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Old 07-13-2020, 10:52 AM   #1
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Calculated Frontal Area and Towing Consideration

I have a 2016 Nissan Frontier 4x4, 4.0L, towing capacity of 6,100#. I never gave the trailer's frontal area consideration until reading a post on this forum and went back to check my Nissan's owner's manual. Max frontal area for towing is 30 square feet and while the airstreams are tapered and very aerodynamics, how does one actually calculate it on an airstream? I expect to purchase a bambi/caravel in the 16-20 ft range.

BTW, I'm presently towing a 10 foot 1966 canned ham weighing @2,000-2,500# with a frontal area of 37 square feet. The Nissan pulls it easily at 65 mph @2,100 rpm. I got 12.5 mpg on my most recent 900 mile round trip (Connecticut to Ohio). Without the trailer, I get about 17 mph on the same route.

PS, I've done a search of this site and do not see any posts about others using a Nissan Frontier. Found one post using a Nissan Pathfinder which has the same engine and several Toyota Tacomas.
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Old 07-13-2020, 11:28 AM   #2
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The frontal area is not reduced by the curvature. Strictly it is the sum of all frontal areas projected to 2 dimensions so it will be in the ballpark of 60 sq. ft. You will be needing about 85 hp pulling level at 65 mph, compared to about 58 hp with your current trailer.
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Old 07-13-2020, 11:32 AM   #3
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The frontal area is not reduced by the curvature. Strictly it is the sum of all frontal areas projected to 2 dimensions so it will be in the ballpark of 60 sq. ft. You will be needing about 85 hp pulling level at 65 mph, compared to about 58 hp with your current trailer.
Thank you, I am interested in how you made the calculation. Can you elaborate?
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Old 07-13-2020, 11:43 AM   #4
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I just used the formula for aerodynamic drag. I used a drag coefficient of .59 which may be a bit high and a mass of 7800 lb. There are some online calculators to make it easy. Here is one. http://www.apexgarage.com/tech/horsepower_calc.shtml
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Old 07-13-2020, 12:12 PM   #5
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Back when I was lost on this point, I found one sorely out of date reference which calculated a 1975 31ft Sovereign at 58.66sq.ft. Brian might know something.

https://ecomodder.com/forum/showthre...ics-32325.html
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Old 07-13-2020, 12:23 PM   #6
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Back when I was lost on this point, I found one sorely out of date reference which calculated a 1975 31ft Sovereign at 58.66sq.ft. Brian might know something.

https://ecomodder.com/forum/showthre...ics-32325.html
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Old 07-13-2020, 12:43 PM   #7
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58.66 sounds pretty close for the 70's Airstreams. The newer 31 footers are quite a bit larger (taller and wider). What surprised me is the low combination drag from the wind tunnel tests. I just plugged in 0.6 for the 4x4 combination, but perhaps it is closer to 0.5
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Old 07-13-2020, 04:16 PM   #8
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Back when I was lost on this point, I found one sorely out of date reference which calculated a 1975 31ft Sovereign at 58.66sq.ft. Brian might know something.

https://ecomodder.com/forum/showthre...ics-32325.html
Based upon Bayoubiker's calculation and reading the ecomodder.com commentary, while I can pull an airstream with my 4.0L frontier, I will likely get worse gas mileage than the 12.5 I averaged with my current trailer since air drag is a greater factor than weight at level towing. Did I interpret this correctly?
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Old 07-13-2020, 05:13 PM   #9
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I think you are spot on Jeff, though the improved engine efficiency at the higher output will help quite a bit, so it won't be as bad as the numbers suggest.
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Old 07-17-2020, 04:17 PM   #10
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I think you are spot on Jeff, though the improved engine efficiency at the higher output will help quite a bit, so it won't be as bad as the numbers suggest.
I've been playing around with the calculator you recommended after reading that frontal area has a larger inpact upon fuel economy than weight. So, I looked at two 2020 Sport models--16 ft vs. 22 ft.

16 Sport: .58 drag coefficient, 64 sq/ft frontal area, 3500 gross weight, 63 mph, requires 67 hp.

22 Sport: .58 drag coefficient, 56 sq/ft frontal area (6 ft, 11.75 inch wide), 4500 gross weight, 63 mph, requires 61.6 hp.

Before you educated me, I would have guessed the 22ft'er would require more work to pull on a flat surface. Seems because it is nearly a foot narrower, that is not correct. Based upon DCPAS's link, weight is a bigger factor on hilly terrain which i expect the extra thousand pounds would be noticeable. Thoughts on my assumptions?
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Old 07-24-2020, 11:52 AM   #11
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Originally Posted by JeffofCT View Post
I've been playing around with the calculator you recommended after reading that frontal area has a larger inpact upon fuel economy than weight. So, I looked at two 2020 Sport models--16 ft vs. 22 ft.

16 Sport: .58 drag coefficient, 64 sq/ft frontal area, 3500 gross weight, 63 mph, requires 67 hp.

22 Sport: .58 drag coefficient, 56 sq/ft frontal area (6 ft, 11.75 inch wide), 4500 gross weight, 63 mph, requires 61.6 hp.

Before you educated me, I would have guessed the 22ft'er would require more work to pull on a flat surface. Seems because it is nearly a foot narrower, that is not correct. Based upon DCPAS's link, weight is a bigger factor on hilly terrain which i expect the extra thousand pounds would be noticeable. Thoughts on my assumptions?
Weight does require more HP going up but if the down grades are not too steep you get it all back. I find my turbo diesel gets about .7 mpg better on rolling hills than on flat and I don't see a drop off until the down grades exceed 2%.
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Old 07-24-2020, 03:23 PM   #12
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Quote:
Originally Posted by JeffofCT View Post
I've been playing around with the calculator you recommended after reading that frontal area has a larger inpact upon fuel economy than weight. So, I looked at two 2020 Sport models--16 ft vs. 22 ft.

16 Sport: .58 drag coefficient, 64 sq/ft frontal area, 3500 gross weight, 63 mph, requires 67 hp.

22 Sport: .58 drag coefficient, 56 sq/ft frontal area (6 ft, 11.75 inch wide), 4500 gross weight, 63 mph, requires 61.6 hp.

Before you educated me, I would have guessed the 22ft'er would require more work to pull on a flat surface. Seems because it is nearly a foot narrower, that is not correct. Based upon DCPAS's link, weight is a bigger factor on hilly terrain which i expect the extra thousand pounds would be noticeable. Thoughts on my assumptions?
Hi Jeff, I think these frontal areas refer to the 2019 Sport Models, The 22FB is narrower. The 2020's are Bambi's as the Sport is not made for the 2020 model year. Just a little clarification but it does make a big difference with the 22FB.

In 2020 all the trailers went to the 8' wide format.

We like the narrower trailer and really like the ability to see around it with our conventional truck mirrors.
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Old 07-24-2020, 04:00 PM   #13
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Hi Jeff, I think these frontal areas refer to the 2019 Sport Models, The 22FB is narrower. The 2020's are Bambi's as the Sport is not made for the 2020 model year. Just a little clarification but it does make a big difference with the 22FB.

In 2020 all the trailers went to the 8' wide format.

We like the narrower trailer and really like the ability to see around it with our conventional truck mirrors.
You tow with a Ridgeline, correct? I've seen some of your other recent tv vs. trailer tow performance. My Frontier crew cab has nearly the identical hp and torque but with a tow capacity of 6,100. I think it would tow 2019 or older 22' sport well.
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Old 07-24-2020, 04:46 PM   #14
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The Ridgeline does a great job with the 2019 22' Sport. A WDH would be a must as well.

I think I would be pushing it with a 2020 22FB Bambi. You might be in a better position with a 2020 trailer. Check your tongue weight specs on the Frontier. Mine is 600 lbs max depending on cargo and people. The 2020 trailers will have a higher tongue weight due to the extra AGM battery on the A-frame. My Sport is one of the lowest in recent years. at 422 lbs according to Airstream published specs.
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