Gorky
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Re: V-Nose Towing Theory
jmtandem wrote: I think you did a pretty good job of delineating the issues of a V nose trailer. Two things I would add. How much compromise inside the trailer will the V nose create and can you live with it? And, where I live the wind blows all the time (almost) and to tow with a V nose there will almost always be a frontal area that the wind is hitting unless the wind is from the rear. So, for me a V nose is not in the cards. In a no wind situation rolling resistance is more important than wind resistance up to around 40-45 miles per hour. The time spent over 40-45 mph is when wind resistance becomes important. So, the nose shape is not that much of an issue under 40-45 mph. Thanks! A V-nose would be a compromise if it prevented a back-hatch from opening, but otherwise it actually increases cargo space a bit and one could probably find another vented spot for propane / batteries on a custom camper build. I don't think wind and wind direction is any factor for the V-nose trailer. From what I've read of real world experience, it's easier to tow in windy places regardless of wind direction. Not sure if that's legit but I could conjecture that because the forward-moving trailer is more evenly splitting the air in front due to the V, there will be a more consistent equally-pressured air on both sides of the trailer. Whereas a flat-fronted trailer is blasting the air out of the way, air doesn't adhere as much to the sides of the trailer, and a crosswind of any angle can switch pressurized air streams from one side of the trailer to the other and cause wobbling. Either way, if wind hits the front of your flat trailer at a 45-degree angle it's going to push on that surface pretty equally to if it hits the side of a V at a 90-degree angle. Wind force doesn't drop away that much with angle change. Hence if you're making wind turbines there is not a huge difference between a 60-degree and a 30-degree blade angle; more important is the overall surface area the wind will affect and spinning stability since mechanical wobbling drastically reduces energy efficiency.2.8KViews0likes0CommentsRe: V-Nose Towing Theory
I was pulling a little 13-foot Serro Scotty (9-foot interior space) with 3.4 V6 and getting 13-14 mpg fully loaded with 2 kids and enough food and camping gear for a month of boondocking. We kept track of almost every tank on a 7000 mile trip, pretty consistent mpg but elevation made a noticeable difference over 4000 feet. The one time we found Ethanol-free non-premium gas we were getting 14.5 or so. Granted the trailer supposedly only weighed 900 lbs dry, it did have the frontal profile of a typical old aluminum trailer and from everything I've read, aerodynamics plays a bigger role than weight in towing-ability so long as the vehicle is comfortably within spec and you're not going uphill. So if I end up with a cargo trailer, if I can squeeze better drag coefficient out of it I would expect better tow ability even if it weighs 500 - 1000 pounds more. The trailer tails on semis get 5.5% better fuel economy at 65mph. Sounds great but I don't know if they make anything for a cargo trailer since that's where the tailgate drops down. I'm pretty sure a smooth bump like NoseCone placed where the front of the trailer rises above the TV would squeeze better mpg. 5th wheel towers seem to have surprisingly good mpg for their weight and for how gigantic the frontal area is. I think it's because their's no gap between TV and trailer and the trailer itself is slippery and round. I usually have a roof box on the TV for extra cargo. I'm thinking of getting a full-width one and modding it with something like the Airtabs mentioned by another poster to help deflect air over the trailer. Popup camper not an option, bears, winters, and serious durability concerns. I'll go buy a diesel first. I remember winters in Texas in a popup; when we were waking up to find ice on the interior of our camper we upgraded to a 50s era canned ham, which was probably cheaper actually. Still no heater but with 6 warm bodies and a sliver of insulation it kept us pretty warm.2.8KViews0likes0CommentsV-Nose Towing Theory
New member, old question. Is it easier to tow a V-Nose or Flat Nose trailer? In context, I'm planning on a custom travel trailer made out of the hull of a cargo trailer and I probably will have to decide between a V-Nose or a Flat-fronted cargo trailers. Since my tow vehicle is tentatively a 6-cyl SUV, and since I plan to live in the trailer and tow it 20000+ miles per year, ease of towing is important not only for the gas savings but for the longevity of my engine and tranny (I.e, big $$). As such, I've been reading everywhere (including here) the various resources ranging from aerodynamics in theory, 2nd-hand observations, marketing materials, actual towing experience, etc. So here is kind-of my summation of the topic to cover the bases and submit it for the review of all the minds here. 1. Shape of trailer's front-end is only a small portion of the total trailer tow-ability equation. Other considerations include: good tires, running gear, and well-balanced load so the trailer doesn't bounce, wag, and provides least rolling resistance. Smooth sides, bottom, and top. Drag-reduction at the rear end. Size of mirrors. Weight. Etc. Road speed is the biggest determining factor, but we can't expect to go 45 mph everywhere. Speed limits on some 2-lane roads here in Montana are 75-80mph, slow gets dangerous. 2. Cargo trailer sales people say a V-nose tows better but should not be expected to noticeably increase mpg. Other people say arrows and knives cut better than bricks, so V of course will cut air better than U. 3. In a wind tunnel, a V-fronted trailer allegedly performs the same or worse than a flat trailer of the same size. The V in front does split the air instead of pushing it, but the split air adheres to the larger frontal area of the V itself, the sides of the trailer, and creates more drag at the square back-end, so the overall friction and drag is the same or slightly worse. I assume the test was done without any TV in front of the trailer but I haven't been able to find any info from the actual testers, just hearing 2nd-hand from other posters. 4. At highway speeds, the size/shape of the TV and the amount of gap between a trailer and TV has more impact than the shape of the trailer's nose. Turbulence coming off the back of the TV will obviously have no impact on the front of the trailer if there is no gap between, and increases the wider the gap until it's virtually the same as if the trailer were stacked on top of the TV instead of behind it. 5. Aerodynamics can be counter-intuitive. A TV with a rounded rear has less drag. A trailer with a rounded front has less wind resistance, on its own in a wind tunnel. But, a TV with a rounded rear towing a trailer with a rounded front means the air will sweep down the back edges of the TV and hit the trailer's full frontal area instead of being deflected over it. That's why lots of folks are disappointed by the mpg they get pulling a lightweight R-Pod vs. a longer and heavier Airstream; the sloping "tear-drop" front of the R-Pod just increases the gap (and therefore turbulence) between the rear ceiling of the TV and the front ceiling of the R-Pod. A cargo van pulling a square cargo trailer actually has less overall wind resistance, although drag at the back of a flat-backed trailer may negate most of it. 6. The gap between a trailer and TV means the air flowing off the back of the TV may try to go all the way across the front of a trailer, increasing resistance and friction. That's why some aerodynamic modifications (especially of big rigs) include a cross flow plate; vertical plate along the tongue between TV and trailer, or a series of smaller vertical fins that discourage air from crossing horizontally front of the trailer. 7. The nose of the V-fronted trailer is usually advanced into the tongue area between TV and trailer. In other words, a flat front is not chopped off at angles to make the V; instead a V is added onto the front of a the flat so the overall interior length at trailer center increases; the gap between middle of TV and nose of V is less than that of a flat trailer. Therefore, I would expect that a V-nose pulled behind a big squarish TV would perform very slightly better (as advertised) than a flat-front trailer with the same length of tongue. The V nose slightly reduces the gap between trailer and TV (at-least at the centerline) and the V will act like a weak cross flow prevention plate, reducing turbulent air flow across the front of the trailer. Since a V-nose by itself does badly in a wind tunnel, the less drag you expect from your tow vehicle (i.e, sloped back end) or the shorter it is comparatively, the more air will hit the V-nose and the worse its affect will be for aerodynamics overall compared to a flat-front. But if you must have a minimum distance between TV and front of trailer, to be able to open a rear hatch for instance, it would be much better to have a flat-front at the same distance from the TV as the tip of the V-nose. Since tongue distance, TV shape, and driving speed are variables determined more by utilitarian necessities (i.e, if you need to turn sharply or can't afford a different tow vehicle) and these will all determine if the V-nose will help or hurt, I would agree with what trailer sales are saying: DON'T choose a V-nose to get better mpg. They're designed to have more cargo space, not better aerodynamics. Hi everyone! Any additional thoughts welcome!22KViews0likes21Comments
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