{"id":475,"date":"2025-06-24T20:17:31","date_gmt":"2025-06-24T20:17:31","guid":{"rendered":"https:\/\/paulhansel.com\/?p=475"},"modified":"2025-06-24T20:24:25","modified_gmt":"2025-06-24T20:24:25","slug":"a-trailertail-for-every-ev","status":"publish","type":"post","link":"https:\/\/paulhansel.com\/?p=475","title":{"rendered":"A TrailerTail for every EV?"},"content":{"rendered":"\n

For a little over a decade, the rare sight of a passive aerodynamic modifier could be seen on highways across America.<\/p>\n\n\n\n

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Source<\/a> <\/figcaption><\/figure>\n\n\n\n

Depending on your vantage point, it could look like the tail of the Enterprise Space Shuttle… or perhaps a deflated pastry box.<\/p>\n\n\n\n

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Source<\/a><\/figcaption><\/figure>\n\n\n\n

TrailerTail\u00ae was a hand-operated origami structure that reduced aerodynamic losses at highway speeds by smoothing the sharp discontinuity between a tractor trailer’s square posterior and the wake of air behind it. <\/p>\n\n\n\n

The operator had to manually deploy it<\/a> before getting on the highway and stow it when not required.<\/p>\n\n\n\n

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Infographic source<\/a><\/figcaption><\/figure>\n\n\n\n

Marketing materials and research studies put the fuel savings of boat tails like TrailerTail at around 5%, with upfront costs of less than $1600.<\/p>\n\n\n\n

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https:\/\/nacfe.org\/wp-content\/uploads\/2018\/02\/TE_Trailer_Aero_CR_FINALFINAL.pdf<\/a><\/figcaption><\/figure>\n\n\n\n

A 2,000-mile trip that would have taken 200 gallons of diesel, costing $720 at $3.60\/gallon, might with TrailerTail only burn 190 gallons. The trucking operator could pocket the unspent $36 of fuel. <\/p>\n\n\n\n

Over the 60,000 to 100,000 miles driven<\/a> that is typical of haulage trucks, TrailerTail could make up almost $18,000 in savings per truck per year, in the days when diesel was flirting with $4\/gallon.<\/p>\n\n\n\n

Fortunately, for the trucking industry, fuel prices relaxed a few years after the TrailerTail’s introduction. The US national average diesel price dropped ~20% from ~$3.60 to $2.80 per gallon between November 2014 and February 2015.<\/p>\n\n\n\n

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Source: St. Louis FRED<\/a><\/figcaption><\/figure>\n\n\n\n

This wasn’t as lucky for the owner of the TrailerTail brand, STEMCO<\/a>, which had purchased<\/a> its original manufacturer ATDynamics in early 2015, possibly near the peak of its valuation.<\/p>\n\n\n\n

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The acquisition provides ATDynamics\u2019 EcoSkirt and TrailerTail products access to Stemco\u2019s existing sales and support network. \u201cWe couldn\u2019t be happier about this match,\u201d said Andrew Smith, ATDynamics CEO. \u201cIn a few weeks, we\u2019ll have an additional 40 salespeople around the country talking about the benefits of these products and delivering the $2 to $3 billion\/year savings to the industry by adding the TrailerTail.\u201d
CCJD<\/a><\/p>\n<\/blockquote>\n\n\n\n

If $2-3 billion\/year is the most the entire industry could save by reducing fuel consumption by 5%, they might find it hard to justify expending capital and operational costs on TrailerTail when the free market handed them a cool $8-12 billion cut in diesel costs for doing nothing at all. <\/p>\n\n\n\n

By late 2020, STEMCO discontinued the product line<\/a>, citing reduced customer cost savings and operator fatigue as primary drivers. It’s no longer even visible in their product catalog. Any currently deployed TrailerTails will likely be removed & recycled over the next decade once their articulations fail.<\/p>\n\n\n\n

Will there be another commercial aerodynamic fairing retrofit kit? <\/p>\n\n\n\n

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TrailerTail wasn’t the first to bring streamlining to the roads. Engineers have been playing with them for the past century.<\/p>\n\n\n\n

Buckminster Fuller had an interest<\/a> in aerodynamic fairings in 1933. He envisioned a kind of flying car suitable for any American to use while commuting or adventuring. It was never more than a prototype, but it was widely viewed.<\/p>\n\n\n\n

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By https:\/\/www.flickr.com\/photos\/saschapohflepp\/<\/a>, CC BY 2.0, https:\/\/commons.wikimedia.org\/w\/index.php?curid=9753368<\/figcaption><\/figure>\n\n\n\n

Cars in the mid-1930s and 1950s were built with enormously long and wide bodies; their styling was driven with the intent of appearing aerodynamic<\/a>, but the bar was low. Chrysler’s Airflow was one of the first designs to have met a wind tunnel before the design was finalized.<\/p>\n\n\n\n

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By Greg Gjerdingen from Willmar, USA – 37 Chrysler Airflow C-17, CC BY 2.0<\/a><\/figcaption><\/figure>\n\n\n\n

Tinkerers didn’t wait for the mass market to advance the state of the art. In the 1970s and 1980s, and through the present, various enthusiasts have busily modified<\/a> their cars to be more aerodynamic:<\/p>\n\n\n\n

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Source<\/a><\/figcaption><\/figure>\n\n\n\n

In most of these cases, performance isn’t precisely reported or estimated. Significant figures and error bars are an extreme rarity. Many rely on simple metrics: “did my MPG meter go up?” and “when I taped yarn tufts<\/a> to it, did they wiggle<\/a> the right way?”<\/p>\n\n\n\n

Some bring a measure of rigor to the field. Julian Edgar<\/a> is one such contributor, authoring multiple books on car aerodynamics and publishing several YouTube videos each month.<\/p>\n\n\n\n

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