What's the best RV/motorhome aerodynamically?
 

Considering stock (especially used) recreational vehicles and motor homes, which ones have the best aerodynamics?

Vixen
 

To my knowledge,the distinction would fall with the Vixen,long dead now.
Relying on memory ( risky ) with her TD BMW 5-cyl she could knock down around 21 mpg in real highway driving.
The roof tilted up for overnight stays.No Cd was published.I would have estimated it at 0.30 or a tad under based on FKFS Omnibus images from Germany.Maybe Cd 0.27.

Check this out:

http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

Esp. see configurations G and H, with CD <0.25 and wheels/tires not optimized, plus sharp roof edges. Basic brick with wheels, streamlined.

The GMC units from the '70's were wind tunnel tested.

http://i146.photobucket.com/albums/r.../IMAGE_062.jpg

I'd say the Dodge/Mercedes diesel van units will be the ones to beat due to efficient drivetrains and relatively small frontal areas.

good recall on the vixen Phil, here's a link
http://ecomodder.com/forum/showthrea...5mpg-4836.html

I know that this will sound bad, but if you are into ecomodding, a school bus with a diesel cummins 5.9 will get 11-12mpg without any modifications. I think that with some minor expenses, you can make a pretty sweet bus that gets 15mpg or better. We got ours for $2200. Keep in mind that this is a 38 foot engine forward flat windshield aero hog with no mods.

What's the best RV/motorhome aerodynamically? The one you modify the most! ;)

that is one of the reasons that I suggest a bus. Cheap to get, good running gear, and most of the time if you have a major failure, you can sell parts off it for as much as what you paid (in my case).

On the other end of the spectrum might be a diesel westfalia camper, maybe good for 30mpg, dunno.

course if you just want a place to stay dry and keep the bears off ya, then a mat in the back of your hatchback (passenger seat forward) can be relatively comfortable.

And a jungle hammock fits nicely on anything from a bicycle on up and is quite dry and comfortable.

Though it would be interesting to see an eco'd bus :)

It depends on your requirements. Where do you want to take it? How much ground clearance is needed to get in/out of camp sites? How many creature comforts are must have? How many people will be sleeping and eating inside it? How many days of food, water and restroom capacity do you need between stops? How many miles do you need between refueling stops? If traveling lots of toll roads, how many axles can you afford? What other dollar or weight budget restrictions might be involved? Don't forget all cargo needed to enjoy the trip and/or destination. If you go somewhere and drop anchor for a spell what kind of auxiliary mobility will you need to get around? These factors may have a higher effect on your satisfaction than how many MPGs you get.

BTW, I can meet (even exceed) the EPA highway number on the sticker of my (stock) truck towing this (aerodynamically stock) trailer including extras.
http://kamperbob.com/EU3kReceiver/GenMounted.jpg

You can learn more about this genre of small car/truck friendly RVs at Egg Central.

Cheers
KB

I always liked the 70s GMC motorhomes. I heard they also set the land speed record for a motorhome, at least for their time.

How about the Lesharo / Phasar / Rialta motorhomes?

Gmc
 

One of my relatives had a GMC motorhome.They would drive it down into Mexico for dove hunting.
They told me that 8-mpg was the best they ever saw with it.
I have no idea how it was driven.

OK, good point.

My interest would be a self-contained motor home (not trailer) with 2 axles, best suited for highway efficiency rather than rugged conditions, that would comfortably sleep 2-4 people. This primarily for business use, where I may be sent to spend weeks at some small town, so could live in the motorhome rather than pay motel and restaurant bills. The job may entail travel all over the US. If the employer would pay me the same money as hotels and restaurants would cost, the motorhome would pay for itself quickly. 2-4 person capacity would presumably have enough room for me to live in and use for office space.

Diesel would be a plus, if conversion to biodiesel oil from restaurants were readily an option. Otherwise, diesels tend to run more expense, i.e., it would take many highway miles before the extra cost of the diesel were offset.

A well-streamlined stock vehicle seems the best platform to start with, as it would already have properly radiused nose, presumably smooth sides and roof, etc.,leaving less modification to do, such as undertray and wheel fairings.

How about one of the mini-motorhomes based on a toyota truck platform. Here's an example from a local craigslist ad:
1987 Toyota Dophin Motorhome

No idea what sort of mileage they get.

Mike

Well, that thing is not exactly laminar flow.

Basic shape is the most important variable at highway speed, and that Toyota cab-over is about as draggy as it gets. Ideally, a VW microbus* shape, but significantly larger, would seem best. However, I don't know about RV/motorhomes or what shapes and efficiencies there may be to choose from.

The GM motorhome appears to be reasonably well shaped, but one of the posters above reports it only got about 8 mpg, which is terrible. Surely, there is a good basic shape out there, suitable for improvement with undertray/pizza pans/wheel spats/air dam/reduced aero mirrors, etc..

The Oscar Meyer weinermobile has better aero than most motorhomes, no thanks to those rocket scientists in Detroit. For that matter, the doggy van in Dumb & Dumber probably beats most of Detroit's work product. Sorry to say.

Any ideas about midsize trucks such as UPS or FedEx vans, but known for efficiency and have good aero shapes? Maybe one of those could be ecomodded and outfitted with bed, chairs, etc..

*per Whole Earth Catalog, the microbus was the most efficient people mover of its day, given fuel burned / people aboard = passenger miles per gallon.
Some larger variation on that theme is what I have in mind.

diesel
 

My neighbor drove to the Yucatan Peninsula every year in a Westfalia Campmobile with Subaru engine.With an open 24-inch boat-tail he could pull 24-mpg.
Camping on the beaches,he and his wife met many couples with the larger modern diesel-powered vans.No owners reported over 20-mpg and they scoffed at Bob's claims of 24.

If low-floor plan airport shuttles could be road worthy, their ultra-low profile, huge interior volume, awesome clean lines and wheel covers could be great for a sexy RV conversion.
Galerie

The little Toyotas reportedly get really bad fe. Surprisingly bad. :(

Dodge Sprinters get decent FE. Kinda pricey, though.

Tent trailer?

Remember the motor in the GM motorhome when placed in another vehicle also typically got 8mpg towing or not.

Perhaps use it as a good rolling chassis and put a 6.2 diesel and a 6sp manual inside? It would be slow as mollasses but get better FE.

Yes, the entire 455 Olds V8 and transaxle setup from the Toronado/Eldorado.

There have gotta be a lot of possibilities for swaps. I'm sure there's something more efficient these days that could be swapped in.

Aerohead WE THINK ALIKE!!!!! (course I was born and raised in Dallas)

When I read the heading that was EXACTLY what came to mind!!!
You memory is correct.
Alll the car mags tested it because...well it could be parked in a garage!!
And that turbodesiel form BMW actually had some decent times. I remember thinking.....huuuuummmmmmmm......I should save this artcle and buy one used some day!

FYI, this is a very interesting project.

1971 vw camper with an 85 turbo diesel (water cooled), $1500, one day left, needs a whole lot of work. Chicago area

Volkswagen : Bus/Vanagon : eBay Motors (item 270573528417 end time May-10-10 06:18:54 PDT)

claims 25 mpg

"15 to 18 miles per gallon achieved by most Ultra owners traveling 50 to 55 miles per hour"

http://www.corvaircorsa.com/feature/ulthappy.jpg

http://www.corvaircorsa.com/feature/smiley.jpg

"http://www.corvaircorsa.com/ultra.html"

I had a 13ft scamp and it pulled very efficiently behind my old diesel pickup.

I would think the Sprinter platform with a pop-up roof would be a good candidate.

(do a google search for sportsmobile since I can't post links yet)

Corvair Ultravan looks aerodynamically good.
Could be made even better by adding a boat tail- extension.

This is the sort of thing I had in mind when I started this thread.

An Ultravan could be made even better with undertray, optimized wheel fairings, pizza pan wheel covers, removal of all that extra crap from esp. the front, flush windows and doors, recessed aero handles, smaller aero mirrors placed where the slipstream is slower, replacement of the headlights with conformal shape, etc..

The Corvair engine is less than optimal, as air cooling means enriched fuel mixture for evaporative cooling. Today, a TDI engine would be in order.

That said, what recently made motor homes are most like the Ultravan in shape and size?

How much are you considering spending on this motorhome? I just started looking to see what is out there, and they are $100,000 and up for something that would be comfortable for 4 people for 2-3 weeks. Just a thought...

http://www.rvtravel.com/blog/weirdrv...er2-710186.jpg:)

Ther ya go!

Weird RVs: Airstream trailer? Well, sort of, but not really

it doesn't smack of great mpg, but I still like it :)

Hmm, identical drivetrain to the GMC motorhome.

The front end of that thing is an Olds Toronado, circa 1969. My dad had a '69 Toronado, bought brand new January '69. They never could quite get the front end alignment sorted out, too much toe-in, and it would not exceed 80 mph despite 400hp and an otherwise not too bad shape for its day. 6-8 mpg, maybe 9 mpg at highway speed. With an Airstream glommed onto the ass end, this rig might get, oh, 5 mpg.

Anybody know of a modern-day RV along the Ultravan line, which reportedly got 16-19 mpg 40 years ago?

Or, perhaps better, a cargo van or small 2 axle truck that comes stock with a good shape, but suitable for further aero improvements and internal refit for RV use?

Its because they are way too underpowered. I passed one recently and it was obviously struggling on the flat section just to maintain 55.

this one claims 25mpg, has a stick shift though, dunno

http://www.youtube.com/watch?v=0owNt...eature=related

dunno if the "underpowered" card makes a lick of sense, its a lot more complicated than that.

Thats what I passed. I don't believe 25mpg under any real world driving for a second. Maybe on a fluke, but not even at 55mph steady should it be able to get 25mpg. Seriously, my pickup without all that extra weight and stuff hanging out in the wind got a max of 28 at 55mph, I usually get about 24 at 75ish.

If a car has to be driven at full throttle it will/should run rich, unless its been modified to do otherwise, and it will burn more fuel than a larger engine that is producing the same power at a lower throttle. When moving several years ago my father inlaw helped us move with his full sized truck, under similar loads my mileage droped from 26 at the time to 17, his droped from 20 to 18. He actually burned less gas because I was straining my engine too much, and his was just chugging along just fine. We even dropped down to 60mph for most of the trip.

I'm skeptical because most cars are much too low on load on the bsfc chart because they are overpowered. adding a bunch of drag (load) should bring it back towards the "sweet" spot, though total consumption still goes up. Even with enrichment, it is usually better to have too much load than too little.

so, if it had a saturn engine :) , if the thing makes enough hp at 2500 rpm and 124.8nm to keep moving then it would be a real good match.

http://ecomodder.com/wiki/images/3/3..._dohc_bsfc.jpg

This thing is the working definition of what NOT to do, aerodynamically,

Modification of it would start with a trip to the crusher, a la Breaking Bad episode a couple of weeks ago.

Now, does anybody know of any RV or truck sorta like the Ultravan, i.e., designed with at least some aerodynamic efficiency in mind, of, say the past 20 years? I have in mind a search for a good used RV motorhome, with nice gentle curvature in its sheet metal sorta like a VW microbus, only bigger.

lol, oh yah, aero :)

that aerostream mashup made me think a teardrop trailer/metro mashup would be sorta cool. if you scaled it up to something caravan sized it might still be pretty good on the mpg and have room for a table/bed.

Well, considering they haven't made those things in a coon's age it ought to get some respect for still being on the job. I still see them in the wild. Amazingly durable. Most that I recall speaking with say 20+ mpg is typical. Hell I've got enough horsepower to haul my camper 100 mph if I wanted to. But I've also got the horse-sense to keep it at 55. It may not be about struggling...

Cheers
KB