How Can Flatbed Trucking Be Aerodynamic?
Aerodynamics: The aircraft engine spools up and the turbines start spinning. The rotation of the blades move faster and faster until you only see a blur. Fuel and spark are introduced and what follows is a powerful explosion. This explosion thrusts the metal beast forward and up into the horizon.
The aircraft has successfully taken off. As it sores upward, there is an invisible war taking place between multiple forces – some pushing the aircraft up and others forcing it back down. These forces are similar to the ones that affect a semi-truck and trailer. While these powerful forces are uncontrollable, with the right understanding they can be manipulated and transformed into financial savings while reducing our carbon footprint.
Invisible Forces
While in flight, there are four forces acting on an aircraft:
- Lift – The force that directly opposes the weight of an airplane and holds the airplane in the air
- Thrust – The force created by a power source giving forward motion
- Drag – The force that opposes an objects motion through the air
- Gravity (Weight) – You should already know what gravity is
Though a semi-truck has no chance at achieving any lift or flight, it is still affected from many of these same forces. It is also influenced by what is known as the ‘low-pressure’ zone, most commonly found at the rear of a trailer. It is here that any streamlines flowing down the sides of the truck fail to remain parallel and crash into each other, causing negative pressure. This turbulence is one of the causes of pressure drag.
The Drag On Trucking
Drag is one of the consistent enemies when it comes to aerodynamics as it acts in an opposite motion to the object moving forward. It can be described as aerodynamic friction, as the more interaction it gets with an object the more it will impact its movement. Here in lies the problem for the truck driver.
Every part of a truck and trailer generates drag. Something as simple as side mirrors can be responsible for 3-5% of the overall drag on a truck. Unlike a typical family sedan, the mirrors on a truck are fairly large. If these two mirrors alone were eliminated, it would save hundreds of litres.
What can make all the difference is keeping any contours on the truck as minimal as possible. If the streamlines can follow an unbroken path around an object, this will positively affect the trucks drag. Basically, any turbulence can be minimized if the streamlines get interrupted as little as possible.
Turbulence = Environmental and Financial Cost
A large contributing factor of turbulence are any gaps found from the nose of truck to the tail of a trailer. These gaps will cause the air streamlining down each side of the truck to change velocity and pressure. From the gaps between the truck and trailer to the large area of exposed tires, these turbulent zones are a big contributor to the aerodynamic drag that will affect your gas mileage.
Another negative aspect created by drag is the aforementioned pressure zone. This is a suction force that follows behind the truck and can actually pull cars into the zone. This drag increases when an object’s contours vary greatly from front to back. Since a truck and trailer combo is essentially just a huge box that comes to an end with an abrupt flat trailing edge, it difficult for the streamlines to efficiently follow the flow of the truck.
A large commercial truck carrying a fully loaded reefer travelling around 100 km/h will consume about 52% of the total fuel to provide the power to overcome all the aerodynamic drag. Considering one of T&P’s driver’s average mileage is around 10,560 kms, any lessening of drag could have far reaching effects for fuel savings and on greenhouse gas reduction.
One obstacle an owner operator may face is not always having control over what kind of trailer they will have to pickup. It is often the case that a trailer owner will be hesitant to supply aerodynamic devices that will only benefit a tractor owner. In spite of this, there are still many ways for a tractor owner to increase his fuel mileage and savings.
Controlling the Force = Savings
Though you can’t see them, knowing the invisible forces affecting your rig and how they function is the first step towards saving you money and cutting down on greenhouse gases. The next step is investing in the right devices that will control them in a beneficial way.
Some of the more common aerodynamic devices are:
- Airtabs
- Tirecaps
- Roof Deflector
- Side Fairings
- Fuel Tank and Step Skirts
- Windshield Visor
- Trailer Skirts
These devices are effective because they keep the streamlines moving evenly by limiting the areas or gaps where they would otherwise collide while the truck is moving. The less interference a truck has with the air around it, the better it will be for efficient gas mileage.
Most of these devices have been designed for trucks hauling reefers or containers, so there is still a challenge for our drivers here at T&P Trucking, as most of them are hauling flatbed trailers.
Help For Flatbed Trucking
It doesn’t help that many of the loads being carried on a flatbed don’t have the best shape when it comes to aerodynamics. Aside from accessories and changes to the cab of the truck, there are not many options for aerodynamic accessories on a flatbed trailer. However, there are a few practices drivers can do to maintain a smooth aerodynamic flow to their loads.
When being loaded, a driver should remain aware to the placement of objects on the trailer, possibly by having their load positioned in a way to limit gaps between objects. While doing this, it’s also important to keep the weight displacement correct for their axles.
Many loads a driver will transport often require it to be tarped. This alone goes a long way to keep a smooth streamlining effect down the object, resulting in better fuel mileage. It is also important to ensure the tarp is securely fastened and there are no edges left loose to flap in the wind. These flapping edges will also decrease your fuel mileage.
Long Road Ahead
When it comes to driving truck, every dollar counts. We know truck drivers work hard for their money, and we don’t want the pay off for their work to be stolen by these invisible forces. By bringing attention to trucking aerodynamics, we hope all drivers will examine their rigs and see if there’s any tactics they can apply to increase there fuel savings. An additional benefit will also be maintaining a much smaller carbon footprint.
Are you using any aerodynamic accessories? We would love to hear your thoughts in the comments.
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References
Sciencelearn.org
Science Direct
NASA
Phys.org
Contributors
Rob Morris
2 thoughts on “How Can Flatbed Trucking Be Aerodynamic?”
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I agree with you that extra measures should be taken to ensure that the vehicle is more aerodynamic. A lot of fuel savings is worth the add-ons. My brother is a trucker; often times he drives a flatbed.
Hey Skyler. Thanks for your comment. A flatbed truck is definitely harder to find aerodynamic accessories for. Does your brother have any add-ons on his rig?