Thats because they go 62mph all day long and 15mph up all the hills, so to try to make up time and to piss off us drivers with fast(er) trucks off they let gravity pull them down the hill and as soon as is levels out they are right back in the back of the line where they belong....
American Trucker
What causes "Dragn'fly" (Drag and Fly)?
Discussion in 'Ask An Owner Operator' started by txmoorej, Apr 25, 2011.
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I never met a truck loaded heavy that wouldn't fly down the hill - maybe I'm not computing that part of the question?
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"Diesel Engines dont engine brake on there own like gas engines do"
Any internal combustion engine will slow against its compression.
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I've noticed some people have a truck that goes up a hill but won't go down very good. I supose those are called flyn'drags
txmoorej Thanks this. -
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Long story made short - Gravity as mentioned and the Numerous other variables, Mechanical and human ! lol

Is this really that hard to comprehend ?
Pa.Last edited: Apr 25, 2011
txmoorej Thanks this. -
It's kind of a weird question, huh? Sure, a heavy load should roll down a hill faster than a light load, but why do light loads sometimes require so much more effort to get up that same hill than a heavy one? See what I mean?
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I voted "Terrain" just because you have to have a hill to drag up and go down.... if you didn't then your question would be pointless (kinda already is LOL)
But the main cause besides that is just weight. 44k+ and your gonna drag up the hill, and coast back down. Newton's lawtxmoorej Thanks this. -
my my my
these are the guys driving out there now.
OH LORD...
this is something you should have learned in second grade...
GRAVITY remember Sir Issac Newton who had an apple fall on his head...
ROFLMAO...Working Class Patriot, txmoorej and Joetro Thank this. -
I suspect it's a bit more complicated than 2nd grade physics.
In fact, I found this page on the Stanford University's site which warns of "heavy duty physics" and shows how complicated vehicle dynamics can be:
![[IMG]](proxy.php?image=http%3A%2F%2Fwww-cs-students.stanford.edu%2F%7Emdevine%2Fpinewood%2Fsystem_diagram.png&hash=d5408cea3f11f3e2f309a1ebc8dd4868)
http://www-cs-students.stanford.edu/~mdevine/pinewood/pinewood_derby.html
It says, "Bottom line: Centering the weight of your car as much as possible toward the bottom, back corner of your car will make it faster during the race."
If weight centered in the back of a pinewood derby racer can make it race faster down a hill, I wonder if having the cargo weight centered near the back of the of the trailer can make it "fly" down a hill faster.
Everything else being equal, if gravity makes a rear heavy truck go faster down a hill, shouldn't it, conversely, be harder to "drag" it up that hill?
If so, this alone would have an effect on performance regardless of equipment or driver behavior.
Fancy formulas aside, surely some of you, like American-Trucker, have made some observations and can chime in on this. Thoughts?Last edited: Apr 26, 2011
rodknocker Thanks this. -
I wish ya'll stop talking bout me
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