afj
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| posted on 12/4/09 at 05:07 PM |
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got bored,made a diffuser
got bored made a diffuser
 
Rescued attachment alan.jpg
eerrrrrrrrrrrrrrrr
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blakep82
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| posted on 12/4/09 at 05:08 PM |
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ooh lookin good 
whats it made of?
________________________
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coozer
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| posted on 12/4/09 at 05:09 PM |
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Interesting, seen a couple today out on our blat and am wondering if they actually do anything or just look bling.
Whats the benefit of having one on the car?
Steve
1972 V8 Jago
1980 Z750
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A1
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| posted on 12/4/09 at 05:11 PM |
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creates lots of downforce and reduces drag i believe
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afj
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| posted on 12/4/09 at 05:12 PM |
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1.2mm ally some rivits and satin black paint and around an hour out of the mad house i call home , just bling as far as im bothered and
cost £11
[Edited on 12/4/09 by afj]
eerrrrrrrrrrrrrrrr
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blakep82
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| posted on 12/4/09 at 05:26 PM |
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i'd quite like one on the truck, to fill up an ugly space under the back panel, thing is, i don't really want to put a floor under the
whole car... there's a lot of space to cover
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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locoR1
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| posted on 12/4/09 at 05:50 PM |
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Very nice i wonder where you got that idea from and who you copyed that of
ive spent the last two days making something for the car hopefully when they are finished they will look very  will be at least another
couple of weeks till there finish thats all im saying for now apart from top secret
 
Description
Check out my CB500T Cafe Racer build diary
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bob tatt
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| posted on 12/4/09 at 06:14 PM |
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how far under the rear tub have you gone with it, is it all the way to the cookpit or just for the bling. v cool by the way.
rob
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gingerprince
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| posted on 12/4/09 at 06:24 PM |
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I hope it's within the regulations
Regardless of whether it actually does generate downforce or not, it must at least help in some ways on a seven. The rear panel with the space
beneath open must act at least in some way as a parachute, so covering it up has to be an improvement. Whether it actually generates downforce is
surely just an added bonus if it does?
All you need to do now is stencil Brawn GP on it and it'll be even quicker
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Snap-off
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| posted on 12/4/09 at 06:36 PM |
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Very nice in black!
There must be something in the air  , I've just fitted one also, covers all the parachute area and fills the empty space at the rear. Got the
idea from Snetterton a few weeks ago.
 
Description
[img][/img]
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mr henderson
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| posted on 12/4/09 at 06:54 PM |
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quote:
Originally posted by A1
creates lots of downforce and reduces drag i believe
Only if they can overturn the laws of physics.
Either lots of downforce, or reduce drag. Not both.
John
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Richard Quinn
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| posted on 12/4/09 at 07:06 PM |
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quote:
Originally posted by mr henderson
quote:
Originally posted by A1
creates lots of downforce and reduces drag i believe
Only if they can overturn the laws of physics.
Either lots of downforce, or reduce drag. Not both.
John
I'd beg to differ.
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afj
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| posted on 12/4/09 at 07:06 PM |
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just noticed snap off we must have got regestered almost together just 6 plates out
[Edited on 12/4/09 by afj]
oh underneth its as big as the rear panel area the only gap in the floor now is the curved section under the diff
[Edited on 12/4/09 by afj]
eerrrrrrrrrrrrrrrr
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Snap-off
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| posted on 12/4/09 at 07:12 PM |
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Yes, Matt.c is one number from mine too.
quote:
Originally posted by afj
just noticed snap off we must have got regestered almost together just 6 plates out
[Edited on 12/4/09 by afj]
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mistergrumpy
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| posted on 12/4/09 at 07:13 PM |
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quote:
I'd beg to differ
No I think John's right you know. If you've extra got downforce, as in extra force acting down on the car then you've just increased
your drag because you've added extra force to the car.
I really like it though and wouldn't mind one on mine should I ever finish it. Just for cosmetic reasons though as my chassis is clearly visible
underneath the badly fitting Luego panel.
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iiyama
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| posted on 12/4/09 at 07:31 PM |
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Actually diffusers add down force without producing much drag. Wings create drag for obvious reasons, this being that there is basically a big plate
at an angle to the airflow. Because it is a wing it has a high pressure area above it and a low pressure area below it creating the downforce. Also
because of this the high pressure trys to get into the low pressure area and creates a vortice, (seen in Malaysia due to the high humidity). This is
also drag as its dirty air. (why all passenger aircraft have the vertical winglets on the end of the wings, reduces the drag so they use less
fuel).
A diffuser is used by making the entire bottom of the car flat, (making the air move faster under this area due to being compressed), when it reaches
the diffuser which turns upward the air decelerates creating low pressure which is the downforce. All the vertical winglets stop the air from
seperating and all this creates very little in the way of drag. Cant get something for nothing!!!
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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Hellfire
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| posted on 12/4/09 at 07:43 PM |
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Hang on a minute, are we talking about aerodynamics and sevens in the same thread here Come on guys, do you really think that making your own
diffuser and sticking it on is going to increase your downforce? They make an otherwise dull but very visible area look interesting, that's
about it.
Phil
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andylancaster3000
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| posted on 12/4/09 at 07:49 PM |
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I think generally speaking underbody aerodynamics such as these are designed to employ ground effect principles and therefore are very favourable as
they induce very little drag for the downforce that they create and possibly can even can reduce drag by preventing turbulent air from exiting the
rear of the car.
By increasing downforce you do not inherently increase drag as downforce is, broadly speaking, a vertical force and the drag induced by it
horizontal.
Very simple explaination from a non-aero engineer there , better info here:
http://www.symscape.com/blog/secrets_of_diffusers
Andy
Edit: Damn, been beaten to it.
[Edited on 12/4/09 by andylancaster3000]
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mistergrumpy
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| posted on 12/4/09 at 07:51 PM |
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I agree with Phil wholeheartedly. Though I must say and I'm not trying to start an argument , it is something that interests me having studied
it in the RAF (and was crap at!) just a conversation but your explanantion sounds not quite right in a few places iiyama.
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afj
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| posted on 12/4/09 at 07:57 PM |
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i made it in the shed, sprayed it black and rivited it on. i for one dont care if it does anything but the diffuser serves 2 perposes 1. it
kept me out the house for a bit and 2. it looks nice
eerrrrrrrrrrrrrrrr
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andylancaster3000
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| posted on 12/4/09 at 08:00 PM |
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To add actually, I think in a practical sense a diffusery looking thing can be useful but maybe not in the normal manner. In most situations the under
axle area of 'seven' is unskinned. By having something there like a 'diffuser' to stop the air going up there I would have
thought it'd help out quite a bit. Yes this isn't going to solve all seven type car aerodynamic issues but every little helps
[Edited on 12/4/09 by andylancaster3000]
[Edited on 13/4/09 by andylancaster3000]
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Ivan
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| posted on 12/4/09 at 08:02 PM |
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quote:
Originally posted by iiyama
when it reaches the diffuser which turns upward the air decelerates creating low pressure which is the downforce. All the vertical winglets stop the
air from seperating and all this creates very little in the way of drag. Cant get something for nothing!!!
I don't agree with this, basically you have to accelerate air to reduce pressure, not decelerate it.
I think what the diffuser does is exactly what it's name suggests, gives the air an easy escape from under the car without the turbulence the
suspension etc. would cause and "diffusing" it into, the hopefully, low pressure slipstream at the back thus increasing the airspeed under
the flat bottom before it and hence lowering pressure and hence increasing downforce.
In fact it might even reduce drag by reducing the turbulence behind the car.
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Hellfire
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| posted on 12/4/09 at 08:03 PM |
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We made ours to keep the diff and driveshafts clean I reckon it smoothes the airflow just about as much as washing and polishing the bodywork
panels which altogether, should equate to a 2 second reduction in our lap times at Teeside.
Phil
[Edited on 12-4-09 by Hellfire]
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Richard Quinn
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| posted on 12/4/09 at 08:08 PM |
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Without any modelling, my gut feeling is that the increase in drag due to a diffuser (not disputing that there is) is less than the reduction in drag
from skinning the boot floor. The nett result being an overall increase in downforce and an overall decrease in drag.
Question for those with soft boot covers (or those that follow mates who have a soft boot cover) - Does the boot cover get pushed up, sucked down or
just flap about aimlessly at speed?
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iiyama
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| posted on 12/4/09 at 08:12 PM |
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quote:
Originally posted by Ivan
quote:
Originally posted by iiyama
when it reaches the diffuser which turns upward the air decelerates creating low pressure which is the downforce. All the vertical winglets stop the
air from seperating and all this creates very little in the way of drag. Cant get something for nothing!!!
I don't agree with this, basically you have to accelerate air to reduce pressure, not decelerate it.
I think what the diffuser does is exactly what it's name suggests, gives the air an easy escape from under the car without the turbulence the
suspension etc. would cause and "diffusing" it into, the hopefully, low pressure slipstream at the back thus increasing the airspeed under
the flat bottom before it and hence lowering pressure and hence increasing downforce.
In fact it might even reduce drag by reducing the turbulence behind the car.
I might have got myself a bit confused! What I actually meant was as the air enters towards the front of the car it accelerates and reduces pressure.
There is a second suction peak at the transition of the flat bottom and diffuser. The diffuser then eases this high velocity air back to normal
velocity and also helps fill in the area behind the car making the whole underbody a more efficient downforce producing device by reducing drag on the
car and increasing downforce.
Clearer??? LOL
Got agree with Phil though, aerodynamics and 7's are sort of an oxymoron!!! :
If its broke, fix it. If it aint broke, take it apart and find out how it works!
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