Attention: TDR Forum Junkies 
The following is a link to the NW Bombers site.
http://www.nwbombers.com/board/ikonboard.cgi?s=3d7bdd6067b9ffff;act=ST;f=4;t=1049;hl=new
The NW Bombers site allows me to post an Excel file I have fooled around with for a couple of years.
The Excel file calculates HP requirements and milage for RVs. If you input your GCVW, RV width and height, and an assumed drag coefficient, the HP requirements for level pulling, hill climbing, head winds, braking HP requirements are calculated and graphed. Level grade fuel milage is also calculated. For your amusement, your terminal velocity with no brakes down a grade is also shown.
Your fuel milage may differ from the calculated values in the spread sheet. The starting values for drag coefficients and efficiency were developed by my fiddeling the values to give a close match for my observations with my 1997 2x4 3. 54 automatic 2500 and 11,000 lb fifth wheel trailer and educated guesses for other drivetrain configurations. If you tweak the input values for area, drag coefficient, and drivetrain efficiency to give agreement with your observed values, then you can see the impact of changing the weight, area, head winds, etc.
The milage calculations use Cummins fuel consumption data for two specific Cummins engines from the TDR magazine. The spreadsheet does not reflect the reported fuel consumption inprovements from revised 12 valve timing, after market cam shafts, after market timing chips, or 180 degree thermostats, etc. The milage calculations also appear to give good agreement with observed values for solo operation of the Ram pickup alone. Input your solo weight and some of the reported cross sectional areas and drag coefficients to see the effect of 2x4 vs 4x4, 2500 vs 3500, accessories, rear end ratio, etc.
Above all, have fun. This free spread sheet is worth every bit you are paying for it.
http://www.nwbombers.com/board/ikonboard.cgi?s=3d7bdd6067b9ffff;act=ST;f=4;t=1049;hl=new
The NW Bombers site allows me to post an Excel file I have fooled around with for a couple of years.
The Excel file calculates HP requirements and milage for RVs. If you input your GCVW, RV width and height, and an assumed drag coefficient, the HP requirements for level pulling, hill climbing, head winds, braking HP requirements are calculated and graphed. Level grade fuel milage is also calculated. For your amusement, your terminal velocity with no brakes down a grade is also shown.
Your fuel milage may differ from the calculated values in the spread sheet. The starting values for drag coefficients and efficiency were developed by my fiddeling the values to give a close match for my observations with my 1997 2x4 3. 54 automatic 2500 and 11,000 lb fifth wheel trailer and educated guesses for other drivetrain configurations. If you tweak the input values for area, drag coefficient, and drivetrain efficiency to give agreement with your observed values, then you can see the impact of changing the weight, area, head winds, etc.
The milage calculations use Cummins fuel consumption data for two specific Cummins engines from the TDR magazine. The spreadsheet does not reflect the reported fuel consumption inprovements from revised 12 valve timing, after market cam shafts, after market timing chips, or 180 degree thermostats, etc. The milage calculations also appear to give good agreement with observed values for solo operation of the Ram pickup alone. Input your solo weight and some of the reported cross sectional areas and drag coefficients to see the effect of 2x4 vs 4x4, 2500 vs 3500, accessories, rear end ratio, etc.
Above all, have fun. This free spread sheet is worth every bit you are paying for it.
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