Exhaust energy use 2011 (without FFE)

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marekk
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote:Also, all of these systems impact the rear only, and given a mandatory C of G, there exists an ideal Center of Pressure, which unless you can balance with more front DF you've just moved rearward. This means that whatever your exhaust blowing is doing, it can't ever be as important as your front wing.
You are right, there is ideal center of pressure point, but if you have more floor/diffuser downforce, you can run less rear wing for the same CoP, and this means less drag.

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ringo
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina what you are saying about teams having fully developed cars is speculation.

Mclaren did add a second to the car and it is reported that Lotus will add 8 tenths.

These exhausts weren't used last year because they are inferior for last years regulations. The DDD allowed holes to be place through the diffuser surface.
The Diffuser is less sensitive to throttle possition if the pipes are set away from it.

I can show you that there is a performance gain, but i would rather wait for the teams to confirm it.
I am not going to take a bias view against lotus becuase they are a propper team with propper engineers. The Mclaren and Redbull aren't alien to the lotus. They abide by the same bodywork regulations so it is understood that the principles of the blown floor still hold. That is more logical than the assuming one team is crap so what works for them doesn't work for the big team becuase the big teams car is super refined.
If KERS is worth 3 tenths a lap in a Mclaren it's still worth 3 tenths in a Lotus.
If EBD is worth 1 second in a Mclaren it's not surprising to hear Lotus leak that their's is worth 8 tenths.
For Sure!!

Sayshina
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Re: Exhaust energy use 2011 (without FFE)

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The top teams are certainly not running fully developed cars, but they certainly ARE running more fully developed cars than the backmarkers. This isn't speculation, this is the historical fact of motor racing. They may be running to the same rulebook, but they're not racing in the same series. Not in any realistic sense anyway. If you have 5 times as much money and 5 times as many highly skilled people working for you as I do, and you don't significantly outperform me, then you should be fired.

These exhausts weren't used last year because they were inferior to what was used last year. When the teams raced with no holes in the diffuser, other than the exhausts, direct blowing was still preferred by all. And please stop talking about that period as though it were the dark ages, it was a couple of years ago.

It's silly to imply that these exhausts are in any way superior when they were universally ignored until the other solution was made illegal. You really don't think somebody tried this idea out 5 years ago? I'd be surprised if they didn't try it earlier than that.

We ASSUME the current methods make for a less sensative solution. It's still a bit premature to be making statements of fact there.

Yes, I'm sure you can pull out yet another Ringosim to prove your point. I just don't understand why you continue to think your fantasy sims carry weight.

Kers is certainly not worth 3 tenths. I am aware that is the number being thrown around the media, but I remind you that journalists as a rule don't even take highschool level physics. Kers will certainly be worth different amounts to each team, depending on how they choose to compromise the system. And by the way, McClaren directly copying RB's exhaust will ALSO be worth a different amount. This is the nature of complex systems, and your to credit individual parts with massive and certain gains are not valid.

These exhausts are not worth 1 second because they can't be. They're not worth 1/2 a second because they can't be. If they were worth anywhere near that much time they would have been mandatory years ago, and would never have been abandoned. You don't remove 1/2 second from your car, not ever.
You are right, there is ideal center of pressure point, but if you have more floor/diffuser downforce, you can run less rear wing for the same CoP, and this means less drag.
Marekk, you're correct in that they could rebalance the car with the wing, and underbody downforce is generally considered to be cleaner than wing generated downforce. But if all they're doing is dropping some drag then these exhausts are worth even less.

My point was that they can't be worth any more than the front wing is capable of balancing. And since the front wing is certainly not capable of easily and instantly adding 1/2 a second, the exhaust blowing certainly can't be capable of doing so either.

shelly
shelly
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Re: Exhaust energy use 2011 (without FFE)

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@sayshina: do not underestimate the power of the exhaust!

I think you are.
I agree with you about darwinian selection of effective solution in f1; but you have to consider that change in the rules changes trade offs also. So exhausts driven floors could be more worthy now that the diffuser is so limited.

About balancing: if exhausts make the diffuse work better, you gain downforce all over the floor, not just rear downforce. It is a bit rear biased, but not 120% rear biased as the rear wing, or 125% front biased as the front wing. So you do not need to counter balance it with a similar amount of front wing downforce. Also you can add a bit of rake to shift forward the center of pressure of the floor
In the end I think the 0.8 to 1 second is a reasonable performane figure, even if we all know it is circuit dependant etc
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Sayshina
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Re: Exhaust energy use 2011 (without FFE)

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shelly wrote:@sayshina: do not underestimate the power of the exhaust!

I think you are.

... but you have to consider that change in the rules changes trade offs also. So exhausts driven floors could be more worthy now that the diffuser is so limited.

About balancing: if exhausts make the diffuse work better, you gain downforce all over the floor, not just rear downforce. It is a bit rear biased,...
I firmly believe many people on this forum overestimate the power of F1 exhausts by at least 1,000%. If there was anywhere near the force some people around here are assuming and you stuck your hand over the outlet it would get blown off.

Yes, rules changes make different compromises necessary. But rules changes seldom make a previously suboptimal part suddenly superior to what used to be the best.

What looks like the current optimal solution could have been run last year and was not. It could have been run with the previous blown single diffusers and was not. What's worse, it's a fairly straightforward solution, especially compared to others being used today, so there's little chance it wasn't at least casually explored in the past.

If you say the rules changed making the old solution illegal and forcing teams to use the next best option, I say absolutely I'm right there with ya. But if you claim that the rules change makes the new solution superior to what was used before I say you gotta show me how because I'm just not seeing it.

The beam wing used to be almost an afterthought. Not it seems to be one of the top points of focus for most if not all teams. But the beam wing hasn't changed in power in and of itself. It's only changed in relative power with so many other parts around it being so heavily restricted.

The underbody downforce is in front of the rear axle, so it can't be 100% rearward biased, but we know it's significantly rearward. If this were not so the cars wouldn't be nearly so pitch sensitive as they currently are. You may not need to fully balance it on the front wing, but I'd be surprised if you didn't need to balance at least 80% of it.

I'm also not so sure you can adjust the balance by changing pitch angle. For one thing, that would change the way the sides of the floor seal, and require a lot of changes to that area, but mostly I suspect teams are running the maximum pitch angle their respective packages will allow. In fact I've claimed a number of times here that the whole point of blowing the floor or diffuser is to enable the car to run more pitch without stalling the diffuser. This claim is based on the F1 designer (possibly Gascoyne, can't remember) stating in print a few years ago that blowing the diffuser then was to prevent the diffuser roof from stalling. Since the diffuser then and now was controled by rule and teams tend to run the maximum angle of attack, the only way to increase this angle is to increase the pitch.

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ringo
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote: These exhausts weren't used last year because they were inferior to what was used last year. When the teams raced with no holes in the diffuser, other than the exhausts, direct blowing was still preferred by all. And please stop talking about that period as though it were the dark ages, it was a couple of years ago.

It's silly to imply that these exhausts are in any way superior when they were universally ignored until the other solution was made illegal. You really don't think somebody tried this idea out 5 years ago? I'd be surprised if they didn't try it earlier than that.

I said the 2011 were inferior to the 2010 solutions specifically, i didn't say otherwise.

The 2011 exhausts are inferior to the past solutions, but inferiority is relative. A 2011 car with the blown sides has a performance advantage over a 2011 car without. We're dealing with 2011 and Lotus is adding 8 tenths, not with driver confidence but with an aerodynamic upgrade.

Now what kind of reasoning is this?
These exhausts are not worth 1 second because they can't be. They're not worth 1/2 a second because they can't be. If they were worth anywhere near that much time they would have been mandatory years ago, and would never have been abandoned. You don't remove 1/2 second from your car, not ever.
come on man, do better than that. You just casted out every single scientific explanation and replaced it with a silly notion.
That is what you are doing here.

I think you are failing to see what is happening.
What would help is if you put up some images of what you call a superior solution and why it is worth 1s then compare it to the 2011 and explain why you think it isn't worth 0.5s.
I'll then put up my reasoning.
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shelly
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote:The underbody downforce is in front of the rear axle, so it can't be 100% rearward biased, but we know it's significantly rearward. If this were not so the cars wouldn't be nearly so pitch sensitive as they currently are. You may not need to fully balance it on the front wing, but I'd be surprised if you didn't need to balance at least 80% of it.
We can calculate that percentage.
For a 46% front balance of the whole car, matching weight distribution, with a 125% front balance of the front wing (given the current rules overhang), wanting to keep constant whole car balance if we put:

P= percentage of front wing downforce to add to compansate floor downforce
fl.fb= floor front balance

we have:


P=(0.46-fl.fb)/0.79

So if fl.fb=0 (underbody downforce acting on the rear axle) P=58%
if fl.fb=0.2(underbody downforce 20% front, 80% rear) P=33%
if fl.fb=0.3(underbody downforce 30% front, 70% rear) P=20%

We see P would be below 60% even if the floor downforce was concentrated on the rear axle. I think a reasoable underbody downforce distribution is between 20 and 30% front balance, this gives us P between 33 and 20%.
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Sayshina
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Re: Exhaust energy use 2011 (without FFE)

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Ringo: If they aren't superior to last years solutions, and last years solutions are not worth 8 tenths, then this years solutions must be worth less.

The can't be worth 1/2 a second because if they are then all of the engineers involved in designing F1 cars, each and every one of them, is too stupid to breath.

Look, there are occasionally clever reinterpretations. Very occasionally. When Tyrell first showed up with a high nose, everybody, including the designer Migot (spelling?) did a bit of dead scratching. And we all should know the story of how ground effect was "discovered" by now.

But these exhausts are a fairly obvious area to explore. If there's a major team in F1 who didn't at least do some CFD on an RB'esque solution 5 years ago they need to terminate some people. This is not a case of "Holy crap, how could we have missed that?".

This is a very different issue than say the double diffuser. In that case we know other teams DID think of it, and the primary factor in whether or not they made one seems to be whether or not they asked the FIA if it would be legal. Some teams asked and were told it would be illegal, others just made one and took their chances. That is, unless Newey is lying.

Is that a scientific explanation? No, not really. It's a matter of faith. I have faith that while 1 person can easily miss an obvious solution, several dozen highly trained highly skilled people, given enough time and budget to explore, are unlikely to do so. And how exactly is it scientific to claim that Lotus are hoping this is worth 8 tenths so it must be?

Could I be failing to see the truth? Certainly. Unlike someone I could name, I don't stick to my argument despite all evidence to the contrary (cough, refueling, cough). I have yet to see what I would call evidence.

I know we disagree on that last point. You see the sudden jump in speed of the McLarens as an outright gain in performance, while I'm near certain it's a correction in balance. I don't know of any way to prove either case without inside information we are very unlikely to come by. I've said several times that I think Ferrari are currently in the same boat, that they're not suddenly slow but rather suffering from a problem, in their case one that didn't happen until the very end of testing.

You can continue to belittle me on driver confidence all you like, it remains a fact. Some of the difference between Vetel and Webber this year is down to problems with Webbers car, but I will guarantee some of it is also down to 1 guy winning a championship last year and the other failing to do so.

I don't really want to digress again, as the OP has specifically asked up not to. But we know specifically that these exhausts effect car balance, so they also specifically effect driver confidence. If you'd like to debate the impact of driver conficence then please make a separate thread and I'll be happy to explain my reasoning there. You might need to pm me on it, as I'm a bit internet challenged.

There's not much chance of me linking images or articles as I honestly don't know how. If you look at my posts you may notice I don't even know how to specifically quote posts other than the one I press the "quote" button on. This HTML crap gives me a headache. Also, many of the things I've read, as well as my own racing experience, are decades old and in many cases I have no idea where I read them.

Shelly, part of our difference is down to how you're calculating. I was simply refering to what you need to put on the front axle, where you're including the overhang in the equation. Clearly, by your method you shouldn't ever need 80%. However, you're wrong about the other 1/2. You don't multiply by the weight distribution. If you add 100% to the rear axle you need to add 100% to the front, or 79% if you include the overhang. Actually, it will be less, because you want the center of pressure to move somewhat toward the rear at speed. This imparts stability on the straights. But you can't have it moving too far as that will give you an understeering pig in high speed corners.

I suspect the ratio from floor downforce is around 10% front, but I'll admit that's more guess than anything. The current cars are clearly highly pitch sensitive. Much of that can be blamed on the wings, but I don't think all of it. And what causes that sensitivity is having the vast majority of your downforce coming from outside the wheelbase.

Again, my original comment was that all this exhaust blowing could never be more "important" than the front wing, a comment I stand by. No matter what teams are doing with their exhausts, I'll bet the primary focus of the teams this year will remain the front wing. That's the trend of recent years, notwithstanding the distractions like F-ducts and pullrod suspensions.

1/2 a second is a tremendous gain, one that normally takes months and hundreds of new parts to acheive. The idea that you can get double that from something that wasn't even worth using last year is to my mind fantasy.

shelly
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote: However, you're wrong about the other 1/2. You don't multiply by the weight distribution. If you add 100% to the rear axle you need to add 100% to the front,
I am not wrong: I added the amount of downforce needed to keep front balance set at 46% (adde 46 to the front for every 54 you add to the rear). I omitted the maths, and that is probably why you misinterpret it.
About understeering in fast corners, I agree with you, but that will lower percentage of front wing more.

Abount overhang: you must take it into account whent you are doing these estimates.
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Sayshina
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Re: Exhaust energy use 2011 (without FFE)

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shelly wrote: I am not wrong: I added the amount of downforce needed to keep front balance set at 46% (adde 46 to the front for every 54 you add to the rear)...

...About understeering in fast corners, I agree with you, but that will lower percentage of front wing more.

...Abount overhang: you must take it into account whent you are doing these estimates.
About part 2, I admitted as much. Well, if we're talking about the same thing I did. You can get away with having more rear bias on the straights, but only as long as you can shed some of it as you aproach the corner. But yes, at the highest vehicle speeds you can get away with less front downforce. I should point out however that current thinking seems to involve reduced rear downforce and accepting the inherent reduction in straight line stability as a price worth paying.

About part 3, it depends and either method is valid as long as both parties are on the same page. Wind tunnel reports normally express the results in terms of gains and losses at the axles. As long as you're referencing off of the axles the specific overhang, front or rear, is irrelevant.

In truth, as you increase the angle of incidence on the front wing you would expect the center of pressure on said wing to move forward, technically increasing your effective overhang. You would also expect the change in flow to disrupt rear downforce in several areas, from side sealing of the floor, to increased positive pressure inside the sidepods. You also lose effective downforce from the rear due to lever effect, requiring less than 79% front to balance. All of these factors work in your favor.

As to part 1: I take .79 (the overhang), multiply by .46, divide by .54 and get .67. Actually, I take 1, divide by 1.25, get .8, multiply by 46, divide by 54, and get .68. Could you explain how you get to .58? I also get .48 absolute for your worst case example, rather than .2.

Again, I feel I'm being a bit misunderstood here. I'm not at all claiming these exhausts are irrelevant, or even not powerful. I said they're 1% of the solution, but 1% is fairly huge for a single part. I simply take issue with the notion prevalent around here that they're 20% or even more.

shelly
shelly
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote:
As to part 1: I take .79 (the overhang), multiply by .46, divide by .54 and get .67. Actually, I take 1, divide by 1.25, get .8, multiply by 46, divide by 54, and get .68. Could you explain how you get to .58? I also get .48 absolute for your worst case example, rather than .2.
Here's my way of calculating.
Let us put:
D=total downforceincrement you get from floor + underbody
ub.fb= front balance of underbody added downforce, which we will leave as a parameter
fw.fb = front balance of the front wing, which we put 1.25 (it moves a bit with incidence, as you say, but just a few millimiters back and forth)
U= total downforce increment form the underbody
F=total downforce increment form the front wing.

We have:
D=U+F

we split into two relations for rear end and front end, and we put the constraint of 46/54 distribution:

U*ub.fb+F*fw.fb =0.46*D for the front
U*(1-ub.fb)+F*(1-fw.fb)=0.54*D for the rear

so we get:

0.54*U*ub.fb+0.54*F*fw.fb=0.46*U*(1-ub.fb)+0.46*F*(1-fw.fb)

F/U=(0.46-ub.fb)/(fw.fb-0.46)

and being fw.fb=1.25 we get:

F/U=(0.46-ub.fb)/0.79

from which we get F/U=0.58 if ub.fb=0, F/U=0.2 if ub.fb=0.3
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marekk
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Re: Exhaust energy use 2011 (without FFE)

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Sayshina wrote: Marekk, you're correct in that they could rebalance the car with the wing, and underbody downforce is generally considered to be cleaner than wing generated downforce. But if all they're doing is dropping some drag then these exhausts are worth even less.

My point was that they can't be worth any more than the front wing is capable of balancing. And since the front wing is certainly not capable of easily and instantly adding 1/2 a second, the exhaust blowing certainly can't be capable of doing so either.
We should try to speak numbers.
Downforce to drag ratio for F1 diffuser is at least 2 times bigger then for a wing.

This means, for every 10 kg of downforce added to diffuser/floor, you can reduce rear wing downforce the same 10 kg and gain 20 kg reduction in drag. Hardly "some" drag.

That's what all this hype around tight rear packaging is about - to get as much of rear downforce as possible from diff/floor and reduce rear wing. Beam wing has no better efficiency then main wing, but due to proximity to diffuser, relatively weak flow around beam wing influence diffuser's efficiency in big way.

shelly
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Re: Exhaust energy use 2011 (without FFE)

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marekk wrote: We should try to speak numbers.
Downforce to drag ratio for F1 diffuser is at least 2 times bigger then for a wing.

This means, for every 10 kg of downforce added to diffuser/floor, you can reduce rear wing downforce the same 10 kg and gain 20 kg reduction in drag. Hardly "some" drag.
marekk your numbers are wrong. Let us accept thtat the diffuser efficiency is twice as big as the rear wing efficiency; but to get the numbers you are writing you are also impliictly assuming that the rear wing efficiency is 0.25. It is aroBetteund 40 times greater than that.
Better estimate would be 0.8 kg of drag gain when you exchange downforce between rear wing nd diffuser
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marekk
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Re: Exhaust energy use 2011 (without FFE)

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shelly wrote:
marekk wrote: We should try to speak numbers.
Downforce to drag ratio for F1 diffuser is at least 2 times bigger then for a wing.

This means, for every 10 kg of downforce added to diffuser/floor, you can reduce rear wing downforce the same 10 kg and gain 20 kg reduction in drag. Hardly "some" drag.
marekk your numbers are wrong. Let us accept thtat the diffuser efficiency is twice as big as the rear wing efficiency; but to get the numbers you are writing you are also impliictly assuming that the rear wing efficiency is 0.25. It is aroBetteund 40 times greater than that.
Better estimate would be 0.8 kg of drag gain when you exchange downforce between rear wing nd diffuser

I've messed it up a little, shame on me :oops:

But on the other hand, i doubt rear wings L/D ratio will be 10, as assumed in your example.
Rough estimation of this type of wing (2 elements, 750mm wingspan, 600mm chord) at near stall angle of attack is around 1.8. Big endplates should increase L/D significantly, so lets say between 2 and 2.5.

My estimation of moving 10kg of downforce from the wing to the diffuser will be 3-4kg reduction of drag. Additionally diff/floor downforce is less rear biased then rear wing downforce. Still significant gains IMO.

shelly
shelly
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Re: Exhaust energy use 2011 (without FFE)

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I think rear wing effciency is greater, around 6-8.
Also if you take it being 2.5 you gain only 2kg drag for every 10kg downforce exachange (delta.drag=10/2*wing.efficency)
twitter: @armchair_aero