By on February 14, 2010

[Note: A significantly expanded and updated version of this article can be found here]

That air presented the greatest obstacle to automotive speed and economy was understood intuitively, if not scientifically since the dawn of the automobile. Putting it into practice was quite another story. Engineers, racers and entrepreneurs were lured by the potential for the profound gains aerodynamics offered. The efforts to do so yielded some of the more remarkable cars ever made, even if they challenged the aesthetic assumptions of their times. We’ve finally arrived at the place where a highly aerodynamic car like the Prius is mainstream. But getting there was not without turbulence.

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Racers, particularly those chasing the coveted Land Speed Record (LSR), were generally the first to employ aerodynamic aids. The La Jamais Contente (The Never Satisfied) was the first automobile to break the 100kmh (62 mph) record, in 1899. Like all the first batch of LSR holders, it was an EV. The driver’s position seems to negate the aerodynamic aids, or maybe he was just posing, and more likely crouched down for the actual run.

The evolution of aerodynamics for LSR cars was remarkably rapid, as this Stanley Steamer Rocket of 1906 evidently shows. And the increase in speed was even more dramatic: the Rocket broke the 200km barrier, with a run of 205.44 kmh (127.66  mph). That would not be bettered until 1924, and not until 2009 for steam powered vehicles.

The first known attempt at streamlining a passenger car is this Alfa Romeo from 1914, built by the coach builder Castagna for the Italian Count Ricotti. Due to the very heavy bodywork, it turned out to not improve on the top speed of the open Alfa it was based on.

Undoubtedly, the real breakthrough aerodynamic passenger car was the German Rumpler “Tropfenwagen” (teardrop car) of 1921. Unlike the impractical and heavy Castagna Alfa, the Rumpler was as dramatically different (and influential) for its completely integrated and original design and engineering. It had a mid-engined W6 engine, and four wheel independent suspension using swing axles which Rumpler patented. The Tropfenwagen was tested in VW’s wind tunnel in 1979, and achieved a remarkable Coefficient of drag (Cd) of .28; a degree of slipperiness that VW’s Passat wouldn’t equal until 1988.

It’s important to remember that the Cd is a coefficient, and denotes the relative aerodynamic slipperiness of a body, regardless of its overall size. A brick of any size has a Cd of 1.0; a bullet about .295.  To arrive at the critical total aerodynamic drag that determines power required and efficiency, the frontal area (cross section of the vehicle looking straight on) is multiplied by the Cd. The Rumpler was relatively very aerodynamic, but it was also quite tall and boxy, which resulted in the one hundred or so production cars being used primarily as taxis. An ironic ending for Rumpler, but his ideas spawned imitations and extensions world-wide, and opened the whole field.

To put the nascent field of automotive aerodynamics in perspective, the typical two-box car of the twenties was more aerodynamic going backwards than forwards, as this ass-backwards car showed. That brings back memories of Bob Lutz stating that the Volt concept would have had better aerodynamics if they put it in the wind tunnel backwards.

Hungarian-born Paul Jaray used his experience working int the aeronautical field, and especially designing Zeppelins, to develop a specific formula for automotive aerodynamic design principles that lead to a patent, applied for in 1922 and issued in 1927.  His approach was influential, and numerous companies used Jaray licensed bodies during the streamliner craze that unfolded in the early thirties. His early designs tended to be very tall, and with questionable proportions and space utilization (below).

His designs eventually became more mainstream, and Mercedes, Opel, Maybach, and numerous other makes, primarily German, built special streamliner versions using Jaray bodies, like this Mercedes below:

The limitation of these cars is like the Castagna Alfa, they were re-bodied conventional cars with frames, front engines and RWD. Jaray only addressed the aerodynamics, not the complete vehicle like Rumpler had. It was a start, but others were taking up where Rumpler left off, like the English Burney, below:

Obviously more Rumpler influenced and less by Jaray, the 1930 English Burney featured a then-radical rear engine and also four wheel independent suspension.

One of the most influential and lasting designers of the whole era was Austrian Hans Ledwinka. After he took over as chief design engineer at the Czech firm Tatra in 1921, he developed the basis of a series of remarkable Tatra cars and eventually streamliners with platform frames, independent suspensions and rear air-cooled engines that Ferdinand Porsche cribbed from heavily in his design of the Volkswagen (VW made a substantial payment to Tatra in the 1960s to compensate them for this theft of IP).

The compact Tatra v570 of 1933 (above) is the forerunner of both the larger Tatras soon to come, and obviously of the Volkswagen. We’ll come back to Tatra later.

This Volkswagen prototype from 1934 (above) shows a very strong resemblance to the cribbed Tatra v570, with the benefit of some further refinement. Although the visual cues are not really as significant as they might appear to us now, because these were the leading-edge design elements of the time, and widely imitated or shared, on both side of the Atlantic.

As this 1934 prototype for an American rear-engined sedan by John Tjaarda shows, the Europeans weren’t working alone. This fairly radical design became tamed-down for the production 1936 front-engined Lincoln Zephyr, of which the less common but handsome coupe version is shown below:

Of course, Americans’ introduction to streamlining had come two years earlier  in 1934, with the stunning Chrysler Airflow (below). An essentially pragmatic approach, the Airflow also kept the traditional Body On Frame (BOF) front-engine RWD standard, but made some significant advances in terms vehicle design by pushing the engine further forward over the front wheels. This, combined with a wider body, dramatically improved interior space and accommodations. The Airflow had the same basic configuration as American cars from the late forties and early fifties. Progress is not always linear.

The failure of the practical Airflow can probably comes down to one thing: that overly flat waterfall grille. That was too much of  a break for the symbolism still engendered in the remnants of the classic car prow. The Zephyr had one, and it was a success, despite not being nearly as a good a car as the Airflow.

An even less pragmatic but remarkably practical and effective American vehicle was the Stout Scarab (above). Aviation engineer William B. Stout designed this extremely roomy mini-van precursor using  a unitized body structure and a rear Ford V8 engine. The first was built in 1932, and several more variations, a total of nine, were built in the mid thirties, but series production never got off the ground, due to an asking price almost four times higher than a Chrysler Imperial Airflow of the times, and even those weren’t selling so well just then.

A much more radical approaches to streamlining was Buckminster Fuller’s Dymaxion. The first of several prototypes also saw the light of day in 1933, in the midst of this fertile period on both side of the Atlantic. The Dymaxion also had a rear Ford V8, but with a tricycle carriage and rear wheel steering, which allowed it to turn on the length of its body.

Another lesser-know variation of the popular Ford V8 engined aerodynamic vehicles was this Dubonnet Ford of 1936, whose very slippery body allowed it to reach 108 mph. I appears to have  Isetta-type front doors for the front seat passengers. About as much crumple zone too.

Let’s jump back to Czechoslovakia and the fertile Tatra design studios. Here are some clays from about 1933 or so, showing the development of both the smaller VW-like v570 on the right, and the larger streamliners in the rear. The first of these, the T77, arrived in 1934 (below):

The T77 was measured to have a Cd of .212, a number that was not broken by a production car until GM’s EV-1 of 1995, which measured at .195.  A remarkable achievement, the long-tailed T77 was powered by a rear air-cooled V8, and began a long series of Tatras until the 1980′s along similar lines. My retrospective of Tatra is here.

Tatra became synonymous with the advanced streamliner of the pre-war era, enabling remarkably fast travel (100 mph) on the fledgling Autobahns of the Third Reich. Favored especially by Luftwaffe brass, they had a nasty habit of killing them, due to its wickedly-abrupt oversteer, thanks to the combination of rear V8 and swing axles. That earned it the nick name of “the Czech secret weapon”.  So many died at its hands, that supposedly Hitler forbade his best men to drive them. In many (other) ways, the Tatra 87 was the Porsche Panamera of its time.


To demonstrate just how far the aerodynamic envelope was pushed in this golden decade of streamlining, this 1939 Schlörwagen prototype was tested originally at Cd .186, and a model of it was retested by VW in the seventies with a Cd of .15. Either of these values put the “pillbug” at or near the top of the list of the most aerodynamic concept cars ever built, like the Ford Probe V of 1985, with a Cd of .137. Built on the chassis of the rear-engine Mercedes 170H, it was substantially faster as well as 20% to 40% more fuel efficient than its donor car. The Russians took the Schlörwagen as war booty and conducted tests as a propeller driven vehicle. It represents a state of aerodynamic efficiency in league with the most aerodynamic cars being considered today, such as the Aptera.

Its important to note that the rise of interest in aerodynamics in the 1930s arose out of the desire to reinvent the automobile from its horse and wagon origins and the assumptions that average driving speeds would be on the rise with modern roads. This made it a forward looking undertaking, as most drivers were plodding along at 35-45 mph outside of cities. But the first freeways were being built in Germany, and improvements in US roads, including the first parkways and freeways were taking place. It also explains the particularly strong interest and adoption of streamlining in Germany.

Note that I have not attempted to survey the influence of aerodynamics on the styling of cars in the latter thirties and up to WW II. Needless to say the influence was utterly profound, and gave us some of the most remarkable cars of the late classic era. But this had relatively more to do with style (and even affectation) than a genuine effort to push the envelope in terms of leading edge aerodynamics. Nevertheless, the benefits and beauty that resulted, like in this Bugatti Atlantique coupe are undeniable, but beyond our scope here.

Part 2: 1939 to 1955

Part 3: 1955 to the Present

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42 Comments on “An Illustrated History Of Automotive Aerodynamics – In Three Parts...”


  • avatar
    Monty

    Paul:

    Thank you for the excellent history lesson. I look forward to the next installment.

    One of the many reasons I visit this site are the entertaining and informative historical posts. Even though I have a broad knowledge of automotive history, I ALWAYS learn something new.

  • avatar
    FromBrazil

    Very, very interesting Mr. P. Niedermeyer. Look foward to the new series.

  • avatar
    psarhjinian

    What I always found interesting about aerodynamics is how the mainstream automobile industry forgot about them from ~1950 to ~1980.

    • 0 avatar
      baabthesaab

      The mainstream industry forgot because the mainstream public did not care. Cars were made to LOOK aerodynamic, but, until the oil shortage of 1973, nearly nobody cared about efficiency, and it’s only fairly recently that enough of the public expect it, and the industry has to deliver aero.

    • 0 avatar
      USAFMech

      Designers “forgot” about streamlining as a design goal because, by the 50′s with all of the advancements in aerodynamic understanding, they realized that the designs would become asymptotic. Eventually, all cars would be variations of tear-drops. Other, more exciting design avenues were pursued.

    • 0 avatar
      TR4

      Perhaps not very “mainstream”, but the SAAB 93 of the late ’50s claimed a Cd of 0.29.

  • avatar
    baabthesaab

    Re: the Dymaxion car: I remember Bucky Fuller telling me that, on one test drive, when a cop hollered at him to get that thing off the road, he opened the window, put his hand on the cop’s head, and steered a circle around him before driving away. Rear steering – wow!

  • avatar
    educatordan

    One of the things I love about aerodynamics is that little changes can make big differences too. Flush windows, more aerodynamic mirrors, and smaller grille openings can make huge differences. I often wondered how much better the coefficient of drag was for the “grille-less” Crown Victoria than for the redesigned ones that had a more traditional grille.

  • avatar

    For the Tatra fans a link to a (German) website with interesting pics: http://www.zuckerfabrik24.de/autos/tatraplan_1.htm

  • avatar
    Btrig

    Paul, you’re one of my top favorite car guys. I always look forward to your consistently informative, insightful, and interesting articles. Keep up the good work!

  • avatar

    Paul,

    According to Paul Schilperoord, who’s written about Josef Ganz, http://www.ganz-volkswagen.org/, Porsche, Ledwinka, and the European automotive scene in the 1920s and 30s, the patent dispute between Tatra and what became VW mostly had to do with the design of air-cooled horizontally opposed engines.

  • avatar

    The luftwaffe staff dying of oversteer on the autobahns–Ludwinka’s revenge!

    I love this stuff, too. Is the DS going to appear in the next installment?

  • avatar
    Monty

    I just realized how much the Jaray Mercedes resembles a Citroen DS. Can’t be much of a coincidence, I’m guessing.

  • avatar
    The Gold Tooth

    I’ve wondered since I was a child why cars don’t have dimpled surfaces like golf balls. It would cut down on the shiny gleamingosity of a new vehicle, but wouldn’t it help its aerodynamics? Anyone?

    • 0 avatar
      Sutures

      As with most questions asked on the internet, the Mythbusters have that one covered. Search for “Mythbusters Clean Car vs. Dirty Car” and you should be able to find the episode.

      Sorry, no quick link. The Mythbusters page on Discovery only had bits of the episode and not the full show. Youtube would be a good resource for this…

    • 0 avatar
      rpn453

      A dimpled surface would decrease pressure drag but increase friction drag, so it may or may not be a benefit, depending on the shape of the vehicle. It reduces drag on a golf ball, but would increase drag on a more aerodynamic shape like an airplane (Cd around .02). Airplanes often do have rough skins immediately ahead of control surfaces, but that’s for maneuverability, not drag reduction.

  • avatar
    Andy D

    You have done again Paul. I go to a fellow E28er’s get together. One of the regulars is a guy who is a native of the town where Tatras were made. He bought the local doctor’s ’33 Tatra roadster. It looks very much like a Model A. Lou found it and rescued the car from being humus. The pictorial of the restoration started with a rusty pile of old car parts. There is not a chassis really, the body is supported from transverse supports hung from the engine/transmission, torque tube and rear axle. When I said the motor looked just like a bug, he got a little hot and I learned about Porsche stealing the design. Porsche/ VW settled with Tatra in 1961. Tatra won. The Tatras and other streamliners are beautiful. Boutique cars with Figoni/Falaschi tear drop bodies like Delage, Talbot, and Delahaye are my favorites.

    If I had a V8 powered bug when I was a kid, I prolly would not be here now.

  • avatar
    tom

    I love the “Tropfenwagen”. I’ve just seen the new Metropolis version with the original footage from 1927 that has been missing till now…they used lots of Tropfenwagen in order to create a futuristic look for their city…and it still works (they even burned one…I almost cried).

    Also, don’t forget the Benz Tropfenwagen from 1922. It was a race car and based on the Rumpler. It was one of the first mid engined race car and with it’s aerodynamic design, it looks a lot like the Auto Union Type C which had its debut a full 12 years later.

    Unfortunately, the Benz Tropfenwagen was not an instant success and when Daimler and Benz started to cooperate (and later merged), Mercedes got in charge of all the racing efforts, effectively scrapping all Benz & Cie designs, so the Benz Tropfenwagen never got the attention and further development it deserved.

  • avatar
    Littlecarrot

    I love the streamlined cars of the 30′s, especially the Tatra.

    My youngest daughter spent time as a nanny in the Czech republic. Whenever she called, I would always ask, “did you see any Tatras?” Unfortunately, her answer was always “no.”
    They are becoming quite rare.

    If I could purchase one car to show in a classic car meet, it would be the Tatra 77.

  • avatar
    rudiger

    A good, concise article on early automotive aerodynamics, worthy of a Wikipedia entry. I’m particularly fond of the Stout Scarab mention with its early minivan layout, making it a vehicle far ahead of its time on not just one, but two fronts.

  • avatar
    gslippy

    The tail on the Tatra T87 (first pic) resembles the tail cone on the test space shuttle Enterprise: http://www.aerospaceweb.org/question/spacecraft/shuttle/enterprise-02.jpg

    The “Dymaxion” name brings to mind a gas analyzer I helped to develop some time ago, by the same name: http://www.ceb.uminho.pt/labs/reequip/MS_58305_64351.jpg
    Not surprisingly, there was no legal conflict in using the name.

  • avatar

    There were 3 or 4 Tatras at the annual Rockville show held outside DC in October, in the 1993 show. All in beautiful shape. Later ones than the ones pictured. I think I also saw one at the 2002 International Citroen Rally which took place in Amherst, Massachusetts that year.

  • avatar
    Greg Locock

    Nice article.

    Presumably in the 20s they were interested in aero because the engines of the time tended to be a bit short on power. Then in the 40s the mass market engines got more powerful and aero could be sacrificed to style.

  • avatar
    blowfish

    When a Gallon of Benzene was under 50 cents in Canada , what are the incentives to use small engine, especially a lot of distance in N America needs to cover in a hurry. We all need Muscle power, anything smaller than 400 cu ins is kind of considered not quite a car.
    A full size car can hold 27 gal on a fill up.

    Even a couple of yrs ago when gas was 2 ish a gal, it didnt stop many folks from buying these big SUVs. Until the gas went nutso over the roof, and the same time the credit crunch happens, quickly changed peoples’ driving habit.

    The mainstream industry forgot because the mainstream public did not care. Cars were made to LOOK aerodynamic, but, until the oil shortage of 1973

  • avatar
    Ingvar

    Don’t forget the Phantom Corsair:

    http://en.wikipedia.org/wiki/Phantom_Corsair

    One of the first full width pontoon cars. It’s made in 1938, I can’t remember a design earlier than that, with fully integrated fenders all around.

  • avatar
    Ingvar

    Another one-off I’ve always liked, is the humorously named “Venus Bilo”. “Bil” is the Swedish name for “car”. I don’t know much about the history or whereabouts, more than it was based on a Volvo chassis, and built in 1933. But I think it’s strikingly beautiful, in some sort of Scandinavian art deco way.

    http://members.chello.nl/j.baartse/carpics/venusbilo.jpg

    http://en.wikipedia.org/wiki/Volvo_Venus_Bilo

  • avatar
    50merc

    Great article, Paul. I too look forward to the rest of the story.

    If I recall correctly, the late-80′s GM A-bodies (Chevy Celebrity et al) especially the station wagons had remarkably low drag.

  • avatar
    folkdancer

    Enjoyed the English Burney ad saying: “slight wear on the tires”.

    Fantastic history. Thank you.

  • avatar
    a-viking

    Great article, but it should have included another few noteworthy production cars. The original Saab and of course the infamous Citroen DS and SM. I always thought GM should have taken the EV1, emptied the battery pack and motor and just added as small Tdi like found in modern VW Bluemotion Polo. That combination of light weight and outstanding aerodynamics would make a perfect commuter car.

  • avatar
    NickR

    What I also find interesting is that these aero cars were, oddly enough, far more streamlined than aircraft (certainly production aircraft). I know wings and radial engines clutter things up but still…

    The Tatra is more attractive than the Porsche.

  • avatar
    eastcoastcar

    Paul, This is a wonderful series. The pictures bring it to life, and I appreciate your efforts here (as well as in other fine series I’ve seen here since discovering the site).

    Thanks very much!

  • avatar
    NickR

    Also, I’d very much like one of those Lincoln’s please…good restorable condition is fine.

  • avatar
    TAP

    Agreed- this is great stuff! Thanks!
    My grandparents never owned a home. Granddaddy sold Chryslers in New York in spring/summer, then drove a company car to Palm Beach to sell them there each winter, and knew Walter Chrysler.
    One year he drove the new Airflow down the coast for the winter, mentally noting reactions it received along the way. By the time they reached the Carolinas, he realized it was a loser, but truly loved the design.
    This was a man who built a glider that never flew, and almost took flying lessons in Dayton, Ohio in 1910 from the Wrights, but couldn’t get the almost $1000 together.

  • avatar
    Mr Carpenter

    Every car guy (or gal) worth their salt should look in awe at any car which sports a dorsal fin on purpose!

    I’ve been to the Lane Motor Museum in Nashville, and it’s someplace everyone needs to go. Plenty of microcars, check. Citroen DS racing car, check. A pre-war luxury Panhard, check. Multiple BMW’s of all eras, check. Tons of Tatras, check!

  • avatar
    potatobreath

    I think there’s a typo. The B5 Passat had .28 Cd in 1998, not 1988.

  • avatar

    Greetings Paul,

    You missed the most aerodynamic 4 wheeled passenger car ever, the 1938 Schlörwagen “Pillbug”:
    http://img.photobucket.com/albums/v724/NeilBlanchard/Schlr-SideProfile.jpg
    http://img.photobucket.com/albums/v724/NeilBlanchard/Schlor-FrontView.jpg
    Cd of this near production car was 0.186.

    Sincerely, Neil

    • 0 avatar
      Paul Niedermeyer

      Neil,
      Thank you for bringing the Schlorwagen to my attention. I have no memory of encountering any reference to it before. I’ll add it to a revision of the text.

    • 0 avatar

      Hello Paul,

      You’re very welcome! I’ve known about the Schlörwagen for a few years now (the folks at EcoModder.com are big fans of aerodynamics!) but those particular pictures I just found this past week; at a web site with a goldmine of pictures related to aerodynamics, including a picture of the Schlörwagen in the wind tunnel: http://www.dlr.de/100Jahre/en/desktopdefault.aspx/tabid-3305/5154_read-8934/gallery-1/216_read-7/

      Sincerely, Neil

  • avatar
    flomulgator

    As far as I can tell, there is no link to Article 3 from Article 2. I had to come back here (Article 1) to jump to 3.

  • avatar

    Hi Paul,

    I have another car that you could include; the 1939 Maybach Stromlinien Karosserie (aka Stromlinienkarosserie), which was a car that was made to do high speed tire testing:

    http://www.maybach.de/images/263_1.jpg
    http://www.maybach.de/images/263_2.jpg
    http://img.photobucket.com/albums/v417/MikeMariettaSC/80MPG%20Honda%20Civic/sw38-ds04.jpg
    http://blog.goo-net.com/chez2007/img/163/inline_15.jpg

    My info is that it had a Cd of 0.16, and it could go 150mph with a 150HP engine.

    All the pictures I have see (the four I linked to) appear to be scans of a newspaper, unfortunately. It certainly appears to have sophisticated cooling vents (on the sides just behind the front wheels and the slots on the hood), and it had a full belly pan, too.

    Sincerely, Neil

  • avatar
    Chris Raber

    Paul,
    Wow, this is a terrific piece of work!
    Great research on so many vehicles.
    Another one you might want to check on as an American example would be the Auburn Boat Tail Speedster of 1929 and the succeeding models through the early thirties.  Very beautiful streamlined bodies that also incorporated advanced engineering.
    Again, fascinating articles!
    Thanks!
    Chris Raber
    Chambersburg, PA


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