damon henry wrote:
It is obvious to anyone that has attempted anything like this in the
real world with real parts that a vehicle will be more efficient on
level ground than with hills.
Well, there are special-case solutions where this is not true.
ICEs have a "sweet spot" where they are the most efficient. This is
usually at a higher horsepower than you need to drive at a continuous
speed. So a classic way to win an mpg contest is to "pulse and glide":
- Start the ICE and run it at its peak efficiency point.
This is a lot of horsepower, so the vehicle accelerates.
- When it reaches a speed where aerodynamic losses would begin
to detract, shut off the ICE.
- Coast back down to some low speed; enough to restart the
the ICE by putting it in gear.
Mileage contest winners since the 1930's have used this technique to get
amazing miles per gallon, even with crude old engines.
Obviously, you don't want to drive on real roads like this. The guy
behind you (or the passenger sitting next to you) would get very annoyed.
But as I recall, sometime in the 1950's, someone set an mpg record where
he drove at constant speed on normal roads and got over 100 mpg. He used
the "pulse and glide" technique; but had carefully chosen his route to
be a loop with a big hill. At the top, he'd shut off the ICE and coast
down. The slope was just right to maintain the normal speed limit. At
the bottom of the hill, he started the ICE and drove back up to the top.
The ICE's optimal horsepower happened to be just right to do the speed
limit back up.
So he got *better* mpg than he would have gotten without the hill, and
could drive at normal speeds as well. :-)
--
We need something like the Manhattan Project. We need some urgency
saying, "Here’s what we should be doing. We’ve got to get off fossil
fuels.” -— Lee Iacocca
--
Lee Hart -- See my Xmas projects at www.sunrise-ev.com/projects.htm
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