Tiny Cargo trailer ideas

[oil pan 4]

What kind of welding machines do you have and how many grinder do you have?

[Angel And The Wolf]

I'm not sure you have the scales right, but, though the sport trailer will not add to your CDA, it will not help very much in reducing the drag on the rear of your SUV. The area enclosed in red is the drag area (low pressure pulling back on your SUV.) A trailor that more fully fills the profile area, and follows the taper at the rear of the profile, will much more reduce your drag. Any low pressure gap between your SUV and the trailer front would pull equally on the two, and the "suck back" on your SUV would be mostly compensared by the "suck forward" on the trailer.

[Fox Mulder]

Originally Posted by oil pan 4

What kind of welding machines do you have and how many grinder do you have?

I have an old Lincoln stick welder and a Hobart 140 mig. I mostly use a couple of dewalt 4 inch grinders, but I have a 7 inch as well.

[Fox Mulder]

Originally Posted by Angel And The Wolf

I'm not sure you have the scales right, but, though the sport trailer will not add to your CDA, it will not help very much in reducing the drag on the rear of your SUV. The area enclosed in red is the drag area (low pressure pulling back on your SUV.) A trailor that more fully fills the profile area, and follows the taper at the rear of the profile, will much more reduce your drag. Any low pressure gap between your SUV and the trailer front would pull equally on the two, and the "suck back" on your SUV would be mostly compensared by the "suck forward" on the trailer.

I put the picture of the Forester, and the picture of the trailer both into sketchup separately and scaled them using known dimensions. The trailer box measures 72", and I don't remember the Forester length off the top of my head, but I used the scale function in sketchup to model them to the right sizes. I'm not a sketchup pro either, but I *think* I got the scale pretty accurate.

Do you think I'd benefit the most from following the template with the tail, or getting the front of it higher up in the stream? If I designed it to be similar in profile to the U haul, I could also lengthen it some, and lengthen the tongue to get the tail of the trailer to match the template. In reality, I'll probably try to keep the front of the trailer down a bit so I can see over it in the rearview, but this conversation is helpful to me, as I think I would like to possibly also build a small camping/travel trailer in the future, possibly sort of plagiarized from the Basecamp. I'm 42, and I tented it for 21 days so far this summer, but I'm not sure I want to keep doing that forever!

[Angel And The Wolf]

You could build to follow the profile, and truncate the front at window level, or you could install a rear facing camera on top of your hatch with a monitor on your dash. If you scale up the U-Haul Sport, you will poke out of the profile in back. The U-haul trailer is a good profile on it's own to not increase drag, but it does not take the tow vehical into account to lessen drag. The more of the rear of your SUV that can be seen over or to the sides of the trailer, the more drag area remains. Take advantage of the trailer to fill in those exposed areas.

[COcyclist]

Fox, in my opinion, the gap is your enemy. I don’t believe that you will lower the drag of the SUV if you do not have attached flow all the way to the back of your trailer so that the entire vehicle follows the template. Bam Zip Pow did gap fillers with his trailer and Aerohead did some experiments with aero trailers. There was a “cargo tail” on a receiver hitch on this site that was built to follow the template but did not improve fuel economy because there was a gap between the trunk and the cargo box. If you read up on Aerohead’s trailer and Bam’s one wheel trailer they were very careful to build fill panels between the tow vehicle and the trailer. These are difficult to do because of the movement between the trailer and the back of the tow vehicle. Even with the fill panels the mpg gains were only a few percent as I recall. IMHO I believe that the best you can do is build something that suits your needs and is smaller than the wake of your tow vehicle so you can minimize mpg losses.

Bam’s thread is long but probably worth reading before you spend a lot of time and money designing and building a trailer for real world use. https://ecomodder.com/forum/showthre...ler-26997.html

[Fox Mulder]

Hey COcyclist!

I think that you're probably right about the limited benefits if I don't close the gap. I also am somewhat limited by what I can get for a trailer. The best options so far are a jet ski trailer, right about 60" wide to the outside of the fenders, the HF trailer which is about 63" or a single place snowmobile trailer if I can find one, which would be about 50", and the tires under it. I was considering building from scratch and using torsion half axles so that I could make it a little narrower yet, but this morning I started thinking that maybe I shouldn't try to minimize the width too much, as the width adds stability. The Forester is about 70" wide, so even at 60" I'm well inside of that. My buddy has offered me his popup trailer frame as a base to start with, which I might do, depending on the axle length. I really want to keep the width to less than the Forester, and seeing out the back window would be nice, although I could mount a cam if I really needed to.

If I keep it relatively low topped, I could haul kayaks on the top of it, which would keep them off the roof of the car for the times that we want to take kayaks, and hopefully down inside the wake of the TV. And if it's relatively square, it simplifies building, I wouldn't have to create a curved structure, or bend ply or create something out of fiberglass. That probably makes it more likely that I'd actually complete it!

So, maybe I should focus my energy on staying inside the tow vehicle's wake, maybe skirt the wheels, and a smooth underside, and minimizing the weight of the trailer. Those should all help to minimize the MPG hit of having the trailer on.

[ennored]

Originally Posted by Fox Mulder

So, maybe I should focus my energy on staying inside the tow vehicle's wake, maybe skirt the wheels, and a smooth underside, and minimizing the weight of the trailer. Those should all help to minimize the MPG hit of having the trailer on.

Also realize that the aero wake/shadow of the tow vehicle has a top view. The template is fit to half the width so it tapers in pretty quickly. The shadow is also only that size if the gap was filled. Air moves in even faster than the template unguided, as it tumbles around, making the shadow area even smaller.

[Fox Mulder]

That’s a good point. When lining up the template for the sides, ie, looking down at the top, would the apex be in the same place, or would that be at the widest point width wise of the vehicle? If it did, theoretically at least, the sides and top could end at different points relative to one another. In reality, I would assume the tallest point on the car is close to the widest, for the front seat passengers.

[Angel And The Wolf]

When I put the apexes at the same point on my Prius, and scaled them the same, they work out pretty good. Of course, your SUV is taller, but wider, so it may work equally well for you. Remember, whatever the shape the rear truncation leaves will need to be wide enough for your trailer plate, and trailer lights.