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Wednesday, February 8, 2012

The Retrofitted Kammback: The Ability to Improve MPGs

The Retrofitted Kammback by               S. Johnston
Using the design principles of aerodynamicist and auto engineer Dr. Wunibald Kamm, I was able to manufacture a retrofit version of his brainchild, the “Kammback”.  In doing so, my personal vehicle experienced significant design changes.  These changes contributed greatly to optimizing its efficiency and ultimately gave great insight as to Dr. Kamm’s genius.
The Ability to Improve MPGs

Spencer Johnston
The Ancient Engineers HUM2930
Dr. George Brooks
Valencia Community College, Orlando Florida

The Retrofitted Kammback: The Ability to Improve MPGs

          The Kammback is an automotive design type created by Dr. Wunibald Kamm.  Dr. Kamm, an automotive engineer and aerodynamicist designed the Kammback to enhance the performance and efficiency of passenger automobiles. The Kammback is an automotive design that capitalizes on the principle of aerodynamics. Automobiles have a relatively short history, beginning with the Benz Motorwagen in 18861.  Aerodynamics in cars has an even shorter history.  It wasn’t until engineers of the 1930s, including Dr. Wunibald Kamm of Germany, began to consider aerodynamics as an important aspect of automotive design and functionality. 
Kamm is responsible for what is now known as the “Kammback”.  This automotive design employs a smooth, tapered back that promotes positive airflow through aerodynamic principle (figure 1).  Automobiles donning a Kammback would see greater fuel economy as well as handling.  After perfecting his design, the time had come for Kamm to implement it.  He did so with BMW in 19482.  Although several vehicles have integrated Kamm’s design throughout the years, perhaps his research has done more good conceptually than practically.  In other words, his work was not in vain.  Through the work he had done, other automotive engineers learned how to further understand the benefits of aerodynamics in their designs.
Kamm’s design principles were not used broadly in the engineering of automobiles at first.  Automotive design of the 1950s and 60s was primarily focused on high-performance muscle cars.  Sadly, much of the accomplishments in automotive aerodynamic design fell to the wayside during this time of excess.  Although widely deemed as aesthetically pleasing and fun to drive, cars such as the ’57 Chevy and the ’67 Ford Mustang did little to nothing in terms of progressing towards further efficiency. 
Following the years of muscle cars, Americans experienced an oil crisis in 1973.  During this time, political pressures amounted to depleted availability of fuel for vehicles.  This crisis also included incredibly high prices when scarce fuel was available.  This was the beginning of modern concern over fuel efficiency in American vehicles.  Finally aerodynamics would return to the forefront of automotive engineering. 
The new concern seemed to affect people big and small.  For instance, in 1973, General Motors introduced the “Aerovette”, which was an aerodynamically superior corvette, designed by a team of GM engineers, perhaps for the conscientious well-to-do sports car enthusiast3. An interesting tidbit is that the program for the Aerovette was shut down by John Delorean, who would later become the founder of Delorean Motor Company and the infamous Delorean DMC-12.4   Perhaps he knew of his plans to build the iconic car that was featured in Back To The Future.  The Delorean remains a cult favorite among car enthusiasts.  Myself as someone who enjoys aerodynamics found the use of rear window louvres to be a monumental plus.
In the years to come, cars were getting smaller, lighter in weight and more aerodynamic than ever.  Cars in the mid-1970s utilized the Kammback and similar designs from time to time, an example being the Chevrolet Vega Kammback (figure 2). 
Because aerodynamics plays a major role in the performance of automobiles’ fuel economy, modern engineers and designers often employ its principles in their beginning stages of work.  Recently, cars, trucks, vans and even commercial applications have begun to receive treatments that are far more aerodynamic than their predecessors, which ultimately help to meet the demands of consumers who are fighting back against skyrocketing gas prices of the early 21st century.  Although these automobiles are moving in the right direction, there is still a significant shift towards aerodynamic design that is much needed. 
Perhaps the most exciting execution of aerodynamics in automobiles is found in the aftermarket.   In fact, one is hard-pressed to find a car on the road today without a spoiler of some sort, most of which are quite obviously after thoughts.  Very few of these affect gas mileage or flow very much either.  The excitement I’m referring to is a new trend referred to as “ecomodding”.  Essentially, ecomodding is the modification of one’s vehicle to obtain better fuel efficiency, which in turn lessens cost of operation and the environmental impact of said vehicle. 
Last year, I purchased a used turbo diesel Volkswagen beetle in an attempt to improve my gas mileage, and ultimately, save my family money.  Already, I have had great success in doing so.  The car’s frugalness has saved upwards of $1400.  Unfortunately, as I have done more research, I have learned that the beetle’s design, albeit cute, is flawed.  I do love the appearance of the beetle.  It is iconic.  It is fun.  It is aerodynamically retarded.  As an efficiency nut and young student of practical engineering, I find this to be almost a paradox.  Why wouldn’t they make the design of the beetle more aerodynamic?  Is this a joke?  Can’t we have it all? 
In my own personal attempt to improve my car’s gas mileage, I saw an opportunity in this assignment to construct a Kammback of my own.  With the knowledge that the beetle has horrible gas mileage as it was, I knew that any improvement would go a long way.  Because of the car’s convex rear windshield, it was somewhat challenging to approach the merging of the car with the kammback.  I found that many materials lacked tinsel.  One day during the political season, I noticed an abundance of campaign signs and thought, “those look good”.  So, after the elections were over, I obtained several of the signs and began constructing the beetle’s kammback.
When I began my experiment with constructing the kammback to attach to my car, I wasn’t as optimistic as you might expect.  After visiting dozens of websites of other people like myself who were attempting to gain high mileage from the vehicles they already owned, I finally came to the conclusion that no one had done exactly this to a beetle before. 
Finally, I dove right into making the thing.  First, I made several measurements to ensure that the pieces were symmetrical.  Corrugated plastic, which is what these infamous signs are made from, were actually quite ideal for this project.  A simple measurement marked the axis of symmetry on one of the signs.  These two triangles became my sides.  I then measured the distance from the front of the would be kammback to the rear.  Conveniently, the signs that I used for the top of the kammback were the same length as the “triangles” I had cut from the other signs.  From here, the process included using duct tape to secure the cuts together as well as to the windshield itself.
After construction was complete, I decided the best way of testing the kammback’s performance was to take it on the highway.  Typically my car averages around 42 miles per gallon on the highway.  This already was a two mile per gallon improvement over the EPA’s estimate of 40.  Because accuracy was important to the authenticity of my project, I fueled up and drove solely on the highway before filling up once again to get a read of my fuel efficiency.   To my amazement, the kammback provided an additional 13.5 miles per gallon, raising my highway fuel economy to 55.5 mpg.
Reflecting upon my project, I’m delighted at my results.  In spite of the extensive observations I’ve made on sites like, I truly did not expect the increase in efficiency that I obtained.  It is easy to underestimate human ingenuity.   Perhaps more interesting to me is that the vast majority of drivers on the road have, in their own ways, overestimated the efficiency in their respective vehicles.  Sure, today’s automobiles are engineered brilliantly.  But, would it bother these other people to know the difference that just a smidge of extra effort put forth on the drawing board would make in their lives?  14 miles per gallon is semi monumental.  Considering that there are more sport utility vehicles, minivans and other large vehicles on the road today than ever, it seems as though there are more that stand to benefit from an aerodynamic design than not.  For instance, a Ford Explorer averages 19 mpg on the highway according to the EPA6.
It is interesting how certain technologies have become standard in our lives.  For the same matter, it can be just as interesting as to why other meaningful strides in technology have not.  Perhaps the modern design of automobiles is what we’ve been conditioned to appreciate in a car, truck or other.  But from an outsider’s perspective, I’m almost positive that there is virtually no difference between an aerodynamic powerhouse (figure 3) and a Ford Taurus (figure 4).
However, beauty is in the eye of the beholder.  A prime example of this would be the western wagon wheel.  Because of the arduous process a wagon wheel’s design and manufacture demands, it is often regarded as a display of beauty to those who are informed about its construction.  In the same way, aerodynamic features of automobiles can be quite pleasing to the eye.  However, a lack of understanding the function of this design often leads the public to experience “an aesthetic nightmare” (Moreira).  Ah, the ignorance.  Before reading about it, I was ignorant of the wagon wheel’s beauty, even the beauty of these aerodynamic designs.  That’s why being as informed as possible about the things we surround ourselves with is important.
To some things up, I have truly learned a lot about automotive design and aerodynamics.  I feel really good about these concepts and think that being informed about them is important as a consumer and as a member of society.  I say a member of society because these damn cars are taking over everything.  Everyone has one.  Some people have two or three.  Mind you these two or three aren’t getting more aerodynamic as they accumulate either!  In the long run I hope that my beetle kammback will do two things:  get me better mileage and get people thinking more about aerodynamics.
Figure 1: 1944 BMW 328 Kamm prototype, via

Figure 2: Chevrolet Vega 2-Door Kammback, via

Figure 3: Mercedes Benz Bionic Car, via Mercedes Benz

Figure 4:  Ford Taurus, via Ford

Works Cited:
5.   Back To The Future, 3 July, 1985.
7.   Moreira, David.  “Auto-Future: Active Aerodynamics”,, January, 2009. 

Other Sources of Study:
-Traffic, by Tom Vanderbilt
-2 Million Cars: Driving Toward Sustainability, by Daniel Sperling and Deborah Gordon