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Published on December 25th, 2019 | by Jennifer Sensiba


Active Aero Fans Improve Aerodynamics, But Will They Go Into Production Cars?

December 25th, 2019 by  

Image by Gordon Murray Design

An article a couple of weeks ago at Road & Track gives us a small glimpse into the future of efficient transportation, but from an unexpected source: a new supercar concept. In short, the car uses a powerful electric fan at the rear, pulling air through ducting to increase the vehicle’s performance in several ways.

There’s nothing new about this basic concept. For example, the Chaparral 2J, a racecar built for the 1970 Can-Am series, used a 55-horsepower secondary combustion engine to suck air from below the vehicle like a vacuum, pulling it down to the track and increasing traction greatly. It won many races, but was banned later because officials felt it was a type of cheating.

Image by Gordon Murray Design

The new T.50 concept also linked above does what the Chaparral did and more. To get more traction, the electric fan at the rear of the vehicle can pull air from under the car to increase downforce and get a better bite on the track at key times. Perhaps more importantly, it can also draw air from key spots near the rear of the car’s body to get the boundary layer moving faster and fill in a vacuum zone behind the vehicle, decreasing drag by 10%.

The computerized fan and duct system can automatically optimize the fan’s use for a variety of things. In some modes, it enhances braking and cornering by sucking the car down to the road. In other modes, it can concentrate its power on reducing drag.

Supercars are far from the only application for this concept. For example, NASA is experimenting with adding an electric fan engine to the back of airplanes (as in the video above), or having the regular jet engines ingest the boundary layer to help reduce drag on the plane’s body.

The variety of shapes that a useful automobile must come in would make it a lot harder to incorporate such designs, though. The basic airplane shape is out in many ways, as it wouldn’t fit the cargo and space needs of many drivers and wouldn’t be very aesthetically pleasing, either. On the other hand, NASA’s ideas may work for cars optimized for aerodynamics, like the in-development Aptera.

Other duct shapes are certainly possible, but would need a lot of careful testing and development to give a real effect. For example, a properly shaped duct could be put in along the rear of a vehicle’s roof to pull the boundary layer air in at that point, and spit it out by the rear bumper to reduce the vacuum zone there. In theory, this could work for an SUV and possibly some pickups, but would have to be tailor-made for each vehicle’s unique shape.

But will automakers think increasing range by up to 10% is worth the expense? Probably not, unfortunately. As the cost of batteries continues to fall, simply increasing the size of an EV’s battery pack by 10-15% may prove to be cheaper than such a system.

We will probably see this design incorporated on a limited basis to only the most hyperefficient EVs and vehicles aiming for outright performance and top-speed–powered by batteries or not. 

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About the Author

Jennifer Sensiba is a long time efficient vehicle enthusiast, writer, and photographer. She grew up around a transmission shop, and has been experimenting with vehicle efficiency since she was 16 and drove a Pontiac Fiero. She likes to explore the Southwest US with her partner, kids, and animals.

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