🚀 go-pugleaf

In article <1992Dec17.011649.987@cmkrnl.com>, jeh@cmkrnl.com writes, in part:

>The flywheel is a great way to store mechanical energy.  However I'm not
>certain about the means for using it.  Somehow the energy must be gotten 
>outside of the container.

	Indeed.  Modern technologies of inverters and induction motors will
	make it a LOT easier.  The RR suppliers (more in Europe than in the US)
	routinely build KW, "four quadrant" (bidirectional) inverters up to
	500 KW or so, with good enough efficiency to replace relays in control
	gear.  The difference is they have a locomotive to move them
	around on.

>Then we come to electric motors to drive the wheels.  Electric motors have
>wonderful torque/speed characteristics for vehicles (they generate maximum
>torque just before stall speed, which may make transmissions and clutches
>unnecessary) but lousy power density -- look at the size of a 1-hp. electric
>motor sometime and tell me how big a motor would have to be to accelerate a
>car fast enough to keep up with gasoline-powered ones.  
	urmmmmm.  Compare, sometime, the size of a 500HP traction motor
	(found in sets of four or six) UNDER a locomotive.  Not that
	dissimilar to a 500 hp gasoline engine.  And Electric motors have
	short term overload characteristics to deliver, briefly, large amounts
	of power above the steady state (Large:  ~10X for minutes, ~double for
	~hour.)  If the batteries are ready, the motors will be.  And modern
	control systems will allow use of the overload capacity without
	impacting the long term reliability of the motor.  "consumer size"
	electric motors (say up to 1 hp) are on a very different part of the
	HP/Volume/Weight space than those for _serious_ power.

I believe the key to (autonomous) electric vehicles is still the storage.  I
have not got numbers here, but best batteries are still (roughly) 10x weight
and/or volume over gasoline in weight/energy.  Flywheels are better, but not,
i think, more than 2x better.

thanks
dave pierson			|the facts, as accurately as i can manage,
Digital Equipment Corporation	|the opinions, my own.
40 Old Bolton Rd		|I am the NRA.
Stow, Mass 01775 USA		pierson@msd26.enet.dec.com
"He has read everything, and, to his credit, written nothing."  A J Raffles