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16th February 2017, 07:58 #151
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Regarding double diffuser. I don't really think it is double. I was reading this book about aeordynamics (by Simon McBeath) and CFD analysis shows that efficient angle of diffuser is somewhere between 8-12 degrees. Now 8 degrees is quite shallow, any road car has this angle. And, as I understand primary function of diffuser is to balance downforce between front and rear (same as rake). So in Fiesta case it could be that front-end has enough downforce thus large difusser angle is not needed.
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16th February 2017, 23:30 #152
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Hi Marcco, the 8-10deg diffuser angle quoted was applicable to the flat bottom formula cars of the early 90's and it changed (the optimal angle got bigger) with the change in the rules specifying stepped floors for the F1 cars (that's pretty much what I do for living). As a general rule of thumb, the higher the distance between the floor of the car and the road, the higher the optimal diffuser angle. Also if we accept the theory that the diffuser will add equal amounts of downforce to both axles of the car (which probably wouldn't be the case with a bit more going to the rear being more probable), then higher diffuser angle than the one on the Fiesta would look more appropriate.
Regarding the double diffuser, the only way it won't be doable is if the rules do not allow it (for one reason or another), otherwise there is no stopping the creativity of the designers.
Regards,
Nick
- Likes: drive (20th February 2017)
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17th February 2017, 05:01 #153
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I like this...
@ Yaris: You didn't mentioned Yaris "nose up" floor design.
Look:
https://www.google.si/imgres?imgurl=...:&vet=1&w=1280
https://www.google.si/imgres?imgurl=...:&vet=1&w=1280
https://www.google.si/imgres?imgurl=...M:&vet=1&w=640
http://cdn-9.motorsport.com/images/m...ota-racing.jpg
https://www.google.si/imgres?imgurl=...M:&vet=1&w=790
It looks like it is purposefully made to receive air under the floor... ground effect in mind.
I see the "side skirts" diffusers looks like a clever trick, but I don't understand why the front part of the skirts is cut away, is there aerodynamic purpose or a mechanic (rocks flying) one.
@ general underfloor aero: I think, we can not be sure that floor generated downforce is a vital part of car performance. Hyundai rear suspension cover were floating massively. As far as I can understand this should kill all floor aero performance.
https://www.youtube.com/watch?v=gwyGvSPtgJ8 (0:41 to 0:47)
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17th February 2017, 18:00 #154
For the guy who wanted the bottom of the car
http://www.ewrc.cz/ewrc/image_browse.php?id=339519
also can be seen the destroyed aero before the rear tyre, wonder how it happened
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17th February 2017, 19:22 #155
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Anyone know what the black boxes at the top of the fenders where the bumper is attached is?
http://www.ewrc-results.com/image.ph...&entry=0&car=0"Die with memories, not with dreams" Scott McIsaac
http://www.motorsportfilmer.net
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17th February 2017, 21:35 #156
Good video for tech analysis:
https://youtu.be/RfTeBPXkTps
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17th February 2017, 22:36 #157
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Before I have forgotten again:
mozesii - thanks for the appreciation.
OldF - great images, thanks, as you would have already seen, I have put them to good use.
SlowSon - thanks, good photo.
jparker - thanks, I will have a look.
J_n_z - thanks.
On a crcuit racer the answer to the question you asked without a doubt would be yes to a raised centre section of a front splitter. On a rally car with its higher ground clearance the effect will be less pronounced, but I suppose (short of this being done to simply increase the ground clearance in the middle of the vehicle to go over road obstacles) it can still help.
The side tunnels on the Yaris - if I was doing it, then my reasoning for moving the leading edge rearward would be to ensure that the tunnels get a slightly cleaner air away from the front wheels and in general increase the mass flow of air to them rather than being shadowed by the front wheels too much.
The importance of aero on a rally car - you are most likely correct about the Hyundai's flapping suspension guards, but that is why I like the rally cars, aero is not king (in massive difference to F1), the mechanical side is of utmost importance. At the same time, with the new rules, aero becomes more and more important without overshadowing the other engineering sides and whoever gets to do the best job on all design fronts will end up with the fastest car overall.
Regards,
NickLast edited by NickRally; 17th February 2017 at 22:41.
- Likes: drive (20th February 2017)
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20th February 2017, 04:21 #158
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20th February 2017, 04:31 #159
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I had mentioned the double diffuser in another thread. It's hard to validate, but if they are using it as such, the air has to come from somewhere? The M-Sport diffuser is very shallow compared to the others. Could it be as or more efficient than the others? Time will tell, we will see who copies who! As a matter of fact, are aero changes allowed during the season or is everything pretty much homologated for the whole season?
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20th February 2017, 08:13 #160
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Thanks again jparker, it is amusing to see how it never occurs to them to point the camera to the underside, which is where a lot of the interesting aero stuff takes place. Of course this is understandable considering that floors so far have not been massive differentiator in performance, but with the new rules, who knows. Funnily though, the Hyundai (the car in the video) has one of the roughest undersides if some of the distant images I have seen are anything to go by.
Last edited by NickRally; 20th February 2017 at 12:15.
Yes I fear so too, you just need to look at the new cost for tourists to get into Venice and when everyone sees the amount of money being made others will soon follow, and prices will go up. As...
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