Sky Sports F1's Mark Hughes takes a close look at the new F1 challengers and the dominant themes around the new looks...
Sunday 17 February 2019 08:31, UK
So now that we've seen most of the new season's cars, what themes have emerged from the extensively modified 2019 aero regs?
Outwash aero is retained
The wider but simplified front wing has not led to any attempt at a return to the pre-2009 practice of 'inwash' aerodynamics, whereby as much airflow as possible from the front wing was directed to the underbody.
Despite the banning of the extra vanes and add-ons at the outer ends of the front wings that were so effective in swooping the airflow around the front tyres and down the side of the car, every team is still attempting to retain the 'outwash' philosophy.
Find out more about Sky Sports F1
F1 2019: All the key dates
Introducing the new F1 2019 cars
Airflow is accelerated down the side of the car and squeezed between the rear tyre and diffuser and as it is squirted through there, so it creates a draw upon the airflow that is coming through the diffuser - thereby increasing the speed of the flow through the underbody.
The faster the flow, the more downforce is created. Getting the flow to curve around the front tyre rather than simply crashing into it, creates a separate flow well outboard of the car down its length, thereby not interfering with the airflow that is being trained and accelerated along the barge boards and sidepods to do its vital job when it reaches the rear of the car.
To retain the outwash despite the banning of the powerful endplate turning vanes and vortex generators, the teams have used the alignment of the simple endplate and the single vortex-generating tunnel on the side of the endplate to help turn the airflow. They have also manipulated the flow through the contouring of the five wing elements and by aligning the flap adjusters and slot gap separators outwards.
Uniquely, the Mercedes W10 has a slight inward orientation of its endplate though not by anything like enough to divert more air to the underbody. It's speculated that this has been done to better link up with the adjacent wing elements in creating a vortex that will aid the turning of the flow around the tyre.
Mercedes and Red Bull still at opposite ends of aero spectrum
Despite such a major regulation change, most teams have retained their existing different approaches so we see that the Mercedes W10 is a long-wheelbase, low-rake car and the Red Bull RB15 is short-wheelbase/high-rake with everyone else somewhere in between, just as in the last couple of seasons.
McLaren seems to be the only team to have had a significant rethink on this aspect, its new MCL34 appearing longer in wheelbase than its very short predecessor.
Mercedes says that the W10 has the same wheelbase as last year's W09 (and therefore also the 2017 W08), maximising the area of the underfloor.
Red Bull continues to prefer to enhance its underbody downforce through the floor's angle of attack by using more rake (front down/rear up). Because Mercedes supplies the gearbox to Racing Point, that car (yet to be seen) can be expected to be similarly long, just as the Toro Rosso (using the Red Bull gearbox and rear suspension) is appropriately short.
A critical part of allowing Red Bull's high-rake philosophy to be effective is how (in plan-view from above) the rear bodywork cuts sharply inwards with an extreme 'coke bottle' profile. This entails stacking some of the cooling components higher in the car than they will be in the Mercedes, but it allows the airflow travelling over that section of bodywork to retain enough airspeed that it can help keep the airflow coming through the diffuser attached even at low car speeds despite the big gap between the diffuser and the ground resultant from the high rake angle.
The Honda engine in the RB15 is similar in geometry to the Mercedes, with the compressor at the front of the engine, linked by a shaft to the rear-mounted turbine. This is in contrast to the rearward-mounted combined compressor/turbine arrangement of the Renault and Ferrari engines.
For Red Bull, switching from Renault to Honda, this will have meant accepting the engine being mounted slightly further back in the chassis (unhelpful in swooping-in that bodywork), but getting payback from the much better arrangement of intercooling plumbing the split turbo allows.
Outwash vs front wing downforce
In the early days of the new regulations, there is predictably a wide diversity of front wing design. The most startling-looking seen so far is that of the Alfa-Romeo C38, on which the wing elements ramp down to a low, flat expanse at the outboard ends ahead of the front tyre. There is a big empty space in front of around 70 per cent of the tyre's width which on other cars is full of multiple elements.
In combination with the outward orientation of the endplates, this allows the air a much better chance of curving around the tyre. But it is at the expense of the downforce generated directly by the wing, with a much smaller area of elements.
Although the Alfa's initial solution (and bear in mind all these wings are simply first iterations and may change considerably during testing) appears the most extreme in favouring tyre outwash over front wing downforce, there is a differing emphasis between each team.
Neither the Renault RS19 nor Toro Rosso STR14 use up the maximum depth permitted by the regulation for the wing elements, preferring instead to taper the elements into a bunch at the outboard ends to aid the airflow in routing itself around the tyre. This is enhanced in the Toro Rosso by a pronounced upwards profile of the bottom of the wing at the outer ends.
By contrast Mercedes, Ferrari and Red Bull - on the initial wings shown - have utilised the full permitted area of wing, albeit with quite different shaping of the elements. The Merc and Ferrari each utilise a slight swoop-up of the bottom edge of the wing to help with the outwash, though not to the extreme of the Toro Rosso.
A few years ago Red Bull began favouring front wing elements that drooped sharply down at the inboard ends, clearing a wider path for the airflow to reach the barge boards which then direct it down the body sides. Part way through last year Red Bull abandoned this practice, reverting to a more conventional layout - but now it has returned, and not only with Red Bull.
Ferrari, Renault, Mercedes and Haas have also adopted it, as the regulation on barge board height (and the limitation of under-wing vanes to two) means those bargeboards now need more airflow to have the equivalent effect.
Move towards narrower sidepods
The limitation of barge board height and the limiting of the under-wing guide vanes to two (where previously there were as many as five) has given the airflow a much tougher time in transitioning between the narrow gap it is forced through (between tyre and nose) and the sudden increased cross-section of the sidepods.
These boards and vanes help the flow remain attached to the body sides and enhance the speed of that flow (to the benefit of downforce), but with their reduced power under the new regs, several teams - most notably Mercedes - have decided to narrow the sidepods instead (with a required deepening of the radiator inlets to compensate for their reduced width). This means less opportunity to shape the pods with much of an undercut (another airflow-accelerating device). The inference is that traditional wider sidepods would have simply been too much to retain the desired airspeed without stalling the flow before the undercut could then accelerate it.
Ferrari too appears to have narrowed its sidepods but perhaps the most distinctive feature of the SF90 (the name celebrating 90 years of Scuderia Ferrari) is the way its rear bodywork tumbles over into a deep undercut within the coke bottle section (much like last year's Sauber) to give an incredibly tight contouring with which to further accelerate the airflow down the body sides.
Get the dedicated Sky Sports F1 channel - the exclusive home of all live F1 next season - for £18 a month in HD with no contract. Get Sky Sports F1.
