Landracing Forum
Bonneville Salt Flats Discussion => SCTA Rule Questions => Topic started by: Bob Drury on June 17, 2011, 03:35:02 PM
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Here is my attempt to keep my ass on the salt............
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Wow Bob, must have found some young kids to post pictures for you? :-P
Nice job :cheers:
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Dyno, I tricked Mr. Hotnut's into visiting.................
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Well, that looks like it will dump most of the air pressure should you find yourself going backward, but, lets not test it ok?
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While talking Bob through the photo resizing process I secretly snapped this shot of me giving thumbs up behind Bob.
LOL
(http://a2.sphotos.ak.fbcdn.net/hphotos-ak-snc6/264795_2063075332542_1114496579_32476559_6754074_n.jpg)
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Now if that doesn't look like your neighborhood preevert, I don't know what does.......... Bob
Hey, I didn't realize I had a grey pony tail............ :cheers: :cheers:
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Bob, nice job,,,
What holds tension on the flap when going frontwards ? Just air pressure ? Why the two inner spill plates (verticle uprights) ?
Charles
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Well Charles, being the mechanical genius that I am, I mounted the tether strap's (hard to see but thay anchor at the base of the two red spoiler support's).
When I got done, I tried the flap and it wouldn't close because the tether hardware hung up on the opening surround.
Being a well organized genius, I started looking for a fix and found it on my screen door.
If you look real hard you will notice the tethers are held together by the screen door spring.
Dodge, I gotta go close the screen door again......... the wind just caught it........ :-D :-D
Sign me: the smartest guy Hotnut's has ever met.................
The two inner spill plates are because Dan said I could have them and it isn't often that he offer's any leeway or freebies, so I said "hot damn" I gotta go for it. (translation: I don't have a clue, but hopefully they add to stability if the air stream catch's them). Bob
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Not trying to be a smarta__ at all but if it were mine I would put an air vent (or vents) from over the real axle to the spot behind the back window about 2" wide and 30 to 36" long relieving the lifting from behind the rear window and take all that "junk" off the trunk. Neil Thompson went right at 300 MPH with nothing but an air vent and the tail lights removed from his 53 Studbaker 40 years ago. All that stuff is drag......................
Check out Bruce Giesler's Studie for the samething. They work and were mandatory for Studies over 175 at one time.
Good Luck......................JD
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Not trying to be a smarta__ at all but if it were mine I would put an air vent (or vents) from over the real axle to the spot behind the back window about 2" wide and 30 to 36" long relieving the lifting from behind the rear window and take all that "junk" off the trunk. Neil Thompson went right at 300 MPH with nothing but an air vent and the tail lights removed from his 53 Studbaker 40 years ago. All that stuff is drag......................
Check out Bruce Giesler's Studie for the samething. They work and were mandatory for Studies over 175 at one time.
Good Luck......................JD
I was told those air releif vents where for classic Coupe,,, not classic altered coupe...
But that did not make sense....not sure the wind tunnel would agree with the rear spolier being drag ....
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CK Talk that over to Dan.....
FIRST: MY BAD THEY ARE AIR "DUCTS"
For some reason I cannot find mention of them in the Classic, Modified Catagory, Altered or Gas Coupe Rule from page 63 thru 70.
But on the first paragraph of 4.CC it sounds a like they are prohibited for directing air and that where they must be getting the prohibition of them. IMO It says "within the car" but not "threw" the car.
Like I said they were mandatory for Studies years ago because all, I mean ALL, of the spun between 175 and 185. All this "Junk" was added because of other cars to hold them on the ground.
To bad if they are not allowed. Geisler's Hanky Panky and the Terry Hunt's old Guam Bomb are probably illegal now....Too Bad
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J.D., while I respect your opinion, I totaly disagree.
First of all, we now run our car's lower with front air dams, resulting in less air under the car.
Secondly the air at the base of the rear window is a low pressure area and any air exiting from behind the rear window is if anything, going to allow less downforce on the rear of the car as the air over the top flows downward's.
Terry Hunt's vents were for the radiator mounted under them.
I would suggest that the major problem with the Stude's of thirty to forty years ago were caused by most guy's putting ballast in the trunk, creating a pendulum, and the high attitude and center of gravity ( partially caused by the tall tires with stock rear suspension's/ala leaf spring's).
I have never been able to find a picture of Neal Thompson's Studebaker. Bruce Geisler said in the end it ran a Corvette front end. Was the body unaltered (chopped or skirted) when it ran those speed's?
Just curious.
p.s. I have another trick up my sleeve at the rear of the car keeping the rear planted, it's legal, it aint weight, and to anyone who has seen my car it is pretty obvious and it's not the spoiler............. but spoilers do work.
Bob
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Bob
re read your #2 if it is low it lifts---the duct was trying to kill the lift area sucking the rear wheels of the ground
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Sparky "you got it." The area behind the rear window on a car that has a defining line causes lift. There is no question about it. I don't care how low it is. It's the air going over the top causing the the problem and the air coming thru the ducts that break it up. I guarantee I felt it in mt 1940 Chevrolet 20 years ago. At 149 for 3 miles nothing moved. At over 150 you could feel the car rear coming up, right in your seat. We went 153 and that was it. No More. If I would have put in an air duct I'm positive it would not have lifted. A 1940 Ford would probably not have the problem until a higher speed because of it's slopping roof line. If you ever drive a car with the "lift" you will know it.
I'm not saying to not use spoilers especially in a car with no defining line. The guys in the past figured it out and the same would work today....Good Luck
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Sparky, I guess the question would be is the lift from that low pressure more than the high pressure created when the air over the top hits the spoiler? Does that air cause a turbulence or keep the high pressure from dropping down before clearing the deck lid?
It's a shame that after all these years (58) no one has had the resources to put one of these car's in a wind tunnel.
When I was reseaching for my car at Speedweek in 96,97 and 98, I talked to every Studebaker driver on the Salt. This included Studebaker Joe, Beard and Glade, Turner and Whitley, Homer Hinchcliff, and my friend Bruce Geisler amongst others. Most ran air duct's.
I asked each about certain features such as straight axles and the air duct's exiting the trunk.
The concensus I gleaned was that many thought straight axles were the only way to fly, but not one of them could offer anything for reasoning other than "that's the way we have always run it".
Granted, the stock Stude front suspension might not be the best, but Geisler's car has run a stock one since the 60's.
The same thing applies to when I asked about the air duct's. Not one of them could tell me if they had any proof of them working. It was more of a "monkey see monkey do" thing.
As I stated in my previous post, the Stude's that ran in the seventies and eighties may have benifited more than today's versions in that we can run a spoiler, but once again we have no proof of the advantage of the ducts whereas the spoilers are a proven design on virtually all full bodied cars. Bob
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When I was helping Keith Young with his roadster we used the air ducts behind the cockpit. The roadster was the old Quincy Auto/Brisette Bros. car that Keith found. LSR myth is that when the Brisettes added the ducts in back to back tests they picked up 18 MPH.
Don't know if that is the truth or just a good story.
DW
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Dan, that's the problem. Wouldn't it be nice if we had a wind tunnel on the West Coast available to the public.
Believe it or not, I live within ten miles of a brand new one that Freightliner installed recently to test new truck design's.
Maybe if I buy a new Mercedes they will throw in a free wind tunnel test.
Here is another interesting tidbit.
When Marlo tested his four foot model, the aerodynamisist had Jim Hume carve a mirror image of the bottom half of the car and mated the two wheel surface to wheel surface.
This was supposedly to simulate how the air reacts flowing under the car at speed.
At that point they are talking way over my head.
This year at SpeedWeek I hope to aim a camera at ribbons on the deck to get a better idea of whats happening.
It would be neat if a Stude with the vent's could do the same to compare.
If I could afford all the sensor's and computer gadgets, it would certainly be neat to see how much effect that speed has on the downforce in the rear.
One more note, as slippery as the nose of a 53' stude is, the shape of the rear is not really what is desired. The way the trunk dives quickly is one more reason I feel that the spoiler help's on this car. Bob
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I'm not sure if you all remember the comments I posted a year or so ago about using oil tests to see the air flow patterns on a car body.
I did my tests on a 2002 Subaru WRX at around 70 mph and could clearly see the airflow over the rear window and rear deck of the car. The rear shape of the WRX window area is quite similar to the 53-54 studebaker bodies, so I think some of the information is applicable.
At speed the air flow along the rear quarter panels is flowing to the rear and slightly up ward as it tries to make the turn into the rear window area on the WRX. It fails to completely make the turn and separates from the body and as a sheet rolls into the void behind the rear window. Visualize this in three dimensions you have two sheets if high speed air flow dumping into the rear deck area off the rear quarters and they roll over and down toward the center of the rear deck on each side.
The airflow coming over the top of the roof does pretty much the same it tries to follow the rear window but fails and part of it forms a turbulent bubble behind the rear window, and the rest flows over the top of that bubble, gets pushed into the center by the air flowing off the rear C posts and "splashes off the center of the rear deck lid.
In the oil test, I placed a dozen or so dime sized spots of used engine oil on the rear deck, then drive at highway speed from one exit to the next -- ie about one mile. I then stopped and looked at what the oil streaks had to tell me.
Below is a picture of the studebaker I had in high school with stream lines showing what I believe the air flow does on that car body based on the WRX airflow.
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second image from the rear quarter showing the turbulent bubble behind the rear glass.
Now we get into the complicated part. The spoilers you guys are using are leaving that bubble of low pressure turbulent air unmodified, and extending the rear deck lid in the area where the airflow naturally tries to re-attach to the deck lid creating a high pressure area on the rear deck and spoiler top.
The low pressure in that bubble helps pull the air flow down and around the rear deck, but it also creates a large low pressure area on the top of the trunklid near the rear glass that is trying to lift the rear of the car.
If you put vents in that area just behind the rear glass, you reduce the pressure drop in that area, but the airflow will not turn quite so sharply in from the sides or top of the car to fill the zone behind the rear glass. That will reduce drag by making the low pressure bubble longer and more tapered, but will move the high pressure area where the air flow tries to re-attach farther back on the deck lid (maybe even missing the stock deck lid).
It is basically a choice of evils situation. Venting into that low pressure zone will reduce lift at the source but it might slightly reduce the effect of the spoiler if it is too short. Putting end plates on the spoiler and in the mid spoiler will help keep the airflow straight as it separates from the rear of the car.
What you really need it a method to help the air make that turn into the void behind the rear glass. One legal way to do that, is to put a slight forward rake on the car so that turn is not so abrupt.
The only way to know for sure is to do some tuft and oil testing to see what the air is really doing back there, and then try venting into that low pressure zone and see how it modifies flow.
To help visualize that bubble of low pressure turbulent air think about the bubble or air and foam that forms on the down stream side of a rock in a stream. Essentially the same thing is happening behind the rear glass in most any car at speed.
larry
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Hot Rod, thank's for posting.
I wonder if my side spell plates would affect that side flow trying to wrap around the back glass?
I think I will try the oil and also attach ribbons to the top of the side spill plates.
Unfortunately, my neighbor's frown on be driving down the street on 25%......... :-D Bob
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Take the car to a test and tune day at your local drag strip. You only need about 70 mph to get good data from tuft tests and oil tests.
Larry
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That is certainly not a bad idea.
Thanx, Bob
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Very interesting information hotrod. I've seen a very similar situation with my late model four door sedan that is similarly shaped to your WRX. After a car wash and with the car still wet, I'll zip down the freeway at 70 or 80 mph to blow the water off. Starting out there are beads of water on the back window and as I increase in speed the beads start to disappear from very outside of the back window and the clearing path slowly works its way towards the middle. Then, no matter how fast I go (still on the freeway mind you) there is still always a strip of water beads that are still stuck right in the middle of the back window. They never blow off or go any where.
BTW the Thompson Stude is severly chopped. I actually saw the car in person recently and was very surprised to find out that it was not only still around but very near by in So Cal. It's chopped so hard that I have a hard time believing Neil was able to see out the windshield.
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I punched in Wind tunnel test on you tube, and found two excellent examples of high and low pressure air flow.
The first is titled A2 wind Tunnel Test All Generations Corvette. The opening car is a 58-62 Corvette with the air wrapping around the roof just as Hot Rod theorized.
The second is titled Mercedes Benz SLS AMG. This one shows both a great shot of the air coming up over the hood and roof, and a great side shot of the air coming off of the roof.
This particular car has a short rear deck and the video shows that the air stream cannot get back down to the deck surface. The Krafty Kraut's solved this with a pop up spoiler that I assume rises at a given speed or possibly even for high speed braking. Now that spoiler (or is it a wing?) looks like it would add a fair amount of drag........... gotta love that damn internet.............. Bob
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I think the two you referenced are include in this group of 4 wind tunnel videos that show how the air flow tries to fill the dead space over the rear deck and behind the rear glass.
http://www.youtube.com/watch?v=FjwyUOq_goI
http://www.youtube.com/watch?v=B29ScK8tIwY
http://www.youtube.com/watch?v=eszhVxE_9-8
http://www.youtube.com/watch?v=jd71qpfUfEg
Larry
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Bob and Hotrod,,,
FYI- I live less than 45 minutes from A2 Wind Tunnel... I have visited there often and helped on several test days with other cars.
I have done lots of research and also learned a lot.
So far I have not had the time, help or money to put my car in there (what a shame) as I don't mind sharring what I learn. But right now I would need 3 to 4 helpers and $2,500 to do it right.
For now I am just adding HP to get my goals,, there will come a point where I have to tweak the areo,, and the tunnel will prove to be my best use of time and funds then.. for now pass me more HP...(there is only so much a NA 255 cu in motor on gas can do)
Charles
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Has anyone ever considered that a Studebaker may not be the best choice to get the job done? (Blasphemy!!!)
Stan
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That does it! CRUSH THE ROADSTERS!!!!!
I recently sold a 53 hardtop (project) at the Portland Swap Meet.
I swear every other guy with grey (or no) hair stopped and looked then told me his story about his uncle, brother, dad or best friend having one in high school.
My own story is being a avid reader of HOT ROD Magazine starting in 1959. I loved Beach Ball Sanchez's car from the first time I saw it.
Over the year's, John Larson's car, the car's of Les Leggit, Joe Pisano, Bruce Geisler, The Burkland's, The Thompson Coupe (thank's T.B. for the pictures), all affected me greatly.
My first trip to the salt in 1996 was to inocently spectate.............. MISTAKE!!!
On the trip home I was planning the car build, and I knew it had to be a Studebaker! I could have had a comfortable retirement, but nooooooooo, I am now in debt up to my eye ball's, and I LOVE IT........... Bob