Mclaren to remove F-Duct for Monza

[Brakefade]

McLaren to remove F-duct for Monza

By Jonathan Noble Monday, August 23rd 2010, 14:42 GMT

McLarenMcLaren will remove the F-duct from its car for the first time this season at the Italian Grand Prix, AUTOSPORT has learned, with the low downforce nature of the circuit negating any benefit the system brings.

The Woking-based team was the pioneer of the F-duct at the start of this year, and the design has proved such a success that all its main rivals have copied the idea. Renault will be the latest to introduce it at this weekend's Belgian Grand Prix.

The F-duct helps provides a straightline speed boost by allowing the drivers to stall the rear wing on the straights - and teams can use it for a simple top-speed advantage or to help them run more downforce in the corners without suffering a drag penalty on the straights.

Although Monza has the highest top speeds of the season - so would in theory be perfect for a straightline advantage - the fact the track requires such a low wing set-up actually makes the F-duct redundant because there is not enough drag for it to get rid of.

McLaren's decision to remove its F-duct for the Italian Grand Prix is likely to become standard practice, with all teams instead set to focus on a low-downforce aerodynamic package better suited to the Monza layout.

All teams had been expected to remove the F-duct at the Monaco Grand Prix earlier this year, but McLaren elected to keep it on its car then – saying at the time that there was no alternative.

"F-duct is something which will work better on the long straight than a circuit like this," McLaren team principal Martin Whitmarsh said in Monaco. "It is a standard part of our car. We don't have a non F-duct variety to fit in any case."

http://www.autosport.com/news/report.php/id/86076

So it looks like that huge advantage everyone thought Mclaren was going to have in Monza is not going to pan out. :Hmm

[Ste]

Well I imagine the engine would be over-revving with the F-Duct on and also the low downforce package. Too much top speed will just start bouncing the car of the limiter.

[zeus2]

Didn't think monza was that much of a low downforce circuit to negate the f-duct advantage, interesting development nonetheless. So what that would mean (based on my limited technical knowledge :-D) is red bull will have to get rid of all that extra dowforce they have, we will have to do the same albeit to a lesser extent and all the cars struggling to generate downforce upto now will be on a more level playing field compared to the top teams? Everything will be down to the engines and the power they can generate which means mercedes engine cars may have a slight advantage ahead of ferrari and then the renaults. The way I see it its 'GAME ON'. Should be an interesting race :clap.

[Tifoso]

I thought they were firing Ramilton from the thread title. :lou

[Silent Bob]

Didn't think monza was that much of a low downforce circuit to negate the f-duct advantage, interesting development nonetheless. So what that would mean (based on my limited technical knowledge :-D) is red bull will have to get rid of all that extra dowforce they have, we will have to do the same albeit to a lesser extent and all the cars struggling to generate downforce upto now will be on a more level playing field compared to the top teams? Everything will be down to the engines and the power they can generate which means mercedes engine cars may have a slight advantage ahead of ferrari and then the renaults. The way I see it its 'GAME ON'. Should be an interesting race :clap.

Yup. Remember Force India last year - 2nd

[Silent Bob]

Well I imagine the engine would be over-revving with the F-Duct on and also the low downforce package. Too much top speed will just start bouncing the car of the limiter.

I don't think any of the teams would give up too much top speed. They'd all want to go as fast as they can. I think they're just saying that the f-duct doesn't make the car any faster with the low downforce wing they'll be using.

[Greig]

I don't think any of the teams would give up too much top speed. They'd all want to go as fast as they can. I think they're just saying that the f-duct doesn't make the car any faster with the low downforce wing they'll be using.

Bearing in mind the rev limit yeah :-)

[Ste]

I don't think any of the teams would give up too much top speed. They'd all want to go as fast as they can. I think they're just saying that the f-duct doesn't make the car any faster with the low downforce wing they'll be using.

Of course they don't want to sacrifice top speed. Having the F Duct there will be no advantage because of the reason they state and also because the cars will be bouncing off the limiter rather than improving top speed.

Essentially they can hit the same speed at Monza without the F Duct due to the low downforce package. So using it would just hamper them in the corners, which would be pointless. :-)

[FerrariF60]

i wonder if Ferrari will do the same??? by that i mean remove it also..
i think it would be wise to do so, since ours is so much easier to remove then McCheaters and we NEED all the speed we can get given that the Merc engine seems to be more powerfull then ours.

then again with the new SHELL blend coming from Spa onwards we could be up there too in POWER as the Merc engine...FINGERS CROSSED...

[Rob]

Mclaren may be realising that this maybe 1 way to be competitive at Monza. As they may have lost 1 of their biggest advantages they have had for a few years. They may well struggle this year over the kerbs, as we do. The Mclaren seems alot more stiffer this year than in recent years. They struggled badly at Hungaroring which is bumpy track. Didnt seem to ride the bumps very well at all. RBR will be strong at Monza, but how strong?? They cannt seem to get enough downforce off the car. As we saw at Montreal, they wasnt as fast there as us or Mclaren. Due to fact they got alot of downforce and cannt get the low downforce and low drag set ups that we can have (we stuggled all year with lack of downforce).

Monza will be very interesting indeed. RBR will not have that massive performance advantage as we have seen.

[Brakefade]

Of course they don't want to sacrifice top speed. Having the F Duct there will be no advantage because of the reason they state and also because the cars will be bouncing off the limiter rather than improving top speed.

Essentially they can hit the same speed at Monza without the F Duct due to the low downforce package. So using it would just hamper them in the corners, which would be pointless. :-)

Well can't they just change the gear ratios to allow higher top speeds?

I don't see why they can't run it. Top speeds can be same with or without, but with the F-duct they can run a little more wing to go around the chicanes and turns faster. I think they're not running it because with the extra bit of wing that the F-Ducts allows them to run would put too much stress on the chassis when Hamilton straight-lines all of the chicanes. Because with more downforce the greater the downward pressure and stress on the car.

This race could be ours, but watch out for Force India and Renault.

[Ste]

Well can't they just change the gear ratios to allow higher top speeds?

I don't see why they can't run it. Top speeds can be same with or without, but with the F-duct they can run a little more wing to go around the chicanes and turns faster. I think they're not running it because with the extra bit of wing that the F-Ducts allows them to run would put too much stress on the chassis when Hamilton straight-lines all of the chicanes. Because with more downforce the greater the downward pressure and stress on the car.

This race could be ours, but watch out for Force India and Renault.

Changing the gear ratios won't change a thing if you can't get rid of the drag. They would just take longer to hit the 18,000rpm limit or they would be very slow through places like the Lesmos and Ascari because the 3rd and 4th gear would be so long.

There will be no reason for them not using it because of stress onthe chassis. Additional downforce doesn't make the car ride curbs and bumps badly, but at Monza they would rather have the lowest possible downforce because straight line speed is key. Therefore, if there was any straight-line speed of the F Duct at Monza, they would use it. As I've said though, there isn't a benefit.

[xlinx]

It could well be that they are getting rid of the f-duct because is pretty much useless in Monza. It will not have that 'collapsing' effect on that low profile rear wings used in that race. Every team that has been using it will replace that huge conduct on top of the engine cover with a much more aerodynamic shark fin.
I think that McLaren will struggle a bit because they integrated their f-duct in their car design from the start, well, at least I hope so.

[WS6TransAm01]

Why bounce off the rev limiter? They can just change the final drive ratio or lengthen the ratios of the gears in the trans which will allow for more top speed.

Even with the 4 race/gear box rule they are still allowed to adjust ratios.

Come on guys...

There is something else a foot here me thinks...

[WS6TransAm01]

Changing the gear ratios won't change a thing if you can't get rid of the drag. They would just take longer to hit the 18,000rpm limit or they would be very slow through places like the Lesmos and Ascari because the 3rd and 4th gear would be so long.


Yeah, I don't buy it.

The F-Duct makes the car faster by stalling the rear wing right? A stalled wing creates more drag than a win that is not in stall. If you disrupt laminar air flow the resulting vortices create MORE DRAG, not less. The F-Duct does not get rid of drag, its gets rid of downforce. get rid of the downforce, and the car weighs less. A car that weighs less can be propelled to a faster speed that a heavier car with the same power.

Perhaps, having the F-Duct on a car with a low downforce setup will create more drag than is acceptable and cause more harm than the benefit it creates by taking weight off the car. In other words, lets say on a medium downforce track the F-Duct removes enough downforce to give the car 10mph more than without it, but creates 4mph of speed robbing drag. The net result is a car that is 6mph faster. At Monza, the F-Duct may give them only 2mph over their low DF setup but create 3mph wirth of drag. Net result is a loss of 1mph.

From Wikepedia:
Flow separation begins to occur at small angles of attack while attached flow over the wing is still dominant. As angle of attack increases, the separated regions on the top of the wing increase in size and hinder the wing's ability to create lift. At the critical angle of attack, separated flow is so dominant that further increases in angle of attack produce less lift and vastly more drag.

Since the car can not move the wing to change the AOA the introduce another stream of air comingo ut of the trailing edge of the wing to seperate the upper and lower air streams, this causes the stall and MORE Drag, not less.

[Tifosi]

Yeah, I don't buy it.

The F-Duct makes the car faster by stalling the rear wing right? A stalled wing creates more drag than a win that is not in stall. If you disrupt laminar air flow the resulting vortices create MORE DRAG, not less. The F-Duct does not get rid of drag, its gets rid of downforce. get rid of the downforce, and the car weighs less. A car that weighs less can be propelled to a faster speed that a heavier car with the same power.

Perhaps, having the F-Duct on a car with a low downforce setup will create more drag than is acceptable and cause more harm than the benefit it creates by taking weight off the car. In other words, lets say on a medium downforce track the F-Duct removes enough downforce to give the car 10mph more than without it, but creates 4mph of speed robbing drag. The net result is a car that is 6mph faster. At Monza, the F-Duct may give them only 2mph over their low DF setup but create 3mph wirth of drag. Net result is a loss of 1mph.

From Wikepedia:
Flow separation begins to occur at small angles of attack while attached flow over the wing is still dominant. As angle of attack increases, the separated regions on the top of the wing increase in size and hinder the wing's ability to create lift. At the critical angle of attack, separated flow is so dominant that further increases in angle of attack produce less lift and vastly more drag.

Since the car can not move the wing to change the AOA the introduce another stream of air comingo ut of the trailing edge of the wing to seperate the upper and lower air streams, this causes the stall and MORE Drag, not less.

Interesting that Kubica thinks Renault's success this week-end will depend on their F-duct performance but that macca think they can bypass it completely with a low-wing setup.

[WS6TransAm01]

Interesting that Kubica thinks Renault's success this week-end will depend on their F-duct performance but that macca think they can bypass it completely with a low-wing setup.

Im just discussing the F-Duct and its effect on a wing from the perspective of someone who has a pilot's lisence. This is what I was tought about lift [downforce]/drag and a stalled wing.

A stalled wing will make less if lift, possibly no lift, but it will always make more drag than a wing not in stall.

[Wingman]

I'm sure this is on the technical forum somewhere, but...

A high downforce Rear Wing is about 1/3rd of the drag of the whole car, and the majority of this is 'Induced Drag' in the form of the wingtip vortices you can see in humid weather (or on aircraft at altitude), where the more downforce you create, the less efficiently you can do it. Stalling a high downforce wing on the straight drops the majority of its downforce, so it has little induced drag, but gains the profile drag from the separation. Spa is a great circuit for the f-duct effect as you want minimum drag from La Source to Les Combes and from Stavelot to the bustop (Eau Rouge and Blanchimont have been easy flat the last few years), but maximum downforce through the middle sector.

Monza is a very low downforce requirement circuit (long straights with few corners), but because it is a one-off the teams are stuck modifying a car which is designed for Barcelona etc, and one of the few ways they can easily drop drag to get the high speeds is to reduce the performance of the rear wing. However, at some point you end up with little or no rear wing downforce, so stalling the rear wing doesn't reduce drag (F3000 cars ran one element of their rear wing the wrong way up one year to go faster - before they were disqualified for modifying their 'spec' cars). Reducing the rear wing performance also makes the work of the diffuser harder (it can separate as it is used to help from the rear wing - Red Bull struggled when they backed off the rear wing for Canada, so this could have been their problem) and you have to reduce front wing downforce to 'balance' the car, which means the cars are less efficient. I have heard that because everyone is so concerned about being slipstreamed at the start of the race, the teams actually run less downforce and drag than the optimum (the fastest config) to cover their opponents - we could see a bigger difference between qualifying and the race hear as the fast cars through the corners get overtaken at the start.

This year the teams have chosen 30 gear ratio pairs, and each of their cars can select 7 of them - if you reduce drag on the car you chose a longer 7th gear, but as the quickshift gearboxes can only work with small rev-drops between gears (ie they have to be close together) and the engine torque is very peaky with rpm, you end up with all the gears being longer. All the teams will have selected a range of 'Monza' long 7th gears, to cover their maximum speed plus the effect of slipstreaming, but as described above, running faster down the straights will compromise the car in virtually every other way.

[Tifosi]

Im just discussing the F-Duct and its effect on a wing from the perspective of someone who has a pilot's lisence. This is what I was tought about lift [downforce]/drag and a stalled wing.

A stalled wing will make less if lift, possibly no lift, but it will always make more drag than a wing not in stall.

I wasn't arguing against your very interesting post :-) , just interested in how different teams are approaching the same issue from different perspectives.

[Greig]

Well this weekend is Spa, Monza is when McLaren are removing it? So I guess the F-Duct will be important this weekend ;-)

[Tifosi]

Well this weekend is Spa, Monza is when McLaren are removing it? So I guess the F-Duct will be important this weekend ;-)

ooo my bad :oops - i misread that one.

[Brakefade]

Very interesting stuff, but whatever the science may be, I hope this hurts Mclaren. It's been too long since Ferrari have won their home GP.

[mad_ani]

Yeah, I don't buy it.

The F-Duct makes the car faster by stalling the rear wing right? A stalled wing creates more drag than a win that is not in stall. If you disrupt laminar air flow the resulting vortices create MORE DRAG, not less. The F-Duct does not get rid of drag, its gets rid of downforce. get rid of the downforce, and the car weighs less. A car that weighs less can be propelled to a faster speed that a heavier car with the same power.

Perhaps, having the F-Duct on a car with a low downforce setup will create more drag than is acceptable and cause more harm than the benefit it creates by taking weight off the car. In other words, lets say on a medium downforce track the F-Duct removes enough downforce to give the car 10mph more than without it, but creates 4mph of speed robbing drag. The net result is a car that is 6mph faster. At Monza, the F-Duct may give them only 2mph over their low DF setup but create 3mph wirth of drag. Net result is a loss of 1mph.

From Wikepedia:
Flow separation begins to occur at small angles of attack while attached flow over the wing is still dominant. As angle of attack increases, the separated regions on the top of the wing increase in size and hinder the wing's ability to create lift. At the critical angle of attack, separated flow is so dominant that further increases in angle of attack produce less lift and vastly more drag.

Since the car can not move the wing to change the AOA the introduce another stream of air comingo ut of the trailing edge of the wing to seperate the upper and lower air streams, this causes the stall and MORE Drag, not less.

I believe thats where u gotten it wrong....The F duct does indeed get rid of DF but the induced drag which is a function of your DF also goes down...

The flow around the rear wing is no longer laminar but heavily turbulent....

On a low downforce circuit, the entire aero package is designed for lower drag...and the relative gain using an F duct is not as much as compared on a high df track...also the added expense of weight with the tubing and the valve....not much...but every bit less helps...

[WS6TransAm01]

I wasn't arguing against your very interesting post :-) , just interested in how different teams are approaching the same issue from different perspectives.

I did not take is as argumentative... no harm done.


I believe thats where u gotten it wrong....The F duct does indeed get rid of DF but the induced drag which is a function of your DF also goes down...

The flow around the rear wing is no longer laminar but heavily turbulent....

On a low downforce circuit, the entire aero package is designed for lower drag...and the relative gain using an F duct is not as much as compared on a high df track...also the added expense of weight with the tubing and the valve....not much...but every bit less helps...

I don't believe there is much induced drag comming from these cars. Induced drag come from the high and low pressure air streams comming from above and below the wing. If a wing is infinate, and the airfoil is of constant shape, where will be no induced drag. The end plates of the rear wing support act to prevent/reduce high and low pressure air from comming together to for induced drag in the shape of wingtip vortices. I am not saying that vortices to not occur, we can clearly see them on humid days but they are greatly reduced and not or major concurn IMHO. The end plates on the F1 car wing act the same way that the winglets do on a B737-900 or Airbus A330-000, the reduce drag to begin with.

I still contend that the reduction of weight, due to reduction of downforce is what helps the car go faster in a strait line.

In drag racing, we try and reduce weight as much as we can. A gross estimate is that for every 100Lbs taken off the car, it will go .1 seconds faster in the 1/4mile.

Weight is what they are fighting, not drag. If anything, the F-duct increases drag, but it reduces enough weight to more than make up for it. By 120mph the cars weight nearly doubles as the weight generated by downforce is nearly 2:1 that would mean that at 120mph the car would weight over 4000lbs! Take that back down to 1400lbs and think about how much faster the car will accelorate! With the right gear, and less weight, the car will reach a higher speed even at the same lever of induced drag.

[Wingman]

TransAm, I think there's a misunderstanding in your post above - Aero downforce is not weight or mass, it is just a force on the car. The weight of the car does not double with speed, the weight = mass x gravity, and this is pretty constant (relativity, non uniform ground and fuel burn effects ignored), but the force on the road doubles: Total Contact Patch Load = Weight + Downforce, and a higher contact patch load increases the potential of the tyres.

Acceleration = Force / mass, so reducing the mass increases your acceleration for the same net force. Accelerating Force = Engine 'Thrust' - Drag, and as drag rises with the square of speed this is a big factor. Extra downforce does increase tyre rolling resistance, so the only reason to drop downforce down the straight is that you also drop induced drag (which is a big factor due to the very low aspect ratio of the wings used - the endplates don't make a wing as efficient as an infinite span, they do help - as I said you can see the tip vortex in humid conditions which is the manifestation of this wasted energy).

[mad_ani]

I did not take is as argumentative... no harm done.

I don't believe there is much induced drag comming from these cars. Induced drag come from the high and low pressure air streams comming from above and below the wing. If a wing is infinate, and the airfoil is of constant shape, where will be no induced drag. The end plates of the rear wing support act to prevent/reduce high and low pressure air from comming together to for induced drag in the shape of wingtip vortices. I am not saying that vortices to not occur, we can clearly see them on humid days but they are greatly reduced and not or major concurn IMHO. The end plates on the F1 car wing act the same way that the winglets do on a B737-900 or Airbus A330-000, the reduce drag to begin with.

I still contend that the reduction of weight, due to reduction of downforce is what helps the car go faster in a strait line.

In drag racing, we try and reduce weight as much as we can. A gross estimate is that for every 100Lbs taken off the car, it will go .1 seconds faster in the 1/4mile.

Weight is what they are fighting, not drag. If anything, the F-duct increases drag, but it reduces enough weight to more than make up for it. By 120mph the cars weight nearly doubles as the weight generated by downforce is nearly 2:1 that would mean that at 120mph the car would weight over 4000lbs! Take that back down to 1400lbs and think about how much faster the car will accelorate! With the right gear, and less weight, the car will reach a higher speed even at the same lever of induced drag.

Cd (Drag co -efficient) consists of the profile drag and induced drag. Not much can be done about the profile drag as the wing profile is fixed. Induced drag varies as the square of the Cl (Lift co -efficient)

The F duct is used to stall the wing by lowering Cl, thereby reducing Cd...Yes its a small amount, but remember the engine is overcoming this drag force and making the car go faster....
No wonder it took Mclaren 80 iterations to get it right...and the F duct gives a speed advantage of 6-10kmph..which is enogh to slip stream and overtake

Also F1 cars are not aeroplanes...so we dont fear falling off the sky when the wings stall....and our cars dont run on Redbull :lol