Big Van airdam/side-skirt design suggestions

[mwilliamshs]

Originally Posted by aerohead

If you have,or have access to a metal brake,she'd come together fast!...

A brake and a slip roller would knock that out in no time but they're certainly not necessary.

Originally Posted by aerohead

...GE makes a great 100% silicone gutter sealant that's UV stable and remains elastic.It's not paintable but comes in colors.If you haven't used it yet,it's worth checking out.

I will NEVER again use silicone sealant on a car or RV. Never have used it on a car but after the crap I've seen and experienced on campers I view silicone as (excellent) lubrication and nothing else.

[oldtamiyaphile]

Originally Posted by mwilliamshs

For a DIY solution to closing the ends, some careful cutting and a little origami would turn this quickie sketch into a nice foil I think...

I think the bulged section is actually a trapezoid with straight sides, and the curved appearance is just perspective. If I wasn't fighting a tongue weight issue (tongue weight is 120kg vs a max permissible 75!), I'd be knocking one up tomorrow. The top would simply rivet to the top of the trailer, and the bottom would rivet to some aluminium angle. I actually quite like the looks of the open sides and it could double as storage for a tarp or ropes etc. Maybe just add a small fillet to the base to stop things sliding out.

[mwilliamshs]

Originally Posted by oldtamiyaphile

I think the bulged section is actually a trapezoid with straight sides....

Agreed

Originally Posted by oldtamiyaphile

...and the curved appearance is just perspective....

Disagree. Cut a flat trapezoid and push its two longer sides toward each other (while keeping them flat against a surface like the front of a trailer) and the shorter sides will curve. That curve is the aerodynamic benefit.

[Angib]

The real textbook on how to make a van more aerodynamic was done by NASA Dryden back in the 1970s/80s:

A Reassessment of Heavy-Duty Truck Aerodynamic Design Features and Priorities
(Oops, first post, so can't link to file - google 88628main_H-2283.pdf and it will get you to their report.)

This has lots of scientific testing of real-world(-ish) aero mods which will teach anyone something - for example they tested a full boat-tail and a truncated one with precious little difference (Cd=0.242 v Cd=0.238).

[Goofy1]

Wow, something I have a tiny bit of experience with!! I modded a 1977 Dodge Van, 318, 4sp and eventually got a consistent ~30mpg.

As was stated by Aerohead the front dam can be flat or a bit taper back from the center with little difference.
Side skirts follow along the rear outer edge of the front tire to the outer edge of the front of the rear tire. Behind the rear tire I tapered mine in slightly, maybe 8 inches or so.

Two things that I did to mine that helped the MPGs:
1. I put two scoops on the belly and ducted the air out the back doors. The scoops were approx 3-4 inches deep and just in front of the rear axle, up thru holes in the floor and thru channels (originally dryer hose) to the exits in the back doors. When I refined this system I had a friend that did aviation sheetmetal actually build hard duct work.

2. I blocked off the grill with a sliding panel system that allowed me to close off almost the entire grill while in motion to let engine air come in from the lower grill opening behind the bumper. Or if in traffic open up the opening for free-er airflow. The engine driven fan was replaced by two electric fans for redundancy and the engine bay was vented thru a NACA type duct on each fender (which coincidentally would defrost the mirror in the winter!).

[McDesign]

Wow - would love to see pix.

[Goofy1]

Originally Posted by McDesign

Wow - would love to see pix.

Sadly all the pictures that I had were destroyed in a house fire many years ago. One of the downsides of military life is that you get sent places where housing may not be the best.

[McDesign]

Shoot - my wife mostly drives my aero-ized Accord, and wants to see what's possible with the obligatory Chrysler minivan each family must have.

Lowering and full skirts were my most effective improvements.

Forrest

[McDesign]

It also occurs to me that a van dam should be called a "Jean-Claude".

Just sayin'

Forrest

[Varn]

I drive a 2005 Econoline and had a 1990 before that. One thing that has helped the economy is to put three layers of metal window screen behind the grill work.

In the winter I have tried removing the grill and installing a coroplast cover flush with the bodywork. It helps but can cause over heating in the warm weather though.

Running the tires at max pressure helps.