KERS connundrum

[Scotracer]

I wont bother explaining KERS again as we've all read press releases and the flybrid system to death but I have an issue with the entire thing.

Scenario: Driver X is chasing Driver Y at Catalunya (for example). He manages to get good drive out of the last corner and has a decent slip-stream possibility. At this point he decides its time to deploy the KERS. With 6.7 seconds worth of full boost, that is nearly the entire length of the straight. He presses the button and gets the full 60kW whack up the arse but then just as he's about to pull out he runs out of revs on the 19,000rpm limit. What use is the KERS then? None.

So, a possible solution:

- When the KERS button is depressed, the engine is given another 500rpm to the limit
- This is FIA mandated via the SECU.
- Without KERS, the 19,000rpm is intact.

It's a possibility but it could also just open another can of worms in terms of cheating the rev limit.

[flynfrog]

why not gear the engine higher to make use of the extra power

[Scotracer]

I had considered that but then you disadvantage yourself at all other points when you're not using KERS. If you look at any on board footage when they are at the fastest part of the circuit you can see they hit the limiter in 7th. There's very little room for adjustment.

[flynfrog]

how many straits do they top out 7th though id be willing to bet that the car spends very little time up there and if you can get there .5 a second quicker and run the revlimiter into the corner odds are they guy behind will be .5 or farther back.

The big question if they took off the revlimiter and the two race per engine rule would kers be worth the weight?

[Ian P.]

Good point. What use will KERS be if the car is going to max out on a straight.
Having just watched the Monza GP, the only way to make it work on the main long straight is to gear the car on the basis that the KERS energy is used on every lap in the same place.
Alternatively, a team could set it up to kick in on a straight where you don't reach terminal velocity. Then it would be an accelaeration boost. Either way, it is likely to be used in the same place on every lap.
One potential aspect of KERS I have not seen discussed is the gyroscopic potential to influence the suspension.
This would only be effective in a flywheel system (Williams for one). If the flywheel is oriented at right angles to the long axis of the car and rotates in the opposite direction to the wheels, it will effectively work against chasis roll in corners. It will load the inside wheels and unload the outside wheels.
Neither a moveable aero device but possibly an active suspension component. Now Williams wouldn't know about that .....????
You wouldn't even need to extract any energy from it to gain a benefit.

[zac510]

You might change the power curve of the engine so that the extra 60kw is better used? Not to worry though, this is just one of the old fashioned engineering compromises that makes motor racing engineering so interesting!

I think it will be interesting to see electronic throttle strategies changed. For example, if the KERS is used at low revs where it is easy to break traction, the engine throttle may be limited electronically to say 75 or 85% so that fuel is not used and the KERS energy takes the horsepower up to the acceleration traction limit.

This would bring KERS into play as a fuel saving device rather than as a top speed/lap time device.

I haven't looked into the rules yet but this might be achieved with some paddle trickery a'la McLaren at the moment.

[scarbs]

KERS will be used to accelerate, in the midrange of the power curve is where it will be felt the most, at top speed the cars drag will eat up its little 60hp output. Revs aren't the issue, all cars are limited to 19k RPM now and they still overtake (occasionally).

KERS will need to be used when the car isn't traction limited, as there's few points where the car is on wide open throttle in a single gear for 6.7s, so theres a lot of control work needed to only introduce it when the car can use it (traction issues, gear changes). It may be that the driver uses it for several corners, may be not using up the full 6.7s if the track doesn't provide a wide open high traction run.
Out of some corners, he might not need the Full KERS power output, is he stuck with the full power delivery? At Monza he could use two laps worth over the start finish straight giving him 13.4s of KERS power! This then gives rise to the issue how does the driver (TV viewer even?) know how much he got left. In some sections of the track he is effectively using two throttles (pedal and KERS button) as the SECU will not allow sophisticated control of the power delivery.

[Scotracer]

Thanks for the replies everyone.

Scarbs, the KERS button brings me on to another question: will its application button be pressure-sensitive? So that they can adjust the amount of torque given from the KERS system? Or will it be, you press the button and you get 60kW in one big lump?

[Ian P.]

Not sure you can call 60 kW a "Big Lump".
Eddie Irvine once commented that with the 3L 10 cylinder engines and no traction control, they could spin the tyres (got it right again...) jut about any time the driver wanted. This won't be as big a problem for the 2.4L V-8s but it begs the question of just how many places on the track that the 60 kW could even be used.
I am waiting for the issue to come up that teams use the computer control of the KERS to produce a version of traction control. This would apply for both acceleration and for breaking.

[zac510]

Ian, was Irvine chatting up your wife when he said that?

The KERS is only being used on one axle so it will be difficult to

the SECU will not allow sophisticated control of the power delivery.

Scarbs, that bit I presume refers to my comments about electronic throttle mapping while the KERS is operational?

Either way this is proving to be an interesting talking point - after doubts from fans and even the teams themselves that the KERS was not unique enough, a few teams are struggling and different advantages and disadvantages are coming out.

[Ian P.]

She wouldn't know an Irvine from a real F1 driver so....no worries's mate.

Back in 2007 there was a ban on anti-lock brakes but the teams were using the traction control system to effectively limit rear wheel lock-up under breaking. Some teams were much better at this than others.
My suggestion is that the KERS system, either using energy extraction or power return could also be used to produce the same effect.
An example, when charging up the KERS (either batteries or flywheel) from rear wheel energy, this could lead to wheel lock-up if not regulated. Fine....now do this energy recovery regulation in such a way as to control or limit rear breaking. Same on acceleration out of a corner that is not traction limited.

Something else for Max to worry about.