Teardrop trailer aerodynamic advice

[4862forestgrove]

Also, have you guys seen any of the theory and testing associated with KF (kline fogleman) airfoils? They are stepped foils and seem to show that the steps associated with a fairing from the vehicle to the fairing and then from the fairing to the towed trailer might not penalize the drag calculations very much and might make the fairing easier to design and construct... KF Airfoils :: explained by Dave Powers | RCPowers.com

BB

[4862forestgrove]

This is a fairing idea for the curved to the front concave design... added hollow "box" at the rear squared off. I'll try a couple of different views this weekend. Top and rear. BB

[Frank Lee]

What purpose does the hollow box serve?

[4862forestgrove]

I was told squaring the back and adding a hollow box at the rear would reduce drag...
BB

[Frank Lee]

Seems to me that hollow box thing is for when it isn't practical to put a real boattail (or built-in boattail form) on.

If you have garage and parkability concerns and make it folding, then yeah. Then it may as well go further to a point.

[freebeard]

Thanks for the input... could you take a quick look at the attached drawing of the treatment of the front radius and tell me which your intuition favors... I believe there are equally easy to build. Thanks in advance. BB

Still in the planning stage right? Aluminum sheet and a Harbor freight trailer?

Re: the nose: Definitely convex. That concave curve you like should be turned around and attached to the back of you Jetta. Customize your tow vehicle to the trailer, but leave it generic so you can move to another tow vehicle.

...When it survives those nasty crosswinds. Be sure to watch the UK Top Gear caravan racing videos before you head out on the road.

In the back: Full -tail? Flat plate? Box Cavity? Eomodder starts to reveal it's schismism. I say go out one nite with a piece of fiberglass pre-preg [activated] and drape it over the back bumper of your neighbor's Prius. Remove it carefully with a spatula before dawn and narrow it up after it hardens.

The frame: Sell it on? You could weigh some different trailers, old boat trailers and such. Then you'll know how much penalty there is for that folding feature. A commercial axle and hitch with some recycled steel stock? It ain't rocket science.

I have one of these and I will be going to him for the parts to get it on the road.

All you need is a round stub axle. Scavenge the swing arm or roll you own and just buy the elastomeric suspension module you can see just inboard of the trailing arm.

As for the aluminum skin, roll the edges and get some aluminum H-channel. Curve that to the required shape and rivet through one skin, the web of the H and the other skin. Easy peasy.

Edit: If you built your own trailing arms you would want to maintain that angular geometry but you could make them straight so they skim the road right behind the tire; and then you could build a full teardrop light-plane style pantaloon off the back of it. I'm ditching the stock fender on my Westy as of now.

[4862forestgrove]

The 1720# HF has no folding feature :-) I plan some welding and a lot of modifications to reduce weight. I'm being talked into the convex shape, your comment about putting the curve on the back of the Jetta is tempting, since I will be fairing the back anyway. I may just do a square front and then try different shells attached to the front of the trailer for experiments. The square would be easiest to build and then I could make the shell I like the best permanent. The shell would cover the batteries, propane, and storage in the front of the trailer.

I'm only into the trailer $270 and can mod if for weight much easier than finding another one.

Thanks for the other points I am considering all input carefully.

[4862forestgrove]

PS - I have a Prius too, that belongs to my wife, so I don't need no stinkin' neighbor, I'll just sneak out in the middle of the night to my garage when she's asleep :-) :-)

[4862forestgrove]

Epiphany! Thinking about using shaped foam rubber like couch cushions coated with liquid plastic for a smoother surface as a flexible gap filler with velcro attachments to trailer... This should allow trailer turns without binding just letting the foam rubber squish and should maintain my radius and be easy to create. I'm sure someone must have thought of this, but, I haven't been able to find it anywhere. BB

[freebeard]

There's a Vanagon/traailer thread on the samba.com. This post is interesting for the aluminum frame, single trailing arms and fender shaped like a bicyclist helmet.

Lots of Harbor Freight-based trailers in that thread