Travel trailer opinions wanted

[Frank Lee]

Originally Posted by dpero

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.

If I may practice a bit of armchair aero... I'm not so sure the "aero" trailer has any aero advantages.

For one, it's leading surface is further away from the tow vehicle's upper trailing edge and surface. Larger gap = bad.

Second, more radius on leading edges than necessary to promote "attached" flow does not reduce drag further. Yes the side edges are sharp but they are on both of them. The "old school" trailer appears to have a generous enough radius on top so no advantage there for the "aero" design.

Third, there is the additional frontal area. That simply ain't gonna help. (BTW-there's that semi thread re: that humpback trailer that's supposed to reduce drag. I don't see how. )

Fourth, the "aero" trailer appears to actually have more rear area, thus it will have a larger trailing wake. That is where most of the aero action is anyway.

Fifth, as a larger unit, it will have more "wetted" area, possibly leading to more surface drag. I wonder how much of an aero hit those corrugated sides cause on the old school unit?

The concept of the aero trailer is sorta nice but the execution of this one makes me think it is not much more than a marketing ploy OR they decided to bias the design in favor of increased interior volume without necessarily adding drag commensurately.

[KamperBob]

I know this discussion started as trailer A vs B but what about C-Z? If aero is NOT a primary decision factor then other requirements trump. If aero IS important then it's hard to beat well rounded trailers from Airstream (aluminum) and Scamp et al (fiberglass). You can learn more about the latter breeds here.
Egg Central

Cheers
KB

[endurance]

Personally, I'd hold out for one of these:

http://www.youtube.com/watch?v=56XL0TysIn0

[aerohead]

I looked at Hucho's book last night.His trailers are generally the same as the two under investigation.And according to Hucho,the 1st trailer would actually have the car/trailer lower drag,around Cd 0.45,based on the frontal area of the trailer.
The 'aero' trailer car/trailer combo would be around Cd 0.53.
The caveat is that the 1st trailer would reduce tongue weight with speed,the 'aero' trailer would be dead neutral and pull well under all conditions.

[dpero]

Originally Posted by Frank Lee

For one, it's leading surface is further away from the tow vehicle's upper trailing edge and surface. Larger gap = bad.

So, would the previously suggested air deflector help this out?

Originally Posted by Frank Lee

Fourth, the "aero" trailer appears to actually have more rear area, thus it will have a larger trailing wake. That is where most of the aero action is anyway.

Yeah, I noticed that also. Maybe some modifications in that area would help?

Originally Posted by Frank Lee

The concept of the aero trailer is sorta nice but the execution of this one makes me think it is not much more than a marketing ploy OR they decided to bias the design in favor of increased interior volume without necessarily adding drag commensurately.

They don't actually market the shape as an aerodynamic improvement. Perhaps because it may be worse judging from your comments? I had first thought it would be better than the K-Z. They market the shape as such...
Uni-Arch fiberglass roof eliminates seams at critical water runoff areas
and...
Visa’s unique arched roof provides 82” of headroom at the highest point
Both of which are very true.

Originally Posted by aerohead

I looked at Hucho's book last night.His trailers are generally the same as the two under investigation.And according to Hucho,the 1st trailer would actually have the car/trailer lower drag,around Cd 0.45,based on the frontal area of the trailer.
The 'aero' trailer car/trailer combo would be around Cd 0.53.
The caveat is that the 1st trailer would reduce tongue weight with speed,the 'aero' trailer would be dead neutral and pull well under all conditions.

Interesting. Thanks for taking the time.



I looked at one last weekend and it seems much larger than the K-Z inside. That taller roof gives it a cathedral feel to it. We will probably go with the Visa. It simply feels much larger inside and has many other features I like. I will have to try to squeeze as much MPG out of it as I can of course. I towed a 4x6 enclosed trailer last weekend and MPG dropped from 21.5 to 15.5 with just that combo. Acceleration was fine but over 55mph and MPG tanked. It also tows quite far behind the van. I would guess just <10 with the camper???

[KamperBob]

As if we needed more proof the RV industry has it backwards...
Galileo RV

Cheers
KB

[aerohead]

Originally Posted by KamperBob

As if we needed more proof the RV industry has it backwards...
Galileo RV

Cheers
KB

Perhaps one unit could have the tongue moved and re-welded to the back of the trailer,then do a side-by-side comparison,one trailer going forward,the other,well you know!

[KamperBob]

Originally Posted by aerohead

Perhaps one unit could have the tongue moved and re-welded to the back of the trailer,then do a side-by-side comparison,one trailer going forward,the other,well you know!

Maybe the Myth Busters would take that challenge. That'd be a hoot!

Cheers
KB

[dpero]

How about your thoughts on this one. I was toying with the idea of building one from scratch but the reality of it (the lack of time) proved otherwise. It is 8.5 ft at it's highest. Never quite finished the design.

[shovel]

Just going on what I've learned from reading + hobby experimentation, I'm going to guess the oldschool trailer is going to be the more efficient one. It's significantly lighter, draws a significantly smaller wake than the "aero" one, and isn't significantly less aero in the rear at all.

Up front the biggest improvement would come from closing the gap between the van & the trailer, as has been mentioned. Might be feasible to attach a "bulb" to the front of the trailer with its midpoint around the roof height of the tow vehicle, extra storage for tarps or muddy boots and at the same time closing the gap a little & providing a bit of radius for air passing to the sides of the trailer.