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.............T--- BEGINNING BODY THOUGHTS ---
.........................--- And Suspension Thoughts ---
After finally finishing my new house I'm ready to start building my lakester (Jan 2005).
It originally was going to be a larger car powered by a small block chevy, but after considering the costs of that car and the size it would be and the associated problems of a parking place for a car that large in my shop I've switched to a 750cc motorcycle based car. This car will be somewhat smaller and hopefully less expensive to build. The challenge will be that I want to go over 200 mph and the present record for a J/GL is 163.88 and for a blown .75 liter motor J/BGL the record is 187.78. Those records were set with two different, but very good cars so I definitely have my work cut-out for me. No matter how this all turns out I'm sure I'll still have fun as I get my enjoyment from designing and building and then seeing if my ideas will work. If I go fast that will be a bonus. NOTE: Latest plans (2013) are to go back to a car engine.
So I hope you will follow along with me on my journey,
Sum
.......................................................................--- The Body ---
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(Rendering above was done by Rex Schimmer, thanks Rex, and is somewhat close to what I hope is the car shape. The front of the side pods will be shaped like an inverted foil and at the back of the car will slope up from the bottom to the top. So the side pods will somewhat resemble an inverted wing with a long flat section top and bottom.)
A number of the lakesters that have been built have the wheels/tires close to the body. A good example of this, and a successful one, is the car on the first page. The other line of thought is to move the wheels/tires away from the body such as Seth Hammond did with his lakester that hold numerous records. My thinking (could be wrong) is that with the wheels/tires close to the body you have ruined the air flow down the side of the car and have taken away any streamlining advantage you have there. Now if you move the wheels out you have good aero down the sides of the body, but pick up the drag of the axles, steering rods, etc. now hanging out in the wind. What Seth and a few others have done is to enclose those exposed parts in a fairing that covers them up and extends for most of the length of the car along the sides of the body out to the wheels ( see the Hammond car for an example ). If you can design this fairing and the car body for a very low Cd (coefficient of drag) you will more than make up for the increase frontal area, at least in theory. Now you end up with a low Cd for the car body/side fairings and have to live with the .4 to .5 Cd of the frontal area of the wheels/tires. There is no way around that since the wheels/tires have to be exposed on a lakester.
My approach will be one similar to the Hammond car except with their car the driver sat behind the motor and I will sit in front of the motor. The first sketch above is a quick drawing of one way to approach what I want for a car shape in top view and side view. In the top view I left the wheels/tires out of the drawing and they would be located just outside the side of the fairing part of the car. This body is too short to house myself, motor, turbo, water tank, gas tank and inter-cooler. It does incorporate an airfoil shape for the body and a neutral air foil shape for the side fairing, which since it is close to the ground will create a small down force on the car in theory.
In the sketches at the left I've stretched the body out some and have still tried to maintain a teardrop airfoil shape where the laminar flow will stay attached to the body as it moves over the car.
Ron Main's record setting "Flat Fire", "Eco Fire" streamline has a lot of the elements I'm looking for in its body shape ( Main's Streamliner )
Frontal views in the bottom of the sketches to the left show two different approaches for the body shape as seen from the front of the car.
The left one would be easier to build as it would not involve compound curves in the bottom half of the body only on the top half of the body. With the car on the left you have to take into consideration the air, little as it may be, that moves under the car and the effects that will have on drag. Also the car on the left would have to be as close to the ground as possible to keep air from under the car, but still have clearance for suspension travel. The one to the right could be further off the ground and not experience some of the drag problems of the car to the left as far as the air going under the car is concerned.
The shape on the lower right involves complex compound curves on the bottom half of the car along with the top half of the car. This body would have a shape that would appear as a neutral airfoil from the top view and would look a lot like the E-Z Hook Motorcycle streamliner that Sam Wheeler drove to a new record at 332.410 mph in the summer of 2004. Here are two views of that streamliner ( E-Z Hook side view ) ( E-Z Hook 3/4's view ). The E-Z Hook has a very low Cd of about .1 and they have done an excellent job on this car and I would invite you to check out their site.
If you are interested in aerodynamics as applied to a race car I would strongly recommend the following three books:
1. New Directions in RACE CAR AERODYNAMICS (Designing for Speed) by Joseph Katz. I just got this book, but after looking through it briefly if you were to only buy one of these three books, I would recommend this one. It is $34.95 and the ISBN is 0-8376-0142-8.
2. AERODYNAMICS for Racing and Performance Cars by Forces Aird. It is an HP book and is a good overview of aerodynamics and presents views on aero issues without a lot of formulas and such. It was $16.95 when I bought it and the ISBN is 1-55788-267-3.
2. THE LEADING EDGE Aerodynamic Design of Ultra-streamline Land Vehicles by Goro Tamai. It summarizes the design and construction issues of solar cars and ultra light land vehicles. This book is heavy into the design of ultra streamline solar cars, but the principals can be applied to any race car. It is much more in debt and a lot heavier into math than the AERODYNAMICS book, but I feel a lot better book if you can wade through it. It covers aero issues to the smallest degree. If you really are building a streamline, lakester or competition couple I would strongly recommend it. Not cheap at $44.95, but that might be a small price to pay to build a body maybe just once and get it as close as you can to ideal. The ISBN is 0-8376-0860-0.
On the following pages I'll go into more depth of what I'm trying to achieve with the aero design of my car as I get to the construction stages of the car where it comes into play.
..............................--- Suspension Thoughts ---
When it comes to suspension at B'ville you see lakesters with no suspension front or rear, suspension on either the front or rear, but not both and some with suspension on both ends. 12 years ago a lot of cars didn't run suspension as the track was smooth. Then the course really started to deteriorate in the mid to late 90's and some cars weren't able to run due to the shape the course was in. With some it caused handling problems and with others there head was being jarred around in the car so much it impaired their vision, especially with cars where the driver was in an extreme lay-down position. I had more than one car owner tell me to put suspension on a car if I was building it from scratch.
Now the course is generally hard and smooth again since the "salt lay down program" has been going on. Since I'll be in a lay-down position and who knows what the salt will be like in the future I have decided to incorporate a very limited suspension in the car. Probably in the neighborhood of about 1/2 inch of rebound and about 1 inch to 1 1/2 inches of compression when the car is at ride height. To achieve that I'll use links and levers to keep the suspension components with in the confines of the car body and not out by the wheels and in the side fairings.
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