The frontal area recommendations provided by Ford are for the entire frontal area of the towed vehicle. This is why there is a separate rating for 5th's and goosenecks. Ford has already taken into consideration where the front facing areas of trailers sit in relation to the truck, and how that impacts performance.

They even include a note that an aerodynamically designed trailer front "can help optimize performance efficiency".

Another way to look at it...

The red area represents a 30ft Grey Wolf trailer that is 8ft wide, 10ft 6in tall. Subtracting 12in for the clearance of the trailer, you get a frontal area of 76sqft. The green adds 36sqft, and is the size you would expect to see if the frontal area of the trailer did not include the frontal area of the truck.



As you can see, that would make for a massive trailer that could not be towed without an escort due to the width, which would be 11ft 5in.

Frontal area considerations are the entire frontal area of the towed vehicle, no need for calculations on part of the end user to subtract the truck.

 

Interesting............Wonder why then Ford did all those calculations in the body builder. Guess since we are not Ford engineers we'll never know.

 

Does this analysis mean that if the frontal area recommendation is <= 60 sq ft for your particular F150, you shouldn't tow that 30 ft Grey Wolf?

Regarding the frontal area, the towing guide says "the maximum trailer frontal area that must be considered for a vehicle/trailer combination. Exceeding these limitations may significantly reduce the performance of your towing vehicle." It doesn't say anything about safety per se, although decreased braking performance and sway could definitely be considered safety issues.

 

The frontal area consideration is a recommendation, not a safety concern. Frontal area impacts the heat generated by the engine, the time it takes to get to speed, and the speed at which one can ascend. It's up to the owner to determine if it is not safe to exceed those limits, more specifically, when exceeding those limits has become a safety concern. Towing a large sail in a flat state with long on-ramps to moderately busy highways is not the same as doing it in a mountainous state with short on-ramps to packed highways.

The body builder guide... mfg's build structures directly behind and over the cab, which means they need different numbers.

 

Run it at 100% of GVW and enjoy. The safety margin is built into the GVW.

 

Increased frontal area will actually improve braking performance like a parachute on a dragster!

 

The trailer is too close to add useful braking. Put a 30ft hitch extension on it

 

 

Not sure why you're calling BS, my combo keeps accelerating until I downshift and engage the brakes on descents with a big ol' flat face trailer. Maybe your idea of 'useful' and 'descent' differs significantly from mine?

The purpose of a (not drogue) parachute it to bring down an object's speed quickly. Trailers aren't doing that for me. Maybe they are for those towing frontal areas well beyond Ford's recommendations, but I wouldn't say that counts any more than saying the brakes are inadequate when you can't stop in 150ft while towing a 13,000lb trailer.

 

A travel trailer adds substantial wind resistance. That's why your MPG go down so much when you pull one. That drag is also effective braking. You can prove this by taking a TT down a big hill at highway speeds and then take a flat bed with bricks loaded to the same weight as the TT down the same hill. That flat bed with bricks will require a lot more use of your brakes because it doesn't have the parachute affect of the TT. If you do this you'll find a substantial difference in how much the flat bed pushes you down the hill.