The demise of off-throttle blown
diffusers looks set to begin at this weekend's European Grand Prix before a
full ban at the British Grand Prix - but what difference will it make and why
has it come mid season?
Many of the sport's leading teams have
been using engine maps this year to gain a bigger aerodynamic advantage from blown
diffusers using two techniques - cold and hot blowing.
Cold blowing involves setting the
exhaust flow to remain constant even when a driver's foot is off the throttle
so that energised air is constantly fed into the diffuser and more downforce is
produced through corners. Hot blowing is a step beyond this, where fuel is fed
into the exhaust and ignited by the exhaust pipes, accelerating the flow
further. The hot systems, which result in net gains of up to one second per lap,
are only generally run in qualifying, however, because the approximate 15
percent decrease in fuel economy and extra stress on the engine make it less
beneficial and more risky to use during the course of a race.
These types of engine maps will be
banned from next month's British Grand Prix (the FIA can monitor this using the
standardised ECU systems) and from then on the blown diffusers will only work
when a driver is on the throttle. Now, however, reports also suggest teams will
not be allowed to change engine maps between qualifying and the race this
weekend - and if that happens, the use of the extreme hot-blown system is likely
to end immediately.
POTENTIAL LOSSES
Formula One is all about how the car
works as a package, and the rear wing and the rear diffuser both contribute to
rear downforce, so there is a trade-off.
The diffuser (blown or unblown) is more
efficient than the wing because it produces less drag for the same amount of
downforce. By feeding consistent exhaust flow through the diffuser, the
off-throttle blown system creates more downforce from the diffuser, so the rear
wing needs to contribute less to reach the overall required level of downforce
- and that simply translates to a more efficient downforce package.
When the ban comes in, teams will lose
the consistent flow through the diffuser. They will still get exhaust flow when
on throttle but not when off throttle - and because the concept of the modern
blown diffusers has been built on consistent flow, this could prove very
damaging to the stability and balance of the aerodynamics.
Ferrari is understood to have the least
effective system of the front-running teams, so they potentially stand to lose
the least - but for all teams there is likely to be some significant design
changes needed to cope with the inconsistent flow, quite probably even seeing
exhaust exits moved once again.
In qualifying, there is a different
story.
The hot blowing creates even more
downforce from the diffuser and, importantly, the DRS system is available
throughout the lap. It is a combination of these that is believed to be giving
Red Bull the big advantage shown in the difference between their qualifying and
race pace.
Again, benefitting the overall package,
the Red Bull hot-blown diffuser is able to provide enough downforce for the
drivers to use DRS in some parts of the track where other teams cannot -
reducing their overall drag at those points and allowing them to go even
faster. If they cannot not use that system this weekend, that could hurt them
hard.
So why ban it now, not at the end of the
year?
Formula One is a place for innovation
and the last few years have regularly seen teams spot and exploit loopholes
that forced the FIA to clamp down - the double diffuser in 2009 and the f-duct
last season.
Both those devices were banned at the
end of the season, however, while this time the FIA has moved for a mid-season
ban.
They state that the decision to act
immediately is because the cost of the system and its impact on engine
reliability and fuel consumption are "totally contrary" to the sport's
objectives - while the f-duct and the double diffuser developments were
comparatively cheap and not environmentally unfriendly.
The cost is indeed enhancing the gulf
between the haves and the have-nots, creating even greater separation through
the field, as Cosworth, who supply Williams, Virgin and HRT, have not explored
the system while mid-grid teams like Sauber and Force India do not have the
resources to implement the systems as well as their more affluent rivals.
That said, F1 has always been driven by
innovation and it is always the teams with more budget for R&D that lead
this. When rival teams tried to ban the double diffuser in 2009, Brawn argued
hard against it and won. Likewise, when the f-duct was questioned, McLaren
defended their design and it stayed for the season. This time, however, Red
Bull has so far been relatively accepting of the ban - so perhaps the system is
not giving them as big an advantage as is made out after all? This week, we
should finally find out.