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Well...probably everyone now knows that Schumacher lost to the eurofighter jet.....he won the 600m (by 0,2s) and lost the 900 (by 0.2s) and lost in the 1200 (by 2.4)....
I just have one question for Ferrari.....why did you send the car with a mid-high downforce configuration?....if everyone pays attention to the car the wings are set to mid-high.....I know that the tarmac was wet....but he was running in a staight line...!!!!I know that due to the high speed of the wheels...if he passed through a very wet spot he probably would lose the rear....but in any case they were running on a run way....he had alot of room for a spin.....so I think Schummy coud have won the 900 if he had a Monza setup....cause in terms of aceleration....auto-start took care of everything.....
I’ve seen the “fight” live on Italian tv. Right after the end of the three runs the journalist asked to Maurizio Cheli (Eurofighter pilot) : “Do you had the time to look at Schumacher during the run ?” and he said :
“Yes, I was constantly looking at him during the whole run and I’ve been truly impressed by the car’s acceleration after the first 2-3 seconds, something I failed to notice yesterday“.
Wednesday in fact he did a test against Burti, I think it was dry but I’m not sure, anyway the EF won. Then he added : ”they must have changed something this night”
Stefano Domenicali confirmed that they changed the wing setup to improve the grip. He estimated the top speed of the car to be about 330-340 km/h with that setup. Actually I’ve read today on a newspaper that after the first 600 m. the car speed was 294 km/h and then it improved by just 10 km/h in the remaining 600 but this source isn’t really technical so I don’t know if the data are reliable, I hope to have more precise info in the next days.
Anyway the answer to Monstrobolaxa’s question for Ferrari is the Cheli’s observation. It (and a read of the first 2/3 chapters of any physics book...)explains exactly what happens on car’s acceleration because of downforce : the grip is = vertical load x coeff of friction. Since downforce increases with speed (square) grip increases with speed (in first approximation the “coefficient of friction” can be considered constant). At very low speed the grip is also very low and TC/LC can’t improve it, it can just exploit the available grip, not increase it. Then as speed goes up you can put more and more force on the ground to increase the acceleration. Obviously acceleration goes up only to the point the engine is capable to apply an higher force, then it decreases.
Schumacher lost the 900 m. run by just few tenths so, maybe, with a dry ground he could have the chance to win because ground grip would be a bit higher (wing setup would be just slightly different IMO). In the 1200 m. run on the contrary the difference was a couple of sec so it looks like an EF win anyway, dry or wet. Nevertheless Cheli pointed out that the wet ground was a bit of a limitation even for him because he had some difficulties to keep the EF standing still at full thrust... it’s not easy to stop a Typhoon...
Location: Covilhã, Portugal (and sometimes in Évora)
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That I know...about downforce.....but.....traction controle tends to equal the wheel speed with the airspeed (thats why F1 cars have pitot tubes (or Prandtl tubes - in french))...and if you try mesuring the downforce of a F1 car the downforce below 80km/h is irrelivant.....it won't help that much traction wise.....at max speed a F1 car produces around 2900N.
And the most importante thing is the instante between being stoped and being in motion....what i mean is since at low air speeds downforce isn't as big as it might seem, so it won't afect the "launch" of the car....so being at Monza or Monaco....going from 0-80km/h will take aproximatly the same time....my point in the setup is about maximum speed....since the were reaching around 300km/h.....they could have taken off "all" downforce...Schummy would have had a higher top end speed....due to the reduction of drag that the car would have!.....and they were traveling in a straight line!
Monstrobolaxa,
you are way underestimating the downforce of a F1 car. If they had to spend 650-700 hp at top speed to generate a DF that is less than half the car’s weight that would be a disaster in term of aero efficiency, on the contrary a F1 is very efficient, considering the limitations. 2900 N is probably the amount of downforce generated at 150-160 km/h with an aero setup for high speed circuits, at top speed it’s about 15000 N.
Obviously I agree that 0 -> 80 km/h acceleration is basically unaffected by downforce and in fact Cheli said that he was impressed by the progression after the first 2-3 seconds. In 3 seconds a F1 is over 100 km/h then downforce starts to be helpful for traction.
Anyway your point that the setup is about top speed isn’t correct, the aim was to minimize the time needed to do a 0-600m or 0-900m. Since Ferrari guys knew there wasn’t a single chance to win in the 1200 m. run (and not because of the wet) they preferred to go for a short distance setup so to maximize acceleration with more downforce. If it was dry they would have adopted less DF ? I don’t know, maybe a bit, but I’m not convinced that a very low DF setup similar to the one adopted in Monza is the best solution for a 0-600 m run. They focused on the shorter distance just hoping the speed was then enough to keep the leading at 900 m and they failed by just 20 meters or so. It’s as always a compromise and since they have all the required data, I’m confident that they’ve chosen the best possible setup to minimize the time required for that distance.
As for the Pitot, are you really sure that the reason the Pitot is there is to obtain the car velocity for the TC ?
Location: Covilhã, Portugal (and sometimes in Évora)
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Reca....sorry...my mistake....I was trying to remember the numbers in Giorgio Piollas book......got then mixed up...just checked it reight now....max downforce at top speed is around 17000N.
About the Pitot tube......at least in the technical books I have the talk about the pitot tube for that purpose......!But....since in the recent past I've been doing alot of mistakes....(must be getting dumber)...I'll look it up again and post back.
Location: Covilhã, Portugal (and sometimes in Évora)
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ok...back with the pitot tube.....there are 2 ways to work the traction control....first....the less comun one (the one I was talking about) the air speed (and air box pressure) is compared with the speed of the rear wheels...and the second the most comun one....which compares the front wheel speed with the rear wheels.....(
Location: Covilhã, Portugal (and sometimes in Évora)
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Just one question....
the grip is = vertical load x coeff of friction. Since downforce increases with speed (square) grip increases with speed (in first approximation the “coefficient of friction” can be considered constant). .............Then as speed goes up you can put more and more force on the ground to increase the acceleration. (Reca)
all is correct....but I'm not convinced about the second part....you say that the more force on the ground you can increase the aceleration.....but a F1 max aceleration is at low speeds (first and second gear)....after that you start to acelerate slowerly....so you do have more force on the tires but in a straight line aceleration it won't help you!
An example:
acelerating from 0 - 100 km/h in 3 seconds (a F1 takes slightly less time)
100km/h - 27,777777 m/s
t=3s
A= speed/time......this camessto an average aceleration from 0-100 of: 9.26m/s^2
Supossing that Schummy reached 305km/h in the 600m.....in the 9.2s
you'll have:
305km/h = 84,722222m/s
t=2s
the average aceleration would be: 9,21m/s^2 (if he had reached a lower speed his average aceleration would have been lower!)
9,21 is smaller then 9,26.....this means that over a long distance the average aceleration declines.....which means that the faster he went the slower he would acelerate....
“Obviously acceleration goes up only to the point the engine is capable to apply an higher force, then it decreases.”
To expand it just a bit :
Force on the ground from the engine is proportional to engine torque * gear ratio. Gear ratio is the ratio between engine rpm and wheel rotational speed. Engine rpm is limited so as speed goes up the gear ratio has to decrease => the force on the ground decreases with speed while on the contrary the grip increases with speed (square speed because of downforce)
At low speed you have more engine force than grip and aero drag is small so the acceleration follows the traction graph growing roughly with square speed. Over a certain speed on the contrary you’ll have more grip than engine force and so the acceleration will follow the (engine force – drag) graph that features a more than linear decrement.
Basically, at low speed acceleration goes up roughly with square speed up to a peak, then it decreases more than linearly with speed. The peak is in the range 150-200 km/h depending by aero setup, gear ratios etc etc etc.
Anyway that’s not the point because the aim wasn’t to reach the highest speed in a fixed time (so to have the highest average acceleration) but it was to complete a fixed distance in the shorter time, a totally different matter.
Location: Covilhã, Portugal (and sometimes in Évora)
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Well...you are correct Reca...but I have another point of view...
Anyway that’s not the point because the aim wasn’t to reach the highest speed in a fixed time (so to have the highest average acceleration) but it was to complete a fixed distance in the shorter time, a totally different matter.
Well...the idea is to acelerate as fast as possible...so if you reduce drag you'll have a bigger aceleration cause The car quickly reached a speed where drag would influence the aceleration!...if the aceleration decreases the need for alot of traction would also be reduced....
If you look it from this perspective: the closest you can get to an ideal aceleration is the usage of launch controle.....if you're able to mantain that aceleration during the distance you want....desides having the highest top end speed.....you'll also finish ahead of the Eurofighter!
If you calculate the aceration from 0-100 (a speed where drag isn't very significante)
you'll have around 9,26 m/s^2 ....like i calculated earlier.....if he by reducing the wing angle, reduce the drag....his aceleration would be closer to 9,26 then the 9,21 he had.....and by calculating his max speed
v=vinicial+(1/2)v x T^2.......he would have a top speed of 335(+/-) (92.99m/s)......that is about 30 km/h then he actually had!
So my question wasn't about the traction cause I assume that the launch and tracion control were working at their best for those conditions.....my question was....if a smaller wing angle reduced downforce and subsequently raised aceleration why did they use a mid-high setup?
You assume that less downforce would have raised the acceleration and that’s true for the average, but on the contrary it would have lowered it when it really counts on short distances, at low speed. Less wing allows to increase the acceleration compared with an high DF setup only well above 200 km/h, say 250. Under 250 the downforce (that at each speed is more than 3 times the drag) allowed to put on the ground a lot of power that otherwise would have been cut by the TC simply because there wasn’t enough grip to use it.
Now an example with an oversimplified velocity vs time plot, take a paper and a pen, I hope you can follow me.
Velocity is the vertical axis and time is the horizontal axis,
Plot the point (1,1) and connect it, linearly, with (0,0), you have a velocity plot. The area under it is a triangle and represents (being the integral of the velocity) the distance travelled with a constant acceleration (the velocity slope is the acceleration) from t = 0 to t=1. The area is = 0.5.
Now, on the same plot, from the point (1, 0.75) draw an horizontal line to the point (0.5, 0.75) and connect that point, linearly, with (0,0). You have now a new velocity plot, the area under it being a trapezium. The acceleration (slope of the velocity) ) for t < 0.5 is higher than previously, then acceleration becomes = 0 so it’s way slower than previously.
Now, if you calculate the average acceleration, top speed/time : triangle 1/1 = 1, trapezium 0.75 / 1 = 0.75.
So the average acceleration with the first plot is higher.
But as I’ve said, what really counts in this kind of races is the distance, and as previously pointed out it’s the area of the figure that shows the distance you have travelled => for the trapezium (1.5 * 0.75)/2 = 0.5625 and that’s larger than 0.5.
As you see you have completed a longer distance in the same time and so you would have completed the same distance (0.5) in a shorter time, to be precise 0.5 would have been completed in (2 * t – 0.5) 0.75/2 = 0.5 => 0.91 instead of 1.
That’s exactly what happens when you have to choose the wing setup for the acceleration run on a fixed, short, distance (by short I mean a lot less than the distance required to reach top speed with a low downforce setup).
With high downforce you’re using the 2nd velocity plot (the trapezium), lot lower top speed but higher acceleration in the first part.
With less downforce you have higher top speed and higher average acceleration, but less grip so a lower acceleration at low speed (triangle).
Obviously if now you draw an horizontal line from (1,1) to (1.5,1) the area under the new line is larger than the area under the line from (1,0.75) to (1.5,0.75). That’s shows that for longer distances the low downforce setup becomes the right choice and so you have to choose the setup according to the distance you have to complete, the rate of acceleration in the two conditions at each speed etc etc... Ferrari guys made the analysis based on the data they had and have found that high downforce was better.
At the end you could also see the triangle as the jet velocity plot and the trapezium as the car velocity because the car advantage is the acceleration at low speed and can be exploited only on short distances. So now you understand why 600 m was a Ferrari win, 900 was close, and 1200 was one-sided race.
BTW, a real velocity plot isn’t as simple as those, but I hope you’ve got the idea.
Does anyone know the weight of the eurofighter during those runs?
I watched the video showing the run. I noticed afterburner was selected arround 1.5s after brakes was released. So the aircraft lost a little time by rolling on just dry thrust.
I don't know perhaps it is not possible to select afterburner under a minimum speed on the Typhoon...
