Eco-RV thoughts?

[Cobb]

Reducing your self imposed speed limit will make the biggest improvements in mpg.

[slowmover]

Cost effective is already present. A TD tow vehicle and an aero trailer. One can be in the 20's without the years of building and testing.

The "cost" is nights aboard over years of use. The truly economical is the one that lasts decades. Miles is mainly a function of affordability. Whether one one moves once monthly and then maybe 200 miles or wants MORE has to be weighed. Most retirees RVng cite $2500-3000 as a minimum income. Less than this is not the point it is that the upfront costs should be done while one is in a career. I'd say it's hard to reinvent the wheel and not particularly effective to do otherwise. Modify existing maybe but keep in mind RV capacity (water and propane and food storage) mean more than RV mpg. It is he solo miles of a combined vehicle that the real savings occur. No moho will ever meet the same test. It is a mobile house and not an oversized car.

Here's a post (along with the link above about the boattail Class C) that may whet your appetite for building:

http://ecomodder.com/forum/showthrea...tml#post456738

[saturndude]

My 1987 Toyota motorhome got close to 20mpg, more like 17mpg. But it was fully equipped and self contained. I miss that rig. But I agree that an efficient tow vehicle and lightweight aero trailer are your best bet.

[slowmover]

after completing a 5000 mile road trip in my 2001 Dodge Ram 3500 4x4 Diesel truck hauling a 27' 5th wheel trailer. I managed a trip average of just over 12.9mpg. My best tank was 13.2mpg.

Some years back I researched the later HPCR Cummins TurboDiesels and how well they were pulling aero all-aluminum travel trailers as that combo is also mine. I found over one dozen reports where the TT in question was from 28-35' in length and weight from 7-11k pounds. Mainly in South Central US. 14-16 mpg was the range where travel speed was 58-62 mph, overall (some claimed more and at a higher travel speed. I wasn't always able to get confirmation about written reports or how well records were kept).

I found 15+ was easy at 62-63 mph. So 16-mpg at my now-usual 58-mph is easy. Goal is to be 17 as an average in the future (for warm climate, low altitude cruising on non-hilly Interstate). And that goal will be from quite careful trip planning and execution. I wish to know my top possible number.

The difference from 13 to 16 is an improvement of about 18% (for averages). That, I'm guessing based on some experience and reading around, is the likely top for a 1T diesel truck pulling most any kind of trailer.

Hitting the 20's will be with a TD car or SUV. Maybe up to 22' with a post 1990 Airstream (to keep restoration costs low). An OLIVER or CASITA would be just as high, maybe higher, so look at them as well. We've one contributor here with a 5'er SCAMP who does 15-mpg with a small gasser pickup (KamperBob).

So, while a trailed combination is likely to be higher (and with a tow vehicle that for solo miles is also quite fuel efficient which is the majority of miles), a moho has to answer the question that really kills average mpg. And that is how long can one park without re-supply be it food, water or propane?

Yes, one can design a scenario where a giant moho can burn less fuel overall than many or most other combinations where extended off-grid parking is expected due to huge onboard capacities. So how one travels is key. But the usual scenario is to move every few days for re-supply or to tow another vehicle. Neither is in any way fuel efficient.

Outline how one expects to travel and this thread will gain some traction. A single man moving every few days is one thing, a family of seven staying three weeks at a time in one spot is another. And so forth.

Staying in motels isn't the cheapest. Cheapest is sleeping on the Grey Dog en-route. An RV has to be put into context.

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[redneck]

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https://www.google.com/search?q=tear...ailer&imgdii=_




https://www.google.com/search?q=tear...tm%3B400%3B331




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[freebeard]

If you don't mind my asking, how much are you thinking of spending on this, and what kind of fabrication is within your abilities?

X2

How many do you need to accommodate? Your post has numerous 'I's and one 'Our". I follow Frank Lee's precept. I have a hollowed out VW Beetle with one seat, a six-foot bunk, a refrigerator, and curtain rods. Two 20-liter gas cans and a compass. I call it a Sport Utility Volkswagen and mainly use it for a van when I'm not off to Bonneville.

Here's a thread:
http://ecomodder.com/forum/showthrea...elp-23091.html
and the design I posted somewhere in it.



It's based on geodesic domes and 1930s beer trucks.

...and my own aerodynamic motorhome design:


______

Edit:

Originally Posted by slowmover

Cheapest is sleeping on the Grey Dog en-route.

[redneck]

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PNW_Steve

I am really hoping to see something that is really livable and can accomplish 20+ mpg highway. Being able to run 65mph and still get 20+mpg would be a bonus.

Check out Vixen motorhomes. 22-30mpg.

Welcome to Vixen 21 Motorcoach Website.





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[Xist]

I think that a camper trailer makes the most sense. It would not require permanently modifying your car to carry a tent mount year-round.

You can sleep in a boat tail!

[slowmover]

I can pull the largest U-Haul trailer (6x6x12) behind my CTD at 18-19 mpg loaded or empty (58-mph/1,725-50 rpm; two 700-mile round trips; .79 of solo). Same height as the bed topper. Adjustable hitch to "level" the trailer. A very stable trailer but hardly aero.

An aero all-aluminum travel trailer takes a penalty of 30% whether we speak of a 1965-spec tow vehicle or one of 2015.

Look to threads on enclosing gap from truck to trailer on this forum. Best truck spec (turbodiesel, manual trans and 2WD) plus a teardrop or boat-tail trailer "matched" to truck is going to average above 20-mpg as a combined rig, IMO , given long distances travelled. Weight is not much of a concern.

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[ennored]

LOTS of info here at Ecomodder, mostly in the aerodynamics forum.

One thread there

(You could add "ennored" to narrow any search you do, most of my posts have something to do with Motorhome or trailer aerodynamics.)

The Vixen, mentioned here many times, is to my knowledge/research, the most RV aerodynamic (lowest Cd) ever built/documented. It's Cd was .29 for a real vehicle, in a wind tunnel. (It also kept the frontal area as small as possible, the roof popped up on the original model, to lower total drag.)

Bill Collins, the Vixen's creator summed up the aerodynamics development very simply. He rounded the front end until the drag got no better, then he tapered in the rear all he could.

A custom build could follow his method. Round the front corners (4% X width radius has been shown to work), then boattail the rear. You'd be under .3 Cd, about 50% of the drag of a "normal" motorhome.

(I MAY have detailed Vixen info soon, just walked by a guy's desk the other day with some Vixen pictures, and his Vixen business card, yes, he worked there. I think he owns one.)