To optimize energy consumption, or how to make F1 greener

[jddh1]

That is the problem nowadays, we dont have very "specific need" designed cars: we have huge SUVs to drive in the city.

Very often I see them in NYC and I wonder: "What's the point?" I have a 80cc Vespa to move around the City.

But for racing, one may start a new series with these ideas. Why not regulate A1-GP to test them? If not that or GP2, why not another filler series that runs in conjunction with the F1 schedule, supported by the F1 teams, say with a budget of 5 million euros a year. I'll say something crazy here, but what if you give the incentive that the points collected on that series can be added to the F1 Constructors championship?

[alelanza]

Many thanks for the answer Ciro!

I have a few more questions:

1-According to that EPA graph, how is 55 mph more frugal than lower speeds? say 45 mph? I would imagine that as long as you are in top gear and somewhere along that sweet spot of the engine, more speed simply means more drag. Unless those low speeds are achieved by means of using stop and go traffic data.

2-Xpensive mentioned gasoline's high capacity to store energy, but i'm wondering how much does the picture change in terms of adding efficiency loses, being 60-65% of those kJ dissipate into heat?
So actually my question is, what's the aprox efficiency of a battery driving an electric motor? how much energy is lost when filling up the battery, how much is lost when discharging it and finally how efficient is the typical electric motor?
How much kJ would i lose going from motion to electricity to chemical and back again?

3-Just an opinion: regarding moveable aero, while i understand the obvious benefits, it does not appeal to me because they will either be controlled by a computer, which i dislike for the same reason most of us dislike TC, or it will be controlled by the driver which to me really changes my perception of what racing is about. I feel drivers as it is with all the engine mappings and kers controls plus FW control (which i dislike) are already in a place where racing itself has started to take a back seat. The 3 playstation controls in one allusion (Piquet was it?) points out that current drivers are already juggling so many things at once. No wonder they're so happy when put on a normal down to earth go kart. I feel even more moveable aero would just seal this tendency,
Of course i understand the nature of this discussion should touch upon such a subject, and i greatly enjoy it and will keep on reading it. I'm only saying that personally it does not appeal to me to see the drivers turned into airplane pilots.

@ jddh1

I really like where you are going. I feel F1 should be about fire breathing monsters accelerating/late braking as fast as possible, as loud as possible, racing lines, grip, weight transfer, etc. Develop a better tyre? brake compound? valve? for sure! but keep it about racing.
Then parallel to that having another series with potential F1 involvement (not necessarily) with a fixed budget and total technical freedom would be great. Throw in doing something akin to what usgp1 guys said about adding reality show elements to it and i think we could have the best of both worlds

[Belatti]

alelanza, very good questions!

1- drag increases with the cube of speed. With the engine on its sweet spot on the final drive, aero drag is not too big and the mileage is still good because that is the best balance between specific fuel consumption and the time it takes to actually travel those miles. For example, specific consumption may be less at 45mph than at 55mph, but if you travel at 45mph it takes longer for you to do your trip.

2- Electric motors are damn efficient:

• Power(hp) Minimum Nominal Efficiency
• 1 - 4 -------------- 78.8
• 5 - 9 -------------- 84.0
• 10 - 19 ------------ 85.5
• 20 - 49 ------------ 88.5
• 50 - 99 ------------ 90.2
• 100 - 124 ---------- 91.7
• > 125 -------------- 92.4

Batteries seem to be efficient too, above 80% in may cases I have found:
http://hallyutech.net/2008/11/12/korean ... ncy-by-90/
http://en.wikipedia.org/wiki/Lithium_ion_battery
http://batteryuniversity.com/partone-12.htm

[xpensive]

Just let me straighten a few useful things out before Belatti confuses everything completely.
At speeds above 100 km/h, aerodynamic resistance makes up for more than 90% of the resistance (F) for the engine to overcome in order to propel the car at constant speed.

# Aerodynamic force is: F = Cv * Cross-section Area * air-density * speed squared/2
# Energy needed is Force times distance.
# Power needed is Force times speed.

Conclusively: Aerodynamic energy-loss per distance goes with the square of the speed and this is why your car typically consumes less gas per km at 100 km/h than at 150.
Aerodynamic Powerloss however, has a cubic relation to speed, why you need eight times the power to move your car at 300 km/ than at 150.

You can then mix things things up with torque-caracteristics (there are acually gearboxes for that) and whatever "sweet-spots", but the above will never change.

And this, is why an F1 car of the 21st century should have full bodywork, talking "green" and energy savings on an open-wheel car is utter rubbish.

[Ciro Pabón]

Well, yes, to keep constant speed you spend most of your energy on air drag.

However, I know no F1 car that moves at constant speed (out of the pitlane), so the "90% spent on drag" figure you give is not applicable.

I ask you to double check the figures I gave. When an F1 car brakes, the bodywork is more or less irrelevant. When it accelerates, up to 220 km/h, I estimate most of the energy is spent on overcoming inertia. This leaves you around 25% of a typical lap time spent at high speed, when the full bodywork does its "job".

Full bodywork has pro and cons: again, I suspect a bodywork, besides the extra weight, makes a car slower on slow curves, because of lateral inertia, robbing you there of part of the advantage of less drag in straights.

Even with a bodywork, I think most of the drag comes from the floor and wings. Is there where the aerodynamic "work" is done, to produce downforce.

Can you provide a figure for full bodywork drag coefficient? I looked around and couldn't find it. It's the only way I know to estimate how much energy you save.

[xpensive]

Good morning Ciro,
The problem with open wheels is that technically speaking you will get a Cv of far more than one, when cross-section area does not really explain the shape. When beholding a top-view of an F1 car you realize that the rear-wheels will not really be in the shadow of the fronts, fronts will help like slip-streaming, but it's almost like a pair of two-wheeled cars closely following.

On top of that, the top surface of the tyres are turning against the air with twice the speed.

A good sportscar of today however, will have a CV of less than 0.3, or so I have been told anyway. Barn-door wings are another matter of course, why our future F1 car should be equipped with retractable such and/or venturi-underbodies.

As for the limited kinetic energy available, I think my humble estimations at the beginning of this thread are reasonably accurate.

[Ruy]

So, what would be a rough estimation of the drag of a F1 car?

i.e. :
if drag = (speed squared) * (drag coefficient), then estimate (drag coefficient);

(I know (drag coefficient) isn't really a coefficient)

Also interested in downforce

[xpensive]

If you give Cv times cross-section area the value of 1.5, it should not be that far off.

This makes for simple calculations, when aerodynamic drag becomes 0.75 times density times speed squared.

Conclusively, an F1 car at 320 km/h (200 mph), has to overcome a force equal to 6700 N. That force, if acting on a 700 kg object means an accelleration of almost 10 m/s^2.

In popular wording, if an F1 car loses all power at 200 mph, it will deaccellerate with one g from air-resistance alone. Think about it.

[Scania]

Well, yes, to keep constant speed you spend most of your energy on air drag.

However, I know no F1 car that moves at constant speed (out of the pitlane), so the "90% spent on drag" figure you give is not applicable.

I ask you to double check the figures I gave. When an F1 car brakes, the bodywork is more or less irrelevant. When it accelerates, up to 220 km/h, I estimate most of the energy is spent on overcoming inertia. This leaves you around 25% of a typical lap time spent at high speed, when the full bodywork does its "job".

Full bodywork has pro and cons: again, I suspect a bodywork, besides the extra weight, makes a car slower on slow curves, because of lateral inertia, robbing you there of part of the advantage of less drag in straights.

Even with a bodywork, I think most of the drag comes from the floor and wings. Is there where the aerodynamic "work" is done, to produce downforce.

Can you provide a figure for full bodywork drag coefficient? I looked around and couldn't find it. It's the only way I know to estimate how much energy you save.

constant engine speed≠ constant wheel speed

[Belatti]

Just let me straighten a few useful things out before Belatti confuses everything completely.

Sorry, I must have said "power used to overcome drag increases with the cube of speed". My fault. Sometimes I oversimplify in order to get quickly to the point.

The question 1- I answered to alelanza was about a street car getting all out of its mileage, not F1 related. Of course, like Ciro pointed out, it was achieved at constant speed where inertia effects are not taking part.

[Ciro Pabón]

I was left with a curiosity about how much real power is used to overcome inertia and how much is used to overcome drag. Again, I took Reca's graph of Speed vs Time for an Albert Park lap in 2007.

I choose the fourth acceleration in the graph (the larger) and took the speeds every second. Then I used the same crude worksheet to calculate the power spent in moving and the power used in drag. This is what I got:



The dark blue line is the power to overcome inertia, the lighter blue line is the power to overcome drag, as percentage of total power. The yellow line is the total power in HP (its scale is to the right).

As you can see, while you are under 170 kph, inertia power is larger than aerodynamic power.

However, I was wrong about the time you spend in "drag regime". After watching the numbers, now I think xpensive is right: I estimate that 57 seconds, out of the 86 seconds of the lap (two thirds of the time), were at speeds over 170 kph.

[xpensive]

Impressive graph Ciro, but it depends on the track I guess, remember I used Monza rather than Albert Park.

Anyway, the same thinking should be applied when considering the amount of energy possible to recover from breaking, when kinetic energy lost though air-resistance is not applicable, right?
If you again look at my draft numbers on top, from 250 kph to 100 with a 700 kg object, there is only a difference of 1400kJ in kinetic energy and how much of that will be lost through the air during breaking? Well, not as much as was lost during accelleration as the timeframe is shorter, but should perhaps not be neglected?

[xpensive]

Hang on a sec Ciro, as much as I buy the two blue lines, I think the yellow one is somewhat out of whack. Why would Fizzi only use 150 Hp when accelerating from 150 km/h?
That yellow line should be flat as Ayers rock to my mind, except for the occational gear shift, and certainly not terminate at a measly 400 Hp at 300 kph?

Or am I missing something essential here?

[Belatti]

X, you just overtook my post

What gets my attention is the 400HP power to the wheel number, taking into account that the Max power of the engine is above 700HP and the rpm range of use is very close in order to maintain that power availiable. It would be nice to check some data like real weight (include 50Kg of fuel) and CD that may be larger, together with frontal area, rolling resistance coeff, etc.
Where are those 300HP???

Here, a good page to check aero drags of Sport cars:
http://www.mulsannescorner.com/data.html

It would be nice to compare that with real current F1 data.

[xpensive]

Amazing stuff Belatti, thanks!
Imagine that big Porsche 917K (Kurz no Langheck), probaby never seen a windtunnel either, with only 3200 Newtons of drag at 200 mph?
I guess that's how to reach 250 mph (400 kph!) on the Mulsanne straight with only 500 Hp?