DDD vs Ground Effect?

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djones
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DDD vs Ground Effect?

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I dont really understand either but as I know it GE is removing air from under the car. DDD also does the same?

If GE is banned why is a DDD design not?

Thanks

timbo
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Joined: 22 Oct 2007, 10:14

Re: DDD vs Ground Effect?

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Ground effect is a name for a particular implementation of same idea -- creating a low pressure under the body.
Initially ground effect was created by a combination of "reversed" wing profile underbody and skirts. To prevent teams from using ground effect flat floor was mandated and skirts were banned.
Since then, designers found means for creating low pressure with flat floors and diffusers.

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WhiteBlue
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Re: DDD vs Ground Effect?

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djones wrote:I dont really understand either but as I know it GE is removing air from under the car. DDD also does the same?

If GE is banned why is a DDD design not?

Thanks
DDDs have as much to do with ground effect as single diffusors. Double deck diffusors are just diffusors with extended geometry beyond what was initially perceived to be allowed by the 2009 F1 tech rules. All they do is increase downforce compared with what is available to a common 175 mm diffusor.

Diffusors and wings on F1 cars are both influenced by ground effect but diffusors and all devices in the car's floor naturally have greater reliance on ground effect than wings by being closer to the ground. That does not exclude ground effect playing a role particularly in front wing aerodynamics.

Air craft wings and F1 aero devices produce up and down wash. Near the ground (all F1 aero is near the ground) the upwash is progressively inhibited.

http://www.allstar.fiu.edu/aero/airflylvl3.htm
Ground effect

Another common phenomenon that is misunderstood is that of ground effect. That is the increased efficiency of a wing when flying within a wing length of the ground. A low-wing airplane will experience a reduction in drag by 50% just before it touches down. There is a great deal of confusion about ground effect. Many pilots (and the FAA VFR Exam-O-Gram No. 47) mistakenly believe that ground effect is the result of air being compressed between the wing and the ground.

To understand ground effect it is necessary to have an understanding of upwash. For the pressures involved in low speed flight, air is considered to be non-compressible. When the air is accelerated over the top of the wing and down, it must be replaced. So some air must shift around the wing (below and forward, and then up) to compensate, similar to the flow of water around a canoe paddle when rowing. This is the cause of upwash.

As stated earlier, upwash is accelerating air in the wrong direction for lift. Thus a greater amount of downwash is necessary to compensate for the upwash as well as to provide the necessary lift. Thus more work is done and more power required. Near the ground the upwash is reduced because the ground inhibits the circulation of the air under the wing. So less downwash is necessary to provide the lift. The angle of attack is reduced and so is the induced power, making the wing more efficient.
To give a very short explanation: An aero foil in free air provides (lift/down)force against air. If you replace some of the air with a solid surface the delivery of the force is helped.

This also explains why aero foils close to the ground are inherently unsafer than wings higher up. If a disruption (curb /accident) increases the distance of the car from the ground the downforce gets progressively reduced. This does not happen as much with wings higher up. They have more drag and are not as energy efficient but the do not have the snap off aspect of ground effect produced downforce.
Formula One's fundamental ethos is about success coming to those with the most ingenious engineering and best .............................. organization, not to those with the biggest budget. (Dave Richards)

xpensive
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Re: DDD vs Ground Effect?

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What do you know, another thread on DDD's, just what the doctor ordered I guess?

Ciro, for crying out loud?!
"I spent most of my money on wine and women...I wasted the rest"

djones
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Joined: 17 Mar 2005, 15:01

Re: DDD vs Ground Effect?

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xpensive wrote:What do you know, another thread on DDD's, just what the doctor ordered I guess?

Ciro, for crying out loud?!
It's an internet forum, not some sort of wiki.

Poeple post questions and yes every now and again the same subjects will be covered.

Unlike you though who clearly has too much time on their hands to write such a pathetic reply, peole cant always spend hours looking through old posts where their exact question may or may not ahve been answered.

Having more psots is also in the interests of the forum and provokes new ideas from new people who may not have seen the original post.

Get a life that man - jesus #-o

Mysticf1
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Joined: 29 Jan 2010, 17:20

Re: DDD vs Ground Effect?

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Personally i would much rather read this thread, even if its been discussed before than to read idiotic predictions about driver supremacy based on ONE pre season test.

This is F1 "Technical" after all.

djones
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Joined: 17 Mar 2005, 15:01

Re: DDD vs Ground Effect?

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xpensive wrote:Removed post
You have no grounds for any sort of argument, so resort to swearing. Well done =D>
Last edited by Ciro Pabón on 08 Feb 2010, 06:01, edited 1 time in total.
Reason: xpensive lost it

Scotracer
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Re: DDD vs Ground Effect?

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'Ground effect' cars were specifically cars that didn't have flat-floors. They had shaped floors:

Image

The current cars still utilise ground-effect but not termed the ground effect cars. It is a bit confusing. Diffusers are a sort of compromise that the FIA allowed.
Powertrain Cooling Engineer

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Ciro Pabón
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Re: DDD vs Ground Effect?

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Please (sigh), if there is an older thread where a new one can be merged, you can ask by using the report button. I agree with djones, for the record. Thanks, Scot, WB, timbo at least someone dares to give an answer.
Ciro

xpensive
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Re: DDD vs Ground Effect?

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And what do you know, a moderator? :lol:

As for "ground-effect", while obviously getting into semantics, the xpression which came with the venturi-cars of the late 70s was related to the novelty of creating downforce by speeding up the air under the car.

Xactly what today's floors, diffusers and even more so DDD's are doing, why the 2010 cars indeed have ground-effect.
"I spent most of my money on wine and women...I wasted the rest"

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