Enclosing trailer underbody

[Gettin Started]

I'm considering enclosing the underbody on my 6 x 12 V-nose, anticipating that it will held smooth airflow underneath and improve handling/gas mileage. Has anyone done this and noticed an improvement?

Google tells me that Coroplast is often used for this, but I can't find installation steps/photos. Absent any specific feedback, I'd use a silicon sealant around the perimeter in addition to screws around the perimeter frame and along cross-members.

I'm also wondering whether FRP sheets would be a more durable option at a roughly 50% cost premium at my local home depot.

Appreciate input from those who have already done this.

[Padilen]

I'm skeptical that it would increase mpg enough to notice. Have or are you insulating first ?

[vigilant1]

Anything under there is subject to damage/breakage/coming loose due to road debris (dead animals, truck retreads, car parts, etc). I'd want to be darn sure whatever I used would be unlikely to come loose and cause injury/damage to others on the road (including motorcyclists). In this respect, Coroplast is less rigid and frangible than FRP, so might be a better choice. Maybe a tightly-installed tarp?

As the trailer's "basement", there will be plenty of reasons to re-access the underneath of the trailer if there are water lines, electrical wires, holding tanks, etc under there. I wouldn't install anything that makes it too onerous to do maintenance. Removing scores of screws would be too onerous, in my book.

[tony.latham]

There's an ongoing competitive MPG race between GMC, Toyota, Dodge and Ford––the truck makers. They've done all sorts of things to bring up the MPG. Air dams and Atkinson cycle engines are a couple that come to mind. None have a covering underneath the chassis and four-bits says they've played with it. Perhaps it'd just create a maintenance nightmare for a truck though.

But give it a shot. Nothing wrong with a little shade-tree R&D.

If it were me, I'd be looking at the fender drag and perhaps a few of these Airtab vortex generators: http://www.airtab.com/

Tony

[Gettin Started]

Already have 2" of EPS under the floor, held in place with adhesive and nails w/ washers through the insulation into the floor. No water tanks or added electrical run under the floor (other than brake electrical), but it's certainly possible that I'll need to access the area again someday.

Some Travel Trailer's have this as an available option (Coroplast is cited an the material typically used). Part of the reason in that application would be to help retain heat directed into the water tank area. Hoping to hear from some that have done this and whether they noticed any impact to handling or gas consumption. I still may do it, just to seal underneath as an added barrier from the elements and to keep my insulation in if the adhesive/nails fail. My gut tells me that FRP would be more sturdy even though the travel trailer industry seems to use coroplast.

[Gettin Started]

There's an ongoing competitive MPG race between GMC, Toyota, Dodge and Ford––the truck makers. They've done all sorts of things to bring up the MPG. Air dams and Atkinson cycle engines are a couple that come to mind. None have a covering underneath the chassis and four-bits says they've played with it. Perhaps it'd just create a maintenance nightmare for a truck though.

But give it a shot. Nothing wrong with a little shade-tree R&D.

If it were me, I'd be looking at the fender drag and perhaps a few of these Airtab vortex generators: http://www.airtab.com/

Tony

Thanks, looked at those as well. For how few miles I'll tow in a year, the payback would take a while. Drag behind the trailer is a huge source that would be great to reduce, but other than airtab I don't see any feasible options that wouldn't get in the way of the ramp door. Reports I see on airtab tend to indicate increased stability with minor impact on MPG (which is still a benefit).

[hankaye]

Gettin Started, Howdy;

As a full time resident in an RV that has Chloroplast enclosing my under belly (my basement is the pass through
storage area in the front), it's purpose is to keep what little heat that is directed to the plumbing and tanks as
can get there and to keep other 'stuff' from dropping on the road. Can not say about the fuel savings this RV came
with it from the manufacturer with it.
The Chloroplast is held into the metal frame with 1/4" self tapping cap screws with washers. There is NO sealant
used in it's installation. I doubt if it will prove to be of any benefit for your needs. Spend those $'s for something nice.

hank

[Padilen]

Already have 2" of EPS under the floor, held in place with adhesive and nails w/ washers through the insulation into the floor. No water tanks or added electrical run under the floor (other than brake electrical), but it's certainly possible that I'll need to access the area again someday.

Some Travel Trailer's have this as an available option (Coroplast is cited an the material typically used). Part of the reason in that application would be to help retain heat directed into the water tank area. Hoping to hear from some that have done this and whether they noticed any impact to handling or gas consumption. I still may do it, just to seal underneath as an added barrier from the elements and to keep my insulation in if the adhesive/nails fail. My gut tells me that FRP would be more sturdy even though the travel trailer industry seems to use coroplast.

I added ridged insulation under mine and used liquid nails and forcing pieces between "floor joists" then I caulked all seams and painted with dry lock paint. Looks good and seems to protect the insulation well. I was under it doing an axle flip and no dirt or debris were on it. I live on and travel dirt roads that had just have been chloride'd. I'll learn if lifting changed this.

[McDave]

I'm not sure if it wouldn't add more drag. Air likes to cling to flat surfaces like walls and roofs and rear doors. look into the airtabs for some data.

McDave

[flboy]

Unless you need it to be insulated, I personally wouldn't spend the effort and the $$. It is more likely to collect road debris, moisture and etc...