Landracing Forum
Tech Information => Technical Discussion => Topic started by: Genuine GM on February 25, 2010, 08:46:51 PM
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I have an idea that might not be legal at B-ville, but that is not what I am curious about. I know many on here know more about airflow than I do, and I need that experience to see if this might work.
If a person was to "collect" under hood pressurized air, directed it through two 4 or 5 inch ducts (one down each frame rail), run the ducts up into the trunk (or enclosed pickup bed) and then duct them out the rear of the vehicle towards the upper 75% of the rear vehicle height.
My thinking is that this would serve three purposes:
1.) help increase under hood airflow (air through radiator);
2.) reduce the under pressure from exiting under the vehicle (lift);
3.) and the air flowing out the rear would alter and lengthen the slip stream over the vehicle reducing drag at speed.
Any thoughts? Would this even be worth the effort. I am thinking drag reduction for both increased speed and better mileage. :cheers:
C. J. Daniel
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MY unprofessional--east tex aggie NON engineer guess is that airdrag is airdrag no matter where its inside or outside
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Great thinking.....
not legal for most classes.
4.A
~JH
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Just for future reference, its called by-pass air. (not sure if its legal in racing or not.) The P-51 mustang had an opening under its nose nacelle that allowed fluid to bypass the airframe. This added to the trust of the aircraft and thus was a contributing factor to its speed. Later down the road, turbo fan's came equipped with a similar nacelle around the turbine to allow this bypass air to mix with the exhaust fumes creating high thrust levels. Theres a lot that goes into this concept, hence why people get paid big bucks to come up with this stuff.
Not sure if it helps (probably doesn't) but your on the right track about fluid flow.
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I think there was a eng cooling radiator in your P 51 "bypass" that added tremendously to the volume hence the pressure increase which created thrust
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Regretably the P-51 "thrust from cooling scoop" is a myth. It was nicknamed "Merideth thrust" after one of the North American Aviation engineers. It turns out that a different engineer designed the cooling scoop, Merideth was the first to point out that their was a marginal amount of thrust recovery from the outlet partially offsetting the cooling drag at high altitude.
As to the ducting question, without adding power to the internal flow with a fan or exhaust ejecta, the drag from the internal flow will be more than just having everything go around the car. It may be remotely possible to take some of the internal air and reduce some aft separation with it, but the only classes that would allow this are streamliners and lakesters and their are far better aero solutions for those.
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Correct me if I'm wrong, but did not the underbelly scoop add additional LIFT to the Mustang?
Was under the impression that the airplane's configuration, turned upside down, of course, influenced Colin Chapman to design the nearly all-conquering Lotus 75's side pods.
Downforce, not thrust, the result.
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Blue, or others ??
I am not sure if you have seen the air outlet holes behind the back glass on many LSR Studebakers ?
I was told that 3 or 4 air duct tubes 2.5 " to 3" diameter from under the car in the third member area,, ducting air to exit the tubes on the deck between the back glass and the trunk would let under car air exit and reduce Lift,, thereby helping keep more downforce on the rear and the wheels on the ground ?
Any Ideas ? I have yet to do this to my Stude and I am only a few weeks from painting,, so it would be nice to know if it helps and is legal for Classic Gas Altered ?
Charles
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Yes, it is legal in your class and proably a good idea in a sStude coupe if you want to keep the front windshield in place.
DW
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Kid. At one time they were mandatory on Studebakers. If you didn't have them you spun at 185 almost a guarentee. With the ability to place all the "areodynamic drag junk" on the trunks guys have quit using them. Fast roadsters of the 50-60's all had them too.
Neil Thompson's Studie Comp Coupe went 300 with the tail lights removed, air ducts and no junk on the trunk.
I like the stock look and you can go plenty fast with air ducts...........Good Luck
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Thanks Guys,,,
I have Junk on the Trunk,, kinda sorta like Hooley's Orange Stude,,, but I guess I shall fab in those ducts to let the air out that gathers above the third member... I thought with the side spill plates and rear spolier , I would be Ok,,, but the ducts sound like they can only help more and not hurt..
Charles
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Blue,
I agree about having all the air go around if possible, but in my scenerio, I am not concerned with B-Ville rules and the vehicle will have a grill, and radiator opening and a radiator. No LSR car with a water tank and sealed nose.
I am talking about a vehicle (street driven, not just legal) that will be ran at the Texas Mile and the USFRA 130 or 150 MPH club, after being driven there.
I am talking about a truck, not an aerodynamic sports car. I know that air gets pressurized under the hood IF there is no place for it to go. Unfortunately, most of the time the best place for it to escape it around the engine and out the bottom.
I do know that Smokey Yunick did extensive testing with airflow ducting 50's, 60's and 70's with slab nosed Chevys. He proved mph would go up by releasing the underhood air, but the actual methodology he used is rather vague and from what I can tell, something he took to the grave. I have most of his books and while he talks alot about it, he elaborates on his methods little. I am sure that was to keep a competitive edge. In one example he gives, in many different books, he was sitting on the floor of a 55-57 Chevy and they where doing 120 mph, he unscrewed the heater block off plate from the firewall and the air flow blew him back, while the car gained 20 mph.
I posted it here, because frankly, when it comes to airflow, the members on most automotive bulletin boards are lost in the woods. I know more than most of them just from my helicopter maintenance background.
Perhaps the best thing for me to do is rig up a manifold with various ports on the firewall, tie it all to a psi gauge and drive at various speeds. Then I can extrapolate some sort of data.
If you check my site listed in my sig, you will see the truck I am modifying to be a rolling test bed of ideas, while we gather parts for the V4F/MGR
C. J. Daniel
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dw-
Would the air vents be legal on a Stude Gas Coupe?
Will6er
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Does someone have the exact wording and underlying argument behind "this isn't legal"?
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Blue, or others ??
I am not sure if you have seen the air outlet holes behind the back glass on many LSR Studebakers ?
I was told that 3 or 4 air duct tubes 2.5 " to 3" diameter from under the car in the third member area,, ducting air to exit the tubes on the deck between the back glass and the trunk would let under car air exit and reduce Lift,, thereby helping keep more downforce on the rear and the wheels on the ground ?
Any Ideas ? I have yet to do this to my Stude and I am only a few weeks from painting,, so it would be nice to know if it helps and is legal for Classic Gas Altered ?
Charles
We have the holes underneath the rear window on Hooley's Studebaker but they are not connected to anything. We made them as we were told they needed to be there. Some said that they needed to be connected to the bellypan and others said to the drivers compartment. Later we were told that we did not have enough holes, that we had to many holes, or that we should cover them as they did not do anything. We finally decided that they must not be needed as no one actually knew what they were for and Hooley has went 250 mph without them connected. Seemed like a good idea at the time.
You get lots of good advise at Bonneville. Some advise is better than others. The most valuable advise comes from people who have had good experiences in your class, and with your body style.
John
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I am very interested in this as well...
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John / WZ
Thanks for your input,,, I went straight to Hooley and got his templates for my rear spolier..
If it works for him at 250... it should be at least Ok for me at 220... I never asked him about the veny/duct holes..
I assume they are needed more for Studes with not rear spoilers/spill plates ??
I assume that me adding them sure can't hurt ?? I am at a point now that I need to decide yes or no,,, ??
Thanks again
Charles
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The thing to keep in mind with advice like this is.......
am I doing the samething as the guy who is giving the advice?
In the case of two fast Studebaker's mentioned they both had CHOPPED TOPS!
Might this make a difference when needing air ducts?
Also keep in mind ducts were used before rear spoilers were legal as Studes never came with a spoiler stock.
And.... well you get my point. Do your home work.
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I think that if it were my decision to make, I'd put 'em in, but make provisions to easily block them off. Then, test it both ways, and maybe even with a couple blocked off and a couple not.
Mike
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I think that if it were my decision to make, I'd put 'em in, but make provisions to easily block them off. Then, test it both ways, and maybe even with a couple blocked off and a couple not.
Mike
This is a good thought.
John
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Yup - tunnel stuff, Charles. Always good to have options. vic
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There's always duct tape and cardboard if they don't work. :-D :-D :-D
Pete
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Thanks All,,
Based upon the point I am at in the build, it seems to me that the best option would be to go ahead and fab in 4 ducts as we have been discussing. Then make flush block off plates. That way I have the option to use them or not.
Then see how it works out in the tunnel.
Vic,,, I may need your help on tunnel day !!!!
Charles
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Will6er,
"Would the air vents be legal on a Stude Gas Coupe?"
Yes, 2010 rulebook, page 67, paragraph 5.
You can use 4.A Air ducts but not 4.C Air Vent, page 38.
DW
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Any questions concerning the ducts can be asked of Bruce Giesler. I know his #219 "stock bodied" Studie has the ducts and has run in Gas Coupe, and Altered and set numerous records over 200; the same for Terry Hunts. Like I said they were mandatory before you could put all the "junk on the trunk".....Good Luck
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Gary Hart's Studebaker has ran close to 250 MPH and I do not think he has the holes. You might contact him for his thoughts.
John
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Gary does have a junky trunk though. As JD mentioned, the holes seemed to disappear after the spoilers were allowed.
DW
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DW230,
For my Stude running CGALT can I remove the drip rail ? I know if I do, I can not run CG and am forever in ALT..just need to know if removing drip rail is allowed ?
Charles
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The Pino Ceccatto and Buddy Jones altered class stude went 201+ in 1974 with a Boss 302 Ford. I just talked to Bud tonight and he said they had the vent holes and big azs water tank in the trunk.
JL222
P.S. Bruce Giesler knows the car well 8-)
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Yes you can.
Page 66, paragraph at top of page, last sentence:
"Drip rails may be removed."
Hard to miss,
DW
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DW,, thanks I saw that but was told it applied to Modified not Altered...
Drip Rails that is,,,
Charles
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Charles-
I've been told that it seems like the drip rails hold the roof together. When they are removed, the roof comes apart. Plan ahead.
Will6er
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will,
Charles-
I've been told that it seems like the drip rails hold the roof together. When they are removed, the roof comes apart. Plan ahead.
Will6er
Yes,, the roof will fall apart if you remove the drip rails,,, but if you remove the rails and weld the seam created it is very strong,, grind the welds and do the body and paint work and it looks as smoooth as a babies bottom,,
ADD A SATIN BLACK PAINT JOB AND THEN YOU have a car with my name on it :cheers: :evil: :cheers:
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Charles, Looks like you are having too much fun! :cheers: Cant wait to see your car on the salt!!!
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Charles, Looks like you are having too much fun! :cheers: Cant wait to see your car on the salt!!!
Yes,, it's fun building a car and sharring that build with all you here on LandRacing.com
even with the problems, the time and cost,, it is still fun,,, getting done and driving her will be even better !!!
Charles
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Charles,
This sentence: "Cars in this class are considered in the Modified Category and should comply with the General Rules of the category." in the Classic Category, Altered Class refers the builder to the Modified Category, Altered Class.
The rulebook is constructed in this manner in an effort to reduce the number of pages and duplicate wording. The class structure is in a format where there are major categories, each category is broken into distinctive classes.
DW
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DW,,,, thanks.... I got it now,,,
Charles