Internal Body Aerodynamics

[vette427sbc]

i think all levels of aero are beneficial in this thread. I think it could turn into a great resource like 69427's weightloss thread. So with that in mind, minor to extreme aero mods are welcome!
I happen to have a (almost) blank canvas underneath my front clip for cooler placement and duct work compared to a stock framed car that is already together. I'm hoping to take advantage of this as much as I can to optimize airflow and maximize efficiency.
Thanks to everyone for their input!

 

[rtj]

They spent a small fortune on cfd and tunnel testing.

[ame]https://www.youtube.com/watch?v=GnNhhOzRcZ0&app=desktop[/ame]

 

[69427]

I was always impressed with this car’s aero work. Goes by 4takt.




If the rad was laid over a bit more, you might be able to dump it out both sides like the Ferrari.

From an engineering standpoint I like the idea of dumping the radiator air upwards (and not down underneath the car), but I'm always a bit uncomfortable when it looks like the placement of the radiator (with its internal coolant weight) and fan (weight) c/g gets located even further ahead of the front axle centerline than the stock location. I certainly understand, and accept, that compromises are always necessary when packaging things on our cars, but I'm always curious if there's a better way to position the radiator.

I'm currently looking around to find a slightly smaller radiator for my car (my Dewitts radiator works very well, and might even be overkill for my needs), that might allow me to run a bit less coolant volume (ie: weight), and also allow me to package it slightly more rearward and upright, moving its c/g a touch rearward.

Just my thoughts and possible plans for a future mod. YMMV

 

[mfain]

Okay, more aero stuff. On my 56 I built carbon fiber "tunnels" - actually long diffuser tunnels - between the frame rails and the outer rocker panel. They start with a rounded fender well close-out fairing which blends into the tunnel. (note, there are a couple of pieces not installed in these photos that blend the air from behind the tire to the tunnel) Note the teardrop shaped jack pad extending into the tunnel - overkill LOL. The belly of the car between the tunnels is a flat carbon fiber panel - again not installed in these construction shots. The last photo is a aero-tapered fairing where the wing mounts to the struts. The struts are also aero/wing shaped to minimize drag.

Pappy

 

[vette427sbc]

Pappy- more killer work! Are you vacuum bagging (I think that's what it's called?) your molded parts? They all look beautiful

I was traveling this weekend and hit a very open and straight section of highway... this had me thinking about how some real world smoke testing might be possible with a long wand held by your most trusted friend in a minimal turbulence "smoke car"... maybe a Prius or something with no downforce aero, but tons of efficiency aero in hopes that it won't totally disrupt the clean air around your own car.
...but first, to find a friend that drives a Prius!

 

[mfain]

Pappy- more killer work! Are you vacuum bagging (I think that's what it's called?) your molded parts? They all look beautiful

I was traveling this weekend and hit a very open and straight section of highway... this had me thinking about how some real world smoke testing might be possible with a long wand held by your most trusted friend in a minimal turbulence "smoke car"... maybe a Prius or something with no downforce aero, but tons of efficiency aero in hopes that it won't totally disrupt the clean air around your own car.
...but first, to find a friend that drives a Prius!

Friends don't let friends drive a Prius! I only vacuum bag the very complex parts. If I can roll the back side, I just treat it like fiberglass. It just takes a little care to eliminate the air bubbles as they will show in the finish. I do yarn tuft testing on an open trailer behind my P/U with the tail gate down. It works pretty good for anything above the wheel wells, but is a little sketchy below that. And it's only a 95 mph wind tunnel - LOL

Pappy

 

[rtj]

You can actually measure/calculate Cd with a coast down test from SAE. Just need a long flat road and do runs in both directions to average out wind and grade.

There are a few variations, I think this is the most straightforward.

coast down testing SAE J1263

Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques J1263_201003

They had always supplied a FORTRAN or Basic program for number crunching. Probably could convert it to excel.

 

[rtj]

Okay, more aero stuff. On my 56 I built carbon fiber "tunnels" - actually long diffuser tunnels - between the frame rails and the outer rocker panel. They start with a rounded fender well close-out fairing which blends into the tunnel.

Nice work. That’s going to be an interesting car.

 

[rtj]

[ame]https://www.youtube.com/watch?v=OY1_HRSzx8U[/ame]

 

[rtj]

[ame]https://www.youtube.com/watch?v=D2dJy6o2Qe0[/ame]

 

[phantomjock]

Blank Slate??

69427 --- Well, here are a couple of ideas to consider.

Split radiator core in two. One side left, one right. Side exit exhaust augmented with fans. Could cleverly "hide" with mesh - or louvers. Exit forward of the front wheels.

OK - enough introduction - time for pictures.

This car has MASSIVE Downforce. It was tested in a wind tunnel and the results are part of the sales pitch.


The point here is the interesting approach to cooling:


I am surprised not to see the engine bay "isolated" from the remainder of the internal flow...


The side exit (quite cleverly with a Gurney forward to spill over the wheel well)


There is (perhaps) sufficient "real estate" in the sides of the C3 nose - maybe with a Greenwood mod:


You might lose a few "points" on subtle - but gain in performance.

Break/Break.

Been typing and grabbing HDDs for pics - Great work here! Pappy nice work on the tunnels.

rtj: was that meant to be a link to a spreadsheet or something for the coast down testing. I have a text that well describes - have yet to get to a "strip" to run. Another great text is the SAE 950626 in PT-49, I gratefully "inherited" form another member here. I'll scan and post "one day." Instructables has a short tut on capturing data for a run-down test too. Takes 2.




Cheers - Jim

 

[rtj]

Jim

Interesting stuff.

I found some photos of a c3 with a horizontal rad, I’ll upload those later.

I’ll see if I can find the sae program. It should be available in excel.

 

[phantomjock]

Grass"roots" Aero-testing

Good work if you can find it:



A lot to see here - wheel well, louvers, and the "pod" action. Pods not do C3, but think of moving/directing flow:


Cheers - Jim

 

[rtj]

 

[phantomjock]

rtj - Nice find. That car has been for sale for a number of years. Wonder if it ever sold?

Here are a couple of laydown ideas from the Nissan Le Mans Prototype
here "unclothed" on a test run:



Here in the shop. Nice use of the real estate up front by using dual radiators too. Note the nice CF work (ala Pappy).


And, you can get too much downforce and grip at the front that may require some balance:


Impressive records with that 800-900 HP Camaro:

NASA STATS since January 2014

Starts 59
Wins 50
Podiums 58
Current win streak (since Oct 2014)
38 class wins
14 track records set or re-set​

Cheers - Jim

 

[rtj]

Looks like you’ve got a lot of info collected Jim.

This is in the Racing Vids thread.

[ame]https://www.youtube.com/watch?v=RSZRZldj9pw&app=desktop[/ame]

 

[phantomjock]

rtj --
I guess as you have been to collecting some great vids - I've been harvesting some build ideas - and mostly focused on "aero-mods" as I'm bent that way.

That is an awesome C4 mod.

Cheers - Jim

 

[rtj]

Way out there. They don’t mention all the bumps around the outer rim. Those have to be pumping air.

[ame]https://www.youtube.com/watch?v=FAeXfg5GoVI&app=desktop[/ame]

 

[vette427sbc]

Whats up with that C4 race car radiator?? It grabs air from the top and vents under (or elsewhere)?? to an aero-amateaur it seems counter productive.

More OEM aero tricks... Now that I know what Im looking at, Ive noticed most newer cars have at least one vortex generator on the side of each taillight. Very subtle. Im not sure how it could be implemented cleanly on a corvette though

 

[rtj]

Whats up with that C4 race car radiator?? It grabs air from the top and vents under (or elsewhere)?? to an aero-amateaur it seems counter productive.

I’m not sure which way it flows, but unless he’s got big pusher fans underneath I’m assuming it goes down. Laying the rad down gives him the body work he wants up front. If the air dam is low it would be low pressure underneath. Normally the flow goes under the engine, so this would be a wash (no change). But, probably cools fairly well.

I imagine he’s developing this without cfd, a wind tunnel, or a big budget.

Originally (before today) I had assumed it must flow up, but after re-watching the vid, I’m leaning to down.