Sucked wing idea

[mep]

Absolutely lacking in any basic technical knowledge or common sense.

If you attempt to couple low airbox pressure to the top of the wing, you simply lower the Cp, simple. Lowering top surface Cp reduces net pressure differential, less downforce.

There are other basic flaws such as the assumption of airbox pressure variation.

Afraid its not a good idea in any sense.

hääää maybe you have a lack of understanding the idea.
Why do you want to suck top surface pressure?
I would suck bottom surface and blow top surface to increase downforce during cornering.
Nevertheless we have that picture with both channels so its fact that they do something we just have to figure out what they do.
Btw. TV commentator said that Mercedes also has a system running on their cars but I couldn't see any fin to the rear wing.
So either commentator was just wrong and has no idea how the system works or they do something else.
I thought about connecting such a system to the diffusor for me this would be much more efficient than on the rear wing.
What do you guys think about it?

[Pandamasque]

I remember clearly hearing a commentator saying that they run the 'active' air through the endplates instead of the fin.

[F1_eng]

"hääää maybe you have a lack of understanding the idea.
Why do you want to suck top surface pressure?"

I didn't want to suck on the top surface, I was explaining that it wasn't a good idea.

MEP, what would be your strategies for blowing the top then? And what is the best way of getting the ducting and openings to the diffuser? Remember the rules regarding the closed sections.

[mep]

Last time I was a bit in a hurry because I was at work so I just fly over the thread. You where writing about sucking top surface but I and maybe others to think about sucking lower surface.

What I want to do is to keep airstream attached to the wings profile and therefore running it at higher angles of attack. For this I make several slits over whole wing span and connect them with the airbox. The engine doesn’t even need to suck anything in. It just provides low pressure and helps to keep air attached. Due to the low pressure and the higher airspeed you create more downforce during low speed and cornering.


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At higher car speed more and more air gets collected by the duct above the airbox and starts to blow through the same holes under the wing. This causes the air to detach from the profile. Increased mass flow, changed flow and reduced air speed under the wing rises the pressure and reduces drag and downforce at high speed. So you get all what you want high downforce at low speed and low drag at high speed.


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[xpensive]

I was thinking... ram-air effect that feeds the blown wing is immeasurably lesser that what inverted functioning would be. Ram-air generated pressure/volume/speed depends on inlet diameter and the speed of car, while sub-pressure of sucked tube depends on capacity of suction device - in this case the engine.

It would even rise as speed decreases and so do revs, right?

So, what I'm recommending would be instead of blowing wing trough aperture at the back, there should be aperture on wing's top connected to airbox. Siphon shape would prevent the air stream from entering duct, and simultaneously direct sucked air in direction of main air stream.

Since engine revs are much more constant than speed of the car, this would be more effective on any part of the circuit.

*This is just a quick sketch, had no time to think how Mclaren's airbox looks like.

I have to admit that I fail to understand this idea. When the very purpose of the airbox is to create an overpressure on the intakes,
by dynamic pressure Rho*v^2/2, how could you possibly suck anything?

[marcush.]

overpressure in airbox..

how could this possibly be? the engine is turning 18k times per minte sucking in
3litres of air with every second revolution ,but additionally due to clever use of intake and exhaust effects even more air gets sucked in.
so its 27m³ + some added through engine physics.
so we have on the other side an area of 0.15m x0,15 m opening travelling at say 85m/s..thats roughly 115m³ per minute at 300km/h.
but ..how would you create pressure in an open box? i´d say yo would have to cut big holes in the airbox to come to a point when there is not more air available than the engine can consume at least at high speeds.
but at lower speeds ,depending on air consumption of the engine you may see a different situation with airbox pressure...so maybe that could do the trick ..

[xpensive]

You will obviously get the dynamic pressure ram-effect on the airbox opening through Rho * v^2/2, I thought this was a given?

A relative air-speed difference of 60 m/s gives you 2.16 kPa or 2% of the atmosphere which in turn translates to 16 xtra Hp.

What did you think the aiirbox was for anyway?

[marcush.]

oh sorry ,if this was misleading.
I did not question there was some ram effect at high speed ...my question was if there could be situations when air box pressure would be lowish.

[xpensive]

We can use your own calcs, 27 m^3/min, or 0.45 per second, at 18k, with an inlet size of 15 by 15 cm, 0.0225 m^2.

Compiling the above means that you will have a neutral situation at 20 m/s, 72 km/h, and a ram-effect above that.

[manchild]

V10 3L engines were sucking in 550 liters of air per second at 19k, so it would be easy to calculate how much 2.4 V8 does.

3000 cc BMW V10:

- 19,000 RPM
- 316.7 Crankshaft revolutions.
- 1,583.3 Ignition sparks.
- 550 Litres of air drawn in.

It's one huge vacuum cleaner that would require airbox with diameter of ventilation cowl from Titanic to create overpressure in airbox.

When it matters sucking air from below, I think that would reduce low pressure zone created by wings curvy shape and therefore reduce downforce. If blowing works below, than sucking by logic works on top.

[xpensive]

I suggest you check marcush calcs above, a 15 by 15 cm opening would in theory pass 1870 liters per second at 83 m/s, or 300 km/h.

Math is a beautiful thing, don't you think?

[manchild]

I'd like to see some formula for those figures.

[F1_eng]

Q=A.V

[xpensive]

Like Volumetric flow (m^3/sec) = Speed (m/sec) * Area (m^2)?

Not xactly the relativity theory that, but you're welcome.

But the point is that the very reason for the airbox is to collect dynamic pressure to build a static pressure above the intakes.
Sometimes called "ram effect". p = Rho * Speed^2/2

[manchild]

I suggest you check marcush calcs above, a 15 by 15 cm opening would in theory pass 1870 liters per second at 83 m/s, or 300 km/h.

Math is a beautiful thing, don't you think?

I got 1916 liters, but regardless...

Speaking of airbox's capacity - if it can pass approximately 4 times more air than engine can consume, why don't they make it much smaller, big enough to supply the engine on highest revs, and expanded just enough to create positive pressure? What benefits are there in having them several times bigger when it can only create more drag?