Aerodynamics part II

By Allen Penticoff

Penticoff2Some friends of mine are living the dream. They sold their home and stuff and moved aboard a big rolling box of a motorhome they call Augustus, or Gus The Bus for short. During their travels so far this year they have been out west and as far north and east as you can go – Newfoundland. Along the way their refrigerator died, so they headed to the homeland of all recreational vehicles (RV) – Elkhart, Indiana to have it replaced. During this sojourn in Elkhart they discovered the RV/MH Hall of Fame and museum in Elkhart, and via her blog, I learned of it. Visiting the museum’s website ( and viewing the gallery of photos, I discovered my dream trailer – a 1930s vintage Bowlus streamlined aluminum trailer. I knew I had to go see this in person and before long, by coincidence, I had a need to be in Elkhart to help transfer a niece home from a vacation with my sister and her husband. So with my friend Dan doing the driving, we went to Elkhart, had lunch and all five of us went through the excellent museum of American motorized camping (no VW Campers) industry.

Penticoff3There I found the 1935 Bowlus Road Chief to be amazed by. Having long been a pilot and armchair aerodynamicist – I’d always felt that the standard box of a trailer or motorhome was grossly inefficient. They truly are. You’d be hard pressed to design something that was aerodynamically worse. A flat plate presented to the airflow with a flat tail end to create lots of turbulence and suction of reverse airflow. Have you ever noticed that when you drive fairly close behind a big box going down the road that it takes far less pressure on the gas pedal to stay in place – you are being sucked along and benefiting from the broken airflow of that turbulence. Then there is that solid wall of air it takes more power to get through when you do decide to pass. My dream trailer would be rounded in front and have a long pointed tail to smooth out the airflow. The Bowlus trailers did exactly this in the 1930s.

William Hawley Bowlus (born 1896 in Illinois – died 1967) was building gliders (engineless aircraft) in 1910 (age 14). When World War I came along he had become an aircraft mechanic and designer. In 1927 he was a designer and project supervisor for the building of Charles Lindberg’s “Spirit of St. Louis.” He and the Lindbergs were friends, Charles having given Bowlus the propeller spinner off the Spirit for his efforts in its success (it is signed inside by all the workers who built it – to Lindberg). Hawley Bowlus would later teach Charles and Anne Lindberg to fly gliders – and both set records in them. Bowlus’ #2 glider license is signed by Orville Wright (Bowlus broke a Wright glider record too). Bowlus designed the first high-performance sailplane in 1930 and would go on to design and build many more – this is where most of his fame lies. But in The early 1930s he formed a company with Jacob Teller to build streamlined travel trailers in California. This was known as the Bowlus-Teller Manufacturing Company, although most folks now just call them Bowlus trailers.

They built 140 trailers and had designs for a motorhome and other innovative products before going bust in 1936. Wally Byam, who had been building and selling kits for a Masonite travel trailer had been involved in marketing the Bowlus trailers and soon found himself owning the company that became known as Airstream. In 1936 Byam modified a Bowlus trailer to put the door on the side instead of the front and called his creation the “Airstream Clipper” named after the famous seaplane of the time. Unlike Bowlus, Airstream would survive to this day with manufacturing moving from California to Jackson Center, Ohio (some were built in California up until 1979). So the slightly rounded box (and more aerodynamically efficient than a pure box) you see in the Airstream trailers and motorhomes has a direct link to Hawley Bowlus, his super-streamlined trailers and the Spirit of St. Louis.

Inside a Bowlus trailer it is long and narrow. You step onto the tongue of the trailer and enter through a refrigerator-like door at the front where you find a small galley to prepare food. In the “cabin” you’ll find a small dinette and a sofa, both of which convert to beds. Back in the tail end are another two berths. It reminded me of a boat and an airplane at once. I would be very fine with towing this. I saw a photo of a not very streamlined Model A Ford towing a very streamlined Bowlus trailer. The streamlined trailer would definitely benefit the Model A’s limited horsepower on a long trip along the Lincoln Highway.

I also came upon a Bowlus trailer in the wild at a big gathering of antique and classic airplanes at Brodhead, Wisconsin. this September. There are perhaps 20 still surviving. The owner had a nice display which showed other Bowlus-Teller products planned as well as that Model A photo. Sadly I was never able to meet this owner. Perhaps next year.

In a way, I’ve long had a “streamlined trailer” in the form of the 26-foot sailboat we have towed all over the country to various sailing destinations. We sometimes camp in it along the way. But it is not nearly so streamlined as the magnificent and nearly perfectly streamlined Bowlus trailers of the 1930s. Folks have long found the boxy sort of trailer to be more practical and spacious, however – so if we someday find fuel prices heading off into the unaffordable range, we may well see a return of these sleek designs – but probably in fiberglass or plastic rather than the labor intense but light-weight riveted aluminum of the Bowlus trailer.

My next Mr. Green Car will conclude this series with a look at the evolving state of tractor-trailer aerodynamics.

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