McLaren MP4-19 Mercedes

A place to discuss the characteristics of the cars in Formula One, both current as well as historical. Laptimes, driver worshipping and team chatter does not belong here.
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Monstrobolaxa
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Joined: Sat Dec 28, 2002 10:36 pm
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Well....what you're asking Mclaren is quite easy to explain.

First after the "cool" air enters the side pod it changes its caracteristics due to 2 factors.

1st - With the expansion of air inside the side pod.....before the radiator...a low pressure will be created...and since air circulates from high pressures to low pressures, air tends to be sucked from the outside of the side pod into it......

2nd - air after passing the radiator tends to change it's density....cause of the equation:

PV=(Rho)T

P-pressure
V-volume
Rho = density
T = temperature

after passing the radiator the tempreture increases, and the pressure drops, it the volume mantains constante Rho has to decrease, this means that air pressure drops......this will mean that the higgher pressure infront of the radiator will be sucked through the radiator.....This means there is a kind of sequence.....hope this makes it a little more clear.

About your other question....don't quiet understand it.....could you elaborate it a little more?

akbar21881
akbar21881
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Monstrobolaxa-from your answer you seem to know things about fluid.Do you take either aero or mech eng?If u are aero eng...its nice to have a "coursemate" here!!!! :D

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Monstrobolaxa
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Hehehe....arbar21881...suddenly you became my best friend around here.... :lol: hehe....I'm in Aeronautical Engineering. but I've only started studying fluid mechanics this semestre....but when I was in high school I read a couple of books about fluids.....I really love aerodynamics ;)

Guest
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Reading the technical fora is always entertaining, but something simply has to be said about expanding air, because it seems that some peoples word is believed simply because they post a lot of messages.
There are two very fundamental laws in fluid dynamics. One says: density * area * velocity is constant (conservation of mass), which means that if the area is going up the velocity has to be lowered. The density is assumed constant and for the velocities we're looking at that is a very reasonable assumption. The other law says: pressure + 1/2 * density * velocity^2 is constant (Bernoulli, valid for flow without losses ie friction). This means that if there is an expansion the velocity drops and hence the pressure rises. Now please continue the discusion and don't stop using your brain.

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Monstrobolaxa
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Well the last post before mine was directly sent at me.....hehehe.....

Dear Guest.....just found one flaw in your post....
(Bernoulli, valid for flow without losses ie friction).
Well....most of the times it's called Bernoulli's equation but the correct name for it if you discard the friction is Lagrange's equation (know this cause we started working 2 weeks ago with Lagrange and the Bernoulli equations......if you want I can also post them) :P

The consevation of mass equation can also be called Venturi's equation.....
What you posted is true....but don't forget that that is suposing that air density is mantained....put that doesn0t really happen....when you expand air it's density is reduced and when you heat it it also decreases....and these 2 things happen inside the side pod.....(lay of Charles and Gay-Lussac, and Boyle-Marriote's lay).

So infact considering that the fluid doesn't vary it's mass, it does slow down.....but I really didn't mention this cause don't think it was too important I was just considering the pressure gradiant in 3 diferent places (outside the side pod, before the radiator and after it).....and I mentioned that the low pressure would suck the air in front of it...so by this probably people understood that the air behind the radiator is slower then the air infront of it.

akbar21881
akbar21881
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Wow...now all terms like Bernoulli,Lagrange,Boyle etc starting to come out.Can't really recall this equation though as I learned these when I was in 1st year,that was 3yrs ago.!!

But since there are quite a number of us who understand thermo and fluid here,anyone fancy having a more detailed engineering calculation for F1 car.We can simplify things..like assuming several type of flow and simplifying the car shape and we can come up with numbers.That would be better than just mentioning high downforce,low downforce etc etc....

for a start F1 car travels at M=0.25 at sea level...now lets start calculating downforce,drag,P,CoG etc...if somebody can give a rough dimension of F1 cars!!!

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Monstrobolaxa
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Well....don't mind if we do......but.....only in a January...next week, we're going to do a test in the wind tunnel....so....only next week, I'll know how to calculate lift, drag....etc....but I'll look it up in the Race car aerodynamics book.....and get back to you akbar

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Monstrobolaxa
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By the way akbar.....do you agree with the guest? or do you think that my post was already complete....even without considering the conservation of mass and Bernoulli?

akbar21881
akbar21881
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I'm not really sure about this.I guess I have to re-open back my first year fluid and thermodynamics notes...these two types of formula(the one that does not involve conservation of mass and the bernoulli eqn) are related in some way.I can't remember but isnt the short one is obtained by assuming several conditions and hence has a "hidden" mass conservation terms in it which was not shown due to some simplification.Suddenly I become interested in control volume again!!!.I'll get back to this later when I've read my old notes.

Good luck with your wind tunnel test.I did it two years ago..testing a NACAXXX..(I can't remember the numbers after the naca) and it was a hell out pressure calculation that need to be done!!

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Monstrobolaxa
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Well....I'm not going to test a NACAxxxx airfoil....we were supposed to test the NACA 0012 ....but this year the professor wanted to give us a harder job.....so we're going to test a cilinder with a single static pressure sensor......and we have to rotate the cilinder 10º at a time....then we'll have to calculate the drag...pressure and velocity distribuition on the cilinder......ALOT of work....LOL....we just don't have to calculate lift because....a cilinder doesn't produce lift...unless it's rotating.....biut in our case it isn't

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Monstrobolaxa, the ideal gas law is of no real use in these situations. It helps you to calculate the absolute pressure of a fluid and that's it. Furthermore you've either learned it incorrectly or misinterpreted the formula. The formula is not p*V=rho*T, but p*V=R*T , where R is a gas constant and V is not the volume but the specific volume (1/rho). so the formula could also be rewritten as p=rho*R*T. An area increase still leads to a lower velocity and hence a higher pressure.
To get back to the radiator: the duct is diverging (The radiator is larger than the inlet) so the flow is slowing down and hence the pressure rises. This actually makes the flow less likely to want to go down into the duct as it sees a positive pressure gradient. Without temperature the pressure after the radiator is lower than in front of it, not because it is sucked through, but because of friction. A radiator has very small holes where the air has to be forced through. And before you say that the flow slows down due to the friction, I'd like to turn your attention to the conservation of mass. Assuming the area at the end of the radiator is the same as at the front (and they are as far as I know) the flow has to come out at the same velocity as it enters it. It is the friction which lowers the pressure. The temperature rise of the air changes the story somewhat but not fundamentally.
So with these hints please do continue the discussion.

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Monstrobolaxa
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...yup...my mistake with the perfect gas equation....

you're right about the fluids......next time just don't call me stupid I've only started studying fluids 2 months ago!

scarbs
scarbs
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You did mention that only the main plane and the first flap element are full length and the 2nd flap terminated at each side of the nose cone(its attached to the nose in the pic in your side).So which element actually producing lift(no..downforce actually ).
Only the middle of the outer sections (i.e. the two dipped sections) produce large amounts of downforce, the section under the nose produces very little being only two elements and higher from the ground.
Is it all three of them or only certain element?If all element is producing downforce..do all of them act as a single wing element with small spacing between them just to regenerate boundary layer or all three of them produce downforce in their own right?

Any multi element F1 wing acts as one elements the slot created between them reduces separation.
Since the 2nd flap is split under the nose,this means that under the nose,there are only 2 wing elements(main plane+1st flap) right?
Correct
Since there are in close proximity with the nose underside,there are only limited amount of space between flaps and nose. So the flow will expand just after the wing??
I don’t know what the flow does in this area, whether the duct (formed by the underside of the nose, drop plates and upper surface of the wing) is converging, parallel or divergent.
This question may sound silly to knowledgable person but I'm so curious to know the answer.If the flow expand after the wing and hence creating a low pressure area and this results in a pressure difference between upper section of nose and undernose in the area just behind the wing.Correct me if I'm wrong but this will results in further downforce
I have been told recently by Geoff Willis that no reasonable amount of negative pressure is created by under the nose of the chassis, and that flow in this region is more about directing it laterally to the sidepods and bargeboards.
I think.Better still can anyone draw the cutaway diagram of the side view of the MP4-19 nose...

I have a go at drawing it for you
The winglet at the sidepod is for vortex management or does it produce downforce as well????
The winglet is there to produce downforce, but it also shapes the flow around the rear of the car. If you could look at the pressure gradient across the wing from outer to inner, more DF is created at the outer end than the inner end. As the end plate and profile are tuned to create more DF at the outer end. If the inner side had the same layout a vortex would flow off the wing tip\endplate and head straight into the rear wing endplate, not very efficient. So the inner end of the wing is endplate’less and uses a flatter profile, this reduces the power of the vortex produced. This philosophy is applied the rear wings upper and lower elements, plus areas of the front wing.
Renault used it as a way to suck the air out from the chimney, hence the close proximity between the winglet and chimney on R23.
Correct
Still in the topic of vortex management,what I believe is the winglet purposes is something to do with flow management that will short after will hit the rear tyre.Maybe it is use to deflect the flow,or to create disturbance so that less drag is produced when it finally hit the rear tyre.
I understand more to direct the flow away from the rear wing.
Small outlet is created at end the ducktail at the rear of the gearbox.How the heat reach that area in the first place???
The gearbox and CV joints create the heat
Is is still part of the main bodywork?I thought the main bodywork is over at more or less in front of rear suspension apart from the top cover which extend further back to aid aerodynamic.
Yes, The duck tail is a derivative of Ferraris concept, unusually the McLaren version keeps the width broad and constant, rather than Ferraris bulged version

Scarbs….
[/quote]

akbar21881
akbar21881
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Joined: Sat Jun 28, 2003 9:49 pm
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at last all curiosity has been answered.thanx scarbs...

Guest
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MP4-19

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All this hoopla over the new Mclaren is just unjustified,we should wait till melbourne to see how the new car fares.
Anyway this is my first post and hope to be the beginning of many more.
Also dont youll think the exhaust outlets on top are too damn close to where the engine is placed wonder how the exhaust must be going out.?
Bye
Hit_guy