Question about flight physics [Lift Vector]

[dok_rp]

Hello folks,

 

I have a rather simple question. I was reading about flight maneuvers and there's a lot about how I should always point my "Lift Vector" here and there in certain parts of the maneuver.

 

I know where the lift vector is when I am flying level flight, but I was wondering where it'd go once I rolled inverted. Does it still come out of the top of the plane? Does it continue pointing upwards? Or does it go like in the illustration bellow?

 

 

Hope I am not sounding too dumb. It's just that every single picture of a "lift vector" I've found only showed it up to 60 degrees of bank or something like that. I could only find one that showed it during inverted flight, so that brought up my doubt.

 

Thanks beforehand for any help. :thumbup:

 

This should be a piece of cake for you top notch guys. :smartass:

[Laivynas]

Actually lift consist not only from profile lift itself but also from angle of attack. You can fly inverted, but than You must increase AA to compensate for inverted wing lift.

 

http://www.newton.dep.anl.gov/askasci/phy00/phy00640.htm

http://www.pprune.org/forums/archive/index.php/t-10978.html

[RvEPaploo]

It Is yes,

lift come from a less air pressure due to the profile of wing, so it hive lift vector from bottom to top of wing , proportionnal of speed.

you ll stall when the air goes out the sirfaces of the wing.

[Kuky]

well lift generated by the wings is always in same direction... vertically "upwards" in respect to wing itself... or that is, untill you stall. Where the aircraft will be heading or where the total lift force genetarted onto whole aircraft at any point in time depends on added force of gravity, AoA, bank, speed, wind speed and direction etc.

[A.S]

See how it flies

 

http://www.av8n.com/how/

 

 

 

Hope this helps, also in other topics......

 

IF NOT enuf .... enoy this standart classic

 

 

Get this one:

 

http://books.google.de/books?id=bSq-cEf0EWsC&dq=&pg=PP1&ots=iCRByPJwtH&sig=n7nIEQ6g5kth7Kiy5sFSkmFNfs0&prev=http://www.google.de/search%3Fq%3D%2522airplane%2Baerodynamics%2Band%2Bperformance%2522&sa=X&oi=print&ct=title

 

[britgliderpilot]

Hello folks,

 

I have a rather simple question. I was reading about flight maneuvers and there's a lot about how I should always point my "Lift Vector" here and there in certain parts of the maneuver.

 

I know where the lift vector is when I am flying level flight, but I was wondering where it'd go once I rolled inverted. Does it still come out of the top of the plane? Does it continue pointing upwards? Or does it go like in the illustration bellow?

 

 

Hope I am not sounding too dumb. It's just that every single picture of a "lift vector" I've found only showed it up to 60 degrees of bank or something like that. I could only find one that showed it during inverted flight, so that brought up my doubt.

 

Thanks beforehand for any help. :thumbup:

 

This should be a piece of cake for you top notch guys. :smartass:

 

The Lift Vector points in the direction that you are generating lift.

 

If you are inverted but flying level, yes, the lift vector will come out of the "bottom" of the wing.

 

 

To put it simply - if you're flying at positive G, the lift vector comes out of the top of the wing, if at negative G then the lift vector comes out of the bottom of the wing.

 

Since the vast majority of flying (although less so for combat and aerobatics) involves maneuvring at positive G, the lift vector can generally be treated as always emerging from the "top" of the wing.

[dok_rp]

Hello folks,

 

Oh gosh thanks a bunch for all the links. It's funny how other people started their questions the same way I did. "Ok I hope this is not a stupid question"... :lol:

 

 

Well, to say the least, all the help was outstanding. Got it figured out thanks to you guys. :thumbup:

[Mugatu]

That's one of the greatest myths of aviation ;)

 

I was tought that by my instructor too. But lift is actually produced by the bending the airflow behind the wing.

 

http://www.grc.nasa.gov/WWW/K-12/airplane/newton3.html

 

It Is yes,

lift come from a less air pressure due to the profile of wing, so it hive lift vector from bottom to top of wing , proportionnal of speed.

you ll stall when the air goes out the sirfaces of the wing.

[RvEYoda]

Many contributions make up lift. AoA and wing shape are both important. AoA alone CAN lift the plane (early approach), but a bent wing will be more efficient and require less (or none) AoA. Then there are other reasons that can provide more lift.

 

Certain turbulence, and also the sonic shockwaves of transsonic and supersonic flight itself for some planes make them have more lift(what my friend calls surfing planes - NOT in any way a general term. Just something we came up with for it :)). I'm sure someone more into the subject can give a better view.

[britgliderpilot]

Many contributions make up lift. AoA and wing shape are both important. AoA alone CAN lift the plane (early approach), but a bent wing will be more efficient and require less (or none) AoA. Then there are other reasons that can provide more lift.

 

Certain turbulence, and also the sonic shockwaves of transsonic and supersonic flight itself for some planes make them have more lift(what my friend calls surfing planes - NOT in any way a general term. Just something we came up with for it :)). I'm sure someone more into the subject can give a better view.

 

Mmmn.

 

The correct answer is all of the above and probably a few more besides.

Essentially, you push air downwards and get a force upwards on the wing.

 

The mechanisms that cause this are varied. I've just finished spending several years being taught most of them, and have come to the conclusion that unless you're involved in detailed aerofoil research, the details don't really matter :P

[nickbrown360]

dont get started on the theory of flight its a never ending debate their is

bernoulli's principle which some people believe and there is newtons laws which other people believe. In flight school you are taught bernoulli's principle. but there are a larger majority of people that think newtons laws are a more reasonable explenation. I think it lies somewhere in between

[britgliderpilot]

dont get started on the theory of flight its a never ending debate their is

bernoulli's principle which some people believe and there is newtons laws which other people believe. In flight school you are taught bernoulli's principle. but there are a larger majority of people that think newtons laws are a more reasonable explenation. I think it lies somewhere in between

 

Neither of those two explanations stand up on their own, and they're not mutually exclusive either. Saying that aircraft fly "because of Bernoulli" or "because of Newton's law" is oversimplifying the matter to a single point and is just plain lying.

 

I've come to my own conclusion based on the theory available and common sense :P

 

I've never heard one lecturer or instructor describe it all satisfactorily . . . but then lecturers are only interested in describing it through the use of maths, and instructors are only interested that you understand something about what's holding you up. C'est la vie.

[Boneski]

This is interesting.... People seem to know all there is to know about Air Combat, Classified Weapon Systems and Tactics... but can't agree on the basics of how flying works! This is the best thread of the year!

 

One things is for sure.... That 120 looks like it's ready to enter the fight! 9gs be damned!

[A.S]

This is interesting.... People seem to know all there is to know about Air Combat, Classified Weapon Systems and Tactics... but can't agree on the basics of how flying works! This is the best thread of the year!

 

One things is for sure.... That 120 looks like it's ready to enter the fight!

 

This is the best comment of the year :megalol::thumbup:

[Mugatu]

It's quite simple you just want to bend the air flow! That's it no more, bernoulli etc is just a method for achieving it!

 

No theories .. it's just a very well understood fact by the engineering community, maybe not so well understoond by the ego's who fly em. :)

[tflash]

You will of course use the theory that helps you to do the simplest calculations. Are you going to measure the air pressure above and below the wing (bernouilli) or the downward bending force on the airflow (newton).

 

It all depends on your setup.

[LawnDart]

There are no stupid questions. The only dumb question is the one never asked!

 

You cannot sum up the reason and equations for lift by simply one principle. Wing designs vary greatly and factor in various ways to create an optimal design for its purpose, speed, type etc. The plane I currently fly IRL has a supercritical airfoil and it's quite easy to see that no one single principle can explain its complex lift equation.

 

In terms of combat flying, placing ones lift vector on the bandit generally means to put the enemy along a line from your nose and straight up above your canopy! It's the direction that's straight up from your seat (the direction where your wings will create lift when you pull back on the stick). You can always roll your aircraft so this vector will point at the bandit when you pull on the stick and this is what you want to do in a furball to "pull" the bandit into your sight and deploy your weapons. It also creates immediate aspect & angle off problems for the bandit if you're engaged defensive.

 

Hope this helps! Good thread...

[Reaper-6]

Not with-standing the RL Pilots input, there’s nothing like seeing it work…

 

http://www.iihr.uiowa.edu/products/dhrm.html

 

http://web.mit.edu/fluids/www/Shapiro/ncfmf.html

 

http://www.efluids.com/

 

http://homepage.usask.ca/~drs694/fluidmechanics.htm

 

 

Where I get Physics questions answered…

http://www.physicsforums.com/forumdisplay.php?f=101

…the right tool for the right job.

[tflash]

Hello folks,

 

 

 

:smartass:

 

 

This very interesting drawing doesn't show two very important vectors: the forward velocity vector and the centrifugal force vector. If this aircraft is in a looping and pulls of course more than 1 G, you will get a simple Bernouilli effect under the wing as if it was flying level: the centrifugal force will "push" the aircraft onto the air under the wings, so that on top of the wings there is underpressure and so a lift vector as depicted in the red arrow. When the speed in the loop drops below a certain treshold, the centrifugal force is lower than the downward pulling G force and your plane will just fall out of the air.

 

But indeed even this explanation is a very crude oversimplification. The bright side is that all the physics involved is rock solid and pefectly calculable. It becomes more difficult if you start counting some thermodynamic influence on the wing surface or the elasticity of the wing.

 

But what the heck, that is why we have computers no?