Author Topic: Couple questions about the GM lakester and lakesters in  (Read 14180 times)

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StraightSix

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Couple questions about the GM lakester and lakesters in
« on: February 11, 2005, 09:43:00 PM »
GM lakester  <-- pop-up warning on that one
   same thing, different site  
 
 Is this the same car that holds the G/BGL record of 179.381mph?
 
 I'm curious about those urethane tires - how well did they work?  How would one go about getting tires like that?
 
 Also generally about lakesters - what is the average drag coefficient of a well designed lakester?

Offline jimmy six

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Re: Couple questions about the GM lakester and lakesters in
« Reply #1 on: February 12, 2005, 12:29:00 AM »
I believe it ran  conventional Bonneville type tires.
 
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dwarner

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Re: Couple questions about the GM lakester and lakesters in
« Reply #2 on: February 12, 2005, 11:27:00 AM »
GM used normal LSR tires, as far as normal is. The show tires are just that, show tires. The math geeks can argue the cd question.

Offline Sumner

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Re: Couple questions about the GM lakester and lakesters in
« Reply #3 on: February 12, 2005, 12:47:00 PM »
Quote
Also generally about lakesters - what is the average drag coefficient of a well designed lakester?  
I'll comment on this, but only from the point that the following is my view only and I don't have any "hard" numbers to back it up.
 
  :)  .  On the first page of my site with the link below I have the names of 3 different books on aerodynamics you might want to look at.
 
 c ya, Sum
 
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Offline John Burk

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Re: Couple questions about the GM lakester and lakesters in
« Reply #4 on: February 12, 2005, 11:34:00 PM »
Straight and 1FAT - Here's a couple of things I've picked up .
 
     Streamlined 3D shapes are called bodies - Thats the key word to find information about the  drag of things like lakesters and streamliners .
     Information about the drag of streamlined bodies close to the ground is scarce.
     Bodies with the lowest drag are rounded in front and pointy in back but needn't be fattest tward the front like a wing .
     Wind tunnels without moving floors give artificaly low drag - You can't believe all the Cd numbers you see .
     On Yahoo look up "Interactive airfoil analysis" (1st item)- It only shows side pressure but you can learn from playing with it .
     Also on Yahoo look up "Aerodynamics of road vehicles" (2nd item), a book review with good info .
     Don't finalize your design till you've done a lot of talking , reading and thinking .

Offline ddahlgren

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Re: Couple questions about the GM lakester and lakesters in
« Reply #5 on: February 13, 2005, 05:04:00 AM »
How often do you think Lola, Williams, G Force et al look up the tough aero questions in "Aerodynamics of road vehicles" or do a yahoo search??
 Dave

Offline JackD

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Re: Couple questions about the GM lakester and lakesters in
« Reply #6 on: February 13, 2005, 08:23:00 AM »
The fastest lakesters are the least efficent and mostly look at each other.
 Right behind them are the smaller classes with a lot more aero.
 In the case of streamliners, one of the smallest is one of the fastst.
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Offline John Burk

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Re: Couple questions about the GM lakester and lakesters in
« Reply #7 on: February 13, 2005, 12:49:00 PM »
There are several reasons why F1 cars don't have low drag bodies.
      The wings and exposed wide tires make low drag impossible.
      The front of the car needs to be a certain shape to direct air to the underbody for down force and to the brakes and radiators.
      There is so much turbulance behind the rear wing and tires there's no way to avoid drag there.
      Passing normaly happens during braking or cornering where drag isn't important.

Offline Stainless1

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Re: Couple questions about the GM lakester and lakesters in
« Reply #8 on: February 13, 2005, 02:04:00 PM »
Tires on lakesters are probably your largest drag factor.  I believe you might find that large tires (24 inches +) spinning in moving air have a drag of 1.16, small tires about 1.21.  
 I always remember something I heard a long time ago at Bonneville.  "It doesn't matter how streamlined it is, it still has more drag than if it isn't there."
 Build the smallest frontal area you can and still fit engine and driver.
Stainless
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Offline Rex Schimmer

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Re: Couple questions about the GM lakester and lakesters in
« Reply #9 on: February 13, 2005, 07:11:00 PM »
I think that I agree with most of what 1FATGMC has said, build the basic body as small and slippery as possible, run small and narrow tires and streamline every thing between the body and the wheels. I also am working on a small displacement lakester, probably an "I" class car, but I have a street rod to finish first so am probably several years away. I am not sure that I agree with Stainless1 that the Cd for Bonneville style tires is as high as 1.2, where did you get that info from? I am planning to run top fuel fronts, about 22 in. OD and make non rotating wheel covers both on the inside and outside. I am planning to make my shape a NACA 6600 series semetrical aerofoil shape in plan view, low Cd, long area of attached flow good pressure gradient. I am also thinking about running a flat bottom, like Costallas cars and very low to the ground, less than one inch, but I don't find alot of info regarding how this affects the Cd. Anyone got some input on this?? I have seen alot on running aero shaps close to the ground, which generally shows that to little ground clearance increases drag, but nothing on flat planes.
 
 I remember reading where some F1 engineer said that the modern F1 chassis is just a "bracket" to carry all of the aero stuff! When you see that these teams are running their wind tunnels 24/7 it just makes you wish you had a couple of hours in one!
 
 A comment about the GM lakester also, they actually built two. GM built the first one with the billet wheels with the rubber bands around them and it was just for show. So Cal Speedshop built the "race" model and it ran some big Dunlop 18s in the rear and 16s in the front. I personally think they were (are) to big but So Cal has got the GM money not me!
 
 Note to 1FATGMC, thanks for running the picture of Seth's lakester, I have looked at that car a million times and never remember that it ran so much caster! Something to remember. It really does hurt to think about it though, what a great car!
 
 Rex
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John Beckett

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Re: Couple questions about the GM lakester and lakesters in
« Reply #10 on: February 14, 2005, 11:59:00 AM »
Open wheels have tremendous drag. May not be as high as 1.2, but maybe it is? Total Cd on a Lakester is probably around/about .45.
 
 JB

Offline Ron Gibson

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Re: Couple questions about the GM lakester and lakesters in
« Reply #11 on: February 16, 2005, 12:55:00 AM »
Rex
   I don't know what top fuel tires you are planning to run or what they are running now.
   When Ron Benham first built the lakester that he sold to Corky Stockham, he ran the skinny top fuel tires because they were rated to 320 mph. He blew one on a pass. No problem, he had another one. Blew another one. Called Goodyear to see what was going on with their 320 mph rated tires.
   Goodyears response was, they ARE good to 320 mph,  for 5 SECONDS, not 5 miles.
   Not trying to advise you on anything, but you might check with the manufacturer to make sure they are OK.
 Ron
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Offline John Burk

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Re: Couple questions about the GM lakester and lakesters in
« Reply #12 on: February 16, 2005, 11:27:00 AM »
If a top fuel tire can handle the speed but not the flexing at bonneville isn't it an air pressure problem .

John Beckett

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Re: Couple questions about the GM lakester and lakesters in
« Reply #13 on: February 16, 2005, 11:52:00 AM »
NO, it's a load problem. Have talked to Goodyear. Drag tires are not intended to run for five miles especially at the pressures that work for us (60 to 100 psi). Centrifugal force pulling on the tire for five miles is often more than the tire will handle. Not to mention the weight of many Bonneville cars far excededs the weight of a tube frame Drag car.
 
 JB

Offline Bob Drury

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Re: Couple questions about the GM lakester and lakesters in
« Reply #14 on: February 16, 2005, 12:05:00 PM »
One more thing to remember, a tire going 300mph at the contact patch is going 600 mph at the top.  Remember this fact when you put a tire not designed for speed on your car.............
Bob Drury