largecar379

OK Doc.....

I don't know crap about flying an airplane, even though my Dad flew fighter jets, but I do know airfoil physics.

top fuel car wings have the largest surface on the bottom of the wing.

F1 car wings have the largest surface on the bottom of the wing.

I could go on, but you know the score.


the "wing" creates lift on an airplane because the largest surface (leading edge to trailing edge) is on the top. This greater surface area on one side causes the air traveling over the larger surface to move faster than the air moving over the smaller surface, creating lift (anti-downforce).

the opposite effect is true for a race car wing. the larger surface is on the bottom, creating downforce (anti-lift).

Last time I checked, airplanes did not work very well when slamming into the ground. The correction to this when flying upside down is with the horizontal stabilizers.....so I have been told. Your examples of experimentals with zero lift/near zero lift wings is a little extreme, but as you say, they are over compensated by the stabilizers.


as I said, all things being equal, when a wing is turned upside down, it creates downforce-----not lift, even though the airplane is upside down----as it relates to the ground.


Thanks for your input.

docmirror

Ah, I see you were referencing only the airfoil, not the whole aircraft. Maybe my misunderstanding, but the way it was worded, it sounded like you were talking about an airplane(from my quote) not flying upside down.

You are correct sir. In the racing world, the 'lifting' surface of the airfoil faces down, to push down on the system which it is bolted to. F1, top fuel, etc.

largecar379

unfortunately, it's what some of us endure......

too bad some can't just debate/discuss the issue (see page 1) without the personal attacks, of which, the last time I read the Charter, are reason enough for removal.


next......

--Russ

largecar379

I should have said:

"As related to the ground", if it's upside down, it's downforce, lift going downward, etc.....


--Russ

mark kibort

symetrical wings on airplanes produce no lift if upsidedown. Its all about their angle off attack .

mark kibort

Technically, the lifting surface on a race car is on top. remember, pressure does the work, not the vacuum. Its differential pressure that lifts or pushes on the wing surface. on a race car, the ambient pressure on the top of the wing is greater than the bottom, so it presses down on the wing and car. on an airplane, this surface is on the bottom of the wing so that the pressure lifts the wing and airplane from the bottom.
airplanes wings can produce downforce, because you can get a differential pressure such that the lower pressure, and higher speed air can be on the bottom, due to the wings angle of attack.
the reason for flat bottom wings is that they are more efficient for some levels of lift (lift to drag ratios). all airfoils have different lift to drag ratios that are shown by their NACA characteristics.

mk

docmirror

Well, debate rages on in regards to the Newtonian vs the Bernoullian effect on the airfoil. The AoA of a symmetrical wing is greater whether upside right, or upside down, cause it is, after all - symmetrical. I personally think it's a function of both, Newtonian and Bernoullian pressures combined to produce lift(downforce). I did my own calculations of Cd(min) way back and found Oswald's theory combined with a lifting theory look by Kelvin don't account for the total lift by the Newtonian(skipping stone) theory. This is also sometimes called 'momentum lifting' theory.

Good value here, with a neat Java tool to disprove the Newtonian(only) lifting value of a given airfoil. No question that there is significant lift provided by the skipping stone function of the air, but it's not sufficient to explain the total lift provided by an airfoil. We can see this in action when a military jet operates at critically high AoA and the air above the wing gets so low in pressure that a vapor cloud appears as the water in the air condenses suddenly.

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong2.html

This guy takes a stab at lifting theory, but makes some minor mistakes which he sluffs off the drag component until later in the evaluation of his lift. By ignoring this drag in his initial equation, it sets the a' well out of line.

http://www.onemetre.net/Design/Downw...m/Momentum.htm

Keep trying folks, I'll kill this thread eventually!
<edit; I'm not going into Euler, because Frankly, we've lost everyone already. >

largecar379

well darn...it was fun while it lasted.



--Russ

mark kibort

Im a fan of both, but i can prove that you can get lift with no traditionally derived newtonian forces! IN fact, i can show a slight negative angle of attack that shows lift . (or downforce). now, AoA is greater on the symetrical air foil for a given lift until you get some extreme AoA's. At some points, they can make more lift

When, you start looking at curved air foils, you start incorporating more of the newtonian forces you mention below.

Another thing to think about is why the old fabric covered wings with no bottoms flew. completely open.

mk

docmirror

Uh, you have it backwards. The curved top portion of the airfoil is the side that models Bernoulli(higher speed, low pressure across a venturi). The action/reaction bottom surface models Newton. Although they are only representations of the two schools, and not a direct coorelation.

Mrmerlin

check this out, some aerodynamic testing

http://www.grc.nasa.gov/WWW/K-12/FoilSim/index.html

Bill Ball

Excellent! Of all the mods on this car, the single flip up headlight mod is probably the best. Flip up the right headlight for quicker turn-in on right turns, and vice versa.

RyanPerrella

there was NO personal attack.

Like i said, i thought it was common knowledge to not speak on subjects we dont really understand? Didnt we all decide its best to sit in silence and JUST LISTEN and LEARN when reading about stuff we have no knowledge in, instead of speaking as if we do?

How is that a personal attack? Now it sounds like you've gone fishing for trouble again and im not sure what your trying to accomplish now.

RyanPerrella

bill
i love how in all that entire mess of a car, you happened to notice that only one headlamp was up. Funny, i think i could look at that a million times and be drawn to some other stupid detail on that poor car then the lamps. There is just so much wrong with that poor orange POS!

nice eye

RyanPerrella

And Carl,

I was a pleasure to meet you at Sharktoberfest!

I also enjoyed speaking to your lovely wife. Her and I both agree that sometimes there is allot RIGHT with disagreeing. And as i told her, if everyone shared the same opinion, the world would be an awful dull place to be!

Keep up the good work.

Cheers