On Thu March 1 2007 4:09 pm, James N. McBride wrote:
> The Rocky Mountain Institute sponsored (and probably still does) the
> development of high mileage vehicles. The last presentation I saw from them
> was over 12 years ago and they claimed to have a four passenger car then
> that could get 500 miles per gallon. It was a gasoline-electric hybrid that
> used an 18 hp gasoline engine that ran at rated speed all the time. When
> not needed for power the extra energy went to charge the batteries. It
> could go 135 miles per hour but only for short periods of time. Their
> target was 1000 miles per gallon. One big hurdle is air conditioning which
> takes about 18 hp by itself. Cars of this type would be a lot different
> from conventional cars of today. The bodies would be very light composite
> material and the seats would probably be mesh to be self cooling. Special
> windows would not let the sun in when warm but would permit light. There
> would be lots of changes in the way cars are made and used. Collision
> safety adds weight and I don't think they had factored that in yet. Much
> can be done when the marketplace demands it.
When I see claims like this I tend to try to do some basic physic analyst on
it. What current vehicle uses the least energy/mile, a bicycle. I googled
energy demand bicycle and when to this site.
http://damonrinard.com/aero/formulas.htm
I took the upright riding position as being somewhat represented of what an
enclosed vehicle be like that was wider but shorter. Picking 30kph( about 20
mph ) energy demand is 300watts, googled energy content of a gallon of gas
124000 btu, 3.4 btu/hr = 1 watt, using an efficency of 40% for an engine
(typical for a diesel not a gas engine) and crunching the numbers I come up
with 932 mpg. That is at 20mph not sixty. Estimating that 90% of the total is
wind resistance and that wind resistance increases as the square of the speed
I come up with 118 mpg at 60mph. While by BS detector isn't going to go off
on this one my doubting nature isn't happy with this one.
It's hard to get around that people are a certain size and for the most part
are only willing to ride in certain positions.
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