V-nosed trailer, will a sloped nose make much difference?

I've been toting around a 14x7 v-nosed enclosed trailer for my UTV for a couple years now. The drag is pretty mind blowing. It feels like I'm pulling a parachute.  I get at least 50% better gas mileage when I'm towing my open car trailer.   I'm looking at larger enclosed trailers that can fit a full sized car. My question is, how much help is the sloped v-nosed configuration?  They're significantly harder to find, but it seems like it could be worth the trouble. Anyone have any insight?

Can I also ask , can you put a wing or extension on the back of the roof to cut down drag and hopefully get a little better MPG

I bet the beavertail flaps on the back end make a bigger difference. I'd guess there is data on the web somewhere.

My girlfriend just bought a travel trailer and it came with little vortex generators which claim a half a mpg improvement.

https://www.airtab.com/

No matter what you do with the nose, you're not getting away from the big frontal area. I've never pulled a v nose myself, but everything I've heard is that they're not substantially better than a flat front. I'd rather have a shorter roof (and correspondingly less frontal area) than even the most aerodynamic front end.

If you've got deep pockets, look into an Aerovault.

californiamilleghia said:

can you put a wing or extension on the back of the roof to cut down drag and hopefully get a little better MPG

I would imagine something to clean up the flow off the trailer AND off the tow vehicle could help. 

In theory, it should make a difference because you're cutting through the air v. smacking it while driving down the road.  The rear wake, however, still exists.  MattGent, I've seen those airtabs before and get the theory that they should work better, but always wonder because I've never seen them used in the real world.  I know big rigs put flaps under the trailers now to reduce airflow and would assume with the increase in fuel costs and increase in deliveries, companies would use them more if they really worked.  They don't seem crazy expensive.

For me, I'll probably buy a v-nose for my next trailer.  From what I've seen, a v-nose isn't much more expensive than a flat and if it makes a difference it's worth it.  It also adds a little more enclosed area for the trailer, anyway, which can be valuable if you're trying to keep the overall trailer footprint a small as possible.

-Rob

As long as the frontal area is the same and the back is flat, nothing else is going to make a big difference. On that note, the best thing you can do for fuel economy is to find a semi truck to draft behind, you don't even have to be all that close to see some benefit. We've seen as much as a 25% increase in fuel mileage from it.

It's still a giant turbulent air blocking piece of metal.

It doesn't matter if it's shaped all aero ish or a flat vertical slab, it still has the same sq foot profile and responds as such.

This makes me wonder about my Suburban vs my old pickup. In theory the Suburban should be better because it punches the hole and the air doesn't get a chance to come down as much. True?

Cactus mentioned these guys, but i found their information to be interesting reading, if nothing else.

https://www.bre2.net/aerovault.info/the-aerovault/

I would assume it is worth a little bit. Closer to a raindrop the better right?

Stampie said:

This makes me wonder about my Suburban vs my old pickup. In theory the Suburban should be better because it punches the hole and the air doesn't get a chance to come down as much. True?

Not exactly.

The roof is smoother, but any air that has punched over the roof is already turbulent. If it's not adhered to the roof, that's just more area for turbulence.  Plus, the air still needs to re-group as it comes off the rear.  Your Burb has a bigger hole at the rear to fill with air.  
 

SV reX said: Your Burb has a bigger hole at the rear to fill with air. 

Yeah, but I assume he wants to put a trailer in that hole.

In reply to Cactus :

That makes a bigger hole (and more turbulent)

Interesting generalization from this document by a complete amateur (me): At a length of 2x the width a flat nose rectangle as a C(Drag) of 1.7, and a rounded nose rectangle has a C(Drag) of 0.7.  I know the wedge nose isn't quite the same, but it seems like a step in the right direction. I was also impressed that simply rounding the edges of a cube took it from 2.2 to 1.2.

SV reX said:

In reply to Cactus :

That makes a bigger hole (and more turbulent)

But one long hole instead of punching one and one half shorter holes?

In reply to MrJoshua :

I don't think it works that way...

My armchair aero thinking suspects that it would help only a very tiny amount. The front end of the trailer is seeing serious turbulence from the towing car, so its shape isn't going to matter a lot. Trying to get laminar flow between the two could help a lot more than the shape of the trailer front. Also, at the back of the trailer is a big bubble of low pressure air, basically sucking the trailer back as the engine fights to pull it forward. 18-wheelers sometimes have those big hinged shutters that help bring the cross sectional area down as the air separates, reducing drag "some amount."

In short, if mileage is a big deal, consider driving slower, really, because drag is proportional to speed squared, so slowing from 80 to, say, 65, would reduce drag by 34%. That's a lot and costs nothing!

All i know is what I experienced.   Pulling with an E350 van.  We had a fairly standard height trailer which was taller than the van.

Then I custom ordered a trailer with the trailer roof being almost the same height as the van roof, along with a V nose built out towards the tongue.  It is one sweet trailer to tow.

SV reX said:

In reply to MrJoshua :

I don't think it works that way...

It does a little bit. Cyclists know this - if you draft another rider, both of you benefit. I've also done a close formation interstate drive in two Miatas running in near-bump-draft separation with a third as a control and saw a 10% improvement over a full tank of gas. Gotta be a little crazy for that, though.

So the right trailer might actually lower drag. It would have to be on a pretty short tongue, though, and you'd have to have a tow vehicle punching a pretty big hole.

If I were looking to drop the drag from my trailer, I'd chop it. Those "Low Hauler" trailers the Harley guys like have a low load floor and a short overall height, dropping their frontal area down. I've threatened to do this a few times...

SV reX said:

Same article has these images:

Making the heights more similar and the gap between vehicles smaller reduced turbulence. The roof line of the Suburban extending all the way to the tailgate instead of dropping down to a low sided (and hollow) truck bed brings ~ 1/2 of the trucks height 8' closer to the trailer. It should reduce turbulence. 

Ninja edit-the original pointy nosed trailers this thread is about should close the gap as well.

Keith Tanner said:

If I were looking to drop the drag from my trailer, I'd chop it. Those "Low Hauler" trailers the Harley guys like have a low load floor and a short overall height, dropping their frontal area down. I've threatened to do this a few times...

Trailers with a pop up style adjustable roof height? (there are probably a million ways to spend your money more wisely, but it would be amusing )

I wasn't thinking of a full-on pop top, but my camper works that way so why not? ;)

My car trailer is just for transport, so a 5' overhead (for example) would be perfectly acceptable. That would get rid of about 2' of the most exposed frontal area (dimensions taken from vague memories).

In reply to Keith Tanner :

Didn't know this was made, till recently:

Tows behind the car effortlessly, (with correct hitch, and not counting mpg hit!)