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Old 05-05-2022, 06:19 PM   #1201 (permalink)
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I rented a 6x12' utility trailer yesterday and was surprised at how awful it pulled, especially empty. I ordered one without a ramp, but they substituted one with the ramp:



I normally get 20-22 mpg going 55-60 mph in my Tundra with no trailer. With the truck & trailer loaded with irregularly shaped items that were mostly level with the truck bed & trailer rails, I got 16-18 mpg.

Unloaded of the ~4,000 lbs of cargo I got even worse mileage -- 14-16mpg. There was a 5mph tailwind when loaded (so a 5mph headwind when empty), but I think most of the difference was trailer aerodynamics - especially with that damn ramp sticking up like an air brake and the cargo mitigating it by acting similar to tonneau cover.

When empty, that ramp really did show the effects of surfing bow wakes of big rigs. I've never noticed it before, but when a passing big rig is first coming up to my trailer, it actually would get sucked backwards into the wake. If you've ever gone surfing it feels exactly the same as when your board gets drawn backward into the ocean before you catch the wave and start surfing forward to the beach.

The scangauge updates kind of slow, but it looked like about a 7 horsepower drag (in addition to the normal 55-60 horsepower to maintain 55mph empty)

Then when the big rig was at my side, I'd get a bit of a draft - maybe 5 horsepower (50-55 hp instead of 55-60. And when the nose of the big rig pulled ahead of my truck by half a car length or so I'd get "surf" a big bow wake which saved 10-15 horsepower (45 horsepower instead of 55-60).


My awesome sketchpad skills of semi truck bow wake surfing/drafting effects:


Today's internet rabbit hole:





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Last edited by Drifter; 05-05-2022 at 06:42 PM..
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Old 05-05-2022, 09:09 PM   #1202 (permalink)
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Normal. My trailer with 2’ sides up and empty pulls like a parachute. Fill it up with something and you don’t notice anything is being pulled.
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Old 05-06-2022, 02:06 AM   #1203 (permalink)
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Quote:
Originally Posted by Drifter View Post
I rented a 6x12' utility trailer yesterday and was surprised at how awful it pulled, especially empty.
Was it so awful that you feared it could lead to what is known in my country as "quebra de asa" (break of a wing)?
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Old 05-06-2022, 10:17 AM   #1204 (permalink)
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The prius gets the same gas mileage towing a 1200lb bass boat, an empty 5x8 trailer, and a full 5x8 trailer. lol
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Old 05-06-2022, 07:18 PM   #1205 (permalink)
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Quote:
Originally Posted by hayden55 View Post
The prius gets the same gas mileage towing a 1200lb bass boat, an empty 5x8 trailer, and a full 5x8 trailer. lol
How does that 5x8 trailer fare aerodynamically-wise?
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Old 05-07-2022, 09:42 AM   #1206 (permalink)
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Quote:
Originally Posted by Drifter View Post
I rented a 6x12' utility trailer yesterday and was surprised at how awful it pulled, especially empty.
A few years back I moved a load of furniture about 500km in my 8x5 box trailer.

The i30 got 30.2mpg loaded and a surprisingly low 30.9mpg on the empty return leg.
Without the trailer it averaged nearly 40mpg.

It seems like poor aero (it's a very boxy box trailer ) may have been more of an issue than trailer weight.
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Old 05-08-2022, 11:15 AM   #1207 (permalink)
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Quote:
Originally Posted by D.O.G. View Post
It seems like poor aero (it's a very boxy box trailer ) may have been more of an issue than trailer weight.
That seems to be the case of most vehicles in general, at least at highway speeds. After engine efficiency losses, the next place most of your energy goes is to move air.
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Old 05-09-2022, 02:13 AM   #1208 (permalink)
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Quote:
Originally Posted by D.O.G. View Post
A few years back I moved a load of furniture about 500km in my 8x5 box trailer.

The i30 got 30.2mpg loaded and a surprisingly low 30.9mpg on the empty return leg.
Without the trailer it averaged nearly 40mpg.

It seems like poor aero (it's a very boxy box trailer ) may have been more of an issue than trailer weight.
Did the suspension went noticeably lower while loaded?
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Old 05-17-2022, 08:41 PM   #1209 (permalink)
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Road trip!
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Old 05-17-2022, 08:52 PM   #1210 (permalink)
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She's a beaut!

Share the trip details.

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