2017-2020 Aerodynamic Regulations Thread

[miqi23]

I made a very basic estimate of the change in downforce and drag based on the basic dimensional changes and Willem Toet's distribution map in this Matt Somers reblog http://www.somersf1.co.uk/2015/11/what- ... erate.html

I assumed the floor contribution proportional to diffuser exit area and floor area and wing proportional to plan area.

I got increases of 30 % for downforce and only 20% for drag.

In addition to these basic dimensional effects the shortened t-tray will make high rake easier to achieve.

If the low rear wing does connect with the diffuser not only will downforce go up but the DRS will become even more powerful.

My expectation is that the rule makers will have misjudged the impact of the changes, as has happened each time they have tried to reduce downforce. If they are aiming at 3-5 seconds I think we might see 5-6.

I think it would be more like 12 to 15% increase in downforce and about 5% increase in drag. Perhaps 2012-2013 levels of downforce.

What method did you use to arrive at your estimates?

My estimate is that the increase of wing area alone (front 13% rear 26%) could yield 10% so 12% looks very conservative.

The front wing width is similar to 2013 cars, swept backwards which would increase the area by a bit. We already know what 2013 cars were capable of. Secondly, the rear wings on 2013 cars once again were quite aggressive compared to 2016 cars, there were no restrictions on main element chord length and the rear wing rule box was bigger. It also had a beam wing which helped the under floor by a lot. The rear wings produced lots of downforce and drag. Moroever, the raised noses on 2013 cars also helped the floor by a lot..

Now, coming to a 2017 car, the nose is lower similar to a 2016 car, the front wing is similar to 2013, the rear wing I would target 2013 levels of downforce (to keep the balance in check since front wings are similar to 2013 cars) but it would have less drag since the profiles are not that aggressive due to the rule box. We are just left with the underfloor - which is wider indeed and also the outlet is bigger but where does it stand when compared to a 2013 floor which had the benefit of a raised nose upstream, a beam wing at its outlet and exhaust gases driving the floor? If you match 2013 floor levels we are already well above 2016 cars.

There is also the addition of bigger front tyres and managing its wake with the bigger bargeboards could be a challenge initially. So, there will be an increase in downforce over 2016 cars but not staggeringly more. Most improvements in lap times would come from the bigger tyres!

[godlameroso]

I think teams are already at 2012/2013 levels of downforce, next year will bring back 2010 levels of downforce and grip, but with much more powerful engines. We could end up with 2006 levels of downforce with half the drag and 35% more power. In other words, race pace will be equal to 2006 race pace, but without refueling.

This year Bahrain was won in a time of 1h 33m 34sec, in 2006 it was won in 1h 29m 46sec. 4 minute difference 57 laps, or an average pace improvement of 4.2 seconds, and that's losing an extra 6-7 seconds for refueling at each stop. BTW I know it was in the heat and the Pirelli tires were garbage in 2013 however the Bahrain race was completed in 1h 36m 00sec

[henry]

I think it would be more like 12 to 15% increase in downforce and about 5% increase in drag. Perhaps 2012-2013 levels of downforce.

What method did you use to arrive at your estimates?

My estimate is that the increase of wing area alone (front 13% rear 26%) could yield 10% so 12% looks very conservative.

The front wing width is similar to 2013 cars, swept backwards which would increase the area by a bit. We already know what 2013 cars were capable of. Secondly, the rear wings on 2013 cars once again were quite aggressive compared to 2016 cars, there were no restrictions on main element chord length and the rear wing rule box was bigger. It also had a beam wing which helped the under floor by a lot. The rear wings produced lots of downforce and drag. Moroever, the raised noses on 2013 cars also helped the floor by a lot..

Now, coming to a 2017 car, the nose is lower similar to a 2016 car, the front wing is similar to 2013, the rear wing I would target 2013 levels of downforce (to keep the balance in check since front wings are similar to 2013 cars) but it would have less drag since the profiles are not that aggressive due to the rule box. We are just left with the underfloor - which is wider indeed and also the outlet is bigger but where does it stand when compared to a 2013 floor which had the benefit of a raised nose upstream, a beam wing at its outlet and exhaust gases driving the floor? If you match 2013 floor levels we are already well above 2016 cars.

There is also the addition of bigger front tyres and managing its wake with the bigger bargeboards could be a challenge initially. So, there will be an increase in downforce over 2016 cars but not staggeringly more. Most improvements in lap times would come from the bigger tyres!

Your estimation of the similarity with 2013 is perhaps borne out by the approach Mercedes and Red Bull have taken to the tyre test mules with a beam wing and skirts on the floor and front wing.

Pirelli are said to be unhappy about the downforce thus provided and were reported as wanting 20% more. What that 20% is I don't know. Whether they have +10% and want 12 or +10% and want 30% was not reported in any of the articles I've seen.

If it is left to the teams I'd expect them to show up with less downforce than they expect to make in 2017 so as not to let the opposition know what they are thinking.

On slightly more detailed points, the front wing will be wider 1800 instead of 1650. So more plan area swept back or not. If you discount the neutral section and the footplates the active, wing or diffuser, area goes up from around 1000 wide to 1150. So potentially 10+% more downforce potential. In addition the t-tray has been shortened so it will be easier to get the whole wing closer to the ground. And the deflection test has been made easier so the wing tips will likely be closer to the ground.

The rear wing is 25% wider so balancing the front wing should be straightforward.

The floor has benefit of width and a bigger diffuser over 2016 and 2013, 14% and 22.5% respectively. In partial compensation for the 2013 raised nose the gap between tyre and nose is wider by 40mm a side. It may be that they will struggle to feed the diffuser, but the potential gains are large. I guess the big question will be if they can couple the lower wing to the diffuser, to gain some of the beam wing benefits.

I don't think controlling the front wheel wake will be big problem. It will be only 20mm further from the floor edge than current.

All in all I think 12-15% is probably conservative. My earlier estimate 30% is probably excessive at the beginning of the regs but I honestly think these cars will have huge amounts of downforce.

You may not be staggerered but Pat Symonds has been.

[henry]

I think teams are already at 2012/2013 levels of downforce, next year will bring back 2010 levels of downforce and grip, but with much more powerful engines. We could end up with 2006 levels of downforce with half the drag and 35% more power. In other words, race pace will be equal to 2006 race pace, but without refueling.

This year Bahrain was won in a time of 1h 33m 34sec, in 2006 it was won in 1h 29m 46sec. 4 minute difference 57 laps, or an average pace improvement of 4.2 seconds, and that's losing an extra 6-7 seconds for refueling at each stop. BTW I know it was in the heat and the Pirelli tires were garbage in 2013 however the Bahrain race was completed in 1h 36m 00sec

I'm with you. Next year's cars are likely to be very fast particularly in low and medium speed. Not only do these cars have more power at their disposal but the deploy it much more effectively than the v8s and don't suffer periods of bouncing off the rev limiter at the end of straights.

I think there are two issues that may curtail them. One is the 105kg race limit, probably not sufficient at the higher speed circuits. The other is that if they are too quick it might be deemed necessary to slow them down. This could be for one of two reasons. Either safety or Pirelli not comfortable. I think the latter is quite possible. Not because Pirelli are rubbish but because they are trying to develop their product with a bunch of paranoids desparate not to provide any advantage to their competitors.

[godlameroso]

I remember hearing Pirelli saying they were moving away from rapid wearing tires. You could just force teams to pit at least once for new compounds say no later than 65% race distance.

[wuzak]

This year Bahrain was won in a time of 1h 33m 34sec, in 2006 it was won in 1h 29m 46sec. 4 minute difference 57 laps, or an average pace improvement of 4.2 seconds, and that's losing an extra 6-7 seconds for refueling at each stop. BTW I know it was in the heat and the Pirelli tires were garbage in 2013 however the Bahrain race was completed in 1h 36m 00sec

The key there is refuelling.

They had much lower fuel on board during each stint - so fresh tyres and low fuel all through the race.

And there was a tyre war on.

[wuzak]

One is the 105kg race limit, probably not sufficient at the higher speed circuits.

I suspect that the higher speed circuits, such as Spa and Monza will have less of a problem than the medium speed circuits.

In fact, I don't think either are particularly fuel critical now.

Just consider that they have 5% more fuel and the race with be 5%+ shorter in time.

[henry]

One is the 105kg race limit, probably not sufficient at the higher speed circuits.

I suspect that the higher speed circuits, such as Spa and Monza will have less of a problem than the medium speed circuits.

In fact, I don't think either are particularly fuel critical now.

Just consider that they have 5% more fuel and the race with be 5%+ shorter in time.

And the average speed will be 5%+ higher. Fuel consumption goes up something between the square and the cube of the speed, so I feel this is bound to make fuel quantity an issue.

I think you are right however that medium speed might be the issue since at high speed circuits the cars will have lower top speeds.

I guess the emphasis will be, as expected, on downforce from the floor to keep drag as low as possible.

[wuzak]

And the average speed will be 5%+ higher. Fuel consumption goes up something between the square and the cube of the speed, so I feel this is bound to make fuel quantity an issue.

I think you are right however that medium speed might be the issue since at high speed circuits the cars will have lower top speeds.

I guess the emphasis will be, as expected, on downforce from the floor to keep drag as low as possible.

For Monza its not that the top speed will be less but rather that the low(er) speed corners will be faster, meaning less time accelerating using full power at low speeds.

In fact, that's why the fuel consumption may be less of a problem at all tracks.

Ultimately, if they can average 310km/h over a lap they will do a race in 1 hour and use 100kg of fuel.

[godlameroso]

This year Bahrain was won in a time of 1h 33m 34sec, in 2006 it was won in 1h 29m 46sec. 4 minute difference 57 laps, or an average pace improvement of 4.2 seconds, and that's losing an extra 6-7 seconds for refueling at each stop. BTW I know it was in the heat and the Pirelli tires were garbage in 2013 however the Bahrain race was completed in 1h 36m 00sec

The key there is refuelling.

They had much lower fuel on board during each stint - so fresh tyres and low fuel all through the race.

And there was a tyre war on.

Yes, and I believe they'll be able to match that pace without having to re-fuel next year. Or at least be as fast as in 2010.

[hollus]

... Fuel consumption goes up something between the square and the cube of the speed...

Fuel consumption is 100kg/h. Regardless of the speed.

[wuzak]

... Fuel consumption goes up something between the square and the cube of the speed...

Fuel consumption is 100kg/h. Regardless of the speed.

Well, anywhere above 10,500rpm.

So, the faster the better (mpg is better).

Also, consider that with rpm below 10,500rpm they are using proportionally more fuel for the speed they are doing.

At 5,250rpm they are using 52.75kg/h. In the same gear at 10,500rpm they will be doing twice the speed, but only using 100kg/h fuel. So, in effect, low speed is using 5.5% more fuel for the distance covered (ie lower mpg, higher l/100km).

[wuzak]

Let's assume the top speed of a car is 320km/h (198.8mph) at 12,000rpm without DRS.

The fuel flow rate is 100kg/h, ~125l/h (assuming 0.8kg/l), ~27.5UKG/h and ~33.0USG/h.

That gives approximately 39 l/100km fuel consumption at 320km/h, or 7.2mpg(UK) or 6.0mpg(US).

At half the rpm, 6,000rpm, the fuel flow is 59.5kg/h, 16.4UKG/h, 19.7USG/h.

The speed will be 160km/h (99.4mph) assuming the same gear. The fuel consumption would then be 46.5l/100km, 6.1mpg(UK) or 5.1mpg(US).

Obviously they won't be using that gear and using such low rpm. They will try to keep the rpm around the 10,500 range as much as possible. Which makes the mpg worse at the lower speed.

Let's assume they are doing the 160km/h section at 10,500rpm, 100kg/h fuel flow rate.
The fuel consumption is 78.1l/100km, 3.6mpg(UK), 3.0mpg(US), clearly much worse than using 6,000rpm. But it won't be at that speed for as long.

Assume that with the new regs we use the same gear ratios and we can do the corner 20km/h faster (ie 180k/h).

We will now be using ~11,800rpm and 100kg/h fuel flow.

The fuel consumption will now be 69.4l/100km, 4.1mpg(UK), 3.4mpg(US).

That is an improvement of 13% in mpg terms.

So by going faster through corners you will actually be using less fuel.

Let's look at another hypothetical.

Suppose the corner is taken at 160km/h at 9,000rpm now. FFR is 86.5kg/h, fuel consumption will be 67.58l/100km, 4.18mpg(UK), 3.48mpg(US).

The new speed at 180km/h is at 10,125rpm, FFR is 96.625kg/h, fuel consumption will be 67.1l/100km, 4.21mpg(UK), 3.51mpg(US). That is around 0.7% better mpg. It's certainly not worse.

They will be slower in the straight sections, which will reduce the mpg. But the increase in mpg through the corners and slower sections should mostly compensate for that, and at some circuits it will more than compensate for that.

[wuzak]

I think that's why the Mercedes team has not had to conserve fuel as much as the other teams over the past 3 seasons. Sure, the power unit has a lot to do with it, but generally they takes the corners faster.

Williams has been slightly different in that they had a low downforce/low drag setup, which meant they saved fuel on the straights.

[turbof1]

Maybe we should also account for shifts in aero-production. Since more downforce will be generated from the underbody, downforce can be removed from the wing where the l/d coefficient is lower. You'll probably end up with very flat wings for circuits like Monza.