Some interpret "deflect" as being off the bottom surface which is not correct. It is only part of the picture.

 

There is no vaccuum above the wing , but there is certainly a reduced pressure.

 

At high AoA's the flow separates and becomes turbulent. Lift is still produced but increasingly a lot of drag.

 

The wing tip vortices are not all of the induced drag. It's happening all along the wing.

 

The air passing through a venturi incurs a small drop in pressure after the venturi due to losses. in the same way. Nev

 

 

[Capn Wannabe]

Here's what *really* happens..

 

 

 

[ayavner]

[nong]

Somebody is going to have to say this.....

 

I think these Mario's Videos are crap. Mario is a self promoting screen hog, in my judgement.

 

Prospective students, I think, should avoid these videos.

 

 

[farri]

I don`t want to put off any student from learning what is required, to obtain their pilot licence or certificate, but this is the way I see it.

 

The accidents that occur don`t happen because the pilot isn`t sure which theory is keeping the aircraft flying. Understanding the forces that keep the aircraft in the air, is mostly for the aeronautical engineers who design aircraft. What the pilot needs to know most, is how to fly the aircraft and keep it flying.

 

Frank.