okay let the debate begin...newton or bernoulli

[rumorhasit]

okay aside from possible spelling errors, which contributes to lift more... newtons laws or bernoulli's theory?

 

[flyifrvfr]

I think lift is a mixture of both. Bernouli for the explaination of high and low pressures, and newton for every action has an equal and opposite action. Newton: air is deflected downward from the wing which forces the wing up. Bernouli: High pressure seeks a low pressure creating lift.

 

[rumorhasit]

But which plays a larger role in lift...? This was an examiners question a few months back...something like 75% bernoulli's and 25% newton or something. I was just wondering...

 

[philo beddoe]

Neither.

Gutenberg is the correct answer.

Because, without the printing press, we would not have pilot certificates, AFMs, FARs, AIMs, company manuals, or the single most important thing that makes flight possible.


Money, and lots of it!


See? If they ever go to a paperless cockpit and a cashless society, look out! All aircraft will instantly fall directly to earth.

 

[flyifrvfr]

I would go with that percentage. Bernouli says that when fluid passes thru a venturi that the fluid speeds up and creates a low pressure. The wing being the venturi and the air being the fluid. Because the wing is curved, the wing breaks the air into to different halves.The air on the top of the wing has to travel a longer distance to meet back up with the air at the bottom. A low pressure is forned from the faster air and a high pressure is formed from the slower air. Since a high pressure always seeks a low pressure, the result is lift.

Because most wings on an airplane are attached to the fuselage at a positive angle ( angle of incidence ) the air that strikes the bottom of the wing is deflected downward. Every action has an opposite reaction, lift. Newtons law comes into effect after the airplane has enough airspeed to fly. Bernouli has the greater effect for lift.

 

[milehigh6080]

You can't break it down into a percentage because it changes with your angle of attack. If you're in low speed flight you're carrying a high angle of attack- the air is moving slowly over your wings so the bernoulli effect isn't as pronounced, but because of the high angle of attack, Mr. Newton is really doing a lot of work for you. In high speed flight, the faster moving relative wind means that you'll have a more pronounced pressure drop as bernoulli describes, but because your angle of attack is so small, there is little chance for Newton to get in there and do the job. You're probably never using strictly one or the other, they both contribute and the percentage depends on your angle of attack and airspeed.

-Milehigh

 

[wingnutt]

always liked tesla myself...perhaps one of the most overlooked inventors ever

 

[avbug]

Making a comparison is nonsensical. It is the "Bernoulli" venturi effect, and attendent loss of local pressure that is in part responsible for the downwash that accounts for the measure of lift produced by a wing, rotor, or propeller.

Your question is rather like asking if it is the head or the foot that makes the body move forward. Or is it gravity?

Any measures of lift values to be divided by source will vary with airspeed and angle of attack for any given air density and weight.

That the value of lift applied upward is the product of the mass and velocity of air moved downward means that it accounts for all of the lift produced. "Bernoulli"'s principle (not theory) acounts for part of the mechanism to produce that total value.

There is nothing to debate.

 

[mmmdonut]

No....

 

[ADF_Fixed]

Well even though newton's " action reaction" is well known in physic. it is obvously bernoulli is the master of lift. Just take the upper surface of the wind (upper camber) overall area. it is definitely more than the lower camber.