F250 and up, max 60 square feet frontal area

TucsonJim wrote:
My manual says the same thing, but the key point here is the part that states "Selecting a trailer with a low aerodynamic drag and rounded front design helps optimize performance and fuel economy. The 60 square feet would be used if the front of the truck and TT/FW were exactly perpendicular to the air stream. It the corners are rounded or the front of the truck and TT/FW is sloped to increase air flow, the effective coefficient of aerodynamic loading is reduced.

A simple trigonometry equation would be if you had exactly 60 square feet and it was sloped at 15 degrees. 90 degrees (perpendicular to the air flow)- 15 degrees slope = 75 degrees. Sin of 75 degrees is .966. Multiply 60 square feet by the inverse of .966 to get the equivalent square foot load. In other words, the recommended limit is 60 square feet at 90 degree impact angle, but 62 square feet at a 15 degree slope.

The example above is very simple, and there are many more factors which come into play. There are variable angles on the front of most TT/FWs, and there are usually rounded corners and edges. The actual wind load (equivalent square footage) could be calculated using trigonometry and/or calculus if we had the design standards of the unit.

One thing that Ford did not explain, was at what speeds this load applies, and what if any effect there is from ambient wind impacts.

rexlion wrote:
Note:
The total area in square feet... exposed to air resistance of
a moving vehicle and its trailer is the trailer frontal area. Do not exceed
60 (square) feet...
trailer frontal area.

Longtrace wrote:
60 ft^2 (5.6 m^2) isn't much. An 8 ft (2.43 m) wide trailer can only be 7.5 ft (2.28 ft) tall - with nothing on the roof - has a frontal area of 60 ft^2. Are there any that short?

TucsonJim wrote:

Ron Gratz wrote:

TucsonJim wrote:
A simple trigonometry equation would be if you had exactly 60 square feet and it was sloped at 15 degrees. 90 degrees (perpendicular to the air flow)- 15 degrees slope = 75 degrees. Sin of 75 degrees is .966. Multiply 60 square feet by the inverse of .966 to get the equivalent square foot load. In other words, the recommended limit is 60 square feet at 90 degree impact angle, but 62 square feet at a 15 degree slope.

That depends on how they define "frontal area".

Usually, "frontal area" means the projected cross sectional area which, for your example, would be 60 sq ft for both the vertical front and the sloping front.

Ron

You're right Ron. That's why I used a simple evaluation if everything was at a 15degree slope. When you put all the rounded corners, slopes, etc. of the TV and the TT/FW, it gets quite complex.

rexlion wrote:
I was shocked when this was pointed out to me today. According to Ford's owners manuals for the F250, F350, etc. there is a frontal area limitation. I'll quote from the 2013 manual, 3rd printing (I inserted the word 'square' for the superscript 2 and deleted the metric numbers):

Note:
The total area in square feet... exposed to air resistance of
a moving vehicle and its trailer is the trailer frontal area. Do not exceed
60 (square) feet...
trailer frontal area.
Note:
Exceeding this limitation may significantly reduce the
performance of your towing vehicle. Selecting a trailer with a low
aerodynamic drag and rounded front design helps optimize performance
and fuel economy.
Note:
For high altitude operation....

First off, it says "Do not exceed" 60 sq ft, but second, it says what to expect if you do exceed it. Is Ford winking at those who tow trailers larger than 7.5' x 8'? I mean, there are some humongously tall 5ers out there!

I'm trying to figure out what to think about these frontal area numbers. Is it just "lawyers' CYA maneuvering," or is there some real cause for concern about drive train longevity or something else?

I've also learned that the Ford Escape 2L Eco with tow package has a 30 square foot limitation in the owners' manual. 231 HP, 270 ft-lbs torque, but limited to PUPs and the like? I'm wondering, if we're taking the pickups' manual with a big grain of salt, can we do likewise with the Escape?

Do other mfrs have the same limitations? I don't recall seeing anything in my Toyota manual about frontal area.

mrkoje wrote:
I just looked in the 2013 Ram 2500 owners manual and it only references "Frontal Area" in a list of towing definitions. It does not mention any towing or size limitations based on frontal area of the trailer.

Apparently, Dodge knows that their vehicles are going to be used to haul monster trailers and designs them for that purpose. Ford on the other hand... well it's in the owener's manual right? :B