Truck/Trailer Aero

[BSwendsen]

Has anyone tried or done the research on truck/trailer aero devices to improve towing MPG?
Pics are for reference only. I have a buddy that pulls an enclosed car hauler, < 5,000 lbs total with ‘20 Suburban. Went from 7.5 to 11 mpg.

We’re towing a 21C with a F250 diesel. Holding a steady 65 mph/1700 rpm, 9.2 mpg.
https://www.icondirect.com/aeroshield-wind-deflector/

[John in Santa Cruz]

Originally Posted by BSwendsen

Has anyone tried or done the research on truck/trailer aero devices to improve towing MPG?
Pics are for reference only. I have a buddy that pulls an enclosed car hauler, < 5,000 lbs total with ‘20 Suburban. Went from 7.5 to 11 mpg.

We’re towing a 21C with a F250 diesel. Holding a steady 65 mph/1700 rpm, 9.2 mpg.
https://www.icondirect.com/aeroshield-wind-deflector/

Which diesel? My old 2002 with the 7.3L got a pretty consistent 13 mpg at 65MPH

[BSwendsen]

6.7… If I really get soft on the throttle I can get 16 highway. My ‘12 6.7 with DEF delete would get 20mpg.

[RangerMan]

My 02 f250 7.3L gets about 17 when pulling my trailer, 22 without.

I have aftermarket devices that help to increase. Stacked tuners. 4in straight thru exhaust, aftermarket Garrett turbo with big head wastegate and 4in up and down pipes to larger intercooler in front of rad, fed air by AFE outside air (cooler) thru oiled filter. 420K now. Best truck ever buitl!

[Chamberman]

Originally Posted by BSwendsen

Has anyone tried or done the research on truck/trailer aero devices to improve towing MPG?
Pics are for reference only. I have a buddy that pulls an enclosed car hauler, < 5,000 lbs total with ‘20 Suburban. Went from 7.5 to 11 mpg.

We’re towing a 21C with a F250 diesel. Holding a steady 65 mph/1700 rpm, 9.2 mpg.
https://www.icondirect.com/aeroshield-wind-deflector/

I do not think that you'll see as much of a benefit as your buddy. Putting this deflector onto the rear of an SUV where it's in close proximity (< 5 feet) to the front of the trailer is an ideal situation. The same is true of a truck with a 5th wheel where the front of the trailer is closer to the cab and deflector.

Using this deflector mounted on the cab of a truck in combination with a pull behind travel trailer that's probably 10' or more behind the deflector is going to see a much lower if any at all improvement in MPG. I read the reviews on Amazon for this deflector and it seemed the most happy customers were those with 5th wheels or SUV's where the distance between the deflector and trailer is minimal, but many reviews failed to say what type of trailer they had.

I believe that you'd do better to install a bed cover/camper shell like this one. I've seen some bed covers that have a step at the rear that makes a bit of a raised 6" air foil at the rear. This type with the raised rear step would probably be ideal. I've actually considered buying a cover for this purpose, but they're a lot more expensive than that air deflector.

[Ron in BC]

I think that this is a situation where the law of unintended consequences can kick in. Folks have been trying the wind deflector thing for years. One negative is that you can create, not a smooth airflow, but a turbulent low pressure area by the propane tanks. The kind that can levitate the cover right off.

I have a hard box cover, love it, worth every penny it cost. Even the increased peace of mind that stuff in it is locked in and out of sight.

At very least I'd have a soft cover or failing that a mesh tailgate.

Strangely enough, I thought that carrying two kayaks on racks would decrease my gas mileage. Doesn't seem to. Maybe the tapered shape deflects air to the side rather than hitting the front of the trailer. Who knows.

Ron

[gklott]

Originally Posted by BSwendsen

Has anyone tried or done the research on truck/trailer aero devices to improve towing MPG?

Airtabs are one example to improve efficiency. Commercial truck industry data and NASA research indicate 2-5% fuel efficiency improvement. That might mean up to 1 mpg improvement for our tow vehicles. It can also improve trailer stability. For the cost, and the annual distances we tow, Airtabs should pay back in a couple of years

Airtabs are on our list to try, on our Sprinter van and our E19.

73/gus

[TTMartin]

Originally Posted by gklott

Airtabs are one example to improve efficiency. Commercial truck industry data and NASA research indicate 2-5% fuel efficiency improvement. That might mean up to 1 mpg improvement for our tow vehicles. It can also improve trailer stability. For the cost, and the annual distances we tow, Airtabs should pay back in a couple of years

Airtabs are on our list to try, on our Sprinter van and our E19.

73/gus

I have AirTabs on our 2017 High Roof Sprinter. I only installed them above the taillights and around the top. I get about 2-3 mpg higher while towing with them. They make no difference in my fuel mileage when not towing.

Top photo does not have the AirTabs, but, shows why they are effective. They help the airflow bridge the gap between the Sprinter and the trailer. This prevents the airflow from wrapping behind the Sprinter and hitting the front of the trailer.

Because they make no difference while not towing, I won't bother putting any on the back of the trailer.

[gklott]

Originally Posted by TTMartin

I have AirTabs on our 2017 High Roof Sprinter.
Because they make no difference while not towing, I won't bother putting any on the back of the trailer.

Thanks. This is excellent information and images. Airtab has good information about Sprinter van and other RV applications.

We are ordering Airtabs for Sprinter and E19. Will report our findings on both towing MPG and qualitative stability improvements. Must now order the Sprinter's Iridium Silver Metallic (code 775) matching paint for the white Airtabs.

73/gus

[Donna D.]

I've been towing in the rain. The back end of my trailer is FILTHY from road rash. It will be interesting to hear y'all talk about how you have to take a toothbrush to all those little plastic bits clean. Seriously. They're going to get dirty and gross. What are your plans?

These are nothing new, they've been around since at least 1998. When was the last time you saw a semi truck use these? Like nearly never. However, they are putting trailer skirt foils along the bottoms of the trailer and have air foils that make the back end of the trailer pointed. The air foils fold up against the doors when not in use.

I worked for a worldwide transportation company for 32 years. We had thousands of semis on the road. The foils were definitely used, those plastic bit aero things.... no. And an increase of 1mpg would be huge when you buy millions of gallons of diesel a year.

[SageRpod]

I would think there is more value in managing the weight of the rig and maintaining proper tire pressure than putting little fins all over my TV and trailer. But that’s me.

[gklott]

Originally Posted by Donna D.

It will be interesting to hear y'all talk about how you have to take a toothbrush to all those little plastic bits clean. Seriously. They're going to get dirty and gross. What are your plans? ... These are nothing new, they've been around since at least 1998

Yes, Airtabs are not new, as we have them on our 2004 30' Airstream Classic. Our plan is to clean them just as we have for more than a decade.

Originally Posted by Donna D.

I worked for a worldwide transportation company for 32 years. We had thousands of semis on the road. The foils were definitely used, those plastic bit aero things.... no. And an increase of 1mpg would be huge when you buy millions of gallons of diesel a year.

Thanks for your observations. We universally see the trailer skirts, and we see about an equal number of deployed and non-deployed rear foils. We also see few if any vented rear mud flaps.

We see Airtabs on trailers, especially out west. You have to look for them.

Your experience is different than that of the North American Council for Freight Efficiency. They document about 7% vortex-generator truck fleet adoption today.

We tow our E19 about 20,000 miles each year, consuming about 1550 gal of diesel fuel. The 1 mpg improvement lowers that to about 1440 gal/yr. At $3.75/gal, that's about $400/year savings. The Airtab installation payoff is 1 year. Even if Airtabs only improve 0.5 mpg, the payoff is a reasonable 2 years. The efficiency payoff numbers are clear, and you don't need to use millions of gallons to justify vortex-generators.

The efficiency numbers are one aspect. We look forward to seeing what stability improvements we can experience, as NASA and other RVers document.

Originally Posted by TTMartin

I have AirTabs on our 2017 High Roof Sprinter. I only installed them above the taillights and around the top. I get about 2-3 mpg higher while towing with them. ... They help the airflow bridge the gap between the Sprinter and the trailer. This prevents the airflow from wrapping behind the Sprinter and hitting the front of the trailer.

I can hope we get the 2-3 mpg improvement as TTMartin describes. His Airtab experience is the travel trailer example of the important tractor-trailer-gap airflow control used by trucking companies.

Originally Posted by SageRpod

I would think there is more value in managing the weight of the rig and maintaining proper tire pressure than putting little fins all over my TV and trailer. But that’s me.

We agree. The first item on our departure exterior check list is checking tire pressure. We are constantly working to reduce weight creep. We've actually dropped more than 150 lbs (5%) in the past 18 months.

Originally Posted by BSwendsen

Has anyone tried or done the research on truck/trailer aero devices to improve towing MPG?

Airtab is one efficiency method to consider, as BSwendsen asked to start this thread. There is value in all efficiency methods if we can reduce fuel use and the resulting emissions. We're all for saving $$$.

73/gus

[CharlesinGA]

The Youtuber Slim Potatohead installed a snow board on his Jeep Liberty in an effort to gain some fuel economy. It did work to a degree.

https://youtu.be/9bvaEYFTKS4?si=B162U-fLV7clHOeF

Charles

[mfschu]

I'm convinced my 2 kayaks improve my mileage and reduce wind buffeting so much that I took them on our trip to Colorado last summer, even though we didn't plan to use them anywhere in the mountains.

[ericw]

Originally Posted by mfschu

I'm convinced my 2 kayaks improve my mileage and reduce wind buffeting so much that I took them on our trip to Colorado last summer, even though we didn't plan to use them anywhere in the mountains.

I have the done the same and it does improve mpg. I then covered the kayaks with a tarp and put a little wind deflector at the back of the kayaks and the mpg improved again. I have tried a wind deflector design without the kayaks since I didn't enjoy stopping at all the boat checks out west but that is a work in progress.

My theory (and some modelling) would indicate that the air goes over the truck and then comes down behind the truck and crashes into the front of the trailer. Kayaks and wind deflectors better connect the two from an air flow standpoint. YMMV.

[Ron in BC]

My theory also.

Yes, the water craft inspections can be a bit of a nuisance, especially two in one day. But it's for a good cause, the invasive species are still spreading.

Ron

[ericw]

Originally Posted by Ron in BC

My theory also.

Yes, the water craft inspections can be a bit of a nuisance, especially two in one day. But it's for a good cause, the invasive species are still spreading.

Ron

I agree they are for a good cause. There are too many invasive species spreading too fast. It just nudged me in the direction of a "boat free" option.

[SageRpod]

Originally Posted by ericw

I agree they are for a good cause. There are too many invasive species spreading too fast. It just nudged me in the direction of a "boat free" option.

Heard on the radio today that Yellowstone is implementing a mandatory 30 day dry period for all boats going into the lake. Not sure how you would police that but there it is.

[TTMartin]

Originally Posted by gklott

Thanks. This is excellent information and images. Airtab has good information about Sprinter van and other RV applications.

We are ordering Airtabs for Sprinter and E19. Will report our findings on both towing MPG and qualitative stability improvements. Must now order the Sprinter's Iridium Silver Metallic (code 775) matching paint for the white Airtabs.

73/gus

Note on the rear of the Sprinter don't try and curve the AirTabs. Just install them with the tips not stuck down. The front flat area of the tabs has the majority of the surface area anyway. After messing up a lot of AirTabs trying to bend them to match the curve, I called the AirTabs guy and he said that letting the tips go straight was fine. Order a few extra as I have caught the tips on branches and replaced a couple of the AirTabs. Luckily I originally purchased enough to go all the way to the bottom of the Sprinter, but, decided to just use them above the taillights.

[TTMartin]

Originally Posted by mfschu

I'm convinced my 2 kayaks improve my mileage and reduce wind buffeting so much that I took them on our trip to Colorado last summer, even though we didn't plan to use them anywhere in the mountains.

I can definitely see that working.