Aerodynamic van trailer

[Hauki]

Hi, I know this has been discussed a lot, and I have searched almost every post on here but I have yet to find many good designs that would significantly reduce aero. I know a guy in Valencia (sorry forgot your username) has some awesome designs/ideas. I have been toying with some designs using the classic tear drop shape template C and this is what I have come up with.





Access would be via a hydraulic assisted opening at the rear.

My main question is, I don't want to taper off completely, I want a sort of boat tail, how much will this impact? Reason being the more I can chop off the end, the bigger opening I can have, which is pretty important as it is a cargo trailer.

If anyone else has done the same sort of idea, or has actually got around to building they're aero trailer and has fuel figures please chime in.

[NeilBlanchard]

The choice is to either pivot the trailer at the back of the vehicle, or to have caster wheels on the trailer.

Truncating the trailer has minimal additional drag. The access door could include part of the roof; like a hatch door on say a Prius.

[Hauki]

Ok I think this will make it more clear what I am trying to achieve. But cutting it off at about 19° rather than go right to 22°, I am lead to believe this will have a tiny affect than if I went to the whole 22°.

[euromodder]

Originally Posted by Hauki

Access would be via a hydraulic assisted opening at the rear.

Rather than lifting the entire rear cone, you could leave the sides in place (good place to have the lights too, as they'd stay in place when the trailer is opened up), drop the lower part as a ramp (always useful) , and only lift up the rear end of the roof (less weight to lift).

My main question is, I don't want to taper off completely, I want a sort of boat tail, how much will this impact? Reason being the more I can chop off the end, the bigger opening I can have, which is pretty important as it is a cargo trailer.

You can reduce the length, as the last part of the taper won't return that much of an improvement.



In this case, starting from a huge squarish rear end of a van, the improvement could be massive.

The image also shows you could use a blunt nose, as it doesn't add much extra drag, but a lot of internal volume.
Anyway, the nose won't be too important, as it'd hide behind the van.
OTOH, you need some taper up front to be able to turn with the trailer

[Hauki]

Ok so far I've got this:

http://www.youtube.com/watch?v=Zhvx2ePt9AQ

The rear will kind of look like this:



The trailor will be be made of a light timber frame, plywood sheets then fiberglass/epoxy/gelcoat so it will be lightweight but strong. However, my carpentry skills are not great so the edges will be 90°, as in not radii(?) or rounded. EG, The sides and top will have the correct curvature to 18° or however far I can go within 3.5/4 metres limitation, but where each side meet will be 90° joints. How big an effect will this have?

OK, I got Sketchup and had a play with it, I don't understand how to do curves, but here is my trailer idea with straight panels, but basically the same.

[aerohead]

Originally Posted by Hauki

Hi, I know this has been discussed a lot, and I have searched almost every post on here but I have yet to find many good designs that would significantly reduce aero. I know a guy in Valencia (sorry forgot your username) has some awesome designs/ideas. I have been toying with some designs using the classic tear drop shape template C and this is what I have come up with.

Attachment 11158

Attachment 11159

Access would be via a hydraulic assisted opening at the rear.

My main question is, I don't want to taper off completely, I want a sort of boat tail, how much will this impact? Reason being the more I can chop off the end, the bigger opening I can have, which is pretty important as it is a cargo trailer.

If anyone else has done the same sort of idea, or has actually got around to building they're aero trailer and has fuel figures please chime in.

If you'll do a Search EcoModder for 'Full-boat-tail trailer' and go to page 25,#248 permalink you'll find some pictorial drag tables which will show the impact of edge radii.
For my trailer projects,the most recent,with the gap-fillers,has registered the highest ever mpg for the towing vehicle.
Without the trailer the highest-ever mpg was 39.With the trailer,I've seen as high as 47.8,at 65 mph.The trailer weighs over 700-lbs (318 kg).
The trailer is yet incomplete and may perform a bit better if I can ever finish it.
I'm very encouraged with results so far.I think that you'll like yours.