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Old 12-07-2012, 08:19 AM   #21
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Yep, frontal area = wind resistance. (minus something for aerodynamics)

There is a new standard that auto mfgs' are starting to use that sets towing limits to include weight and maximum frontal area (usually 60 sq. ft) as well.

Some of those monster 5th wheel toy boxes you see must have over 100 sq. ft. of frontal area



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Old 12-07-2012, 08:37 AM   #22
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They say a tonneau cover on a pick up pays for itself in a short amount of time by eliminating the drag of the tailgate. I wonder it a cap would do the same when towing a trailer? Raz
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Old 12-07-2012, 08:57 AM   #23
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I think that "They" are trying to justify the cost of a tonneau cover.

You would have to save a lot for a long time to get up to the $300+ a fiberglass cover will cost.

If a tonneau cover did much to improve eonomy it would be touted as a fuel saving option (or even standard equipment to improve CAFE) on new pick-ups.

However, at least in theory, both that or a camper top may help some, but I wouldn't count on recovering costs as a reason to install either.


OTR Trucks use several devices to reduce wind resistance and drag, but they are amortized over a million miles or so and a lot bigger fuel bill than mine. If a trucker can gain 2% mpg that's a lot of money over the long haul.



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Old 12-07-2012, 09:29 AM   #24
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From the over-the-road trucking perspective, only 2% of the drag of the trailer is attributed to weight. That's as compared to aero drag being 20% at highway speeds.

In the same area, aero drag goes up as a function of the square of speed. I read through an article from Peterbilt which said that at about 50 mph the aero drag begins to exceed the normal rolling resistance of the system (engine, powertrain, tires etc.) At 75mph it(areo drag) was 2.5 times the mechanical resistance. With today's far more streamlined cars and light trucks I expect the aero drag to exceed rolling resistance at a lower speed.

Aside from any satisfaction you might get from going through the weight reduction excerise (and I'm wondering where trailer resale enters into the analysis), there is the improvement in braking and handling to be had.

So, my sense of it is that if I were only concerned about fuel economy I wouldn't bother. If I had a marginal tow vehicle then it's worth the effort. In my case I have an adequate tow for the trailer and goodies I travel with so I'm not particularly concerned with trailer weight. Within "normal" bounds.

I was involved (I coordinated the experiment and analyzed the data) in an extensive study with a carefully measured (wind tunnel for aerodynamic drag, test weight) and instrumented vehicle (high accuracy speed sensors, vehicle and ambient air speed, temp and humidity), and wheel-end torque meters.

A significant variable was ride height. Lower was better. And we're talking about fractions of an inch making a measurable difference (with our equipment). I'm tempted by 15" tires to gain some ride height but I know that raising the trailer still higher out of the tow vehicle's wind shadow would measurably reduce my mileage.
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Old 12-07-2012, 09:39 AM   #25
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I think that "They" are trying to justify the cost of a tonneau cover.

You would have to save a lot for a long time to get up to the $300+ a fiberglass cover will cost.

If a tonneau cover did much to improve eonomy it would be touted as a fuel saving option (or even standard equipment to improve CAFE) on new pick-ups.
Well Bob you made me look. With my truck an improvement of 1/2 mpg (17-17.5) over 50k miles at $3.50/gal comes to a little under $300. I really have no way to know whether I improved 1/2 mpg and if so whether it was because of the tonneau this is just an academic exercise. Still ignorance is bliss..... Raz
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Old 12-07-2012, 09:41 AM   #26
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That 55 MPH vs 75 MPH is a very valid point.
Here's some personal experiences with Toyota -Sunrader motorhomes:
55 MPH=18 MPG, 65 MPH=15 MPG , 70MPH=12 MPG.
These numbers are for the 4 cylinder/automatic chassis and have been supported by numerous postings 55 vs 70 = 33%+ reduction in economy.
I have seen the same differences towing a Scamp, Big Foot or my Compact-II.
Besides that, the towing speed limit in California is 55 MPH (Tell that to the truckers!)

Note to P.Raz
And that savings would only occur at highway speeds. Any mileage in town would not be improved.



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Old 12-07-2012, 09:59 AM   #27
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Nothing tows like a Scamp(or others of that design, Boler ,Eco,LoveBug,ftc.) Weight isn't all there is to it.
I have owned and towed lots of fiberglass trailers including such trailers as Scamp,LoveBug, Companion, Compact/Hunter, Trailswest, Trillium and more.
Accelleration, handling and fuel economy are as much dependent on shape and stature as on weight.
If you want an extremely light trailer which tows like a dream, get a Taurus Cadet.
Others to consider would be LiteHouse,Little joe, or Playpac.

A Scamp 13 will start at around 1100 pounds, even less with an older one with plexiglass front and rear windows and 1200# axle.
It would be easy to build a "fully equipped" Scamp 13 and keep the weight at a realistic 1200 pound target weight.


One thing to remember... A parachute weighs almost nothing, yet it will stop a car going over 200MPH!
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Old 12-07-2012, 10:06 AM   #28
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That 55 MPH vs 75 MPH is a very valid point.
Here's some personal experiences with Toyota -Sunrader motorhomes:
55 MPH=18 MPG, 65 MPH=15 MPG , 70MPH=12 MPG.
These numbers are for the 4 cylinder/automatic chassis and have been supported by numerous postings 55 vs 70 = 33%+ reduction in economy.
I have seen the same differences towing a Scamp, Big Foot or my Compact-II.
Besides that, the towing speed limit in California is 55 MPH (Tell that to the truckers!)

Note to P.Raz
And that savings would only occur at highway speeds. Any mileage in town would not be improved.
I had a similar experience this past fall. Drove out to the forest with my FJ and a utility trailer to cut some firewood. Typically travelled at about 120 kph on drive out. On drive back with trailer loaded with about 1500 lb of firewood (but little change in wind profile on the trailer), I travelled at about 100 kph. On way home I had significantly better gas mileage towing the heavier trailer at a lower rate of speed than on the way out with the lighter trailer and towing faster.
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Old 12-07-2012, 11:53 AM   #29
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They say a tonneau cover on a pick up pays for itself in a short amount of time by eliminating the drag of the tailgate. I wonder it a cap would do the same when towing a trailer? Raz

I have seen studies where they took multiple trucks and tracked fuel economy with a tonneau cover, tailgate up, and tailgate down. There was no clear winner. For different vehicles, different setups were slightly better. Fuel economy is obviously greatly influenced by frontal area, but also the shape of things not in the frontal area (the shape of the sides and the back end for example). One piece of evidence of this is all the skirts the semi trailers are using now.
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Old 12-07-2012, 12:41 PM   #30
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Also...if you travel which ever way the wind is blowing that helps! I've intentionally waited a day for the wind to change before leaving on a trip due to a strong headwind that changed to a tailwind the next day. Drafting can also help on head-windy days! Just don't do it behind me!

Travelling with a 1/4-1/2 tank of gas to save some weight when going over mountain passes for example can make the climb a bit easier on the car (or maybe it just seems easier!).
There are lots of little things that can add up to ...lot's of little mpg/weight savings. There probably isn't going to be "one" big way to save mpg's, or else it probably would have been done by the manufacturers in the first place.
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Old 12-07-2012, 02:11 PM   #31
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I've definitely noticed the wind direction issue.

And I've always though that travelling south was going downhill, and returning home, northwards, was a long uphill slog!

But seriously....
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Old 12-07-2012, 02:34 PM   #32
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And I've always though that travelling south was going downhill, and returning home, northwards, was a long uphill slog!

I thought that if the tongue of the trailer was lower than the back it basically was rolling downhill.
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Old 12-07-2012, 03:12 PM   #33
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From the over-the-road trucking perspective, only 2% of the drag of the trailer is attributed to weight. That's as compared to aero drag being 20% at highway speeds.
Wow - I am loving the discussion here!!

I think it might be worth noting that flatland mpg is one thing, while getting over a mountain pass with substancial climbing could be quite a different story. I live in California and just about any campsite that is worth going to requires getting UP to it, usually on narrow twisting roads.

The more weight the trailer is, the more stress you put on the car - the motor, the transimission, and the brakes (going down). A heavier trailer will also have a greater effect on handling, on twisty roads and cross winds.

My Scion XB is about 2500lbs (standard trans) - one of the lighter cars you can buy! It puts out about 105hp, and is not rated for towing. However, I have read that it is capable of pulling trailers (apparently the US generally has a much lower towing capacity rating than other countries for the same vehicles). I personally haven't tried towing with it yet, although I do have a hitch on it for a bike rack (it is very low!) I'm not sure I would trust this as my primary tow vehicle, but I am curious to try it just to know...

My wife's Toyota Matrix is heavier and puts out about 130hp - we have used it to put a cargo trailer (listed at 1100lbs empty) accross the US. Maybe not exactly ideal (you need to be a little patient going up), but we were still getting about 24mpg - 31-33mpg without the trailer. Overall, this trailer is a little smaller than an eggshell camper, but I would guess every bit as heavy with a load...

But I also appreciate the importance of aerodynamics and drag - ideally, you would want a lightweight, aerodynamic trailer
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Old 12-07-2012, 04:12 PM   #34
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snip.......- ideally, you would want a lightweight, aerodynamic trailer
As someone else pointed out, you sound like the targeted buyer for a teardrop trailer.
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Old 12-07-2012, 05:47 PM   #35
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Tip #1 Don't even think of opening this bag of worms:
"However, I have read that it is capable of pulling trailers (apparently the US generally has a much lower towing capacity rating than other countries for the same vehicles)."

They are different for several reasons & towing limits may be higher, esp in Europe. One reason being that they aren't always the "same" car and the story goes on ad nauseum from there. Except for those that like to think "outside the box" as they call it, it is generally recommended that you stick with the towing capacities set for your vehicle as shown in the owners manual for that vehicle.

Tip #2 Learn from others mistakes, not your own. When your Mom told you not to touch the stove because it was hot, did you have to touch it anyway, just to see what it was like?

Tip #3 You may get poor mpg's going up that hill, but the trip down will help offset it with higher mpg's. I sometimes see as high as 60 on my MPG indicator on long downhill runs.



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Old 12-07-2012, 05:54 PM   #36
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livinlite.com all Aluminum trailers, no wood in them might be an idea for you orange.

edit: they were also Ranked #1 by an independent, third-party consumer publication amongst all Ultra Lightweight Trailer Manufacturers. Post is on their facebook. I didnt read the article.
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Old 12-07-2012, 06:14 PM   #37
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As someone else pointed out, you sound like the targeted buyer for a teardrop trailer.


Yes, I am familiar with teardrop trailers - part of my OCD is my need to research the hell out of everything!

I don't know what it is about them: I really want to like the concept, but I can't seem to visualize an awesome experience in one. I guess it could satisfy my curiosity about sleeping in a coffin, but is seems you still have to do most things outside: standing, cooking, eating, cleaning, going to the restroom, etc. It seems like a lot of effort lugging this thing around (many of them are not much lighter than a Scamp), for not much bang for the buck.

If I were going to go that route, I think this could be better: http://www.autohomeus.com/rooftop/columbus.php, and serve most of the same purposes (as long as you have some sort of tailgate - both of my cars do). I actually really like this concept, but $2800 seems a bit steep (you can never find them used - I've looked!) Incidentally, I wonder if having this on the roof would improve the aerodynamics if you were ALSO pulling a trailer?? Sleeping 4 comfortably with some level of privacy? Hmmm...

Now, this concept seems pretty intriguing:
http://www.crickettrailer.com/
But again, not cheap: $10000 - $18000, and not super light at 1200lbs to 1500lbs. But moving in the right direction...

Truthfully, my favorite (somewhat accessible) trailer to date is the Burro - it sort of has that cool retro rocketeer/stormtrooper thing going for it (love the external hinges and tail lights!) I am drawn to these types of trailers for being mini-houses (about as small as you could go anyway!) No moving parts, self contained, private, and (the illusion of) safety. All this seems to make the hassle of dragging this thing around worth while...
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Old 12-07-2012, 06:24 PM   #38
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Very interesting discussion but one point has not been answered. Is it better to keep heavy items, eg propane tanks, battery, jerry cans of water, etc in the TV, rather than the trailer while towing?
It was noted that removing the battery from the trailer and just using the TV 7 plug, everything will run as if the trailer has its own battery. Is this correct.
Thanks, Jim
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Old 12-07-2012, 06:28 PM   #39
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Hello all,

I am currently in the market for a small (13 foot?) fiberglass trailer - actually, I've been interested in getting one for years, ever since I saw the first one on the freeway (a Scamp trailer).

Anyway, it seems like one of the greatest advantages to this type of trailer is weight (or lack of) and efficiency - in theory you can pull it with a standard sized car.

I've searched around and I can't find any information on possible ways to actually lighten the trailer even more - what can be done?

For reference, I am a cyclist and weight is the name of the game - people regularly "trick" out their bikes to be as light weight as possible. Lighter means faster, and more efficient.

If anybody could point me in the right direction, it would be super helpful.

All the best...
Lots of info on this site including one owner that changed out the frame to aluminium on his boler
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Old 12-07-2012, 06:33 PM   #40
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livinlite.com all Aluminum trailers, no wood in them
I looked at several of these trailers and liked what I saw for the most part. They are the closest in comparison to molded fiberglass that metal can get. Being inside one gave me flashbacks to living aboard a US Navy ship.
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