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Old 03-28-2010, 01:59 PM   #21 (permalink)
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[QUOTE=slowmover;167985][I][B].

"If someone were so inclined, a good project helpful to all would be to design an alternative air-conditioner shroud, as those roof units are used on all types. That the manufacturers have low-profile units now only illustrates the problem."

An inexpensive alternative that is sometimes used, is to mount a conventional 5000 BTU window air conditioner to the front or back of of the travel trailer. Either location fills part of an aerodynamic low pressure area that otherwise creates drag. Also this arrangement does not add to the frontal area as a roof top unit does. If need be, you could install ducting to carry cool air to the opposite end of the trailer. Often you could also arrange to park the trailer so that the air conditioner is in the shade most of the day which would make it a little more efficient. Of course you would need to hook up to an AC source when parked or use a large capacity DC to AC converter.

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Old 03-29-2010, 11:59 AM   #22 (permalink)
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If you want an areo camping trailer, try a motorcycle trailer. My friend had one that he pulled behind a Honda Goldwing
Mustang trailers
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Old 03-29-2010, 12:02 PM   #23 (permalink)
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[QUOTE=4536;168059]
Quote:
Originally Posted by slowmover View Post
[I][B].

"If someone were so inclined, a good project helpful to all would be to design an alternative air-conditioner shroud, as those roof units are used on all types. That the manufacturers have low-profile units now only illustrates the problem."

An inexpensive alternative that is sometimes used, is to mount a conventional 5000 BTU window air conditioner to the front or back of of the travel trailer. Either location fills part of an aerodynamic low pressure area that otherwise creates drag. Also this arrangement does not add to the frontal area as a roof top unit does. If need be, you could install ducting to carry cool air to the opposite end of the trailer. Often you could also arrange to park the trailer so that the air conditioner is in the shade most of the day which would make it a little more efficient. Of course you would need to hook up to an AC source when parked or use a large capacity DC to AC converter.
Yes, but . . window frames are not built for this load; the A/C must be secured somewhere for travel (damage potential all around), etc. I have seen A/C mounted internally (done very well), but it takes up storage space that is usually at a premium (where weight, shape and road performance take precedence). It is favorable, however, that the roughly 100-lbs of weight is lower on the chassis, but a roof mount directly over the axles helps offset this problem of COG and FF/RR balance.

Todays RV A/C units are, unfortunately, disposable unlike those of yesteryear. Cheaper in all ways with no field serviceable parts. So any shell mods must accommodate ease-of-removal. Even for mobile command units, etc, the tendency is to use roof-mount, for sliding a new one in place takes not much longer than describing the work. Obtaining the services of a factory-trained technician and parts/supplies for something more exotic is not tenable for time-critical operations.

Granted that, somewhere, there is a combined HVAC unit for heat & cooling. Initial expense, size, NVH would all be problems, even on high dollar units (one must, essentially, go to units spec'd for million-dollar buses [NEWELL]). Obtaining the services of a factory-trained technician and parts/supplies for something "exotic" is not tenable for time-critical operations OR ordinary travelers.

There is a "solution" for combining water heating and space heating in the PRECISION TEMP line of models, but, again, ducting, water & gas plumbing, plus electrical must be re-engineered. This would free space for an A/C unit, but overall costs at this point have become quite high once an internal-mount A/C is specified. Ducting a small trailer is fairly straightforward, but for larger (say above 25') expenses mount.

For safety' sake, an engineer should be employed to review such major changes as above. RV's are both houses and cars, with a bit of sailboat thrown in. Plumbing for water (from pressurized external source OR from internally-pressurized tank[s]), propane, two electrical systems (12V and 120V), two and three-way operable appliances, etc, etc. There are any number of governing bodies one may argue take precedence: Shall it be RVIA, USCG or NEC? UL or . . . ?

Remember that in many regions A/C is a necessity for a majority of months. Shade is desired but not always available. Combine the viable lack of A/C options and the the desireability of some aero work becomes clearer (where mpg is chasing small margins all over the place). Simplest solution is where economy and long-life are not affected by safety/space/damage concerns.

Thus the point about a more aero A/C enclosure. It is in line with the OP request, ought to be fairly low cost for DIY, and, hopefully, help to manage airflow a bit. It is applicable to virtually every RV. Other roof vents (plumbing, kitchen oven, refrigerator; ventilation passive or powered) tend to be "low profile", but once one adds a second A/C (on larger RV's), storage "pods", solar panels, multiple telecomm antennas, etc, well, . . a "dirty" roof needs all the help it can get.

.
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Old 03-29-2010, 05:38 PM   #24 (permalink)
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This iswhat my 1976 Boler looks like. Boler sold the plans and the name changed a few times, the latest being "Scamp". This is not my trailer, just while reading this thread I thought I would jump in so I found one on Google.

This thing is a work of art in practical design. Nearly every square inch of the interior was used, now with a few mods of mine, it is ALL used. I haven't towed it in a few years as a friend has been living in it, (yes LIVING in it). But I know with my 1965 Skylark with a little V8 you didn't even know it was there.

All the cabinets, bed, bunk, etc. are made of fiberglass and formed to the inside of the body. I have had people ask to go in while I am out camping. And I get the same response everytime "It gets BIGGER when you go inside!"

Brian



These are the same colors as mine. Groovy huh?






Last edited by MARTINSR; 03-29-2010 at 05:47 PM.. Reason: More photos
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Old 03-29-2010, 07:14 PM   #25 (permalink)
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Here is an "Ultravan" that was made in the sixties, powered by Corvair. It was made by an aircraft company and believe me, it's construction looks like it! We have one in the shop right now.

Brian




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Old 03-29-2010, 08:47 PM   #26 (permalink)
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Another plug for fiberglass

Quote:
Originally Posted by MARTINSR View Post
...1976 Boler...
Right on. Boler was great ancestor to many brands, most of which vanished but a few remain on market. I posted on the other currently-active trailer thread.
http://ecomodder.com/forum/showthrea...tml#post167980
For a more direct link you can learn more about these wonderful little campers here.
Egg Central

Cheers
KB
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Old 03-29-2010, 08:55 PM   #27 (permalink)
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Yeah, I was going to sell the thing, my wife didn't want me to. My buddy needed a place to live so there it is still. I am now glad I saved it as I have been going on VERY long roads and haven't camped in years but I look forward to going again. I went on ebay looking to see what they do for and they sell for a heck of lot more than what I paid for it 20 years ago! You know what I sold to buy it, a tear drop! Yep, a real, vintage all aluminum tear drop made by an aircraft mechanic right after WWII and even had components from war birds!

Anyway, here is the floor in the Ultravan, it is made of the holding tanks!





It has a FULL belly pan under it.



This thing is very cool, he just got back from a trip all the way to Delaware from Oregon!

Brian
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Old 03-29-2010, 10:24 PM   #28 (permalink)
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Here’s a little AutoCad study I did on travel trailers. I’m assuming a guy who drives around with a trailer at least 20,000 miles a year – enough to make this rig worth the effort.

Length is 34 feet from hitch to tail and its 79.9 inches wide (doesn’t need marker lights and come fair to a standard SRW pickup). In “down” position the top is 64 inches above grade (same as my pickup).

I married the “Hi-Lo” concept with an 80 inch wide Bowlus Road Chief and put a 70 inch long tapered tail on it. The tail reduces wake area by 58%. I gave it a “toy hauler” configuration. The same configuration would work OK as a straight cargo trailer or as a travel trailer.

Like the “Hi-Lo” the trailer comes in two parts: a “tub” that carries the payload and a “shell” top which is raised once the trailer is parked. The “shell includes a flip-up tail cone that tapers in at an 11 degree angle in all aspects. The dimensions of the “tub” dictate that I cannot taper the top until the back of the “tub” is cleared. This assumes full “tub” cargo height all the way back.

Instead of having a cancerous tumor on top of the trailer for HVAC, I would build mine into the nose of the trailer, along with propane cylinders and maybe even a generator.

Why is it so long? Answer: To regain space lost by making the trailer low and narrow. The “tub” (payload) volume is 240 inches long by 76 inches width (interior dimension) by 54” high. That comes out to 985,000 cubic inches. Your average “Wheaties Box On Wheels” is 104 inches wide by 80 inches high (interior dimension above load deck). So the load volume of my aero trailer is roughly the same as a 10 foot long standard trailer. At best, Spartan accommodations for two. The triple axle is probably not necessary unless you carry Die-Hard batteries for cargo.

I also did a 108 inch wide by 80 inch high version that makes a fairly good car hauler.

Is it aerodynamically superior to the average box on wheels? Of course. How much? I don’t know. A wind tunnel would be necessary to determine that, but I’d say it had better beat the box on wheels pretty bad to justify parking a 34 foot trailer.

BTW, sorry about the shabby picture of an AutoCad drawing. I an not much of a hand at sharing data files (I’d rather think about cars) and AutoCad (as I know it) wants no part of Ecomodder, so I simply took a picture to help everyone visualize what I’m talking about.


On edit.
Forget the attachment. The durn thing just will not co-operate. If anybody cares, send me a PM and I'll send you a 1.35 Mb picture or a .dwg file if you want it.
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Old 03-30-2010, 12:07 AM   #29 (permalink)
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Looking at this page, I'd have to say that the makers should try to get the good designers and the good salesmen onto the same teams. The acres of 1X2 and house-siding garbage out there are disheartening.
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Old 06-28-2010, 08:32 PM   #30 (permalink)
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I bet would this trailer would do very well behind a SUV. 7 feet wide ,total height only 7 1/2 feet , the sides even taper inward behind the wheels and it almost fits the ideal profile

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