Offroad trailer Vs Roof tent MPG

[KLAKEBRONCO]

What I was wondering is if we covered the airgap between the trailer and the top of the trailer, it should cut down the drag.

A simple way is to take a cover like a roof top tent cover that has longer sides that goes from the top of the tent down to the body of the trailer. If you did something like this with a hard V, like a ship hull in the front to deflect air, that should make a big difference. Just looking at pulling a AT Horizon with a RTT gets much worse MPG than a bigger, bulkier and much heavier Jayco Baja

I am just thinking out loud, but it sounds like it should work. First part would be to find a cover that does not let air pass through that's about the right size and see if that makes a difference, then maybe find something to attach to the battery box that is a deflector.

If it works, seems like it should pay for itself pretty quick. And you would think that just eliminating the air gap between the RTT and trailer would make a huge difference

If I understand correctly, you might be on to something. I want to do the same to the roof rack I have, when I install it. Basically skirt the sides and front so that air doesn't pass under it.

 

[MOAK]

re-fuel mileage

Ok,,,, trip to Moab, completed, over 6,000 miles 18 days off road. Pulling the trailer we averaged right around 14 mpg. What killed our mpg were the headwinds from Kansas west, and Texas, heading east. The best mileage per tankful was 17.5 with light tailwind. The worst tankful was in west Texas with 35 mph headwinds, that tankful dropped to lower than 7 mpg. With all that said and done, we lost about 1 mpg pulling the trailer over having a "Kanga Pouch" up top. I'll use my trailer any day over getting all that gear on and off the roof.

 

[STREGA]

I agree, it is way easier to put away the tent on the trailer than on top of my FJ.

I averaged anywhere from 13.5 to 16 mpg on my trip to the Expo, I was pulling a AT Horizon with a Globetrotter RTT as well as a RTT on top of my FJ also. I'am pretty sure I will pick up a couple of MPG's when I remove the RTT off of the FJ. I usally average about 19.5 to 20 mpg's with no RTT or trailer. I also have a small homebuilt teardrop that weighs about 1000 lbs and average almost 18 mpg pulling it, I don't know yet if the Horizon will get as good of mpg's as the teardrop it is alittle wider, taller and heavier but it's still mostly behind the FJ slipstream so I'am hoping it doesn't have to much impac.

Update on mileage: Just returned from a 3k trip to California. With the RTT removed from the FJ, I was optimistic about picking up a couple of MPG's, but the best that I did was only a 1 mpg increase. I kept my speed at posted MPH or less(California has a max of 55mph when pulling a trailer although you will be run over by everybody out there if you do the legal speed limit). Had some headwind in places, and did a lot of back highways instead of freeways whenever possible. I'am a little disapointed, but hey what are you going to do. I do all the things to help get the max MPG's like proper tire inflation, vehicle maintainace, slowing down alittle, etc. So overall it looks like the Horizon is going to get about 2 to 3 mpg less than the teardrop. I think its due to a few things like:

Wieght-teardrop loaded is about the same as Horizon empty.

Profile-rear of teardrops gentle sloping curve as oppose to squared off rear of the Horizon.

Tire size and tread pattern-teardrop has a narrower tire with highway tread as opposed to the Horizons BFG's AT's.