Aerodynamic By Design

I get a lot of questions about the aerodynamic performance of Living Vehicles, and rightly so. After all, the LV is shaped a bit box-like, with straight walls and curved corners. How could it move aerodynamically down the highway and get good fuel economy? Won't a more aerodynamic travel trailer shape equal less drag and less fuel consumption? It's time to answer the question of aerodynamic drag.

As trailers are towed and don't move on their own, the question of air flowing over the trailer is part of the aerodynamic equation and a vital part of the conversation. We must consider how the aerodynamic performance of the truck and trailer perform together as partners.

Large Trailer Aerodynamics

Let's start with the semi-truck, one of the most common large vehicles today. After all, the large box container being towed behind the semi-tractor is not very aerodynamic and is quite boxy. However, millions of semi-trucks are cross-crossing the United States every single day. Here again, the box container must be pulled by a semi-tractor.  Look at a semi-truck and trailer combination, and the answer becomes obvious – they are effectively one cohesive vehicle. The tractor's front is aerodynamic, pushing air up and over the box container portion of the combined vehicle package. 

Semi-truck and tractor-trailer

Case Study: High-Speed Trains

Look at a high-speed train. These are the most aerodynamic ground transporters on the planet, capable of incredibly fast speeds! The front end of the train looks like the tip of a missile. However, if you remove the bullet tip of the train, it is a flat edge box-like surface, just like a semi-truck trailer. When all the train cars are connected with the highly aerodynamic front locomotive, the train becomes an aerodynamic masterpiece, capable of speeds over 200 mph.

Bullet train - about as aerodynamic as they come

Let's look back at travel trailers and the Living Vehicle. As the truck will always be the leading edge, the truck's aerodynamics is a crucial component; how the air flows up and over the trailer are fundamentally interconnected and must be analyzed as a package.  

SUVs, Cars, & Aerodynamic Trailer Design

The lightest travel trailer makers who tout the aerodynamics of trailers are somewhat misleading and irrelevant. The RV industry may conduct wind tunnel testing, but of course, without something pulling it the data is meaningless. Most of these bullet-shaped trailers, especially teardrop trailers, are designed for a smaller tow vehicle. Regardless, if ultra-light travel trailers -- typically made of lighter material -- a smaller car will be less effective in pushing moving wind up and over the trailer; even so-called ultra-lite travel trailers are not light enough to pull safely during your family's next adventure in bad weather. Aerodynamic autos and SUVs are designed to keep the air slipstream in close contact with the top sides and wheels of the vehicle, bringing the airflow down towards the car's rear end to reduce air turbulence. 

Lightweight trailer design with a smaller car pulling it

Take a trailer towed by a highly aerodynamic Tesla Model X. The aerodynamics of the sleek Model X is one of the sleekest and smoothest cars on the market, with air flowing up over the car and back down. When considered alone, separate from a trailer, this is pretty sweet. Unfortunately, when attached to a trailer, this type of vehicle produces fast-moving air directed down relatively low behind the Tesla and smacks into the trailer's leading edge. This fast-moving air hits the massive front trailer wall -- regardless of the shape or light weight – not so great.  Because of this, the trailer must also be aerodynamic to compensate. When taken as an integrated unit, this design is a disadvantage because the trailer has a significant amount of air pushed against it. There's no way around it. Trailers can be tall, varying in length, and designed to stand upright. So it's a tall vehicle – it is a trailer. 

Travel Vs. Livability

Indeed, some companies prioritize spending miles on the freeway over livability.Some trailer companies like Airstream and Bowlus are perfect examples of lightweight trailer designs. Prevalent in this style are curved walls, low ceilings, and a central corridor of circulation that looks and feels like the interior of an airplane aisle. If a trailer designer is required to tow less spacious cars and SUVs, then there is no choice but to design a seemingly aerodynamic trailer. After all, the car towing the trailer isn't designed to push air up over it and does less from the holistic aerodynamic equation; it's an aerodynamic liability.  These trailers are primarily designed for shorter-range trips (think weekend recreational vacation) and significantly compromise interior livability. Back in the early 2000s, when I started my experience with a different method of travel and recreation, a marine instructor shared with me that "every boat is a compromise.” She said, "You need to determine first what is most important to you and your intended use before jumping in to make the best decision for you and your family.”

Living Vehicle Aerodynamic Design

Living Vehicle models its design after a more substantial volume because we maximize interior living space with durable materials and consider the most important design consideration.  Living Vehicle is designed as a truck and trailer combination, much like the mighty semi-truck.  This intentionally maximizes interior space and livability.  From a traveling perspective, this is similar to semi-truck and trailer design, where the truck pushes airflow over the trailer. Critical points on the trailer are designed with aerodynamic considerations on the leading edge. 

Living Vehicle with an ideally-equipped truck

Aerodynamic features are part of the aerodynamic solution, such as the radius corners to the left and right and the radius edge all along the roof.  This tandem provides a smooth air transition that considers the truck's proper aerodynamics when attached.  In addition, the square and hard angle of the rear end creates a knife-edge profile for the air to release from the trailer and pass over the circulating air zone directly behind the trailer.  This space is purposely designed to hold equipment, such as bikes, surfboards, and other toys.  The slipstream of airflow is calm, like the eddy in a river, so outdoor gear storage is protected from fast-moving air. 

Not All Tow Vehicles are Created Equal

Suppose you place an extremely high value on aerodynamics and plan to spend most of your time on the road traveling.  In that case, an adequately configured truck will easily accomplish your goal.  Start with any modern-day truck and add aftermarket parts to the rear end, and voila!  A purpose-built aerodynamic union between truck and trailer.  This can also be accomplished with a more affordable camper shell, platform, or roof-top tent.  Purpose-built solutions also place a wind deflector on the top to leverage this even more.  This wind deflector feature is found on nearly every modern-day semi-truck to unify the tractor and trailer into one.  This is the beautiful part about functional trailer design!  The truck is inherently flexible and may be configured specifically to optimize for whatever you value most.  

Leading Edge Aerodynamics

As we begin to drill down to the details of the Living Vehicle design, several components complement the efficiency as the trailer passes through a wind stream.  To the front edge of every Living Vehicle, the top and side corners are rounded.  This leading edge provides a smooth, rounded surface for wind travel.   The width of the Living Vehicle is a bit wider than the truck pulling the trailer.  Because of this difference in width, an area of the LV is exposed to the direct leading edge wind force.   The gradual transition from the flat front allows this fast-moving air to be directed to either side and flow gradually around the front, then towards the rear.   


Flat Front Wall

A pocket of dead air sits between the car's rear and the LV's front wall.  Because the truck deflects most of the leading airflow up and around the LV, it makes perfect sense to design the front of the trailer to be perfectly flat, just like the semi-truck example.   Just behind the front wall is valuable space, and we want to maximize the functional livability inside the Living Vehicle. 


Tried & True Design

I love taking design ideas from tried-and-true industries. One of my favorite parts of trailer travel is the concept that the truck Is not fundamentally part of the living space, like motorhomes, busses, or coaches. There are tremendous disadvantages to having your engine directly attached to your home. It will be one of the most expensive, unwieldy vehicles you hardly ever drive.

These large vehicles with integrated engines, like buses, motorhomes, and diesel motor coaches, perplex me. Historically, anything with an engine depreciates significantly over a short time. Every mile on that odometer reduces the value of anything connected to that engine. One of Living Vehicle's best parts is that it is not connected to the drive system. The truck that tows your LV is available for many other uses. An RV with an engine (think motorhome) is like a ball and chain. You must take your entire residence whenever you want to go anywhere. Or you have that additional automobile following behind you, and now you have two engines to maintain and pay for. Most relevant to this article is the tremendous challenge of overcoming the rolling box design of most motorhomes when designing for aerodynamic performance. It's hard to make a big square box move through the air. 

Not all Living Vehicle customers are the same, and not everyone needs the best aerodynamic travel trailer. Some customers plan to place their Living Vehicle on land as a semi-permanent installation. After the initial delivery, the LV, in this case, will rarely see travel again. Why would we waste valuable living space with angles and potentially misguided aerodynamic design to compromise the most critical value, livability?   


Ultimately, we design Living Vehicle based on our customers' needs and offer ultimate flexibility, comfort, and live-ability, all while staying true to essential values – comfort and freedom. The bottom line is an LV is designed for living. After all, it is a Living Vehicle.