James O'Neill's Blog

March 26, 2011

F1: The hidden effects of moving wings

Filed under: Uncategorized — jamesone111 @ 10:25 pm

There seem to be divided opinions about the effect of the “Drag reduction system” introduced in F1 this season. The rules are that

  • Drivers can operate device to lower the effective part of the rear wing, cutting both lift and drag. The wing returns to its original position when the driver applies the brakes.
  • In wet conditions this will be disabled
  • In qualifying the drivers can use this at will
  • In the race it is armed remotely by a system in race control – if the car close enough to the one in front (the margin will be 1 second to begin with – this my change over the season) at a specific point the following driver can lower his wing for a specific section of the track – typically the longest straight. .

“Push to pass” divides people: we had it in the days of turbo engines: in the 1980s we had qualifying engines which wouldn’t last a race distance; the boost button in a race gave a burst of similar power – for a sustained period it was a case of “The engines cannae’ take it”, nor could the tyres, and fuel would run  out. We it had when KERS first appeared;  “Kinetic Energy Recovery Systems” are currently a gimmick: energy stored, rate at which it is returned (Power) and time over which the return can take place are all constrained. F1 talks about being greener, removing the limits on KERS would be an obvious way and I’d have it feeding extra power in when the driver applied full throttle. Now we have it with wings.

Predicted effect 1. Last use wins. IF it turns out to make passing easy then if two cars are evenly matched, drivers won’t want to be re-passed, so they will time their passing move to use the wing at the last moment

Predicted effect 2. More tyre stops. There was always a decision to make: sacrifice position on-track by making a stop for fresh tyre – or hold out ? The harder it is to overtake the bigger the advantage of fresh rubber needs to be before stopping becomes the preferred option – because as Murray Walker always used to say “Catching is one thing, passing is quite another”.  So picture the scene with a dozen or so laps to go the first two cars have been on hard tyres for a good few laps and the leader is being caught: thanks to DRS the 2nd place car gets past. The former leader’s his car is fractionally slower but on fresh soft tyres could go 2-3 seconds a lap quicker – enough to catch the 20-30 seconds a pit stop takes with a couple of laps to go. Most of the tyre advantage will have gone by the time he has caught up: previously it would have been easy for the new leader to defend for the last couple of laps. Now if the chasing car can get within DRS distance he should be able to make a last gasp pass.  In the wet inspired changes of tyres win races – it didn’t really happen in the dry – until now.

Predicted effect 3. The return of slipstreaming. The FIA banned slipstreaming… OK, not as such. Imposing an 18,000 Rev limit banned it. How so ?  Without a limit on revs, in top gear, revs and speed increase until the acceleration force coming from the engine matches the retardation force from friction and aerodynamic drag.  Reduce drag by slipstreaming and top speed and engine revs will increase. But what if gear ratios are optimised to get the best lap time with no slipstream (in qualifying) – hitting the maximum Revs as the driver hits the brake at the fastest point ? If revs are limited the car won’t go any faster with the aid of slipstream.

With the ability to use DRS in qualifying, the optimum is to hit 18,000 in low-drag trim at the fastest point. The teams can’t change gear ratios after qualifying and the race the cars will be in high-drag trim most of the time – so they won’t be reaching 18,000 revs and will have a margin for slipstreaming.

Predicted effect 4. Race pace trumps grid place. Grid penalties become less effective. The advantage of starting ahead of a car which is faster than then yours / or disadvantage of starting behind a slower car varies with the difficulty in passing. Since the car can’t be reconfigured after qualifying, making overtaking easier might mean car set-up is tilted more towards race configuration than qualifying. It also means taking a penalty for a precautionary gearbox change (say) is smaller

Whether or not any of these things happen remains to be seen. Still: fun season in prospect.

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