Modding "The Party" (aeromods on 2011 Ford Fiesta S sedan)

[RiderofBikes]

MAN o MAN, am i getting good at repeat stuff eh?

Onto the new diffuser! I wanted something i could build off of as time went on. Soooo...

Went to HD, bought a full sheet of 1/4" sandply finish board, had it cut for a 4' x 5' piece i was going to use for the base, and used the rest for various cabinet projects around my new condo! For a bit of weather proofing, I slapped some Kilz130 a couple layers on it. then went to town!

Using my existing mounts under the car gave me a decent spread of mounting points.




Basically used good wood screws and drilled them right into the horizontal lip of the bumper for the outer support, the front edge(closest to torsion axle) I used the same screws and just drilled straight into the spare wheel housing.

playing with the boattail, and wheel skirts


^Sadly, because of the Tire change, i am not able to reuse my wheel skirts as they are now out of compliance

[RiderofBikes]

Rear wheel boat tails!!! The diffuser worked as intended quite well, but not as good as it could of, obviously since the car was so high and whatnot...

The materials used were scraps of the same 1/4" sandply cut to match the 1" thick Pink foam insulation cut to rough shape, which also was used for sturdy mounting from layer to layer from to underside of the base.



This seems pretty low, and it is but still haven't managed to hit anything(knocks on wood) just dont back into the curbs!!

As you can see the bowing of the wood, but its only dew to the humidity, it usually springs back but doesn't disrupt the flow

[RiderofBikes]

So, I think works wonders as like the first Excessively LOOOOOW Airdam i did, but without the downforce-like symptoms.

I used some 90° bendable vinyl corner edging along the very front horizontal edge of the bumper.





Used up the last of Garden edging in the center, and went bold and overdid it with the Coro in front of the wheels, ironically this worked out waaaayyy better than expected, plus its all flexible still in regards to hitting or scrapping something going forwards. it just folds into itself and springs back!

Still working on the fronts of the wheel for better deflection, but works as-is. will get to it again eventually

[RiderofBikes]

So, in the case this design might actually work, as in a different approach instead of building to the proper shape from the top(canopy wise), i decided to start from the bottom up... Well, more like, filling-in the dead zone along the trunk area...

In all I've been able to witness driving, it's working, albeit ...ugly.
I can see a definite reattachment of airflow around the back, and a lack of vortex generated from the central antenna and D-pillars ..Yay While not able to gain more speed/distance during coasting as the Full Kamm, i coast longer, at a more steady speed, so still an improvement



^^still have all the flexibility to adjust the length of "spoiler" to actually match template, but i don't think that would change much, reattached flow seems to be good, with consistent separation top and sides

Still indecisive about side skirts, but i do have rear wheel strafes in front for now

[Thenorm]

i've always wondered about modern sedans. the rear glass transition always seems smooth enough. that I bet the air stays attached, even though its sub template and producing a low pressure zone (acting like an airfoil)

And as long as you have a horizontal or convex surface at the end to turn the air flow again and produce a high pressure zone, it might work better than a kamm back.

case in point is the new mercedes CLA which gets an absurdly low Cd and even the prius which is sub-template

So for your car, maybe all you have to do is extend the horizontal of the trunk out closer to template

[Thenorm]

heres a thread talking about this.

One thing your car has going for it is the slope of the rear glass. everyone else who has tried this ahd flow separation at the roof.
http://ecomodder.com/forum/showthrea...tml#post200303

[RiderofBikes]

Originally Posted by Thenorm

i've always wondered about modern sedans. the rear glass transition always seems smooth enough. that I bet the air stays attached, even though its sub template and producing a low pressure zone (acting like an airfoil)

case in point is the new mercedes CLA which gets an absurdly low Cd and even the prius which is sub-template

So for your car, maybe all you have to do is extend the horizontal of the trunk out closer to template

I get what your saying, but i think 1 thing overlooked with cars such as these as well as talked about the (Pontiac Aztek), and I've tried experimented with an extended section off the trunk lid to match template + half Kamm, didnt work out as well tail + kamm or the Full Kamm ive had before. This car is well under template meaning it's just too low and short. because the low pressure zone has already been created with little influence at the edge of the trunk(being base model/no added spoiler) to help pressurization,(if any) for better flow.

Red=Fiesta, Yellow=Prius/maybe Volt too


While yes, the Prius has better boundary layer characteristics(because its a solid arch from start to finish). The Bens also has a more gentle curvature between the rear glass and boot hatch and a generous radi around the D pillars, WAY better than a rear glass coming down to the horizontal plane of the trunk... There is that pocket of turbulent air still swirling away.
This doesn't mean i dont have decent airflow stock, but with the centralized antenna there's a locked vortex down the middle of the rear glass so there is no constant pressure for a chance reattachment that far out and that low

Basically, im filling in that void where the vortex is and reducing the curvature between the glass and trunk profile by raising the "trunk height"... so to speak.

[aerohead]

Originally Posted by Thenorm

i've always wondered about modern sedans. the rear glass transition always seems smooth enough. that I bet the air stays attached, even though its sub template and producing a low pressure zone (acting like an airfoil)

And as long as you have a horizontal or convex surface at the end to turn the air flow again and produce a high pressure zone, it might work better than a kamm back.

case in point is the new mercedes CLA which gets an absurdly low Cd and even the prius which is sub-template

So for your car, maybe all you have to do is extend the horizontal of the trunk out closer to template

*So far,the research has demonstrated that drag minimums are only found with the 'Kamm'-form,or wing section.
*Any geometric interruption along the 'ideal' pathway triggers boundary layer separation,which is exactly what streamlining seeks to eliminate.
*Yes,you can achieve reattachment,but you'll have turbulence,or vorticity,or both,and the kinetic energy of each of these can NEVER be recovered in the form of pressure recovery,leaving a situation of lower base pressure, higher pressure drag,and overall higher drag.
*The drag of Mercedes-Benz latest Cd 0.22 offering can still be cut in half.And it requires Kamm's full monty.
Here is Kamm's personal car of circa 1941,Cd 0.23

Here is a 'dirtier' model (the only surviving car) Cd 0.37 (with compromised belly pan

Here is the Kamm-form with full tail,with Cd 0.12,and less with wheel fairings (as with 2013 Cambridge University Eco Racer,Cd 0.10.

[RiderofBikes]

A sad sad day upon us, but alas, we must say goodbye to a great car and project. Hey accidents happen. The car performed great on its last voyage! My fiance who was driving to work in a very bad storm, hydroplaned on a sloping bend section of interstate that usually has a cascade of water. Long story short, just a little sore, and a couple minor bruises. Even as cautious as SHE is, Stay safe everyone!!




In light of this event, made me research the next car to get, even more than usual. The thing most if not all of us convey through the modifications of our vehicles is safety, first and foremost, and as much as we'd all like to strip some of our eco cars to the barebones, and those who choose to modify a chassis/suspension, or integrated safety equipment, please do so with caution! Especially if your not the only one who drives these vehicles, not everyone has the same mindsets as the person who's making those changes.. Mine were of cosmetic function, but all the same.. Thank you Everyone for the support and advice with his project, I'm pretty sure the next one will be just as fun and hope you guys will enjoy it too!!

[nemo]

Glad to here there was no one seriously injured.