Frontal Area, v Wake Area, v Boat Tail Wake Area, Projected
 

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The tires are 10 inches wide on both vehicles. The distance between
the tires on the truck is 56 inches on the truck and 80 inches on the
trailer. This staggers them enough to make a frontal area for the
tires of 8 sq ft or 4 sq ft per side. The low point on the truck is the
front air dam which is only 7 inches off the ground. The Truck can
be treated as 72 inches wide for air dam purposes.

This means the low point on the truck adds 6.6 sq ft to the frontal
area of the rig in total. 8 sq ft for the tires totals to 14.6 sq ft. The
frontal area of the trailer is 72.75 sq ft and adding 14.6 sq ft to that
yields 87.35 sq ft. rounding up for skylights could bring this total up
to 88 sq ft and up to 90 sq ft.

If I can reduce the wake area of the trailer to 36 sq ft adding the tires
adds 8 sq ft to that for a total of 44 sq ft. So using the low figure I am
seeing.

88/44 = 0.5 which means the ratio is 50%. Half of that is 25%

1.25 x 8.2 mpg = 10.25 mpg.

There is some plumbing pipe under the trailer and the axle. Using a
higher figure of 90 sq ft yields

90/46 = 51.1% / 2 = 25.55 %

1.255 x 8.2 mpg = 10.29 mpg.

Basically these rough estimates are looking more and more like a
2 mpg improvement. That amounts to 122 gallons of fuel v 98 gallons
of fuel over 1,000 miles. At $2 a gallon that would save $48 of gas.

John Gilkison

This is for Phil Knox and others. Got a side view of the trailer today to show the roof line of the trailer. Yesterday I bought five 3/4 inch 4x8 ft panels of foam board for my boat tail project. I wanted one inch but they did not have any in stock. At only $13 a sheet I figure I can glue waste pieces to the back side of the panels to strengthen the edges and mid points of the panels and end up with a stronger lighter panel.

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Holding a 4x8 ft panel up to where it will go for the boat tail project.

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Holding a 4x8 ft panel up to the passenger side to show how it goes past the spare tire. Next step cut the 25 degree down angle on the top of these panels. Bevel the attachment edge to 10 degrees.

foam board
 

Yer on yer way buddy!:thumbup:
Honk if you have a small one!:D

We took the trailer to Camping World Wednesday morning to drop it off to have the Washer/Dryer combo looked at because of a door latch mechanism failure. We had a windless morning for the 49.7 mile commute which is very unusual. Long and short of it I did set the trip B counter. We came up with 49.7 miles using 4.9 gallons of fuel for an average of 10 mpg. My on board computer system reads fuel consumption about 3% low so factoring that in we probably used 5.047 gallons which means we averaged at least 9.847 mpg. Not bad for towing 9,000 lbs with 100 sq ft of frontal area and 49 feet of total length with the truck and trailer.

Not bad for... fixing a latch on the washer/dryer?

The 3/4" material would be stiffer if it had a slight curvature. Make some lens shaped ribs with a tension tie on the flat (inner) side (so it will resist flattening back out).

Your straight angle cuts will become curves at the miter. You can relax the angle and get the same rear cross section.

Also—massively boat-tailed wheel spats.

Nice trailer, and going to be a nicer trailer.