by JaggedEdges » Sun Mar 05, 2017 2:14 pm
Tackling the weight question, even though the plywood is "heaviest material possible" line has been proven utter BS,
Taking the following premises...
Average smaller vehicle and TnTTT combo around 4500lb
Most miles done on faster roads, 50mph plus, not much city stop/start.
20 mpg towing average.
Effect of weigh on consumption at highway speeds is through the rolling resistance which is one of the lower components of total load on the vehicle at approx 15%
If we assume that in a combo, trailer contributes 5 of the 15 total, this, and varying the weight +/- 500lb about a median of 1000lb is plus or minus 50% then we're playing with about plus or minus two and a half percent of the gas mileage. this is 12-13 extra gallons per 10,000 miles, or about 40 bucks worth of gas.
What do we think the lifetime mileage might be for an averagely frequent camper, 50,000 miles??? That's $200..
Anyway, for the spitball "average" situation, a super light drop not going to save you all that much in gas, so it better not cost you $$$ more to build than an average one. Be sure though that it's apples to apples, you can look at the bad mileage some of the big "crouchy" drops get and say "Weight!" but remember that at 6 wide and 5 high they'll have practically double the frontal area of a 4x4, and aero drag is almost all the rest over that 15% rolling resistance drag.
I'm not saying though that this is definitively the way to go for you or "May as well make it heavy." Because optimal use of material will be lighter, and save money in construction. Then there are not easy to quantify costs, like strain on the tow vehicle. Now larger ones with 3000lb and up towing capacities, there's probably going to be no noticeable difference. However, when you get lower tow capacities, where usually the transmission is the fuse, then the last couple of hundred pounds up to and over the manufacturer rating is probably quite non-linear for transmission wear and eventual replacement or repair cost. So you are not necessarily looking at gas mileage savings there. Towing with something like a Caliber, Vibe or an Element, you're definitely going to notice the difference between 500lb and 1500lb. Most people with V6 minivans, midsize SUVs however will say it tows a small trailer or popup "Like it's not there", so more room to play.
However, stuck with your average commonly available trailer frame at about 300lb and your average load of kitchen and equipment at 100-200lb by the time you add stove, cooler/fridge propane tank and all the trimmings, what your structure/skin choice is, is only around half the weight you're playing with for the all up weight on a smaller one, as shown in previous post, box made of thick slabs is gonna be about 400lb, so yeah, not going to be able to influence the outcome by all that many pounds on that score. I think that $40 per 10k would be optimistic amount of saving for a sensible 1/4" skinned foam and stick sandwich vs the moutaineering tent nailed to a flatbed.
(Probably at the same weight as the 3/4 walled benroy anyway, but you have R5-6 instead of R1 if that walls.)
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