| From: | R Andrew Hayden <rahayden@*****.WEEG.UIOWA.EDU> |
|---|---|
| Subject: | Late night calculations and another possible direction |
| Date: | Fri, 12 Feb 93 20:14:40 CET |
This approach isn't going to work right. I spent abotu two hours
last night running equations and punching buttons on my poor
calculator and it just isn't working right. I have an alternate
suggestion, though:
--------------------------------
All transmissions on ground vehicles (save drones) are inherently
geared towards a cruising speed of 100 km/h (about 62mph). Of
course, accessories are available to change that (overdrive, for
example would add 25% to the cruising speed). Redline speed is 2x
cruising speed (200 km/h) and also increases with the addition of
accessories.
The biggest flaw with our system was that there was no way to
determine maximum weight that an engine could move. All that
would happen is that cruising speed would get lower and lower and
lower, but there was no place that weight would overcome the
engine. Now, granted, it is possible with a really elaborate
gearing system to get a lawn mower engine to move a car, but that
isn't very realistic.
So, by using an arbitrary cruising and redline speed, you can then
use engine power to yield two things: Max Weight and Acceleration.
Here are some thoughts:
Max Wt = Pulling Power / 100
Pulling power is USUALLY equal to the Power of the vehicle's engine,
but some accessories might increase pulling power (for example, a
special heavy-duty cargo transmission).
------------------------
Now, as for acceleration, we could do two things, we could come up
with an equation, which is proving difficult, or we could estabish
some kind of blanket table of Max Wt. v. Vehicle Wt.
For example:
100%> Vehicle Wt. > 80% of Max Wt: Acceleration is 10 km/s^2
80% > Vehicle Wt. > 60% of Max Wt: Acceleration is 15 km/s^2
60% > Vehicle Wt. > 0% of Max Wt: Acceleration is 20 km/s^2
These yield 0 to 60 times of 10 sec, 6.67 sec, and 5 sec, just as a
comparison.
This means to get some really good acceleration, you are going to
have to put in a big honkin' engine, or get accessories that effect
power or Max Wt (turbo charging, special transmission, whathaveyou).
--------------------------------
The last question we have is still one of economy. In the RBB
economy ranges all over, but often times is in the area of 30 - 50
km/liter for most standard cars and cycles. We need to decide how
to do this.
--------------------------------
Finally, the question has come up about how powerful elec. engines
are. No matter what, a gas engine is always going to give you
more horsepower, acceleration, and raw power than a comparably
sized elec. engine. Electric is much more fuel efficient, though.
That is reflected in our equations.
[> Robert Hayden <] [> ____ Come out, Come out <]
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