Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Eco-RV thoughts?

ennored · 11-25-2014, 05:26 PM

A Sprinter chassis could be a nice base. My father-in-law's Navion gets about 16 MPG at 60MPH.

OP talked about making his own "box", could be any chassis under it.

Here's where I'm at:

That's a 100" wide (standard RV widebody width), 25' long (random, but reasonable length) box. The front end just needs a little rounding, as little as 4", but I've shown about a 12" radius, a little more than the bare minimum. The back is 50% of an ideal boattail, about 89" long and coming inboard about 15" on each side. 50% tails have been shown to return very close to what full tails do, more just steals interior volume. Think of this as a top view. I'd propose about the same in side view, only the bottom would be a little flatter, probably dictated by the chassis used. Cd should be under .29, maybe as low as .25, about where the Dryden van got to.

Note that the shape in front or rear view would still be close to a rectangle/square. That is, it would have more or less flat sides and roof. I've done that to make it easier to build, and have useable interior space. (Round tube RVs, like an Airstream or GMC motorhome often have cabinets inside that have curved backs/tops. Box of Cheerios doesn't fit.)

Also note that at 100" wide, it's 19% wider than a Vixen. At 25', it also happens to be 19% longer. Relatively speaking, a Vixen has about half of the rear taper I have shown. There's a strong argument to be made to simply copy a Vixen. Bill Collins added taper until a standard bed (75" long) didn't fit anymore. Mine wouldn't fit a bed that way, aero is a higher priority, right?

11-25-2014, 05:26 PM	#30 (permalink)
ennored Master EcoModder Join Date: Sep 2012 Location: Motor City Posts: 281 Thanks: 0 Thanked 223 Times in 138 Posts	A Sprinter chassis could be a nice base. My father-in-law's Navion gets about 16 MPG at 60MPH. OP talked about making his own "box", could be any chassis under it. Here's where I'm at: That's a 100" wide (standard RV widebody width), 25' long (random, but reasonable length) box. The front end just needs a little rounding, as little as 4", but I've shown about a 12" radius, a little more than the bare minimum. The back is 50% of an ideal boattail, about 89" long and coming inboard about 15" on each side. 50% tails have been shown to return very close to what full tails do, more just steals interior volume. Think of this as a top view. I'd propose about the same in side view, only the bottom would be a little flatter, probably dictated by the chassis used. Cd should be under .29, maybe as low as .25, about where the Dryden van got to. Note that the shape in front or rear view would still be close to a rectangle/square. That is, it would have more or less flat sides and roof. I've done that to make it easier to build, and have useable interior space. (Round tube RVs, like an Airstream or GMC motorhome often have cabinets inside that have curved backs/tops. Box of Cheerios doesn't fit.) Also note that at 100" wide, it's 19% wider than a Vixen. At 25', it also happens to be 19% longer. Relatively speaking, a Vixen has about half of the rear taper I have shown. There's a strong argument to be made to simply copy a Vixen. Bill Collins added taper until a standard bed (75" long) didn't fit anymore. Mine wouldn't fit a bed that way, aero is a higher priority, right? Last edited by ennored; 11-25-2014 at 05:41 PM..