Long/short chord DRS

[beelsebob]

Apologies if this has been discussed before, or if it's teaching your granny to suck eggs, I'm only just really getting a handle on how rear wings work. With it in mind that I'm a complete novice to how this works, can someone tell me whether this argument for short chord rear wings makes sense...

• With a short chord, the lower plane may actually be long enough that it would stall without the air through the slot gap to increase the pressure a little and keep the flow attached.
• When the DRS flap is open, this would cause the lower plane to stall too, and reduce drag even further.
• When the DRS flap re-closes, you might then have problems getting the flow to reattach to the lower wing (leading to Merc's early season problems with a short chord DRS).

With a long chord, basically, you don't get the benefit of the lower plane stalling with the DRS open.

Is this anywhere along the right lines?

[MIKEY_!]

That all sounds good to me. The position of a short chord flap in the open position may be directing air downward in such a way that it detaches air near the top of the main flap or more likely assists the kind of separation you mentioned.

With a short chord, the lower plane may actually be long enough that it would stall without the air through the slot gap

Just a thought

[shelly]

I was thinking: in winter testing DRS use is free, isn't it?

Do you expect teams to use a computer activated drs to simulate the effect of a rear wing exhaust blowing solution they do not want to show in the first test?

Then they would test the real thing in the last test, leaving less time to copy it

[gixxer_drew]

Apologies if this has been discussed before, or if it's teaching your granny to suck eggs, I'm only just really getting a handle on how rear wings work. With it in mind that I'm a complete novice to how this works, can someone tell me whether this argument for short chord rear wings makes sense...

• With a short chord, the lower plane may actually be long enough that it would stall without the air through the slot gap to increase the pressure a little and keep the flow attached.
• When the DRS flap is open, this would cause the lower plane to stall too, and reduce drag even further.
• When the DRS flap re-closes, you might then have problems getting the flow to reattach to the lower wing (leading to Merc's early season problems with a short chord DRS).

With a long chord, basically, you don't get the benefit of the lower plane stalling with the DRS open.

Is this anywhere along the right lines?

I haven't read the F1 rules but I think this will depend on details of the shape of the main plane vs the flap. Sorry for the verbose explanation, I read some other posts about the bypass ducts to the wings and wanted to talk about that as well.

Lets say you have a two element and your final angle on the flap is 60 degrees. You can have the slot in any number of arrangements of how far along that total curve you would put it. And it can be places that would surely stall were the main plane alone or that wouldn't and its all gonna be shades of that. But I am going to guess that the placement of where you would want it optimally isn't done in without taking in total car effects, not just a perfect wing tested in free air. So it could be any number of ways depending on any number of factors, including how much you optimize your wing for DRS vs non DRS use. Which in turn would depend on where you think you might be running in the pack and thats just one factor I can dream up.

It seems like your using the word stall to imply less drag forces? I see the word "stall" getting all sorts of weird meanings on this messageboard that I think maybe originated in trying understand how stalling with the bypass ducts reduced drag where "stalling" in context of aircraft wing is almost certainly larger drag forces.