wind drag/weight conversion
I hope this doesn't stir anything up. I heard an interesting comparison idea from a friend the other day. He said with a truck pulling a trailer. For every foot the trailer extends above the roof l...
Forum Discussion
mkirsch wrote:
They don't call them rules of thumb for no reason.
This pretty well says what the OP was looking for, a general rule of thumb. THis is no different than the WB/Trailer length ROT that folsk throw around. Or the max trailer is 2xGRAWR that I learned back in the early 80s before manufacture GCWR ratings became prevalent. WIth this, the more HP, lower gearing you have, the better the performance/speed, generally speaking.
As noted by many, including myself. the actual how much more or less HP is needed for a given frontal area vs another style, can vary from a low of say 100, to a high of 160-170 hp for the same wt load, depending upon the shape etc of the given load. Assuming the same speed, and a level grade.
Going up hills, addition hp is based on weight only. For 15K, it is about 40HP per 1% additional grade you go up. A 4% grade would be about 160 hp plus the 105 or 135 hp amounts I quoted earlier, or in the 260-280 hp range. plus or minus depending upon the aerodynamics of the rig.
Marty
