2012 Stalled wings, F/ W ducts & DDRS

[Tatsu333]

A little primer on how the f-ducts worked...

First, remember that on a blown wing the blowing prevents the stall - it doesn't cause it to stall. The wing is built in a way that would ordinarily stall, and then the blowing is introduced to prevent it. So on the old McLaren, when the driver 'activated' the f-duct on the straight, he was actually cutting the flow. The gist of this is that there's really no way that the wing duct is involved in the actual blowing, since it opens when you'd want it closed and so would be doing the opposite of what it should. That's why I say that it has to be the switch.

I am pretty sure you are incorrect there. Think in terms of an aircraft wing - it stalls BELOW a certain velocity, which is why when a plane takes off it needs to increase speed to generate lift. Extending flaps, etc. lengthens the chord of the wing, allowing it to continue generating lift at a lower velocity.

So, flip it over, and below a certain speed the wing on an F1 car is stalled and does not produce downforce. Old-style F-duct blowing did not prevent stalling - it encouraged it. From Scarbs' post on the original F-duct's last iteration in Suzuka 2010:

"Teams have known for a long time that stalling the rear wing drastically reduces downforce and as a result reduces drag. This is because the large flow structures coming off the wing break up and shed the drag inducing effect they have. Many teams have tried to exploit the rules by flexing their rear wings to create just such an effect, but the FIA has outlawed this via a number of deflection tests and latterly the slot gap separator.

McLaren have now found that they can stall the rear wing, if they blow airflow out of a slot at right angles to the underside of the rear wing. But this in itself cannot be exploited unless there is a means to switch the airflow on and off. With the driver controlled F-duct, controlling the flow either to the stalling slot or to a neutral outlet, McLaren can achieve the ideal situation of a downforce wing setting for corners and low drag for the straights."

Looking further at that article, I see what you're saying (Pup) about the fluidic switch - I didn't quite understand correctly how that had worked in the past. I would note, however, that the rear wing holes on the W03 being exits, not intakes, does not mean that they couldn't serve the same function (reducing backpressure down a certain path for the air to divert it). In the case of the W03, though, I don't see where the "neutral outlet" for the airflow would be (that the rear wing holes would "switch" the flow to or from), based on what we know/think so far. What other openings do we see in the rear wing? I suppose that "neutral outlet" could even be supplementary cooling ducts to the radiators, or ducted down to the diffuser for more downforce, or somewhere else hidden by the bodywork and still technically legal for that matter.

On this page of Scarbs's blog, he talks about the 2011 rule changes that effectively banned slots in both the beam wing and the main rear wing (outside of the central 15cm), so something else other than "traditional" slot-blowing of either wing surface has to be happening if it's affecting the rear wing.

All we really "know" right now is that activating the DRS appears to expose holes in the rear wing endplates, there appears to be a duct running through the rear crash structure, Charlie Whiting (who would have as detailed an explanation of the operation and function of the entire system from Mercedes as anyone) has approved the whole system as legal, and another team principal has said that Mercedes has "found a creative solution to circumnavigate" the regulation(s) that resulted in the old-style F-duct being rendered obsolete.

All of the above taken together almost makes me think the solution just might be as simple as it first appears - the holes blow air (ducted through the rear crash structure from some point ahead of it) across the outer edges of the lower face of the upper wing flap to further reduce drag when the DRS is activated. If the "neutral outlet" were sending the air down to the diffuser for more downforce, and that flow were diverted when DRS is activated, it would have the additional effect of reducing downforce in the diffuser when DRS is active. Talk about an aero balance shift, though!

This would maybe allow them to run a more aggressive flap for better downforce in corners when DRS is not active, but would mean they couldn't open the DRS as early in corners during qualifying (because of the proportionally greater loss of rear downforce). It will be interesting to see how early (or not) the Mercedes drivers activate the DRS compared to the other teams in the other practice sessions and qualifying (FP1 was not televised where I live).

Again, all speculation...

Whatever, I'm just happy that the car seems pretty handy so far from FP1! We'll see the real story tomorrow and Sunday, one way or the other.

[thisisatest]

mach 0.3 is pretty close to 200mph, isnt it? and the mach 0.3 is a general rule, right? im sure theres a gray area around that speed with some compressibility to account for.

[ernest]

Very odd, just watching FP2 on One HD and during Schumacher's last run they had some on board footage, at least twice during the lap on straight or nearly straight sections he took his left hand off the wheel and put it down against the cockpit side, it really didn't look like brake adjustment, so maybe either him and Ross Brawn are having a little joke about F Ducts or the king of the loopholes has found another interpretation of the driver movement influencing aerodynamics rules. Also my understanding of the blown rear wing situation was that rather than it being made illegal which it wasn't, at least in it's passively activated form, that the teams had agreed that it was a development financial black hole and had agreed not to pursue it?

[hardingfv32]

mach 0.3 is pretty close to 200mph, isnt it? and the mach 0.3 is a general rule, right? im sure theres a gray area around that speed with some compressibility to account for.

I am sure there is some very small amount of compressibility below mach .3 but this seems to be the convention:

"Generally, for theoretical and experimental purposes, gases are assumed to be incompressible when they are moving at low speeds--under approximately 220 miles per hour. The motion of the object traveling through the air at such speed does not affect the density of the air. This assumption has been useful in aerodynamics when studying the behavior of air in relation to airfoils and other objects moving through the air at slower speeds."

Brian

[thomin]

Also my understanding of the blown rear wing situation was that rather than it being made illegal which it wasn't, at least in it's passively activated form, that the teams had agreed that it was a development financial black hole and had agreed not to pursue it?

I haven't heard about that, but I guess it'll depend on Mercedes' pace. If Mercedes is really quick, the F-duct will be hard to ignore for other teams. Which would of course work in Mercedes' favor. Not only that it would cost the other teams cash, but it would also cost them time they would otherwise use to improve the car in other areas.

So let's hope that the system works really well

[shelly]

I stick to my opinion that merc are stalling the fw via drs.

Having seen scarbs' post following the same line has reinforced that, as I think he's on of the best f1 tech sources on the web.

I have not seen anything yet that would lead me to think they are not blowing the fw.

[Raptor22]

1) What is demonstrated need for an DRS signaled F-duct system? How does the DRS signal coordinate with your desired outcome? It is my claim that no benefit can be delineated.

2) Considering the implication of air flow in ducts, the front or rear routing schemes have not the slightest chance of delivering a useful flow to the wing surface. Look at the old McLaren F-duct and note how large and straight it was required to be to function properly.

Brian

once again your complete lack of understanding of science leavings me wondering what you really do in your day time...

The 2010 F-duct did not use the long ducting for flow but rather for pressure signalling.
The flow was provided by stronger sources. i.e. the inlet in the roll hoop.

In the case of the Merc the pressure for the FW will come from the opening in the nose.
For the rear wing the flow will come from either the roll hopp ilet or the engine airbox.
All that is needed is a pressure signal to make the switching.
In the scenario I posted much earlier in the thread the opening of the DRS can provide that signal by opening a flap or conduit or even closing it (depends on detail design).
if the switching requires a low pressure signal then the DRS opens a flap which sends a pressure signal to the switching in the FW and RW.
If it closes a conduit then the pressuer build that results in the accumulator will exceed the release valve (a simple membrane) and the flow exits the slots.

There are quite a few ways to skin this cat. Its not about flow through long pipes but pressure signalling. Pretty much the same way bagpipes, flutes, trombones, trumpets, french horns and those stupid swiss horns work.

[Raptor22]

Also my understanding of the blown rear wing situation was that rather than it being made illegal which it wasn't, at least in it's passively activated form, that the teams had agreed that it was a development financial black hole and had agreed not to pursue it?

I haven't heard about that, but I guess it'll depend on Mercedes' pace. If Mercedes is really quick, the F-duct will be hard to ignore for other teams. Which would of course work in Mercedes' favor. Not only that it would cost the other teams cash, but it would also cost them time they would otherwise use to improve the car in other areas.

So let's hope that the system works really well

Driver activated F-ducts were banned, not DRS activeated F-ducts.
Those are Charlie Whiting's words not mine. Quit argueing.
It does not have to be passive either. Nowhere in the rules does it ban F-ducts. Only driver activated.

DRS is a legal driver activated system. If it happens to do something else then thats legal according to any interpretation of the rules.
If you wish to start banning all driver activated devics then we will can decide the drivers world championship by who has the biggest smile because, brakes, steering, clutches gearboxes etc will all be banned

[ian_s]

I just had an epiphany: the holes in the RW endplates simply CAN'T be inlets. Because the air rushing over them will suck air OUT. It's pretty basic aerodynamics.

This is what I think is happening.. DRS rear wing and DRS air box. The air box is large source of drag at high speeds.

I think the DRS also vents the engine airbox at high speeds - when the air box pressure is already saturated. Even if you use it at low speeds it will not affect the engine. This is because the absolute pressure in the air box will be slightly less. At higher speeds when the engine is running at full power and it cannot pump in enough air into self the excess pressure can be bled off. If this is not true and the engine does lose power... the reduction in drag will make up for it.

[urk]http://img.photobucket.com/albums/v626/ ... switch.png[/url]

Uhm, at high speed the air box is already sucking in air very very strongly. You would not gain anything by reducing pressure in there even further.

I agree with this, i don't think the openings in the rear wing end plates are inlets, i think they are outlets.
i also think they aren't linked with the air box, i think the inlets for these ducts comes from somewhere with a higher relative pressure, maybe near the sidepod inlets, or the second opening behind the main inlet on the engine cover. when the DRS is activated, more air is introduced where the moving element meets the end plate, possibly reducing the vortices you can sometimes see coming off the rear wing. these vortices induce drag, so if you can reduce them, you reduce drag.

[Dragonfly]

Well, I read at several places they didn't actually use the enhanced DRS wing today.

[myoozikk]

Here's a pic of DRS hole on the Merc rear wing...

[hardingfv32]

once again your complete lack of understanding of science leavings me wondering what you really do in your day time...

Now, now is this necessary?

I am board with the value of a DRS signal circuit, but I still do not think it is possible to get the signal to the nose. The fluid switch requires constant flow to create or maintain a signal. It is not a pressure activated switch. Look at the size of the hole in the wing side plate, that is not going to provide enough flow to travel all the way to the nose.

Brian

[hardingfv32]

I agree with this, i don't think the openings in the rear wing end plates are inlets, i think they are outlets....
possibly reducing the vortices you can sometimes see coming off the rear wing. these vortices induce drag, so if you can reduce them, you reduce drag.

1) I theory there could be high pressure at the DRS opening. The louvers on the endplate are there to relieve pressure.

2) Or the flow over the hole could draw a vacuum and create low pressure in the DRS hole. Flow outward could function as the signal.

3) I do not appreciate how adding flow is going to reduce vortices. Again, that would seem contrary to what the louvers are going.

Brian

[skgoa]

I just had an epiphany: the holes in the RW endplates simply CAN'T be inlets. Because the air rushing over them will suck air OUT. It's pretty basic aerodynamics.

This is what I think is happening.. DRS rear wing and DRS air box. The air box is large source of drag at high speeds.

I think the DRS also vents the engine airbox at high speeds - when the air box pressure is already saturated. Even if you use it at low speeds it will not affect the engine. This is because the absolute pressure in the air box will be slightly less. At higher speeds when the engine is running at full power and it cannot pump in enough air into self the excess pressure can be bled off. If this is not true and the engine does lose power... the reduction in drag will make up for it.

http://img.photobucket.com/albums/v626/ ... switch.png

Uhm, at high speed the air box is already sucking in air very very strongly. You would not gain anything by reducing pressure in there even further.

I agree with this, i don't think the openings in the rear wing end plates are inlets, i think they are outlets.
i also think they aren't linked with the air box, i think the inlets for these ducts comes from somewhere with a higher relative pressure, maybe near the sidepod inlets, or the second opening behind the main inlet on the engine cover. when the DRS is activated, more air is introduced where the moving element meets the end plate, possibly reducing the vortices you can sometimes see coming off the rear wing. these vortices induce drag, so if you can reduce them, you reduce drag.

Damn, now that you mention that... they COULD actually be inlets. Inlets routing air to... *drumroll* nowhere important. Just letting air enter at those points would drastically reduce pressure and thus drag. No need to stall the mainplane. And when you don't car about drag, you get to have more pressure at the rearwing ends than you would want to have without this. Just route the air out the starter motor hole or something like that.
I am not saying they are doing that (why would they have the slits in the endplate?) but it's much more logical than either blowing or stalling the front wing. The latter has been conclussively disproven by FP1, anyways.

[PlatinumZealot]

There are a lot of holes in the front wing stalling theory.

The main ones being.

1. slots in the front wing
2. air passages in the bulkhead/chassis.

If we can establish these two things then we are on our way.

For number 1. We need photos of the underside of the F-duct wings.

I have propsed a theory, but it just a guess..only photos will show what is right or incorrect.

This is better than babbling on and on.