MPG = Air Resistance vs Speed vs Weight
Improving MPG had me wondering, so I found a definitive calculator to make the math easier. http://ecomodder.com/forum/tool-aero-rolling-resistance.php Vehicle weight [1]: 10,000lb (TV & TT) Crr ...
Forum Discussion
weight is in most cases a secondary effect in towing mpg. It comes into play when accelerating or when going up/down a grade. At a constant speed on level ground weight is a very secondary effect. Wind resistance is by far the dominant,effect.
If your going over very hilly terrain or stop and go traffic, or constant changing speeds, then the weight can have a effect. It's effect is 1/2MV^2 where M=mass, V= change in velocity. Or if your going up/down hills its related to M*d Where M=mass and d= the CHANGE in elevation. If V is constant and d=0 mass doesn't have much effect. It increases rolling resistance and a few other minor effects on economy.
I have two trailers, one a 7'wide cargo trailer 5,000lbs loaded. the other a 9,000lb 8' wide TT that is also about 2' taller. Difference in mileage over the same course is rather small. Towing the "big" one I get 10-12 depending on mountains or not. Towing the smaller one is 11-13, occasionally 14 on very flat ground on the interstate at constant speed. Roughly a 10% hit going from the small frontal area, low weight to the large frontal area and a big weight increase.
also, to do a calculation of speed effects you REALLY need to know the Cd and actual frontal area. not a trival task, even a square wall trailer front has a Cd well below one, the longer the lower it is for the same frontal area, and some of the frontal area is blocked by the TV.
The calculations shown by the OP show a mpg less than 1/2 of what I get pulling a 10,000 trailer with a 9,500 lb truck at 60ish.
If your going over very hilly terrain or stop and go traffic, or constant changing speeds, then the weight can have a effect. It's effect is 1/2MV^2 where M=mass, V= change in velocity. Or if your going up/down hills its related to M*d Where M=mass and d= the CHANGE in elevation. If V is constant and d=0 mass doesn't have much effect. It increases rolling resistance and a few other minor effects on economy.
I have two trailers, one a 7'wide cargo trailer 5,000lbs loaded. the other a 9,000lb 8' wide TT that is also about 2' taller. Difference in mileage over the same course is rather small. Towing the "big" one I get 10-12 depending on mountains or not. Towing the smaller one is 11-13, occasionally 14 on very flat ground on the interstate at constant speed. Roughly a 10% hit going from the small frontal area, low weight to the large frontal area and a big weight increase.
also, to do a calculation of speed effects you REALLY need to know the Cd and actual frontal area. not a trival task, even a square wall trailer front has a Cd well below one, the longer the lower it is for the same frontal area, and some of the frontal area is blocked by the TV.
The calculations shown by the OP show a mpg less than 1/2 of what I get pulling a 10,000 trailer with a 9,500 lb truck at 60ish.
