Aerodynamic vehicle towing a non-aerodynamic trailer...
 

Had the pleasure of towing a 6x12 U-Haul trailer loaded with furniture. My question is...does my aerodynamic additions become a hindrance when towing a big trailer? Would've it been better if I had a normal cab-high camper top installed? The towed trailer is higher than the top of my truck roof. The gap between the back end of the aero cap to the front of the trailer is around 5'.

My indicated mileage over 110miles was 15.2mpg (1 extra stop) with the trailer loaded and 17.6mpg coming back empty. I haven't made this run before without the trailer. I'll git my chances in the upcoming months. ;)

I normally see between 25-28mpg highway with all my aero mods installed.

My aero mods fer this run are:
Full belly pan
Rear diffuser (4°) extended beyond the rear bumper
Partial side skirts
Rear skirts
Rear wheel skirts
Rear wheel strakes
Aero cap
67% top grill block

I had to remove my lower grill block so my transmission coolers would become active since I was towing a heavy trailer. I'm guessing the loaded trailer weighed in over 3500lbs. :D

Personally, I can't imagine why they'd be a hindrance. If I'm missing something, Though, I'm not picking up on it.

The rear end of the trailer is eating up some FE, not sure about the front of the trailer though.

Yes a square topper that most nearly matches the trailer would be best, just as it is on tractor-trailer rigs. Your rig was sort of presenting some frontal area twice.

Be careful about blocking the air while hauling a trailer. Your engine is having to make 33% more power than it would normally and probably the peak amount of power is another third more than that that.

Since my aero cap is built with a hatch just like Bondo's aerolid, I was wondering if it would've made any significant difference by setting the hatch so the top of the hatch is level with the top of the trailer. It would look kinda like an F-15 air brake that's not fully deployed. :D

http://i17.photobucket.com/albums/b6...la_top_fnt.jpg

I guess I would have to fill in the open gaps between the hatch and the sides with the open hatch configuration, right? ;)

Piccie of the trailer hooked up before I turned it in... ;)
http://i677.photobucket.com/albums/v...ps8a320662.jpg

BTW...the flag isn't hooked up to my truck. It's just in the background with the house. ;)

My fuel mileage ended up being 16.58mpg. Still not too bad... ;)

...the numbers don't lie.

We like recycling...
http://ecomodder.com/forum/showthrea...tml#post236561

Thanks for adding the pic.

In pulling that exact trailer round-trip twice from Corpus Christi to Beaumont on the same route I was otherwise covering solo (thousands of miles), I saw 18 mpg where the solo miles were never less than 24-mpg. A reduction of 25% with a 12-13k combo. Trailer towing generally extracts a 30-40% penalty (whether we are talking a combination from 1969, or one from 2009; where other things are the same). High compression is the reason the for the lower percentage change. I'd always be happy with 30%+.

The gap is significant between the vehicles. I vote, at present, for aero to each as appropriate versus trying to make them one. A dedicated combination would make for the latter approach.

A NOSECONE (brand) would be better on the trailer than would a bed topper on the truck.

In the meantime, get you a MASTERLOCK adjustable hitch to level out the trailer as much as possible. Best performance on the trailer tires will result. Using a certified weight scale to get best trailer loading (as measured on individual wheel readings) with any sort of regular load (See CAT Scale Locator).

Where the trailer is taller than the tow vehicle is tough. My travel trailer is considerably taller than my pickup and a very long ways back.

A recent RV forum discussion yielded a DIY on air deflectors. Note the differences in height and distance of the two vehicles.

DragRacingOnline: 2008/technical

This trailer would also benefit from a NOSECONE as well as a TRAILER TAIL. As the latter is in excess of $2000 for a Class 8 box van, I'd imagine some fabrication costs would be present for custom sizing (and the NOSE CONE ain't cheap either). Handling issues with trailers -- of any size and behind any tractor -- are always of concern. The report on AIR TABS is consistent with other reports, elsewhere (despite what this forum presents).

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