Landracing Forum
Tech Information => Aerodynamics => Topic started by: xxobuick on August 15, 2014, 08:54:23 PM
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Ok, so on a vintage coupe, say you have lengthened the nose, put fairings over the suspension in a tear drop shape, wheel covers on the outsides and insides of the wheels, skirted all the way to the rear axle, full belly pan etc. The front tires are 23" front runners. Now, the front wheels and tires are still not covered as far as fairings go, is it worth it to go ahead and make tear drop shaped fairings to go over the wheels and tires? I see cars built both ways. This is on a Comp Coupe By the way. Since we have more time since speed week is delayed we are looking at ways to improve the aerodynamics as much as we can.
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The best improvement would be to get a smaller car.
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Yes, that would be the best improvement. Gotta work with what we got for now.
Here is some shots of what we got:
(http://i.imgur.com/3Jfffx3.jpg?1)
(http://i.imgur.com/JXOW2fg.jpg?1)
(http://i.imgur.com/eDGdnNB.jpg?1)
Car is up on stands right now, so sorta hard to see how low it is, but we have about 1" off of the ground.
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Build covers... run it with and without... bet with goes faster :cheers:
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Very nice metal work! Especially the nose.
Don
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Cool car XXO! I would definitely try to cover the front wheels with some sort of fairing. Looks like we're both running the same class. You have unlimited options from the cowl forward. I say you take full advantage of it! I would try to do something similar to the wheel fairings on the Mormon Meteor. That should help quite a bit and it'll look really good!
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You could get serious & put them inside the nose!
Sid.
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You could get serious & put them inside the nose!
Sid.
Exactly what I've been thinking but at this point a lot of work. Is there a reason why you didn't go with a narrower axle? With it and doing as Sid suggested you could have a lot better aero. Since the frontal area is the cars widest point you could still get the tires/wheels inside and still have a great nose like what you have built.
Your workmanship is great and I like the way you are sending a considerable amount of the air down the sides of the car vs. up and over it. You will still have plenty of downforce in the front and better aero.
(http://1fatgmc.com/car/Temp-1/XXOBUICK-2.jpg)
I can envision cutting what you have done down the middle from the cowl down past the scoop and moving it out and apart in the very front to cover wheels/tires on a narrowed axle. Then fill in the center of your pie cut with more metal and ending up with a little wider front but still rounded and still getting the air down the sides of the car.
Some work at this point or maybe in the future but I think you would have big gains by doing it.
(http://1fatgmc.com/car/Temp-1/XXOBUICK-1.jpg)
If you keep the axle fairings running them further back and keeping the taper top and bottom under 7 degrees would also help in that area,
Sum
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Thanks guys. We do not plan on cutting this car up, that's why the top is not chopped and the stock frame and axle is under the car. We mocked up some... uh... pods I guess you could call it, to completely cover the front wheels. Should be able to knock oneout in the next day or three. We'll be using knowledge gained from this car to build a radical chopped and stretched version soon.
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The reason we haven't went with a solid front axle and narrowed it is because we are still using this car as a dual purpose car, or triple, etc. We can go back to production in about two hours of bolting on the fenders, hood, running boards, etc. So this way we can go from PRO to GC to ALT to GCC, etc. We are planning on building another car as a single purpose Comp Coupe car for next year.
I really appreciate all your guys help and thoughts, and we will try and get as much of it done as we can before world finals/new speedweek in about a month!
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I know the Flatcad guys swap a lot more than body panels when they swap classes.
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Thanks guys. We do not plan on cutting this car up, that's why the top is not chopped and the stock frame and axle is under the car. We mocked up some... uh... pods I guess you could call it, to completely cover the front wheels. Should be able to knock oneout in the next day or three. We'll be using knowledge gained from this car to build a radical chopped and stretched version soon.
The reason we haven't went with a solid front axle and narrowed it is because we are still using this car as a dual purpose car, or triple, etc. We can go back to production in about two hours of bolting on the fenders, hood, running boards, etc. So this way we can go from PRO to GC to ALT to GCC, etc. We are planning on building another car as a single purpose Comp Coupe car for next year.
I really appreciate all your guys help and thoughts, and we will try and get as much of it done as we can before world finals/new speedweek in about a month!
That all makes sense and can't wait to see the next version :cheers: :cheers:
One additional thought and you probably have already thought about this.
I like the radiused opening on the scoop entrance and we made that change to the Stude this year but I'd also think about..
(http://1fatgmc.com/car/Temp-1/XXOBUICK-3.jpg)
... getting rid of the depression behind the lip and take the outer edge of the radius and tapering it back to the nose to help eliminate the turbulence (drag) that you will get with the lip as it is now since all of the air won't enter the opening. You could go from the outside of the lip back to the nose with a widening taper that would help to send the air not going into the scoop down the side of the car. I tried to show what I'm trying to describe in the photo above.
You guys are doing some fantastic metal work,
Sum
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Ok, we can take a tube and do that streamlining from the velocity stack going back to the body. Thanks for the advice.
The next thing we are considering is if it will be beneficial to make a big spoiler/air diversion that will get the air that is going to hit the windshield diverted so it doesn't get to the windshield. Obviously we would make it out of something clear, with a metal framework for support. So basically we would have a panel that is either in the shape of a v, and up-wards sloping that starts at the top of the nose, and goes back to the cowl. Or just have a spoiler that goes about 2-3 feet in front of the back of the hood to get that air started over the top of the car. The angle of the windshield is not terrible, but is definitely not optimum. It is a V windshield, so I would think that would help also.
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Covering the front tires will definitely help- so will a narrower from axle. We actually change from axles between altered and comp coupe- out comp coupe setup is 9" narrower.
Good luck!
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Ok, we can take a tube and do that streamlining from the velocity stack going back to the body. Thanks for the advice.
The next thing we are considering is if it will be beneficial to make a big spoiler/air diversion that will get the air that is going to hit the windshield diverted so it doesn't get to the windshield. Obviously we would make it out of something clear, with a metal framework for support. So basically we would have a panel that is either in the shape of a v, and up-wards sloping that starts at the top of the nose, and goes back to the cowl. Or just have a spoiler that goes about 2-3 feet in front of the back of the hood to get that air started over the top of the car. The angle of the windshield is not terrible, but is definitely not optimum. It is a V windshield, so I would think that would help also.
I think without wind tunnel time trying to improve the windshield deal would be a crap shoot. Anything you make might end up with a big turbulent area behind it if you didn't get it exactly right so that the air left it and ended up on top the roof. Also you might end up with rules infraction or tech might not like you looking through the windshield and whatever you are going to build. I'd leave that area alone for now and work on it with the next car.
In 2013 we were rushed with things but John was able...
(http://1fatgmc.com/car/14-Hooley/974%20scoop-1.jpg)
... to make us the scoop above in a hurry which was a big help to us. We didn't get a chance to try and go fast so it didn't hurt us but I wanted to get a radius opening on it and was able...
(http://1fatgmc.com/car/14-Hooley/974%20scoop-2.jpg)
... to get that done before SW this year and also tapered it out and up some to help a little with air flow past it,
Sum
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I have done quite a bit of testing of velocity stacks on our cylinder head flow bench and see lots of gain with the radiused velocity stacks. I am just not sure exactly how far to push the stack out in front of the nose. I guess the goal is to get the air before it gets directed around the body.
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A good feature on a fender is the ability to easily take it off to knock the salt out of it between runs and before you go home.
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Last night Dave and I talked about salt building up under our wheel covers. The piece that covers the tread area is not dissimilar from a motorbike fender. We are planning on including a brush or scraper of some sort, but how much clearance would you guys recommend we have over the tire? Would half an inch be sufficient? An inch? Two? Our basic idea is to add to the small fairings we've built around the suspension and axle, covering the wheels and fading back into a "tear drop" sort of shape. I'd post pics but but our cardboard mock up is ugly as sin...
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Heres what we came up with:
(http://i.imgur.com/1OToVTF.jpg)
(http://i.imgur.com/c6Qrypl.jpg)
(http://i.imgur.com/3Apy2He.jpg)
(http://i.imgur.com/DyyzmLU.jpg)
(http://i.imgur.com/mlJOTL9.jpg)
(http://i.imgur.com/BPAzyxx.jpg)
(http://i.imgur.com/6Vw17cM.jpg)
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Last night Dave and I talked about salt building up under our wheel covers. The piece that covers the tread area is not dissimilar from a motorbike fender. We are planning on including a brush or scraper of some sort, but how much clearance would you guys recommend we have over the tire? Would half an inch be sufficient? An inch? Two? Our basic idea is to add to the small fairings we've built around the suspension and axle, covering the wheels and fading back into a "tear drop" sort of shape. I'd post pics but but our cardboard mock up is ugly as sin...
The Danny boy streamliner has brushes on the tires, you might check with them.
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In 2013 we were rushed with things but John was able...
(http://1fatgmc.com/car/14-Hooley/974%20scoop-1.jpg)
... to make us the scoop above in a hurry which was a big help to us. We didn't get a chance to try and go fast so it didn't hurt us but I wanted to get a radius opening on it and was able...
(http://1fatgmc.com/car/14-Hooley/974%20scoop-2.jpg)
... to get that done before SW this year and also tapered it out and up some to help a little with air flow past it,
Sum
Quick question regarding air inlets......
Why have a tube sticking out creating drag as opposed to a more flush mount?
Is the car in these pics forced induction or N/A?
I have an idea for my turbo car for something like this: Some flush eliptical holes(not so hung up on the size.... that will create a bit of drag I know) going to a plenum that separates the heated post radiator air flow and engine compartment heat from the turbo air inlet.
(http://i742.photobucket.com/albums/xx66/ttviper1/IMG_5893_zps56e1e179.jpg) (http://s742.photobucket.com/user/ttviper1/media/IMG_5893_zps56e1e179.jpg.html)
(http://i742.photobucket.com/albums/xx66/ttviper1/IMG_5894_zpsd553757f.jpg) (http://s742.photobucket.com/user/ttviper1/media/IMG_5894_zpsd553757f.jpg.html)
(http://i742.photobucket.com/albums/xx66/ttviper1/4-Link%20GTS/Airbox7_zps1d836919.jpg) (http://s742.photobucket.com/user/ttviper1/media/4-Link%20GTS/Airbox7_zps1d836919.jpg.html)
The first 2 pics are from a different turbo setup than the last pic. I have a shorter radiator than the one pictured in the last picture whose bottom edge would be more like the depth of the furthest back part of the plenum in the last picture and the bottom of the elliptical holes in the first 2 pics.
My reason for doing this would be to have the coolest, most pressurized air feeding the turbos. I am thinking there would have to be a measurable augmentation to the compressor map at 200, 250-300 MPH.
Any ideas, suggestions, criticisms? Thanks!
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The air right on the nose will be turbulent & separating. Picking it up ahead of that will get you clean, consistant high velosity air & will also help to sharpen the aerodynamic shape of the front end.
Sid.
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The air right on the nose will be turbulent & separating. Picking it up ahead of that will get you clean, consistant high velosity air & will also help to sharpen the aerodynamic shape of the front end.
Sid.
I see.
Thank you for the advice!