Travel trailer opinions wanted
 

Hello all. I will be purchasing a travel trailer and have it narrowed down to a couple options and would like some thoughts as to the aerodynamic consequences of the two. Tow vehicle will be a 2011 Toyota Sienna SE. I chose these two because of the lower weight, single axle, and narrowness of them.

First option is a K-Z Sportsman Classic 19BH. What appeals to me about this one is that it is only 7' wide and 8'2" high. Unfortunately it is very squared off. It is also much less expensive than option two.
http://lh5.ggpht.com/_KBUbO5zit_E/TK...-Sportsmen.jpg

Second option is a Gulf Stream Visa 19RSD. This one has what seems to be an aerodynamic shape to the roof line. Unfortunately it is 6" wider at 7'6" and 1'6" taller at 9'6" (including the AC).
http://lh3.ggpht.com/_KBUbO5zit_E/TK...ienna-Visa.jpg

My question is; Do you think the taller & wider Visa cause more aerodynamic drag because of it's height & width? Or would the better shape negate it's size? I would consider removing the rooftop AC on the Visa to help out the aero.
http://lh5.ggpht.com/_KBUbO5zit_E/TK...-Sportsmen.jpg

(If your wondering, I used Inkscape to create the images.)

For the issue of the AC you could just add an angle to help direct air over, around and back down it remove some of its extra drag. I would assume that adding a ramp on the roof of the van to direct the air over the trailer would help reduce the drag.

The main aerodynamic gains are to be made at the rear, not at the front.
Neither design is anything like aerodynamic at the rear, but the visa has a curved top with a slight downslope that might offset its bigger bulk.

Based on your pics, I'd go with the second one: Better overall shape, less draggy stuff hanging off the side, appears to have had at least some attention to aero drag in the design. You could make a simple and light aero fairing for the AC on top. After going past the relatively sharp leading edges of the first trailer, aftward flow would probably be so buggered as to exceed the drag of the second design.

Which would be easier to add Coroplast belly and wheel fairings to? Which has better surface texture from the getgo? Which weighs less?

the second one is about 25% more frontal area, and about 12% heavier

19bh frontal area 8232 sq in, about 2500 lbs
visa frontal area 10260 sq in, about 2800 lbs

given the general boxiness of both of them and a van to break the wind up front, I think the 19bh is gonna start out ahead and pull away from there efficiency wise.

I second the "add a wing to the van" comment, they make a big diference.
Unfortunately my toyhauler's ramp doesnt lend well to a kamm, but the 19bh does.
Oh, and i love my KZ, great trailer, see below.

All great comments so far. Thanks.

The wing idea would be doable... perhaps attached to the roof rack.

As far as the weight difference, I'm not too concerned as the van's max is 3600 lb so I would be staying close to that with either trailer. They are both single axled so that also limits total weight. I am having a hard time believing what's listed in the brochures for weights as I have seen it vary 200ish lbs on the same trailer from different sources. However, the Visa makes sense that it weighs more. A little research last night on my part showed that weight makes little difference at speed.

The exterior on the Visa is very smooth besides the windows and awnings. The 19BH is the traditional corrugated aluminum sheet.

That's a huge difference in frontal area! The Cd would have to be much better on the Van-Visa to make up the difference... correct?

I will be looking at a Visa this weekend. I am afraid I will like it more as it appears to be of better quality. The price reflects that also at almost $5K more.

The Visa has it external tent on the other side, but overall it looks better streamlined on the bigger pictures :
http://www.gulfstreamrvtrailers.com/...ERDHighExt.png

Actually, it looks a lot like the streamlining template - it's just cut-off very early.

I think in this case the rearal area is key, as the tow vehicle is blocking frontal area in ways which may not be clear cut i.e. if #2 has 25% more frontal area does that mean it is presenting 25% more area to the wind? Not this time.

So I think aero load differences tween the two will be very minor compared to the functionality of them (which one suits your needs better?) and of course the price.

Hucho's book/ caravan trailers
 

Hucho has a section on travel trailers and some wind tunnel results for generic forms.
I don't have my book with me.Anyone?