09-15-2017, 12:06 AM

(09-14-2017, 04:46 PM)pogson Wrote:(09-14-2017, 02:43 PM)Rickb Wrote: You obviously haven't seen the specs on the SRK's twin front wheel drive motor and are making assumptions.

This SRK platform photo looks like a simple, solid, and efficiently engineered drive train package with 70% of the vehicle's weight over the twin motor front drive wheels for enhanced performance and agility in a little over a 1000# vehicle with motors centered between the front wheels.

I'm not making assumptions. "Scale" is about mathematical/physical principles. For instance, if you examine a cube of one unit of length, it has a surface area of six square units and a volume of one cubic unit. If I cut it up into smaller cubes, say, eight cubes, the total volume/weight remains the same but the surface area is now larger, 12 square units.. Similarly, if one has a design for an electric motor, one can increase its power by lengthening it or increasing its diameter or both. Invariably the scaling causes the larger motor to be more efficient than two or more motors of similar design and total combined output equal.

An obvious example: Take a big motor and cut it into two halves. You might think the losses due to the resistance of the windings would be the same but we now miss two cross-pieces to make a circuit so more conductor has to be added to make the thing work.We need the same current as before to get the same power so our resistive losses are higher. Worst case is replacing one big motor with two identical motors. If you actually use twice the power, losses and efficiency would remain the same but you drain the battery twice as fast. So, you have to use only a fraction of the capacity of the motor and efficiency plunges. You have twice the weight, double the number of bearings and fans and internal air-resistance for no gain at all except acceleration perhaps which is rarely useful and dangerous.

Not only are you making assumptions, you are making incorrect ones. For a simple example, see Tesla. Their dual motor cars have better performance and economy than their single motor vehicles with the same battery packs.

I'm done.