DRD 2013

[amouzouris]

Does anyone have an idea how the switch actually works? I'm imagining a door with a variable force spring holding it closed, but I'm assuming it is more complicated than that in reality.

That is actually illegal. But would be the most effective way of doing this.
This is basically how turbo wastegates work.

[NathanOlder]

I am too, very interested in how the actual switch works.

[ringo]

ok, here's how an f duct switch works:




This was back in 2010? but this version was self switching. It switched at a certain speed.

Got a video somehwere on f1 technical but i can't find it.

Basically i sized the tubes based on a momentum equation. That way i can cause one stream to hit another stream and get a desired angle of the resulting stream to go down the desired tube. The mid chamber was designed to cause the resultant flow to attach to the desired tube once switched.
It is only when the speed drops below a certain level with the flow detach and the switch opens.

[autogyro]

I remember that Ringo.
I think Brawn ran with it when developing the idea for air switching the front wing blow and switching it side to side in corners.

[shelly]

I agree on the basic mechanism : a Y shaped pipe with a pilot flow coming form a secondary pipe that influences the main flow to take one branch or the other.
In the classic f duct the pilot flow was governed by the driver opening or closing the communication with the low pressure inside the cockpit.; with a passive solution, how would the switching ringo described take place? You would need the relative strength of the main and pilot flow to be different at different speeds.

[shelly]

Piola wirtes today on omnicorse.it http://www.omnicorse.it/magazine/25302/ ... posteriore that "for the system to work, a tri-phase solution is needed".
In my opinion redbull has not tested any drd yet, and the pylon shown yesterday is a different testing device; but anyhow the hint to 3 phases is interesting, as till now we have thought just of on-off.

[turbof1]

Based on what we have seen, are we going to see drd during the melbourne race? Sauber looked to have tested it more extensively then the others, so they might feel confident enough to use it.

[flyboy2160]

with the drd air inlets just alongside the airbox intake, i suspect you have to consider whether the airbox intake is spilling or not and whether the little gap between the drd intakes and the airbox wall would take care of all the spill. the spill would happen at high speed.

my only experience is with jet engines on fighters. there, you either have a variable size intake (typically via a pivoting ramp like the one shown below on an F4) or the fancy bump intake on the F35 or you have to eat the drag from the slower speed air that gets spilled out.



insert an imaginary video here by the lovable italian guy on scarbs' website who explained the coanda effect with a spoon and a faucet: "you see we have a small funnel under the faucet, like so. when the water is flowing slowly, it all goes through the funnel hole. but when the faucet is opened up, all the water cannot go through the funnel. it fills up and flow back over the top, like so...."

[shelly]

Based on what we have seen, are we going to see drd during the melbourne race? Sauber looked to have tested it more extensively then the others, so they might feel confident enough to use it.

In my opinion lotus have a big advantage. Than merc (mike elliott) and after those two sauber.

[Rikhart]

Found a low tech, and incomprehensible, but interesting video:

http://www.youtube.com/watch?feature=pl ... JfFkPDTVho

In this case there isn´t a "switch" at all, its all down to the pipe size, and amount of air going in the system!

[shelly]

Nice video. What's the factor causing the water to exit fro the top exit beyond a certain mass flow? On top of may head I would say it is the concentrated loss of head caused by the exit below that raises the pressure inside tha "pipe"until it is bigger than the hieght difference. Would it work with air and air?

[Rikhart]

Nice video. What's the factor causing the water to exit fro the top exit beyond a certain mass flow? On top of may head I would say it is the concentrated loss of head caused by the exit below that raises the pressure inside tha "pipe"until it is bigger than the hieght difference. Would it work with air and air?

I would agree its the pressure build up, the lower straw can no longer extract all the water, so it starts going up the top one. Wonder if DRD could be this simple, all it would take would be to get the lower exit pipe size right, and it would switch the wing blowing at the desired speed!

[flyboy2160]

Found a low tech, and incomprehensible, but interesting video:

http://www.youtube.com/watch?feature=pl ... JfFkPDTVho

In this case there isn´t a "switch" at all, its all down to the pipe size, and amount of air going in the system!

i don't think this is a valid analogy because of the mass and fluid head of the water with the tube at an angle.

air going into that pipe will try to exit the 'off axis' pipe 'without' the gravity effects acting on the water.

no sale.......

[ringo]

After doing some CFD tests.
I have received a 7.15% reduction in drag from the rear wing.
With a 15.44% reduction in down-force when the DRD is activated.

Make of it what you will i suppose. This is using the same model i have posted earlier in the thread.
Overall efficiency of the wing is reduced; as expected when a wing stalls, as there is more lost on the downforce side of things.

Seeing as though the drd will operate on the straights it's probably viable. This is assuming that the design i have is optimized, which it is not. But i feel there is some truth to the general operation of the design and the returns.

Better 7% reduction than nothing huh?
There may be some correlation to the DRD and the degradation of the tyres as well, looking at the reduction in down-force from the rear wing. When this thing switches of right before a turn, there will be implications on the tyres, especially if the car may be setup for a certain level of grip in the turns when drd is not in effect.

Overall i think these results should give you something tangible to work with. Whether it be finding out top speed increases or brake distances.

As a reference, my rear wing makes 268 lbs of downforce at 50 m/s. and 112lbs of drag.

[shelly]

Thinking about why lotus ears are fixed to the chassis and not removable as sauber's: I remember Allison in an interview in Monza 2011 saying that due to front exiting exhausts they had discovered unexpected effects about the behaviour of the car. I have not been able to find the correct reference in internet, so I am maybe mistaken, but if I remember correctly he said that they had found that not perfect alignment and sealing of bodywork panels and floor caused them significant effects on performance.

this could be the reason why they have chosen to have a permanent intake for drd: to avoid having unwanted effect due to piping and bodywork alignment.