Blown Diffuser??

[gcdugas]

I'd expect the principles would remain the same, ie FIA limitations on the number of maps for each fuction, and similar controllable parameters.

Anyway, the point is that the basic design of the SECU allows for some variability in the spark maps. Unless someone knows otherwise, we'll be safe to assume that is still the case.[/quote]


I was sent this from someone on Lames Allen's blog clicky

[gibells]

You can easily map the engine to allow it to keep the throttle slightly open even when the throttle is closed (ie not pressing the accelerator), so that there is always fuel going to the engine. I know they do this on some bike engine's to make the pick up easier when coming back on throttle.

I expect Redbull's answer to be something simple like this, even if it means there are less gases going through the diffuser. Also, the slit in the diffuser may be tuned so that it is first to pick up any exhaust gases before the rest are spilled over the top of the diffuser.

Also, has anyone considered where on track you would be when in 'off throttle' conditions? I expect it to be just coming into the corner. [thinking out aloud here] Viz. that's just where you'd need downforce. ???

[Richard]

Also, has anyone considered where on track you would be when in 'off throttle' conditions? I expect it to be just coming into the corner. [thinking out aloud here] Viz. that's just where you'd need downforce. ???

Downshifts as well.

So the car loses rear EBD downforce just as it is slowing down and the weight is thrown forward. That is compounding the loss of rear grip, a tough double whammy.

[DaveW]

So the car loses rear EBD downforce just as it is slowing down and the weight is thrown forward. That is compounding the loss of rear grip, a tough double whammy.

Forgive me, but your statement implies, together with many of the preceding posts, that a flat undertray "evacuated" by a diffuser has a centre of pressure close to the rear axle. Is that really the case?

[Richard]

Forgive me, but your statement implies, together with many of the preceding posts, that a flat undertray "evacuated" by a diffuser has a centre of pressure close to the rear axle. Is that really the case?

Good point. I guess the current DDD are more balanced that at the start of 09, so thinking aloud ....

The flat under tray only extends to side pods. There is no floor in front of the side pods. So if there was an even pressure under the floor, it would still result in a rear bias.

Also, undertray pics show the the evacuation of the undertray is takes place behind the cockpit. There will be losses along the length of the tray, so that would infer a centre of pressure biased to the rear?

Make sense?

[BreezyRacer]

I have no way of knowing for sure, but based on the Double Diffuser inlets and VG's along the splitters I would have to say that the best setups (RB, Renault, and Ferrari) probably have the center of pressure in the same basic area as the center of mass.

Thus, as you speculate, losing the diffuser doesn't result in a rear imbalance on those cars. Think about it .. when was the last time you saw a Red Bull get loose .. even under power. It's not that they couldn't do it, but that they don't have a particularly weak end of the car. Now consider the McLaren .. it's the loosest car on the grid. Fortunately they have one driver that likes it like that ..

[WhiteBlue]

The document is four years super ceded by reality. I bet they have a lot more maps now. Howe would they change the gear specific maps that McLaren invented. The original SECO program has probably seen 50 updates and upgrades now and the same is probably true for the SECU firmware and hardware with some smaller numbers.

BTW, MES (Mclaren) was contracted to supply the ECU hardware/components and Mclaren's user software was "altered" and "rewritten" through Microsoft oversight and programming, so that an "outside party" (other than Mclaren) could allow FIA control over the programming code, so that any alteration of code could be regulated. There are quite a few articles on this, namely Race Car engineering...
http://www.racecar-engineering.com/alla ... of-f1.html
So if there has been upgraded amounts of usage to the unit, it has been because the FIA allowed it to happen.

Sure, I wasn't suggesting anything untoward. The FiA had to pick a competent system and Ferrari had got their Bridgestone tyres. So it was McLaren's turn with the ECU. I believe that the FiA competently controls that unit but I don't believe that Microsoft gave anything but the name for the first years, frameworks for stuff like GUIs, simulators and the OS for the Laptop apps they do with the control. I haven't heard that they have made any huge progress with car electronics. When USF1 in winter revealed the list of their technical partners it was named McLaren Electronics again if I'm not very much mistaken.

http://www.mclarenelectronics.com/

F1 unit http://www.mclarenelectronics.com/Produ ... G-310B.asp

[DaveW]

Also, undertray pics show the the evacuation of the undertray is takes place behind the cockpit. There will be losses along the length of the tray, so that would infer a centre of pressure biased to the rear?

Make sense?

Probably does... The McLarens seemed to have problems keeping the rear wheels behind the fronts during Friday testing. However, I could imagine that it might be possible to achieve a compromise that didn't lose much to the field power off, but still gained power-on performance without risking engine reliability. RBR's performance gains certainly appear to be through high speed (power-on) corners at some cost through low speed corners & trap speed (though the last was reasonable at Silverstone - I guess they now have the F-duct).

[WhiteBlue]

http://www.grandprix.com/ns/ns22436.html?

"All the systems are different," Michael said. "Ours is most like the Red Bull when you look at the exhaust exits and how we are working the diffuser, but the Mercedes one, Ferrari and to an extent McLaren, which I haven't seen properly as it was only on for a day, are different.

"They all vary by where they blow the diffuser. You only have a certain amount of energy so you can't try and blow all of it because there's not enough puff, you might say. There's only a certain amount of energy in the exhaust and you have to choose where you blow it. Red Bull's is obviously fully optimised and it made sense to have a look at what they were doing."
Michael is also convinced that Red Bull is using some sort of throttle trail system to produce more stable and consistent downforce from a double diffuser which already has a bigger area due to Red Bull's lone adoption of pull-rod rear suspension.

"It's very easy from a chassis point of view," he explains, "but the problem is doing it without damaging the engine, because you've got to retard the ignition significantly so that you get the gas to fire in the exhaust system and produce a lot of high energy air coming out of the exhaust but for very low engine torque. Doing it places considerable strain on the exhaust vales.

"We're into that but we haven't done it at Silverstone. We're trying it with Cosworth on the dyno but haven't got anything signed off for now. Judging by their pace you'd probably say that Red Bull are the only ones doing it at the moment, although Renault is using the same engine so they've probably got something signed off too.

"It also increases the fuel consumption and so it's not something you would do in the race, only in qualifying. It's only for one or two seconds when you hit the brakes, so it's not like running a retarded mixture all the time, so it's pretty realistic to get it done, we just haven't done the work yet."

Confirms special Q3 mapping and that Williams is developing that as well.

[l4mbch0ps]

You can easily map the engine to allow it to keep the throttle slightly open even when the throttle is closed (ie not pressing the accelerator), so that there is always fuel going to the engine.

Unfortunately, this is illegal. The throttle plate must correspond directly to the throttle pedal - ie: full throttle on the pedal must be full opening on the actual throttle.

5.5.3 The minimum and maximum throttle pedal travel positions must correspond to the engine throttle minimum (nominal idle) and maximum open positions.

[WhiteBlue]

5.5.3 is an important point to observe, but not an unsurmountable problem.

It is not said how the throttle function is working between open and closed position. One normally assumes it is linear. That need not be the case. Let us assume that the lowest 1% of the throttle pedal range works exactly like a standard throttle. From that point the upper 99% of the throttle pedal has a totally different characteristic.

In the upper 99% segment the throttle pedal commands the throttle to go to 100% open to use the full mass flow of the engine. In that map the power modulation is completely done by ignition retarding and potentially by tuning the injectors for fatter or leaner injection.

All the driver has to do is switch to his Q3 map at the end of his out lap. He will not need zero throttle pedal position at all for a hot timed lap. As soon as he is on his in lap he switches the special map back to normal. He can now use the linear pedal function again. The special throttle map he uses still complies with all the rules.

Perhaps it is even called the infamous "boost button" at Red Bull which we know from Ciaron Pilbeam's radio call to Webber in Turkey.

When the rivals openly discuss those tricks with their engine suppliers you have to assume that the inventors are really successful with the trick. Sam Michael would not talk the way he talks if this is a bit of imagination from James Allan. Expect some frantic work being done in Maranello, Brixworth, Viry-Chatillon and Northampton.

[CMSMJ1]

It does have to be linear though WB...

0% throttle and 100% have to relate directly to the pedal 0 and 100% locations.

Interesting indeed.

A point raised earlier about motorbikes keeping the throttle open under braking - this is to assist in keeping the rear wheel spinning and stop too much backing in. Not really to assist with pickup of the throttle. my bike has a slipper clutch and I set the idle high to mimic this affect - when I close the throttle, the revs d not drop below 3k revs and so stops the rear locking on downshifts

[WhiteBlue]

It does have to be linear though WB...

0% throttle and 100% have to relate directly to the pedal 0 and 100% locations.

No it hasn't to be linear. Only the minimum and maximum points are defined. There is no definition of the throttle function between those two points. At least I fail to see it in the regs. Please point out where it says it has to be linear.

[CMSMJ1]

It has to be linear to be driven correctly - I have read your prevous post several times and though there is a lot of words, it says nothing I can understand.

You say, "It is not said how the throttle function is working between open and closed position. One normally assumes it is linear. That need not be the case. Let us assume that the lowest 1% of the throttle pedal range works exactly like a standard throttle. From that point the upper 99% of the throttle pedal has a totally different characteristic.

In the upper 99% segment the throttle pedal commands the throttle to go to 100% open to use the full mass flow of the engine. In that map the power modulation is completely done by ignition retarding and potentially by tuning the injectors for fatter or leaner injection."

No..how does this work?

Advancing or retarding ignition is not a magic bullet. Ignition advance is a tool to allow for the ignition of the fuel before the compression does it for you. It does not affect in a useable way the ability to produce the power in the engine by an appreciable amount. it is a tool to prevent detonation which is bad for power, the valves and the health of your motor.

[Richard]

WhiteBlue - good points. A small detail is that the SECU spec restricts changes to throttle map to times when the car is stationary for 3 seconds. So the change would be implemented for Q3.

I imagine that they could have an aggressive version for Q3 and a softer version for the race to protect the engine. You wouldn't want too great a difference, otherwise the drivers would struggle to adjust to the loss of downforce.

2.14 Throttle Pedal Processing
<snip>
2.14.7 FIA Configuration and Limitations
Pedal map selection change with car stationary 3 seconds only.

Curiously the fuel map spec states:

Table 1 (Section 2.3)

driver fuel map selection with different value for high and low throttle positions.

So they could play with the fuel maps during a race to give higher exhaust volume at low revs, and low speed torque. The extra torque doesn't lead to wheelspin because they extra exhaust gas gives them more grip. It becomes a virtuous circle