Internal Body Aerodynamics

[rtj]

Lots of negative comments on this one. Kind of neat, but why? That thing that pops up must increase cd.

[ame]https://www.youtube.com/watch?v=fSQxN6rJ1qg&app=desktop[/ame]

 

[phantomjock]

Been meaning to follow up here - great video and interesting approach. And, surprisingly - it does fit into INTERNAL BODY AERODYNAMICS as well! There are a few interesting points in the video -- like wear a helmet/goggles as bugs, rocks, etc. Don't follow the "path". and the speed range was intersting. For those not wanting to check the video try this on:


By the way - incase you missed it, I offering one of my Hoerner texts at a special VM price link here: http://www.vettemod.com/forum/showthread.php?t=11674
it is a great bargain at the price for its condition --NEAR PRISTINE--and worth its weight in gold for its information regarding fluid dynamic drag!

Cheers - Jim

 

[rtj]

You get a good look at the rear diffuser, also the front and rear fender flares are chopped off on the back up to the wheel center height.


[ame]https://www.youtube.com/watch?v=mCElwtx05pU[/ame]

 

[vette427sbc]

Reinforcing some aero stuff Pappy pointed out earlier on his Viper regarding wheel well exit ducts... I have a McLaren 720s In the shop with some cool wheel well aero.
Two huge ducts on each corner of the bumper feed coolers, and then exit out the side of the bumper AND the wheel well towards the side of the car.






And a nice contoured exit duct behind the front wheel:





This car should be here for a few more days if anyone has any pic requests... its an engineering marvel. Ill be looking over the rest of the aero... this was the first thing that caught my eye

 

[phantomjock]

AWESOME!!!
Real LIVE Spy pics!
WOW - I hope you are not sorry to have asked:

1. What is going on inside the engine bay?
2. How about the radiator and splitter/diverging ducts you've shown us-- inside the hood?
3. Rear fenders - are the ducts venting from wheel well - or intakes to the well?
4. Rear (bumper area) exits - are they "fully open" to the rear wheel wells - or shaped ducts?

This guy has some smarts - but I think he dresses himself: https://youtu.be/SlQEXQMQ75Q

Thanks in advance - hope you get to try it out!

Cheers - Jim

 

[rtj]

Reinforcing some aero stuff Pappy pointed out earlier on his Viper regarding wheel well exit ducts... I have a McLaren 720s In the shop with some cool wheel well aero.
Two huge ducts on each corner of the bumper feed coolers, and then exit out the side of the bumper AND the wheel well towards the side of the car.

Now I see, the air exits in front of the tire and is directed outwards. Kind of like the F1 in some respects where they create that vortex.

The largest opening is below the orange marker light, right? It kind of blends in.

 

[vette427sbc]

Now I see, the air exits in front of the tire and is directed outwards. Kind of like the F1 in some respects where they create that vortex.

The largest opening is below the orange marker light, right? It kind of blends in.

Yes thats correct...
I had a bit of a crazy week at the shop during that cars visit so I didnt get to do much more investigating... But I have a few other interesting ones here this week that I snapped some more pictures of.

Please excuse the poor picture quality... my iphone has seen better days :crap:

The F430 has very similar front ductwork to the mclaren. A bumper exit, and a wheel well exit, towards the outside. I also find it interesting that some portion of the wheel well vent on both the mclaren and ferrari direct air DOWN.



This is kind of odd though... the center duct has no purpose for coolers. But instead it necks down to almost 1/3 the size of the opening and goes under the car. Maybe an attempt to speed up airflow under the car? Or possibly a case of form>function


This is looking towards the front of the car showing the bumper duct to the belly pan


It also has a vent in the rear of the rear wheel well. The vents are directional based on front/rear of the wheel. This vents to a large opening in the rear bumper.



On the ford GT, there is NO wheel well venting, front or rear. The only heat exchanger is the radiator, and that vents from the hood. Vent opening in the bumper is 28"x5" (140in^2) and the exit is two 13"x9" openings (234in^2 combined)



The only other interesting aero on the GT is a small wicker on the rear, and a pretty functional looking rear diffusor (Ill grab pics of that later) Otherwise its pretty mundane (aero-wise!) This is a Heffner Twin turbo car. I bet its anything but mundane to drive!

 

[rtj]

Interesting on the downward jets at the front. VTOL jets in hover with forward motion might be analogous. Basically the downward jets impacting the ground roll up and force the on-coming air to divert around. Of course the speed ratio is way higher for hover. (Jet speed over forward speed). I’ll see if I can find a pic.

Congrats on getting such cool cars in your shop.

 

[BBShark]

Wow! You get a "hands on" look at the best of the best.

 

[rtj]

Took a bit to find the search term, but this works: jet ground plane in cross flow.

 

[vette427sbc]

Thanks, guys! Working on, disassembling and modifying these types of cars has really helped with the design and engineering of my Vette and other classics cars/ hot rods that we build here. It’s a great learning experience and keeps us up to date with new materials, techniques, etc...

The jet ground plane is interesting. I wonder if that phenomenon is the intention of those downward vents? They aren’t just on these performance cars, I’ve noticed them on a lot of other cars in here too.

Another trend I’ve noticed is that only Toyota/Lexus takes advantage of vortex generators. They are all over their cars. Multiple on the taillights, and very often on the side view mirrors (to prevent wind buffeting with the window open I assume). Haven’t noticed them on Tesla’s or other hyper mileage type cars...

 

[phantomjock]

Took a bit to find the search term, but this works: jet ground plane in cross flow.

Very Interesting - and I'd bet that image is for a "Hover" jet? Any link for a jet that has forward motion? I recall from designing a hovercraft (Uni-days) that the tough problem we faced was sustaining the jet underneath while moving at speed. To keep the air bubble underneath the hovercraft (including skirts et al) we needed to have a lot of air to support at speed - more than at rest.

Clearly what we'd want here is to provide is negative lift under the chassis - to make downforce and this might be a way move the air out from underneath. The pics Chris shared show some interesting ways to do that. Thanks!

This seems to be an area to work with out a lot of external "stuff" - splitters skirts, wings, etc. (but they look so cool).

Cheers - Jim

 

[rtj]

It is for jet in hover with crossflow. You can see they drew the crossflow velocity with the boundary layer type profile ( zero at the ground). Not exactly the same as the car, but analogous. Also, velocity ratio for the car will probably be closer to 1.

But, they made them (extra cost) so there must be a benefit, like forcing air to go around the tire. Just guessing.

 

[COLE SWEAT]

Make new rocker moldings out of thin aluminum which are 1 to 2 inches longer. This will act as side skirts keeping flow out from underneath. Lower is always better for side skirts.

Creative use of black paint could disguise how low they are.

Also, the spare tire area is a mess, a diffuser would be too obvious for your goal, at least a smooth under belly would help.

We're on similar wavelengths here. Several years ago I pulled the stock rocker panels off and made 2" lower/wider replacements with Lexan sheet, and painted them semi-gloss black. I like the looks better, and so far no one has seemed to notice the change.

I had an aluminum bellypan on the car for a year or two, but my unscientific perception of the setup convinced me that the weight (about 30#) was hurting me more than any actual aero improvement was helping.

I've also looked into doing something at the rear, but so far I can't justify the weight of a diffuser. My current direction is to reduce the slight understeer I have, and ignore the rear until it becomes the limiting factor during cornering.

Are you running a rear sway bar?

 

[69427]

Make new rocker moldings out of thin aluminum which are 1 to 2 inches longer. This will act as side skirts keeping flow out from underneath. Lower is always better for side skirts.

Creative use of black paint could disguise how low they are.

Also, the spare tire area is a mess, a diffuser would be too obvious for your goal, at least a smooth under belly would help.

We're on similar wavelengths here. Several years ago I pulled the stock rocker panels off and made 2" lower/wider replacements with Lexan sheet, and painted them semi-gloss black. I like the looks better, and so far no one has seemed to notice the change.

I had an aluminum bellypan on the car for a year or two, but my unscientific perception of the setup convinced me that the weight (about 30#) was hurting me more than any actual aero improvement was helping.

I've also looked into doing something at the rear, but so far I can't justify the weight of a diffuser. My current direction is to reduce the slight understeer I have, and ignore the rear until it becomes the limiting factor during cornering.

Are you running a rear sway bar?

No. I'm running the '84 Z51 rear spring, so I've got plenty of rear roll stiffness. I've been focusing my efforts at changing the front suspension geometry to improve the front grip.

 

[rtj]

6 yrs old.

[ame]https://www.youtube.com/watch?v=J7Yb_6wW0uk&t=35s[/ame]

 

[rtj]

[ame]https://www.youtube.com/watch?v=s8dp9m6c_ro[/ame]

 

[COLE SWEAT]

RTJ
This has nothing to do with what your talking about, but
Have you put the body back on your chassis? I did the trailing arm adjusters that eliminates the shims and now the that it’s done I’m wondering if the body is going to fit?
Do you know if it does?

 

[rtj]

RTJ
This has nothing to do with what your talking about, but
Have you put the body back on your chassis? I did the trailing arm adjusters that eliminates the shims and now the that it’s done I’m wondering if the body is going to fit?
Do you know if it does?

Should fit. I did the original frame with the body on. The second frame, got sold. I retired early, then decided to go back to work. I sold some stuff preparing to move (the frame) and then stayed here. The frame I had bugged me a bit, because it really wasn’t good enough to spend a lot of hours on. So selling it was maybe a good thing. Start with a better one if I try again.

Start a thread on your upgrade. I’m interested to see.

Edit: the only interference is taking the bolts out or putting them in, I cut the fender flares.

 

[rtj]

Another big dollar super (hyper?) car, but I’ve never seen the canards (vortex generators on steroids) before. He says they give big drop in drag.

[ame]https://www.youtube.com/watch?v=gkmjOR55DwU[/ame]