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Truck Test 2013: Do Aerodynamics On Your Truck Work?

Truck Test 2013: Do Aerodynamics On Your Truck Work? 800 533 TruckScience

Fitting aerodynamic equipment to a truck can result in a fuel saving of as little as 1%.  Here we examine a recent truck test to look at the effectiveness of aerodynamic equipment on eight-tonne vehicles.  Your decision to use such equipment might just be influenced by whether you’re carrying bread or milk.

Truck Test 2013

South Africa’s Truck Test 2013 was run over 3 days in April, to benchmark the productivity of 14 eight-tonne vehicles from FAW, Foton, Hino, Isuzu, MAN, Mercedes-Benz, UD Trucks and Volkswagen Trucks and Buses.   Our partner in South Africa, HTM, was involved in the running of the test and some interesting observations were made about the impact of aerodynamics on the performance of the vehicles.

With and Without Aerodynamics

To investigate the benefits of using aerodynamic equipment, participants ran 2 van-bodied eight-tonne trucks in the test – one without any additional aerodynamic equipment and the other with cab-mounted wind deflectors and front and bottom side skirts.

Test Conditions

The vehicles were driven by professional drivers, who were permitted to reach a maximum speed of 85 km/h.  No driver swaps were made in the course of the test.

The Route

The vehicles were tested on 2 routes, as follows:

Route Profile on Day 1 of Truck Test 2013

Route Profile on Day 1:  A 34km trip over undulating terrain to a truck testing facility, where an intensive stop-start operation was simulated over 21km with severe gradients, and the return trip of 34km.

 

Route Profile on Day 2 of test

Route Profile on Days 2 & 3:  A 248km highway route, to simulate the intercity trips commonly undertaken by the eight-tonne segment.  The vehicles were driven fully laden on the outward journey and empty on the return trip.

It’s worth noting that the test was conducted at an altitude of approximately 1200 metres above sea level, where the air is thinner than at lower altitudes and therefore aerodynamic equipment is likely to have less of an impact.

TruckScience Simulations

Before the test was run, HTM used TruckScience to estimate the fuel consumption of each of the vehicles over the routes.  The actual fuel consumed over the course of the test was on average 5% less than that simulated by the TruckScience Performance module.  This was put down to the calibre of the drivers, as manufacturers put their best drivers at the wheel.

The Results

Fuel Savings for vehicles with aerodynamic equipment fitted

Day 1Day 2Day 3Route TypeStop-startHighwayHighwayPayloadFull legal GVM*Full legal GVM*EmptyAverage Fuel Saving1%3%9.6%

* GVM = Gross Vehicle Mass

The results tabled here illustrate that the greatest fuel savings (almost 10%) were achieved where the vehicles were running empty on a highway, with the least savings (a mere 1%) achieved when the vehicles were fully loaded and driven in a stop-start scenario.

The role of speed

The vehicle with consistent speeds between the reference vehicle and the aerodynamic vehicle showed an overall fuel saving of 3% over the three days.

The vehicle that produced the biggest reduction in fuel consumption when fitted with aerodynamic equipment travelled at an average speed of 2.2% less than the reference vehicle, so one can conclude that its reduced speed contributed to the fuel saving.

Carrying bread or milk?

Because the aerodynamic equipment on these vehicles weighs approximately 150kg, it must be remembered that its presence reduces the payload capacity of the vehicle. Therefore, the benefits of using the aerodynamic equipment are greater where the limiting factor on payload is space, for example, when delivering bread, than in a situation where the limiting factor is weight, for example milk.  In the case of the milk, when the payload has been reduced to allow for the aerodynamic equipment, the overall average Productivity* saving comes in at just under 2% over the 3 days of the test.

* Productivity = (Payload x Average Speed) / Average Fuel Consumption

Do aerodynamics on your truck work?

Is investing in aerodynamic equipment worthwhile?  As with most things, it depends on the application.  Fuel savings must be weighed up against a possible reduction in payload, the cost of the aerodynamic package and its envisaged service life.

Read more about Truck Test 2013 in these articles in Focus On Transport magazine, Heavy Hitters and Watching The Numbers.  Note: TruckScience is branded TransSolve in South Africa.

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