AND TRUNK, THE AERODYNAMICS!

AND THE TRUNK - AERODYNAMICS!For a start I suggest the readers-to motorists to conduct a little experiment. Once outside the town, stop by high-speed stretch of highway and watch whizzing past you cars. However, here you need not to watch but rather to listen. A quarter of an hour you will learn to distinguish aurally, the main types of cars: a sound portrait of the major role played by a characteristic noise of the flow over the body. But here comes a car with a roof rack and audio, the picture changes dramatically. The impression is that the car literally pushes through the dense unyielding environment. By the way, the impression is confirmed by experiments in wind tunnels. Purge models and full-size cars with roof racks have shown that increases dramatically the so-called Cx is the drag coefficient. But it depends on the speed and fuel consumption.
Especially it is a shame to install lattice trunk — this kind of air brakes on such cars as the VAZ-2108, “Tavriya” or the new “Moskvich”, with significantly lower Cx, than machines of the previous generation (VAZ-2108, it is against 0,38 0,47 in VAZ-2106), with consequently reduced fuel consumption.
 
Meanwhile, the car with a closed trunk of a streamlined “aerodynamic” shape, the fuel consumption would be not much more than a car without trunk. In addition, this container will allow you to transport things in any weather.
 
To make such a trunk is not too difficult. First you need to utformat of fiberglass and epoxy resin bottom of the container, which is a replica of the roof of your car. To do this, on the surface of the body is stretched plastic film. You only need to make sure it had no holes or gaps (otherwise you can mess up the paint). Film prihvatyvaya adhesive tape-adhesive tape, and on top of polyethylene is laid several layers of fiberglass impregnated with a binder is epoxy resin mixed with hardener (ratio: 8 volume parts resin to 1 part hardener). Then everything is covered with another layer of film, which in one way or another, is pressed over the entire surface of veclachi. The easiest way to do this is by posting on the roof of the plastic bags half-filled with river sand. After the curing of the binder Vileika is clipped to the outline of the roof; its thickness should be 4…5 mm.
Then from dural pipes Ø 22 mm is going to frame the future of the trunk. When bending tubes, it is recommended to use the templates out of cardboard or thin plywood, repeating the corresponding contours of the roof — this will ensure that frame its contours. Pipes are joined through dural gussets and rivets or screws with nuts.
 
Fig. 1.
Fig. 1. “Aerodynamic” trunk and its main elements (for VAZ-2108):
1 — frame (dural tube), 2 — deflector 3 — deflector bracket, 4 — the shell of the boot, 5 — Luc.
 
Fig. 2. The frame of the trunk.
Fig. 2. The frame of the trunk:
1 — the lower longitudinal elements 2 is a longitudinal top elements, 3 scarves, 4 — rail, 5 — rear cross base 6 — front crossmember of the base.
 
Fig. 3. The preparation of the body to vitlake the shell housing.
Fig. 3. The preparation of the body to Vileika body shell:
1 — wire, 2 — frame, 3 — polyethylene film.
 
Having assembled the frame and making sure that it fits the roof of your car, tight fit an it with plastic wrap (it can fix and tape) on the outside of the frame. Then the frame is flipped upside down and suspended from the ceiling of the Studio — better on a thin steel wire, as shown in our drawings. After that, the polyethylene laid stekloreza, impregnated with epoxy resin. The thickness of veclachi should be 3…4 mm. to obtain a smooth surface of double curvature, on top of mats laid plastic film, which is filled with a layer of river sand. This should be done carefully, all the time watching the character of the resulting surface. I must say that the curvature form of the shell will depend on the thickness of the layer of sand in a given place, therefore, in the curing process of the resin (this is 2…3 hours), you can make adjustments to the hull shape of the trunk, adding or removing sand from a particular plot. If you need a local, rather sharp bending of the surface on the area of interest of veclachi superimposed sand filled long plastic bag, or an ordinary stocking. After curing of the resin the polyethylene can be easily removed and the shell glued the top layer of fiberglass.
Access to the trunk is carried out through hatches in its side surfaces. Manhole covers is a reinforced foam and two layers of fiberglass side shell. Please note that you must first seal the sidewall from the inside with strips of foam with a thickness of 10…15 mm, then two layers of fiberglass, and after the curing of the resin to cut out the hatches on the planned circuit, it is possible to make fine teeth vygruznoy saw or better yet, a saw blade with a cloth.
 
Cover can be mounted on the hinges, but still better to make removable. To fix their best furniture locks, having a cylindrical pull-out tab and the “English” key.
 
Docking of the housing the Luggage compartment bottom is made with strips of fiberglass and epoxy resin.
 
At the turn of the roof of the trunk, it is desirable to set the deflector, wing-shaped aerodynamic surface designed to improve flow around the rear of the machine. The deflector can be applied to the wall of epoxy resin and fiberglass or bend out of sheet aluminum 1.5 mm thick.
 
Final surface finish includes Vykurovanie, the putty surface composition on the basis of epoxy resin and talc finish Vykurovanie and painting the trunk in several layers with intermediate grinding of the surface.
 
According to the magazine “Popular Mechanics” (USA)

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