Landracing Forum
Tech Information => Aerodynamics => Topic started by: Dynoroom on May 27, 2011, 11:49:35 AM
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Lots of aerodynamic information can be gleemed from many sources including books, magazines, internet, personal testing, ink or oil drops on your vehicle or even visual notes from others.
But my question; is there a formula to determine the L/D (lift/drag) ratio of ground effects tunnels? I have found some data from the IMSA GTP cars run in the 1980's that allow as to how much down force & drag they had with different setups but no details on the tunnels used to generate them.
My Arssumption is the tunnel cone should not exceed the 7 degree rule, and may want to be much less than that. But for a given length, height, & diameter can we somehow determine it's L/D ratio?
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Mr. Dynoroom, I have spent over 2 years researching just that subject, and have found that those people that know really don't want to tell very much of what they know. I worked with some very sharp airplane aero people for a while, and we did figure a way to make some of their computer programs work to come up with some usefull info for tunnel design. Contact me, or see me at the lakebed in june, and we can talk.
ED :cheers:
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Great new section to the board!
I am interested in this question as well. It came up in another thread and the JCB Diesel liner was used as an example. They use tunnels on that car.
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Michael, I was able to catch my buddy Steve (one of the suspects on the roadster) before he left for LeMans today. He was one of the designers for Reynard and Spice IMSA cars and has done lots of tunnels, and in his words. "There is no formula for L/D on tunnels, but 7:1 to 10:1 was often quoted for tunnels and 3:1 for (good) wings and spoilers. That 7 degree figure was also tossed around generally, but I don't really know how much is based on fact.
The IMSA cars always ran as much tunnel as the rules allowed and the different aero setups (high downforce/medium/low downforce) were done mostly by topside stuff- which usually pulled additional air thru the tunnels to varying degrees- and variations of inserts in the nose underside. Plus fender "S" flaps, side splitters, and wheel arch exit treatments on the car sides. The rear wing moved fore/aft and sometimes lower in various setups and the front fender louvers could vary in opening or be flush/proud, or blank. You see a lot of radiator exit wickers in photos of cars in high downforce trim, but that wasn't about downforce (usually it hurt downforce and increased drag). That was because the HDF courses were slower speed and the cars struggled to keep coolant and oil temps down".
I remember Trevor Harris mentioning something along the same lines long time ago at a IMSA race when we were struggling with our aero setup. Last year at Speed Week we went around looking at most of the tunnels on cars and did notice that many of them were not correct (mainly to steep of an exit). Tony
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Points noted Tony, knew you would chime in here. Thanks. Trent
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Mike,
I have copies of two technical reports,
1. Airflow Beneath an Automobile, SAE Technical paper 741028 by Buckley and Laitone.
2. Performance and Design of Straight, Two Dimensional Diffusers, from the March 1967 Transactions of the ASME by Reneau, Johnston and Kline.
The first is 7 pages, it is interesting to note that one of the sponsors was Collin Chapman's Group Lotus Car Co. The second is 9 pages. Both are sprinkled with formulas alas none of which calculate drag. I copied them both from the Lockheed technical library back when I was contributing to the GNP.
Back in the 80's, with the aid of an engineer from the good old lazy L, I designed and fabricated skirts for our modified roadster which effectively converted our flat belly pan into a ground effects tunnel (diffuser). We already had rake, going from 3" ground clearance at the firewall to 9" at the rear. The short story is that it worked great, we pulled all of the weight out of the car (500+ lbs.) and traction was seemingly unaffected.
Wait for it!
However if the car pivoted even slightly because of wet salt or wind gusts the flow stalled and the car spun instantly.
We went back to ballast.
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Mike,
I can highly recommend a book by Simon McBeath called "Competition Car Aerodynamics". Chapter 6 of this books delves into ground affects technology and provides some very good theory backed up with some very illustrative CFD prints that show what is going on in a ground affects configuration. I am sure you can buy the book from Amazon or from the Automotive Book Store in Burbank.
The basic "ground affects" configuration is and inlet section, a throat section and a diffuser section. The majority of the down force is generated in the throat section as it is the area , if designed properly, that the air is at maximum velocity and therefore at the lowest pressure. The diffuser is typically a flat plane that is parallel to the ground. The function of the diffuser or "tunnel" is to reduce the velocity of the air coming from the throat section to the velocity of the surrounding air which minimizes aero drag. The amount of down force generated in the diffuser is small compared to the amount generated by the throat section. The angle of the diffuser should be such that the air flowing thru it does not separate or stall. On a typical road racing car, F1, Indy or sport car the length of the diffuser is dictated by the ruling body and therefore teams try to have the highest diffuser angle that they can to maximize its effectiveness where as on a Bonneville car you can let the diffuser hang out the back of the car which would allow you to run a lower diffuser angle to insure its proper function.
Rex
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These are some diffusers from LMP cars. They are both very similar, but if you look closely you can see the subtle differences.Tony
Audi A10 Diffuser
(http://i273.photobucket.com/albums/jj236/maguromic/AudieA10Diffuser.jpg)
Penske Porsche Spider LMP
(http://i273.photobucket.com/albums/jj236/maguromic/PorscheSpyderDiffuser.jpg)
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:-oTony Ride hight or transport hight :?
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Sparky, The Audi on top is in race trim, the one on the bottom is transport height. Lets throw another log on the fire with some coupe and F1 diffusers. This web site http://www.gurneyflap.com/ has lots of good pictures of diffusers and aero stuff from all sorts of race cars. Tony
F1 diffuser from the gurnyflap web site.
(http://i273.photobucket.com/albums/jj236/maguromic/F1diffuser.jpg)
Corvettes at LeMans
(http://i273.photobucket.com/albums/jj236/maguromic/corvette_Lemans.jpg)
(http://i273.photobucket.com/albums/jj236/maguromic/corvette_lemans_2.jpg)
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Mike,
I can highly recommend a book by Simon McBeath called "Competition Car Aerodynamics". Chapter 6 of this books delves into ground affects technology and provides some very good theory backed up with some very illustrative CFD prints that show what is going on in a ground affects configuration. I am sure you can buy the book from Amazon or from the Automotive Book Store in Burbank.
The basic "ground affects" configuration is and inlet section, a throat section and a diffuser section. The majority of the down force is generated in the throat section as it is the area , if designed properly, that the air is at maximum velocity and therefore at the lowest pressure. The diffuser is typically a flat plane that is parallel to the ground. The function of the diffuser or "tunnel" is to reduce the velocity of the air coming from the throat section to the velocity of the surrounding air which minimizes aero drag. The amount of down force generated in the diffuser is small compared to the amount generated by the throat section. The angle of the diffuser should be such that the air flowing thru it does not separate or stall. On a typical road racing car, F1, Indy or sport car the length of the diffuser is dictated by the ruling body and therefore teams try to have the highest diffuser angle that they can to maximize its effectiveness where as on a Bonneville car you can let the diffuser hang out the back of the car which would allow you to run a lower diffuser angle to insure its proper function.
Rex
Great primer Rex! Also check out Carrol Smith's "Engineer to Win" - Chapter Sixteen!
7° is the magic angle for no separation. The steeper angles can be driven efficiently by the position of the rear wing or exhaust. Aero has lots of interactions so use every tool you can to help to understand it. If it was easy all the rocket scientists would be doing it! :-D
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I would love to hear about exhaust!!
ps
Is the exhaust used to speed it up?
help it redirect?
or make it less dense
Or all of the above?
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The fact that you saylift to drag ratio should cause you to stop and think....
We have a very long straight away...any drag will slow you down!!!!!!!!!!
computer simulation shows that until you are running 350 mph...lead is better every time!!!
LEAD = "DRAGLESS DOWN FORCE"
Akk
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Note the above author's credentials.
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rolling reistance is also a form of drag :-P
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Yes rolling resistance exists and at speed is small compared to aero drag.
My earlier comments about lead are not meant to belittle underbody design! My point is that there are better ways to get down force at Bonneville. Properly shaping the underbody can result in significant drag reduction!!!!! Don't waste drag reduction trying to get down force....below 350 mph...
Akk
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I could not agree more with AKK's comments regarding using aerodynamics for down force on a Bonneville car. All methods of aero down force have a lift/drag ratio, even under body tunnels and both the down force and the drag increase as the square of the speed, which means the horse power to over come the drag increases at the cube of the speed, so even what may appear to be a small amount of drag can become considerably larger with only a small increase in speed. We have discussed before the possibility of controlling a wing angle such that it produces a set amount of down force at any speed which would also control the drag but I have not seen anyone try it.
Rex
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The fact that you saylift to drag ratio should cause you to stop and think....
We have a very long straight away...any drag will slow you down!!!!!!!!!!
computer simulation shows that until you are running 350 mph...lead is better every time!!!
LEAD = "DRAGLESS DOWN FORCE"
Akk
Akk, how much do your cars weigh?
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The 23T 920/928 with lead rack full...2928 lbs. rear and 1358 lbs. front....total weight 4286 lbs.
with lead rack empty 2182 lbs. rear and 1350 lbs. front... total 3532 lbs....(note the car is built with a lot of steel and has 800 lbs. of lead built into the floor)
One year running B/GMR on the long track with good salt coefficient of friction=0.6, with a full lead rack was 3 mph slower than with empty lead rack!
We have learned the hard way that too light in the rear causes spins! Our discipline is to add weight if the tires spin in second gear...if we cannot spin the tires in first gear we remove weight....
The logic is ....second gear is about 1.5 to 1ratio... thus in high gear with 1 to 1 ratio we have a 50% traction safety factor!!!!!!
The 23T has no up or down aerodynamic force, it is neutral..ie zero lift to drag ratio... no induced drag
Akk
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Thanks for the info Akk! :cheers:
Your cars are VERY impressive! Have either one been in the wind tunnel? If so what kind of drag are you seeing, if any? Thanks again for the info, and I agree that weight is better than a wing at Bonneville but what do you do when there aren't any more places to put weight? Do you think that ground effects are the way to go? Wing? Fin?
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If it spins the tires, add weight, if it doesn't add nitro!
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If it spins the tires, add weight, if it doesn't add nitro!
LOL! :cheers:
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In the word's of the late, great Randy "Macho Man" Savage: Ooooooooooooooooooh yeah!
Tip the can............. then tip a Beer............. :cheers:
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I am trying to pull this thread back to aerodynamics....
Carroll Smith has written some good books about building race cars...he is a straight shooter as he admits that his earlier books were not right on ground effects...however he has some good points...the nose of the car should have the same ground clearance as the body at the rear...the middle can be closer and form a venturi in the middle...the high velocity can create down force with minimal drag...our car has never been in a wind tunnel...
Akk
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More than half the HP is inertial - you still have to accelerate the lead! :-o You don't have to accelerate down force! :-)
You have to push hard against both but there is a balance or sweet spot in all things! :cheers:
Still easier to find than the G-spot though! :-D
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When you are entering the 5th mile and you are looking for that last 200 rpm on the tach, the last 4 or 5 mph, it ain't inertia and acceleration that you are fighting it's aero drag.
Rex
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Put a wing on it and you will never get a chance to find that last few mph's! You will have downforce and be running 20 mph slower......
Akk
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Akk,
why no rake :?
with a round shape on the bottom how would you determine the ground clearance
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In the middle ...where the oil pan and transmission hang down...ground clearance is about 2.5 inches....nose about 8 1/2 inches...back bottom of turtle deck about 11 inches...the small rake is to prevent the flat part of the bottom from ever being higher in the front than in the back...suspension travel +_ 1 inch ie.9.5 front 10 rear...
The goal was to have the whole car neutral...the suspension allows ride height/spring rate verification of up or down forces....the car is aero neutral...but you can see torque lift of the nose and rear squat...about 1/4 inch...
Akk
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Question rephrase Have you ever read how much clearance a cylinder needs agl :?
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Sparky,
According to Katz, "Race Car Aerodynamics" for a car with a shape similar to yours, a long round tube with an aero nose and tail, minimum ground clearance should be in the range of .03-.05 of the length of your straight section, so if your car's section between the nose and the tail is 100 inches long the minimum clearance should be 3-5 inches. What is happening is that the air traveling along the body to the rear of the car is probably turbulent and this causes a pretty dramatic increase in the thickness of the boundary layer and if the boundary layer begins to contact with the ground it will cause separation of the boundary layer from the body and this will generate trailing vortices's which expand and therefore cause more of the attached boundary layer to separate and greatly increase drag. Low looks great but it is slower.
Rex
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I really have enjoyed reading this thread, as downforce has been on my radar relating to my streamlined sidecar. My outfit was designed with the use of a model in a wind tunnel in Christchurch N.Z. Due to the rough and uneven road selected for the record attempt there, a fair amount of downforce was built into the fiberglass body via an under body tunnel and an inverted wing form on the outrigger platform.
I got some good still pictures at last years BUB, (thanks Scooter!), of the outfit at 180mph. The pictures show an amount of squat on the rear wheel that I would like to reduce. Question one, Is it Aero or is it Mechanical?? how can I separate the two? Question two, would filling in the tunnel of the undertray be dangerous to the balance of the outfit?
I wish I was smarter :-D, but then I might not be having this much fun!
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Sparky,
According to Katz, "Race Car Aerodynamics" for a car with a shape similar to yours, a long round tube with an aero nose and tail, minimum ground clearance should be in the range of .03-.05 of the length of your straight section, so if your car's section between the nose and the tail is 100 inches long the minimum clearance should be 3-5 inches. What is happening is that the air traveling along the body to the rear of the car is probably turbulent and this causes a pretty dramatic increase in the thickness of the boundary layer and if the boundary layer begins to contact with the ground it will cause separation of the boundary layer from the body and this will generate trailing vortices's which expand and therefore cause more of the attached boundary layer to separate and greatly increase drag. Low looks great but it is slower.
Rex
Whats Katz say about flat bottoms Rex? In the same context as Sparkys round lakester.
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Tman,
Per Katz a flat bottom car should follow the same h/l, ride height over length, ratio of .03 to .05 mim. ride height. When you go lower drag increases, again per Katz. Jack Costella doesn't happen to believe this as is shown by ever time one of his cars sets a new record.
Rex
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Years ago when truck manufactures began to design toward better aero their mantra was to move the air only "once".
A lot of "stuff" that was experimental then --you are begining to see running up and down the higway every day now!!
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Tman,
Per Katz a flat bottom car should follow the same h/l, ride height over length, ratio of .03 to .05 mim. ride height. When you go lower drag increases, again per Katz. Jack Costella doesn't happen to believe this as is shown by ever time one of his cars sets a new record.
Rex
Be careful when you say lower is more drag. In some cases yes, but not always. Some cars like to be really low and others have a sweet spot that get better lower but there is a point that they might go too low and gain drag after a certain height. In some ride height studies you can get more downforce and lower drag with the right attitude and configuration. Reading some of the posts it seems a lot believe that downforce = drag and that is not always the case. And some think that Katz book is general enough to apply to every type of vehicle, but I would be careful what you assume. You know what they say about assuming? Makes and ASS-U-M-E (makes an ass of you and me)
You have to know what the goal is for your type vehicle, class, top speed, and where your car is to start off. I agree that landspeed racers should not use a wing or even ground effects (in most applications) at Bonneville. The only time I would recommend a wing (high downforce config) is in a 1 - 1.5 mile like Maxton, TX, Loring when there is high HP and you need to get it to the ground in a hurry because you need the acceleration. Fact is that with the variety of vehicles in LS racing there is no right answer to a lot of questions. Some things might work well on one type of vehicle and not others.
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care to comment on round bottom vs. flat bottom :?
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I wonder how Fast Freddy's 386 mph lakester could go without the wing?
Somethings wrong here :evil:
JL222
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care to comment on round bottom vs. flat bottom :?
I prefer round bottoms. :-D :-D :-D Tony
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Thanks, Tony -- you saved me from having to say that. . . :-D
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I wonder how Fast Freddy's 386 mph lakester could go without the wing?
Somethings wrong here :evil:
JL222
You are comparing apples to oranges. Freddies car is not mortal. :cheers: Wayno
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More than half the HP is inertial - you still have to accelerate the lead! You don't have to accelerate down force!
You have to push hard against both but there is a balance or sweet spot in all things! "
When one has as much HP as FF does you have to get it to the ground-------- Remember a lot of the FUEL guys run to the 3 and click. :? they get to run more often that way, as in a back up run. 8-)
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More than half the HP is inertial - you still have to accelerate the lead! You don't have to accelerate down force!
You have to push hard against both but there is a balance or sweet spot in all things! "
When one has as much HP as FF does you have to get it to the ground-------- Remember a lot of the FUEL guys run to the 3 and click. :? they get to run more often that way, as in a back up run. 8-)
Know this...Freddy ran to the 5
JL222
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Dave, (A2WindTunnel)
Katz is talking about just aero shaped bodies, for the "round" body he is talking about an aero shape, i.e. symetrical wing section, for the side view and an oval shape in cross section. The flat bottom shape is 1/2 of an aero shape in side view with a flat bottom. Neither is encumbered with wheels, tires, axles, etc the things that a typical Bonneville streamliner or lakester would have. I would speculate that a lakester designed with the wheels far enough away from the body could come pretty close to this configuration. (See pictures of the Aussie lakester)
I do agree with you that individual cars, especially NASCAR shaped cars, probably like to be ran as low as possible as they have pretty "dirty" undersides and lowering effectively reduces frontal area. I am not sure that I agree you can have free down force with out drag, I would wonder if you have seen these results that it might be more a function of your tunnel design, i.e. no moving floor, no wheel/tire rotation and less than optimum ratio between the car cross section and the tunnel test area cross section (blockage).
One additional note regarding generating down force with a body that is wing shape in side view, similar to the NACA airfoil shapes both symmetrical and also cambered, will generate down force simply by running them close to the ground. No angle of attach is required. This is because as you lower the shape the air flowing on the bottom has to gain velocity because it is required to travel through a restricted space, this increase in velocity will cause the pressure on the bottom to be reduced (Bernoulli strike again!!) and this generates down force. Again if you lower it to much, such that the boundary layer of the body begins to interfere with the ground plane it will block the flow and the down force will go away.
Sparky, the comment "More than half the HP is inertial - you still have to accelerate the lead! You don't have to accelerate down force! " is mostly BS, when you get to the speeds you are looking for, 300 mph+, the inertial loads are very small compared to the aero loads. The basic equation for force to accelerate is F=MA which is a linear equation, the equation for aero force is a function of the velocity squared and the required horse power is a function of the velocity cubed!! These forces rapidly pass the inertial forces. If you have huge horse power and are looking to run a big number, 400+, then you may be concerned about inertial acceleration because if you can accelerate faster it will give you a longer time to overcome the aero forces at the target speeds. This would only pertain to Bonneville and not El Mo or the eastern mile tracks as acceleration is important at those tracks.
Rex
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So, whats the bottom of Speed Demon/Flatfire look like?!?
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Reasonably clean without the skirt, extremely dirty with the skirt.
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Sparky, the comment "More than half the HP is inertial - you still have to accelerate the lead! You don't have to accelerate down force! " is mostly BS, when you get to the speeds you are looking for, 300 mph+, the inertial loads are very small compared to the aero loads.
Rex
If you reduce the weight of a 4000# vehicle by 500# (12.5%) that vehicle will get to it's potential terminal speed quicker and enter the traps faster. The shorter the run the more evident that is. But since that weight is needed for traction let's reshape the vehicle (add "Ground Effects" tunnels?) keeping the drag the same thereby improving the L/D and the V² will dial in the needed down force just as the aero door is trying to slam shut! Then the exit speed will be what is wanted. If the rules say you can't do that then you just have to throw more HP & lead at your lead-filled brick and hope for a really good traction day! (2X in a row!)
It's the area under the combined inertial, aero and rolling HP curves. How to reshape those curves within the limits of physics and the rulebook! And where to put the (aero?) lead and.... sounds more like a balancing act to me?? There is more than one way to skin a water buffalo and the water buffalo doesn't like any of them! :-o
Now if that's mostly BS then I guess my comments aren't really welcome here! :-(
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Woody, as a coinsure of all things water buffalo (roadsters) I enjoy your impute. :cheers: Tony
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"Reasonably clean without the skirt, extremely dirty with the skirt."
Blue, would you please elaborate on that statement.
Speed Demon seems to manage air flow around, rather than under the car.
Help us understand why a flat bottom, about 1 inch from the ground would be significantly cleaner than with a skirt, preventing the underbody airflow.
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Woody@DDLLCC,
Please do not construe my comments as not appreciating your thoughts regarding the use of tunnels for generating down force, my only comment is that "nothing is free" if you generate aero down force you will also generate drag. How do you propose to (your quote) "reshape the vehicle (add "Ground Effects" tunnels?) keeping the drag the same thereby improving the L/D ". Also remember that the traction at Bonneville is typically at a .6 or less coefficient of friction which means that whether you are accelerating a 4000 lb car or a 3500 lb car you are going to be traction limited so they both will accelerate at the same rate until the "gound effects" on 3500 lb car can begin to generate sufficient down force to increase traction and by this time the speed that the car would be at most of the traction is needed to overcome the Vsquared aero load not the acceleration load.
Woody, your turn to call my comments BS. If we don't kick this kind of stuff back and forth we can learn anything.
Rex
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Rex, Woody: chill. IM<HO, this conflict is coming up because everyone is starting to ask the really hard questions about how drag, L/D, inertia, and ballast-based traction all contradict each other in the current designs. Hard questions about previously misunderstood subjects cause strong opinions from smart people. You're both smart enough to understand what really works, the frustration is coming from a limited and partially inaccurate database.
Let's start with Rick's question and A2's comment about ride height vs. drag and design. Any car without a full under tray has tons for stuff hanging out in the breeze for air to hit. This leads to separation and stagnation drag (correctly simplified as "pressure" drag, incorrectly labeled "turbulence") on every single component. One effect of all of the individual components is that the separated boundary layer under the car grows exponentially as the air blows around all of these protuberances. For this reason, many years of Nascar R&D focused on the shape of oil pans with wings on them to act as downforce generators and to smooth things out.
As we lower the car without any other changes, this thick and disturbed boundary layer will tend to choke the flow between it and the ground. This will cause both drag and lift. Where this has already happened, raising the car may decrease drag by reducing the choking effect and giving the air under the car a place to go.
Lower the car/block the front to the limit/skirt the sides: the pressure under the car is reduced, downforce is increased, and very little air from under the car makes it to the back. Why would this be an issue for LSR when it isn't for other racing? In LSR, we need to reduce drag. Without some air to fill in the back of the car, we have base drag: separation.
Now, a clean belly pan is going to have less drag than a bunch of miscellaneous components hanging out in the breeze. So for a conventional car layout, the lowest drag/highest downforce arrangement would be letting a managed amount of air go under the car, skirt the sides, and direct that flow to help fill in the tail separation. The designers of the Gus Gus streamliner have talked about this and how challenging it is.
A clean belly pan with a skirt at the front may generate even more downforce, simply by lowering the nose; i.e. changing to more negative alpha ("rake angle") without raking the chassis itself.
But there are costs: That skirt just stopped any air from going under the car to be used at the back end; more separation, more drag. The air under that smooth pan and behind the blunt nose skirt is fully separated (more drag) and has no energy to be managed for downforce. To get some downforce in a conventional car that air under the car must start out organized, be accelerated to achieve lower pressure (downforce), and stay attached and organized in the pressure recovery area to the tail where it can be directed up instead of just randomly out.
"Increasing downforce without increasing drag" sounds great, and it actually occurs when we start out with a badly separated back end or dirty belly, then clean things up and direct the air properly. If tunnels are used to do this, it appears that tunnels yield downforce and lower drag (for a bad design).
Whether using pencil or CFD, try making sure that every that every square inch of cross section at the back of the car had a source up front and that it's streamline is smooth going around every inch of length, top, bottom, and sides. I'm not going to go into all of the detail theory other than to say, there is no "hole" to close: if the car makes a hole in the first place, go back and start over.
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Fast Freddy has proven that downforce and wings work with his 386 mph lakester, and were not taking the spoiler off the 222 car.
Jim Hall [one of the first to use spoilers] in the Chaparral book tells how downforce from spoilers improved lap times by being able to apply more throttle sooner in corners. Hall also found out you could run a good amount of spoiler angle without lossing rpm at top speed.
Hall had their own private race course [ Rattlesnake] for testing.
Look at the ralley cars with wings and the slower speeds they run at.
Its BS to think that Freddy would run 20 mph faster [406 mph] without a wing in his current lakester.
Don't forget Joe law's 349 mph winged C lakester
JL222
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Interesting discussion, Gentlemen. Lots to think about. It sounds as if my stressed aluminum chassis bottom panel should work just fine as a belly pan.
Regards, Neil Tucson, AZ
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Don't build something that will slow you down, You might as well use lead!
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All this sounds very interesting,,, But is there a formula that will tell me how much rear wheel HP is needed for my 53 Studebaker to go 200MPH ?
I am headed to Loring with my backup "C" motor in 2 weeks makes the same peak HP as the E but at a lower RPM but more TQ all through the range..(my old E motor finally gave up and we don't have all the parts yet to get it done before Lorig,, hoping for WOS).
The C accelerates harder but gives up before the mile.. (only pulls to 7200 rpms,, we are fixing this witha re do now),
The E needs a faster push but revs and pulls all the way to 8500+ (the standing mile is to short for the little E)
How can areo help me in a standing paved 1 and 1.5 mile track and also what chnages for Bonneville ?
Charles
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You can get a ball park guess using the old rule of thumb that power goes up at the cube of the speed.
As I recall the Studebaker coupes of that period in street trim needed about 12 -15 hp to cruise at 60 mph.
200 mph / 60 mph = 3.333
3.333 cubed = 37.03, so it will take a "minimum" of 37 times the power it takes to cruise at 60 mph.
If that number is 12 hp, then you will need 444 hp (if you body is essentially stock configuration)
and if it is 15 hp, you will need a minimum of 555 hp.
There are also some discussions regarding power require in the formulas forum, this one has a simple program I wrote that helps calculate the power required with a bit more detailed input information.
http://www.landracing.com/forum/index.php/topic,7775.0.html
Larry
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1000 hp will be ball park.
DW
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Cajon, my 53 Stude went 219 @ 4300 lbs. with 630 h.p. 435 cu. in. in B/CFALT
Last year it went 238 @ 5200 lbs. with 835 h.p. 496 cu. in in A/CFALT
Bruce Geisler ran his 53 from the early 60's until four years ago with probably at least 20 different engine combo's. He once told me that 500 rw h.p. will get you to 200 in a 53 Stude.
By the way, my 219 was at 7200' density altitude with my 1960 Old's motor............. Bob
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Yeah, Bob --
But I bet those HP figures were Washington (like North Carolina) figures, not 5500-7500-ft. figures.
Stan
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Stan, right you are....................
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Did DW230's number 1000 hp number go over EVERBODY'S head(s)?
What yrs truly is pretty sure he was stating is:
ALL you landspeed DREAMERS need to actually experience Salt Flats racing and find out on your OWN what your rig really can do.
More than one experienced Elmo/Bonnevile racer thinks a few of these salt flat posers don't have the cojones to even show up with a race car.
Off my soap box!
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Bob, you know I love your car,,, but my E motor on Gas will never have the power you have,,
Did you weigh the 4300 lbs for that 219mph run with the 630HP motor in order to plant the power to the Salt or the keep the rear from coming around and spinning ?
With me in the car the total weight is 3600lbs,,, 52% on the rear,,, I do not think I will over power the the Salt (break traction) in 2nd, 3rd, or 4th. Gear,, will I be to lite to keep the rear from wanting to spin and pass the front?
Since I race in Standing Mile and 1.5 mile venues backe here,,, this weigh works real good,,, but yes I do have provisions to add weight very low and centered in wheel base or slightly back of center.
Charles
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Did DW230's number 1000 hp number go over EVERBODY'S head(s)?
What yrs truly is pretty sure he was stating is:
ALL you landspeed DREAMERS need to actually experience Salt Flats racing and find out on your OWN what your rig really can do.
More than one experienced Elmo/Bonneville racer thinks a few of these salt flat posers don't have the cojones to even show up with a race car.
Off my soap box!
Hey Bystander,,, I sure as hell hope you where not calling me a poser,,, or doubting my cojones... as you don't know me,, and I sure as heck hope your smart Acura comments where not directed at me,,,
..also the reasons some of us back east have not been on the Salt yet with our race cars , may very well be a matter of time, distance and money,, not lack of cojones.
Charles
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Leave Bystander alone. He's old, misinformed and crotchety. He thinks you're still taking votes on the paint scheme. See you in August.
Stan
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Stan,,, September WOS is the plan.
Charles
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Cajun... I have used the 'Bonneville Pro' computer program sold by RACING SECRETS .COM for many years
for the 222 Camaro. You can input all your specs that you know about your car and engine and you can figure
out some you don't know after it computes.
Inputs are track conditions, elevation -barometer-temp-ect. Track --one mile asphalt--El Mirage--Bville 3 mile
and 5 mile ect. weight-tire size -gear ratio-trans ratios- frontal area- drag coefficient-lift coefficient- rpm --hp--torque, after inputting data click on TS [time slip] and it computes speed in hundred of sec in time--distance traveled in hundreds of a mile--mph and acceleration rate what gear and rpm.
Inputting Stude data 793 hp- 595 tq at 7000 rpm 3600 lbs-19.5 frontal area .3 cd- 3.3 gear ratio 91.4 tire roll out [29'' tire] and 1 mile track is 201 mph
For bville with 793 hp and 5 miles-- 235 mph
Bville and 200 mph---510 hp
JL222
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:? :? :? What does any of this have to do with "ground effects". Aren't there enough other threads for general chatter ? :? :? :?
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John, I am not familliar with that program but find it eerily close to the results I posted (and my comments's from Bruce Geisler) in my earlier post.
Cajun, the added weight is needed for the higher speeds handling and low speed traction. Terry Hunt's stude ran (I believe) 235 mph with a SBC D motor.
Efenn, sorry, just answering questions.
After a few hundred post's you will get used to it......................... :cheers: :cheers:
Bob
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Bob... I started with your hp figures and weight using the inputs for the 222 camaro already in program.
I had to reduce the frontal area from 20.5 to 19.5 to get your speed, or I could have reduced the CD and left
the frontal area the same.
Its also easy to change hp figures by mutiplying + OR - [ 1.1 OR .9] or whatever 2 or .5 then on closing program ask if you want to save inputs, no in your guys case, so program goes back to 222 data. Cool :-D
JL222 :cheers:
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Not wanting to reserrect this topic, cause it's not cogent, but how about the kid in the '40s that smeared GRAPHITE all over his Soap Box Derby racer and his FACE AND HELMET to cut down drag.
As I recall, he WON the Akron event!
(Gilbert Klecan, Sand diego, Ca).
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IB, Stop giving all the secrets away. :cheers: Tony
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How about with 'Production' body classes?
I've seen lots of 'em with their noses slammed, bumpers on the ground, and tails in the air...
Is that better than a level, stock ride height?
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Not if you're otherwise acceleration limited, AKK and Stan!
But I will agree that if the high aero downforce Landspeed cars are spinning their wheels w/o getting full throttle, I'm not sure there's an alternative.
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Not wanting to reserrect this topic, cause it's not cogent, but how about the kid in the '40s that smeared GRAPHITE all over his Soap Box Derby racer and his FACE AND HELMET to cut down drag.
As I recall, he WON the Akron event!
(Gilbert Klecan, Sand diego, Ca).
If that's true, us guys building and racing old British bikes should have an advantage!
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I spray Pam on the lower half of the bike ... but not for an aero advantage. Makes clean up a lot easier.
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good idea, joe.
guessing that's good for the salt out west and the bugs in the east ?
bill
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lets see if I have this right :evil: we are spraying PAM on the walls of the difuser tunnels so that we will not have distrubance seperations tha wil kill our traction aid :? how can we see the bug splats and salt spray streaks inside of a strake tunnel to know if it did or didn't :-o work
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lets see if I have this right :evil: we are spraying PAM on the walls of the difuser tunnels so that we will not have distrubance seperations tha wil kill our traction aid :? how can we see the bug splats abd salt spray streaks inside of a strake tunnel to know if it did or didn't :-oworked
lol.
looks like the thread got sidetracked .