Anonim

TESTING

A breeze in the bells and whistles

Sympathetic, dangerous, useless …

We determine in the wind tunnel the pros and cons of spoilers, deflectors, pads and other fashionable products of this kind.

Sergey MISHIN

What you will not see today on a car of a car mod! If only it looked “cool”! Such an enthusiast spares no effort and money by buying attachments, the purpose of which is encrypted in high-tech names.

We decided to find out how such "jewelry" affects (or does not affect) the performance of the machine. The market chose what, according to sellers, is in high demand.

Let us clarify that our task included only a fundamental assessment of such products. Do they correspond to the purpose declared by the manufacturer? For example, does the fly bucket protect the windshield from insects. How does the installation of such accessories affect the aerodynamics of the car, visibility, noise in the car, interior ventilation …

The work was divided into two stages. At the first, our experts evaluated each mounted element and their combinations in real traffic conditions. At the second, the aerodynamics of VAZ 2109 and VAZ 2110 cars were examined with various variants of the “dodger” in the wind tunnel of the VAZ Technical Development Directorate (formerly Scientific and Technical Center).

Both cars were equipped with 175 / 70R13 tires, two exterior mirrors, and rear-wheel aprons. By the way, for the curious: even these little things are noticeably reflected in the aerodynamics of the car. For example, standard exterior mirrors can increase the “streamlining factor” - the product of the aerodynamic drag coefficient CX and the cross-sectional area F of the machine (Table 1) - by 0.011 m2.

Specialists explained to us the purpose of each aerodynamic element. So, the deflector directs the air flow to one or another zone, for example, behind the fifth door on the VAZ 2109, reducing its pollution due to the "suction" of dust, smoke from the exhaust pipe, etc.

The spoiler reduces turbulence when the air stream separates from the body - and this reduces aerodynamic drag.

The wing (wing) creates a lifting (pressing) force under the influence of the incoming air flow.

So, here are the purge results. Some - let's say right away - are just unexpected. For example, a “fly swatter” noticeably - by 2.7–2.8% - increases the aerodynamic drag coefficient of the car, and protects from the “bombardment” with pebbles only that narrow hood area that it covers. The deflector, which the owners of the cars of the “eighth” family set on the “back of the head”, copes well with its role as a “cleaner” of the rear window, practically without affecting the drag coefficient. But … noticeably worsens the picture of vertical forces acting on the axis of the car. Remembering this is especially important for overly temperamental drivers on a slippery road, as well as for those who, “saving”, equip studded tires with only the drive axle, leaving the other to do.

Recently, even a serious company has a similar problem. It turned out that the "Audi TT" in the configuration without a rear spoiler at a speed of over 200 km / h almost completely loses traction of the rear wheels with the road. This is the result of a serious “puncture” in aerodynamics.

Manufacturers of "body kit", as a rule, are little interested in such "little things"! And it’s out of the question to coordinate their “works” with the car manufacturer, for which these decorations are provided. Meanwhile, of the “decorations” presented in our test, only the pads on the door handles and edges do not affect the safety for which every auto manufacturer is responsible.

The hitch elements, of those that are named here (as well as others), can be useful or harmful from the standpoint of aerodynamics, and not only it. At the same time, some negative effects - for example, a radical change in the distribution of lifting forces along the Samara axes with a deflector - are almost impossible to predict speculatively without research in a wind tunnel. Be sure to keep this in mind when buying such accessories.

And now let's move on to the most important thing - the results of blowing attachments in a wind tunnel (prices in Moscow are indicated).

COVER ON THE HOOD, popularly referred to as the "Fly Swatter".

The intended purpose is to protect the windshield from insects.

Manufacturer - Aileron Tuning, St. Petersburg

The price for the "tenth" family is 600 rubles.

The price for "Samar" is 500 rubles.

Wind tunnel test results

VAZ 2110 - an increase in drag coefficient of 0.009 (2.7%). An increase in aerodynamic lift on the front axle by 19.7%, on the rear axle by 10.2%.

VAZ 2109 - an increase in drag coefficient of 0.013 (2.8%). 23% increase in aerodynamic lift on the front axle.

Expert Assessment Results

On machines with overlays, mosquitoes and midges continue to beat on the glass and spread on it in the same way as without overlays, which is understandable. The naive people who believe that the “fly swatter” is capable of fundamentally changing the nature of the flow around the machine by raising the flow over the roof is an inexhaustible contingent for dealers in these products. Demand creates supply! But the fly, meanwhile, is not made of air - and therefore flies in accordance with other laws. This is true for much denser grains of sand, pebbles and … just stones. Actually, the "fly swatter" protects from the bombardment only that narrow zone that it covers. Therefore, if you develop the idea, then you need to make the "fly swatter" the size of a bulldozer knife - and then the whole car will be protected. But why then pay a considerable amount for the design of the machine!

The pad is again attached not to the air. Sand is well sucked into the narrow gap between it and the hood along with the whirlwind that arises, which is difficult to remove without removing the cover. And since both the hood and the pad vibrate in motion, the grains of sand leave ever deeper scratches on the paintwork. In some cars under the "fly swatter" the paint was rubbed to the metal.

Pluses are doubtful.

Cons - a slight increase in fuel consumption and aerodynamic lift; rubbing on the front edge of the hood under the pad during prolonged use.

The pictures clearly show that the main airflow attacking the windshield, “fly swatter” almost does not change.

Diagnosis: "Fly swatter" is not only useless - to some extent even harmful.

OVERLAYS FOR SIDE GLASSES.

Presumptive purpose - reduces blowing air and rain in the cabin with open windows.

Price - 100-200 rubles.

Wind tunnel test results

The drag coefficient is practically not affected.

Expert Assessment Results

Visibility has significantly deteriorated due to the "expansion" of the windshield frame. It’s hard to see anything through the pads 2110 - very dark. Linings 2109 are not transparent at all. (By the way, on a dirt road and transparent ones will become opaque - do not forget this.)

At the same time, drafts in the cabin were reduced, especially with a partially open window, a drop of rain penetrates into the cabin less, cigarette smoke is well drawn.

Pros - weakening drafts in the cabin, protecting it from rain.

Cons - a decrease in visibility.

Summary: Changing the "flea". The linings improve the air exchange in the cabin, weaken the drafts, but this is achieved by the deterioration of visibility.

The windshield pillar (VAZ 2109) with the trim seems twice as wide.

TRUNK LID SPOILER VAZ 2110.

Estimated appointment - "for beauty."

Manufacturer - Aileron tuning, St. Petersburg.

Price - 900 rubles.

Wind tunnel test results

VAZ 2110 - reduction of aerodynamic drag coefficient by 0.005 (1.5%) and aerodynamic lift on the front axle by 7%, on the rear - by 41.5%.

Expert Assessment Results

During normal operation, no changes in the behavior of the vehicle were noted. An additional brake light on the spoiler is considered useful.

Pros - improved aerodynamic performance of the car.

Cons - not marked.

Summary: Nice. Useful in terms of aerodynamics.

This is how the dozens spoiler works in a wind tunnel.

SPOILER ON THE DOOR OF THE TEST “SAMARA”.

Estimated appointment - "for beauty."

Manufacturer - Aileron tuning, St. Petersburg.

Price - 800 rubles.

Wind tunnel test results

VAZ 2109 - decrease in aerodynamic drag coefficient by 0.007 (1.5%) and aerodynamic force pressing the rear axle to the road by 14.6%. The front is practically not affected.

Expert Assessment Results

No changes in vehicle behavior were noted. The tailgate glass is slightly less polluted - the spoiler partially cuts off the disturbed air stream from the door, raising dirt, dust or snow from the roadway.

An additional brake light is useful.

Pros - reduced rear window pollution; streamlining the car. Cons - not marked.

Summary: Nice. Useful in terms of aerodynamics.

DOOR HANDLES

cars "SAMARA".

Presumptive appointment - “so beautiful”!

Price - 80 rubles.

Wind tunnel test results

The drag coefficient is practically not affected.

Expert Assessment Results

It has become more difficult to use door handles - it is more difficult to find a trigger. Design is a matter of taste …

Pluses - no.

Cons - no.

Summary: Sheer trifle.

Handsomely?..

DEFECTOR TO THE “NAP” OF “SAMARA”.

Presumptive purpose - reduction of pollution of back glass.

Price - 200 rubles.

Wind tunnel test results

The aerodynamic drag coefficient is practically not affected.

Aerodynamic lifting force at a speed of 144 km / h increases on the front axle from 21.4 to 36.5 kgf, and on the rear axle changes from pressing (-15.5 kgf) to lifting (35.3 kgf).

Expert Assessment Results

The rear window is not soiled in rainy weather. The efficiency of the deflector depends on the correct installation.

Deflector vibrations occurring at certain speeds are noted. Experts attribute this to its lack of rigidity in combination with a significant mass - a deflector made of steel sheet.

Pros - prevents contamination of the rear window.

Cons - significantly increases aerodynamic lift.

Summary: Useful for maintaining rear window cleanliness.

Danger at high speeds. Most undesirable in winter, on slippery roads, especially if studless tires are installed on the rear axle.

It is advisable to install a deflector paired with a spoiler - it can significantly compensate for the lifting force caused by the deflector on the rear axle.

The deflector directs air along the glass, reducing the vacuum behind it.

SPOILER OF WIPERS OF THE WIPER (it is estimated on the SAMARA car).

The intended purpose is to increase the efficiency of glass cleaning at high speeds due to the additional aerodynamic clamp to the glass.

Price - 50 rubles.

Wind tunnel test results

The aerodynamic drag coefficient is practically not affected.

Expert Assessment Results

Improving the efficiency of cleaning glass was not noted.

Pluses - no.

Cons - no.

Summary: Discarded money.

DOOR PROTECTIVE COVERS. Evaluated on a SAMARA car.

The presumptive purpose is to protect the paintwork of the doors when they open when they touch the “neighbors” in the parking lots and with the walls in the garage.

Price - 30 rubles.

Wind tunnel test results

The drag coefficient is practically not affected.

Expert Assessment Results

The pads really protect against damage to the edge of the car door when it comes into contact with the wall of the garage or the sidewall of a nearby car.

Pros - justify the appointment.

Cons - no.

Summary: Lining is useful for those who use tight parking lots and narrow garages. From the point of view of aerodynamics are almost harmless.