Written by | Little Devil
In the pursuit of the highest speed, human beings have always been quite persistent, in addition to using their own legs, we are also trying to use a variety of animals and machinery that can be driven to pursue this kind of racing excitement, and the most addictive of them may be racing.
When we tried to break through the various speed limits with cars, we found that air resistance had become the most difficult "enemy" to date. Because on the highway, more than half of the energy of the car is used to push away the air.
Of course, after decades of experience, we are not completely helpless to deal with air resistance, and the streamlined body built according to aerodynamic characteristics is a "weapon" to combat air resistance.
Speaking of speed, I have to mention the famous Bugatti, Bugatti's Weihang and Chiron are recognized as the fastest sports cars in the world.
While other sports cars are still complacent about the top speed of more than 300 kilometers per hour, both of Bugatti's sports cars have broken through the 400km/h speed mark, and most people naturally think that the automotive field is dipped in Bugatti's light, and only in recent years has reached a speed of 400km/h.
But you may not know that as early as 1938, Mercedes's W125 ran a top speed of 432.7km/h on the public road!
So how did the Mercedes-Benz W125 surpass Bugatti in decades? In fact, it depends on aerodynamic efficiency.
In general, when the speed is high, the aerodynamic force required to push the air away is proportional to the cube of speed, while mechanical losses such as drivetrain and rolling resistance are only linearly proportional to speed. Therefore, at high speeds, aerodynamic power can easily account for more than 90% of all the energy needs of a car.
Bugatti's Wei hang and Chiron can have such a high speed performance, in large part because of the "power miracle", because the 8.0-liter four-turbo W16 engine itself can provide extremely high power and torque output, but in terms of aerodynamic efficiency itself, its performance is not outstanding, and its air resistance coefficient is about 0.36, even higher than some SUVs.
For some professional cars that are also pursuing speed, such as F1 cars, because of the extreme lightweight performance, do not require particularly high aerodynamic efficiency, usually their air resistance coefficient is about 1.00, this number looks very bad, but it has enough power to overcome the loss of air resistance and use downforce to transmit power to the ground.
So if it can't achieve bugatti's high engine output, nor can it achieve the lightweight performance of an F1 car, what way can a road car push up the speed?
The Mercedes W125, which has an output of "only" 495kW (still a huge power by 1938 standards), can run at a speed of more than 400km/h by its extreme streamlined body, because the air resistance coefficient of this car is only 0.235, which is more than one-third higher than the aerodynamic efficiency of Chiron!
Of course, the purpose of road cars is to carry people, preferably in a practical, safe and affordable way, so their constraints are very different compared to sports cars or racing cars. Still, as we mentioned earlier, even at normal highway speeds, air resistance remains by far the most important source of energy loss.
So you'll find that even before the breakthrough of electric vehicles, automakers have been sparing no effort to find ways to reduce these losses. After all, aerodynamic efficiency directly affects the fuel consumption of a car. For example, Ford experimented with various body shapes in their "Probe" concept car series. Among them, the wind resistance coefficient of ProbeV is only 0.137!
If this shape is so practical for fuel efficiency, why don't all car companies make cars like "Probe"? In addition to practicality, one of the biggest problems is that many people don't like this style.
A few people who are interested in aerodynamics, you may be able to convince him to accept such a look, but you can't convince others, and car companies obviously understand that cars facing the mass market need to be more in line with the mainstream aesthetic.
Of course, recently some car companies have tried to create an electric vehicle that conforms to the aerodynamic characteristics as much as possible in terms of styling and maintains a good appearance, such as LightyearOne (wind resistance coefficient "less than 0.20") and Mercedes-Benz EQXX (wind resistance coefficient of 0.17). It should be noted that neither car was mass-produced.
Although these two cars look good, their shape is undoubtedly still with a certain "compromise". For example, these two cars use a long and low tail design, which is obviously not common in modern family cars, nor does it meet the aesthetics of mainstream market users, so even if they are mass-produced, they are not very likely to become mainstream cars.
Relatively speaking, cars like tesla model SPlaid and LucidAir are actually more impressive, although the wind resistance coefficient of these two cars is slightly higher than that of LightyearOne and Mercedes-Benz EQXX, both around 0.20, but their shape is more like ordinary cars - that is, they have not made any compromises in design, so they are more attractive to the mass market.
With the advent of electric vehicles, the focus has now shifted to the issue of endurance. Every 1kWh/km of energy consumption saved makes electric vehicles cheaper (fewer cells are required to travel the same distance), lighter (batteries are lighter), and more efficient (lighter weight means lower rolling resistance).
The biggest reason why many people are reluctant to accept electric vehicles is the anxiety about range, and aerodynamics once again plays a crucial role before the battery makes breakthroughs.
If the automaker gives an electric car the better streamlined shape it is, the higher the range of the car in the same battery configuration, and the higher the likelihood that it will be accepted by consumers.
Tesla's focus on aerodynamic efficiency is no coincidence, and we can clearly see from the styling that not only its cars and SUVs, but even the semi-trailer Semi has adopted a streamlined design.
Tesla isn't the only electric car maker to focus on aerodynamics, and in fact latecomers like Lucid and Rivian are also trying to create as streamlined shapes and smooth body surfaces as possible for their vehicles.
With "uncompromising design", what can we achieve in the future? This may depend on the automaker's definition of "uncompromising design", as some designs simply take time to adapt.
If you insist on using open wheels, then the ENO.146 concept car launched by GAC Aeon in 2019 is a good example of what kind of electric vehicle is possible in the future. The wind resistance coefficient of this car is only 0.146, which is lower than the Mercedes-Benz EQXX, and the car still looks normal in terms of vehicle proportions and tail length.
Or car companies can choose to further refine the existing design, adding only a little compromise. In the case of this Tesla Model SPlaid, as long as its rear wheel is partially covered (like the Rear Wheel of the LightyearOne), its wind resistance coefficient can be reduced by 3.5%, and the wake and energy loss caused by the "splitting" of the air in the rear wheel will be greatly reduced, which is very important for aerodynamic efficiency.
In fact, car companies can go one step further and change the overall layout of modern cars - starting from scratch and designing a new shape with the goal of the highest possible efficiency, which is exactly what Aptera has done. The waterdrop-shaped solar three-wheeled electric vehicle has a drag coefficient of only 0.13, and it is said to be able to support up to 1609 km of endurance.
Nowadays, the aerodynamic efficiency of automobiles has been greatly improved, especially with the transition to electrification of automobiles, the market is particularly concerned about the endurance performance of these electric vehicles. But it's clear that these electric vehicles haven't reached their limits in terms of aerodynamic efficiency, and we expect to see more streamlined electric vehicles in the near future.
Some electric cars may look ordinary because they are geared towards the mainstream user market, but they cleverly hide various aerodynamic design techniques under their bodies. There will also be some electric vehicles on the market that look completely futuristic, and these cars will also attract more specific audience users. But one thing is certain: aerodynamics will play a more critical role in the design of future electric vehicles. 【END】