A 0.12 C Auto Body Shape and Video
Sep 28, 2017
Phil Knox tested a five foot long model of a 0.12 Cd Auto Body Shape at the Darko Wind Tunnel in Ogden, Utah on Friday September 15th, 2017 and it tested as advertised. We discuss the implications of this shape in this blog and in a video we shot in my garage on Tuesday September 26th, 2017 where we show the model
by John Gilkison, and Phillip Knox
On September 28, 2017 Phillip Knox had his 5 foot long model of a 0.12 Cd auto body shape tested at the Darko Wind Tunnel in Ogden, Utah. It tested out as advertised and would fulfill all the claims we have been making for this auto body shape in our feature articles and blogs on the subject. See the article “A High Speed Aerodynamic Paradigm” at EV World, and the blogs “100 Miles per Hour and 32 Miles per Gallon”, and 100 MPH and 100 MPG e.
On Tuesday the 26th of September 28, 2017 Phil and I set the model up in my garage and shot a 14 minute and 50 second video about the model explaining the amazing attributes it has and how such an auto body shape could increase the fuel economy, and lower the energy requirements of the current crop of electric vehicles today. You can view the video at.
The 0.12 Cd Auto Body shape was first described by a Hungarian researcher Paul Jaray who worked for the Zeppelin Works in 1922. It was tested in the wind tunnel at the Zeppelin Works and met the 0.12 Cd criteria. Other researchers who tested this shape over time were Wolfgang Klemphere, Walter E, Lay, and Baron Fachsenfeld. All of them came up with similar results.
Cambridge University tested and used the shape in the World Solar Challenge in 2013. So have many others in MPG and Solar challenge runs. Doctor Paul Mac Cready the creator of the GM Solar Racer said in 1991 the EV-1 would be a 100 MPG car with an IC Engine. The EV-1 was inspired by the auto body shape.
Taking the two lowest MPG for the Tesla Model S and X (because of all wheel drive) of 100 MPG e and 90 MPG e respectively and a current Cd of 0.24 the 0.12 body would cut the drag in half which would result in a 25% increase in highway MPG. The Model X would get from 90 to 112.5 MPG e and the Model S Highway MPG e rating would increase to 125 MPG e.
Other Electric cars with less slippery shape would fare even better. The Chevy Bolt with a 128 MPG e rating on the highway would see an increase to 160 MPG e or more because its Cd is not as low. Similarly the Nissan Leaf which I rate at 114 MPG e on the highway would see a increase to 143 MPG e. Given that these cars have a Cd that is higher the 0.24 they would see even better numbers given that the ratio of improvement would be higher than 25%.
Range on the highway would be increased dramatically also. A 238 mile Chevy Bolt could see an increase to 297 miles. The 2018 Nissan Leaf from 150 miles to 187 miles. Given the higher drag shape of both of these cars (as compared to the Tesla) you would easily have a 300 MPG e and 190 MPG e capable cars respectively.
We pointed out in the video the aft body shape beyond the 50% of frontal area would need to be deploy able. Driving around in city traffic with such a long shape would be both unnecessary and dangerous. Mercedes Benz has demonstrated deploy-able aft body panels in one of their prototype vehicles recently so we know this can be done.
The way this would work is that when you got on the highway and increased your speed to 45 MPH or higher the aft body would then deploy. You would have to have an override capability because there are times when you would still be in traffic at these speeds and you would not want the aft body deployed for safety reasons. It would be more of an enable feature rather an override. The default state would be not to deploy.
In 2013 Phillip Knox and I wrote a feature article for EV World titled A High Speed Aerodynamic Paradigm which you should read to get a deeper explanation of the capabilities a lower drag auto body form like this gives motor vehicles. You can find this article at.
One of the biggest complaints we had was about our blogs on the subject was that most people did not know what this 0.12 Cd Auto Body Form looked like. This is why we wrote the feature article with pictures. The high speed paradigm (90 MPH to 100 MPH) was postulated simply to get people’s imagination fired up about what lower Cd shapes meant for vehicular performance. If the shape can yield high mile per gallon returns at 100 MPH one can only imagine what the shape can return at current interstate speed limits of 75 MPH or less.
Some pundits were upset about this high speed paradigm and suggested we were trying to get people killed or even worse people would be forced to drive at these high rates of speed even if they did not want to. Nothing could be further from the truth as we indicated in our articles such a set up would require three lane roads with the right lane reserved for normal traffic, the middle lane for passing, and the left lane reserved for high speed traffic only.
We did suggest that a 25% increase in allowable interstate highway speed (to 100 MPH) would decrease travel times in the country dramatically and the body form required to do these speeds would increase MPG’s at normal speeds dramatically also. A 111 MPG return for an IC engine car at 55 MPH would constitute just such a dramatic return. Traffic as a matter of course would have to slow down for congested areas near and in metropolitan areas.
Regardless of speed low drag shapes save fuel, increase range, and allow for better performance at all highway speeds. They are of course of marginal use in city traffic. Hopefully there will still be open highway travel at speed in our crowded future.
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