I know a lot of scale enthusiasts will say I'm crazy, but to my mind there is no beating wing cars for pure slot racing fun. The longer I play in this hobby the more speed I want and whether running cobalt or ceramic magnets the maximum speed can only be had by taking advantage of the aerodynamics.
When I ask people at the track why they are not racing wings I get a few pretty consistent answers. "Too expensive" is the most common. When I point out that a World 12 is virtually the same price as a high performance 4.5" NASCAR I'm told that just the body is worth 25 bucks and they can't build their own. These same people are racing scale bodies that resemble the original's down to the driver's signature on the door. So, I figure if I can teach people to build wing car bodies maybe I'll have more playmates.
A few basic principles are needed before I get into
the mechanics. A wing car body works by channeling the air over
the car and creating down force to keep the car in the slot.
This avoids the need for heavy chassis parts. The beauty of using
aerodynamics is that the faster the car is going the more down
force is being exerted resulting in quick acceleration, breaking,
and cornering. It follows that the more banked or swoopy a track
is the less down force is needed. This will affect your choice
of body style, spoiler thickness and height, side dam shape and
mounting position. In short the more swoopy the track, choose:
The class your running in also influences these choices. Very generally speaking faster classes use more down force, but there is plenty of room for "tinkerage"
So, lets get started. You've managed to get your new Parma Phantom, O/S Corvette, Koford Peugot, or Alpha Jaguar out of the bag and want to know what to do next. You may have noticed that it's clear, so it's a good idea to paint it. A good quality paint is required to prevent chipping and peeling and I don't think you can beat Pactra Racing Finish. You want light even coverage and the only way to accomplish this is to spray it. Pactra offers spray cans but they tend to give too heavy a coat and I would recommend an inexpensive Badger air brush which can be used with a compressor or available air cans.
Masking is next. Four areas require masking, driver window, numbers, details, and sides. Many manufactures now offer custom masks for the driver window. Use them. I recommend masking for numbers and details rather than using decals because it's lighter and cheaper. It's not necessary to buy custom masks as they can easily be cut out of masking tape or adhesive labels with backing available at any office supply store. Painting the sides adds weight and makes mounting more difficult so I always mask them off entirely. The best way to mask the sides is to lay a wide piece of masking tape on a smooth clean surface edge. Lay the side of the body over the tape and trace out the profile. Cut it out with an X-acto and apply it to the inside of the side. Repeat the process on the other side. When applying the side mask err on allowing a little paint to get on the side rather than masking off the top for best appearance.
Thin your paint to the consistency of milk using a high quality lacquer thinner or the product recommended by the manufacturer. I use 20-30 psi and adjust the spray on a test board. If it's too "gloppy" you may need to thin the paint more. Allow about 20 minutes for drying in front of a light bulb before removing the masks and putting on the detail coats. Remember to apply as little paint as necessary. Paint is weight of the worst kind being well above the center of gravity of the car. If you want you can add some detail to the surface of the shell using a Staedtler Lumocolor 313 pen, available at any office supply store.
TRIMMING AND MOUNTING
Using a protractor draw a vertical line down from the top of the kick on both sides. Measure down 30 mm along this line. Decide how long your body is going to be. I generally use 145 mm but you may want it longer for a tricky road course. Measure from the 30 mm point of the vertical line to the front of the body about 1.5 mm below the top of the shell. You should be thoroughly confused so take a look at figure 1 below.
Now take your best, sharpest scissors and cut the front of the body at 145 mm and cut the sides along the horizontal lines. Cut out the rear section of the shell behind the kick but leave the side section behind the 30 mm line. I like to mount the body to the chassis at this point to define the position of the rear wheels. The chassis should be on a mounting block that allows the guide and tires to "hang over". Place the body over the chassis so the bottom edges are on the mounting block flush with the bottom of the chassis side rails. You can now move the body back or forward to the desired position. I usually mount the top of the kick about 4 mm behind the rear axle. Mounting the body further back increases tire bite, forward increases nose pressure. The car runs looser with the body forward but may get through glue better. Once you've decided on position make sure the guide is free and push through your mounting pins. Mark the position of the rear tires with the bottom of a tire vial and remove the shell from the chassis.
AIR CONTROL DEVICES
Slick 7 offers an excellent complete wing kit that only requires you to choose thickness. For most applications, use .005 side dams and .005 spoiler. For more down force you can try a 7 thou spoiler. The diaplane is pre-bent and fits nicely below the front of the shell. You may wish to lighten it by using a hole punch on the mounting tabs. Cut two pieces of half inch fiberglass tape each 1 inch long to attach the diaplane at each side to the under surface of the shell. The bend should line up at the front of the body and the diaplane should extend directly forward without pointing upward or downward. You may have to bend it against a flat surface to accomplish this. The side dams are mounted next. Position them so the rear wheel cut outs are aligned with the rear wheel marks and the bottom is flush with the bottom of the shell. I always use pin reinforcements between the shell and the side dams, "ninja stars" (Slick 7 part 118) on the front and body washers (S7-138) on the back. They prevent the pins from pushing through and keep the body useful for a few races. Apply body adhesive to the side of the shell, stick on the reinforcements then apply the side dams. To attach the spoiler I recommend using double sided Scotch tape. This allows easy removal in case you want to change it in a hurry.
The side dams require trimming and I would recommend doing this before application. The forward edge must be cut off at the front of the shell. Mark the position and cut at the same angle as the stock dam. For swoopy tracks you can trim the top and cut a scoop in the center, but for most tracks running them stock is fine. I also trim the diaplane by shortening it about 2 mm and rounding off the corners. If you have too much down force the spoiler can also be trimmed down. I have seen some people cut holes or divide the spoiler but I would recommend against that as it tends to increase turbulence. We hate turbulence. At this point your body should look something like this:
It is important to strengthen certain parts of the shell both for durability and improved performance. 1/2" fibreglass tape, 3M mailing tape and small staples are used. I've never seen two people reinforce in the same way, so I'm going to tell you how I do it, but if you have a better idea, go for it.
The front of the side dams take a real beating and need added strength to be an effective air collector. Run a piece of fiberglass tape down the inside of the front edge, bend it at the body then across the front of the body and onto the diaplane. Make sure it gets right down into the corner between the wing and the body by bending the wing back when applying it. The angle should extend it about 2/3 the way across the diaplane and the two sides should be symmetrical. Some people fold the tape under the diaplane and extend it underneath but I don't like putting anything under there as it tends to get involved with the track surface. Here's what it should look like:
Further strength is added to the wing fronts with two layers of mailing tape 1" wide to the outside. The first is applied parallel to the front edge and the second perpendicular to the top. Laying them directly over each other encourages peeling. Want to see what I mean?
Anyone who races wing cars knows that the bottom of the side dam tends to come away from the front of the body in the heat of the action. My pal Cam showed me a little trick to help prevent that common problem. Cut a 2" piece of fiberglass tape in half lengthwise to make two 1/4" x 2" strips, one for each side. Lay each on the inside of the dam parallel to and just above the front of the body for about 3/4", then fold it around to the outside of the dam where it should run at about 45 degrees downward then underneath the body. Confused? Check out the diagram.
The diaplane needs to be unified with the body to serve its important function of cutting the air and directing it over the shell in a "laminar" manner. Simply run a 1/2' strip of fiberglass tape across the joint between the shell and diaplane. It should extend to the lower quarter of the front of the side dam to further secure it to the front of the body like so:
Next seal over the whole front end reinforcement with mailing tape across the front of the shell, diaplane and up the side dams.
The rear of the body requires far less reinforcement. I just run a piece of 1/2" fiberglass tape from the inside of the rear body mounting hole, over the wheel well and onto the rear side dam extending beyond the rear of the body. This secures the rear of the side dam to the shell and at the same time strengthens the rear body mount and reduces wing flap. Add a staple above the front and rear wheel wells and I think you are done! Check it out.
Now I'm sure that everyone out there and his mother has a way to make this wing car body better, faster, smoother, sexier, nicer, neater, sweeter, more durable, usable, raceable, and better suited to warm climates. So if you have suggestions share them with the world by writing me.
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