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Old 11-04-2019, 06:28 PM   #21 (permalink)
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close the gap between truck and trailer as much as possible (preventing cross-flow)
it's where the V-nose will help, and a vertical baffle plate along the centreline, too - allowing for vertical articulation


Consider rounding off corners, if possible

but NO semi-circular rounding off on the rear (in plan view)
It'll make the trailer sway : Coanda-effect working sideways, aft of axle/pivot -> sway

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Old 11-04-2019, 07:50 PM   #22 (permalink)
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Vortex street.
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Old 11-05-2019, 01:34 PM   #23 (permalink)
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I once was interested in buying a travel trailer with a V-nose. After all, such a nose configuration works for boats in water; why not trailers in air?

After looking into it, I decided against the trailer because owners reported no perceptible economy gain, and some said that it didn't handle as well in side-winds.

I ultimately decided against it, mostly because the trailer's design had the tongue weight too heavy for my tastes.
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Old 11-05-2019, 04:50 PM   #24 (permalink)
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Quote:
Originally Posted by MeteorGray View Post
...... V-nose............. and some said that it didn't handle as well in side-winds.
At a hovercraft rally I had an opportunity to witness a triangular style hovercraft yawing back and forth unable to fly in a straight line. I was positioned well in front of the craft on shore and the struggle was memorable to say the least.

Similar to this:

Yellow Jacket Hovercraft


The side wind was very gentle, other craft with rounded bows had no such issues.
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Old 11-05-2019, 06:59 PM   #25 (permalink)
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Quote:
Originally Posted by MeteorGray View Post
I once was interested in buying a travel trailer with a V-nose. After all, such a nose configuration works for boats in water; why not trailers in air?

After looking into it, I decided against the trailer because owners reported no perceptible economy gain, and some said that it didn't handle as well in side-winds.

I ultimately decided against it, mostly because the trailer's design had the tongue weight too heavy for my tastes.

Crosswinds are what matter. Low ground clearance on independent suspension. All edges radiused. Full-enclosed. FE will follow.

Not owning one at present isnít any bar to start testing:

1). TARE weight of tow vehicle. This can be combined with;

2). Highway FE test of tow vehicle.

ó A CAT Scale 45-50/miles from home out on Interstate. Obtain weight after topping fuel tank to auto shutoff. Correct tire pressure to spec (cold read at home).

ó On a loop back to the same location, 100% use of cruise control at your choice of 62,3, or 4-mph. Same as when towing. As you know, keeps you right below commercial traffic. The catbird seat. (Iíd note accel/decel events plus forced pass).

This is the optimum MPG. Can be reproduced by anyone. Changes are only temps, winds and traffic volume.

Engine hours against average MPH is the data desired to make judgments.

If you have ó or have had ó another travel trailer, then the tow vehicle loaded to the same weight value, but unhitched is the real number wanted.

A). What is the percentage drop from the previous? Against what weight increase (per axle)? (Assumes tires are again optimized. Numbers on the book).

B). As TT Towing FE is more about mechanical deficiencies against an almost universal 40% towing penalty, getting a baseline on:

1]. TV wheel alignment, steering slop, brake drag and engine air handling (is where to concentrate). Verify.

2]. The (not previously discussed) TRIP PLAN. Where to stop (location in same lane of travel) Where to park & how to park. (Easiest egress).

All familiar with your commercial driver experience. Choices all made in advance.

The familiarization loop can be used with stops each time. A rest area. A travel center. A KOA Campground. A WallyWorld truck-friendly (Trucker Path). A 200-mile total loop for testing incorporating these stops. Refining the how-to. As itís never obvious until one does it.

Drive one trip leg at a time. Only. (Kills anxiety).

The ideal is steady-state cruise. Any deviation is what kills FE with a heavy (relative) rig. Accel & decel count total per trip. Laid-back attitude. Get there when you get there.

ó If a gasser, a vacuum gauge dash mount (time manual control of downshifts versus using rpm).

ó A feedback gauge showing percent of engine load. (Least isnít best overall, but an acceleration strategy is). Otherwise, keep load under 80%.

Obviously, some of this needs a trailer. But the first two scale tickets and two loops wonít. Nor will attending to TV mechanical.

Gear wanted:

ó Brake controller. A TUSON DIREC-LINK is current state of the art. Itís better than the ones integrated with todayís vehicles.

ó A Hensley-patent hitch. (Hensley brand or improved Pro Pride). Cheap at twice the price for what it does.

ó Budget item to convert TT to DEXTER TOR-FLEX axles with disc brakes.

ó Budget item to use TUSON Trailer Brake Actuator for Antilock.

The transitions are what matter (accel/decel). Thus the need for average mph against engine hours for a trip. Total Time Steady State is far less than people expect. Even after cutting idle time, the need to minimize energy use in transitions are the killer.

One can cut the number & degree of steering inputs to a minimum. Same for use of throttle and brakes.

But where the TT design/equipment is obsolete (leaf springs plus drum brakes) thereís a minimum to accommodate them which isnít THE TRUE MINIMUM.

AFTER these comes aerodynamic considerations. The above are safety-related (loss of control accidents lead the pack for all RVs), as familiarization can be a painful process. Takes 10k-plus miles over a wide variety of year-round conditions encountered.

Commercial driving is a help. A step up. But it isnít enough to cover the twins of Safety & FE.

Test, and record. Most FE gains around here arenít being subjected to noise-elimination. Mechanical deficiencies addressed. Baseline performance improvement (the TV can also be improved via wheels/tires, shocks, anti-roll bars, etc).

I ďknowĒ what I should be averaging with my rig. And isnít the 15-mpg average for which Iím called dishonest using a one ton to pull a 35í. Itís 17+. All of the above applies.

You can start today if you desire.

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Old 11-05-2019, 07:12 PM   #26 (permalink)
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MG, the “goal” (as you’ve seen me say) is being happy with the per nights aboard cost of an RV. How many years & miles expected. Finance, insurance, maintenance factored. It’s often $350-$400 the way most people do it.

One trailer TYPE is the longevity king. And the family vehicle properly-spec’d for that, FIRST, is the tow king. It won’t be a pickup unless one is a farmer or a contractor as minuses far outweigh pluses.

One trailer DESIGN is the FE King (as it’s optimized for safe handling: crosswinds). Happily, these two are the same.

The lowest cost per mile (and per night aboard) is also the lowest risk per mile.

But only if properly-mated to the right family vehicle.

1). From the annual nights aboard number (5k miles annually), what percent of those daily hours is spent at steady-state cruise? (As you’ve broken it out). How has this changed travel plans? Real numbers. Not feels good stuff.

2). What is the cost reduction per night of FE maximization in this approach? As the other costs (mainly depreciation) outweigh it? (Costs above and beyond initial purchase. Will spending to save work?).

3). Versus having a tight-spec family vehicle (Safety & FE), what was the Tow Vehicle penalty for owning a less efficient vehicle (cpm)?

It’s not just the trailer, in other words. The best outcome IS the trailer-first approach. All else follows, is where savings are most obvious.

The last item is also a budget set aside. A hard-surface, covered parking spot on your property with 30A (minimum) electrical plus water & sewer.


Use a clean sheet of paper.
Sharpen several new pencils.

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2004.0 DODGE Ram QC/LB 2500 2WD/NV-5600 305/555 ISB. 7,940-lb. Stock. 200,000 miles/5000-hrs @ 40-mph average.
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11-cpm solo & 19-cpm towing; 21-mpg average past 54k-miles
Sold: 1983 Silver Streak 3411

Last edited by slowmover; 11-05-2019 at 07:28 PM..
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Old 11-05-2019, 08:09 PM   #27 (permalink)
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All good advise of course, but it's a toy hauler.

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Old 11-12-2019, 09:31 PM   #28 (permalink)
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Most of that addressed to MeteorGray.

Crosswinds are still what matter. A V-nose is wasted space. Needs a Trailer Tail.

RV Nomenclature: a toyhauler is living quarters with enclosed toy space. Usually a fifth wheel pulled by Baby Daddy in a jacked up 4WD.
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2004.0 DODGE Ram QC/LB 2500 2WD/NV-5600 305/555 ISB. 7,940-lb. Stock. 200,000 miles/5000-hrs @ 40-mph average.
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Old 11-13-2019, 02:50 PM   #29 (permalink)
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gap

Quote:
Originally Posted by euromodder View Post
close the gap between truck and trailer as much as possible (preventing cross-flow)
it's where the V-nose will help, and a vertical baffle plate along the centreline, too - allowing for vertical articulation


Consider rounding off corners, if possible

but NO semi-circular rounding off on the rear (in plan view)
It'll make the trailer sway : Coanda-effect working sideways, aft of axle/pivot -> sway
Testing has shown a 16% drag increase associated with the gap.
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Old 11-13-2019, 02:58 PM   #30 (permalink)
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the British option

Decades ago,an English company offered an inflatable bulbous nose for caravan trailers,which would convert a 'shoebox' into an 'Airstream.'(at least at front)
If memory serves me,it was good for a 28% drag reduction.I had a graphic,but lost it in the PhotoBucket takeover.
A study of contemporary inflatable advertising (recently Halloween pumpkins) will illustrate the concept.And any 12-VDC automotive HVAC blower fan would be adequate for inflation.Gentlemen,Start Your Sewing Machines!

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