Spaceclam
Cruisin' Guzzisti
So i read once that motorcycle news clocked a stock G11, with a 180 lb/ish rider, 0-60 in 3.9s, i think it was. In real world terms, that sounds reasonable. Slow for a bike, but gives a carrera a run for it's money.
But i got to thinking. 70 hp at the rear wheel, how is this possible, from a physics standpoint. So, i whipped out my calculator, and did some math.
520 lbs + 180 lbs rider =700 lbs, or 317.5kg
60mph=26.82m/s
if V(final)=V(initial) +AT, then 26.82=0+3.9A, acceleration = 6.8776 m/s^2. (That's about 2/3 of a G force laterally)
Distance=.5*A*T^2 so the distance traveled in 3.9s is 52.3m. So total joules = 52.3*317.5*6.8776, =114207.3J,
spread over 3.9s is 29283.9 joules/second (watts)
1hp is 740 watts, so that's an average of 39.5 hp. Basically, only 57% the energy measured at the rear on a dyno wheel turns into actual motion in this instance.
I know a tremendous amount of energy goes to squat the suspension, there's a slight delay for shifting gears and starting off, and the tires flex a lot, and some wind resistance towards the end. But are these things really THAT inefficient?
Just to put things into perspective. If the engine is running at 10% efficiency (90% loss) through the drag, there is a 10% loss in the drive train, (90% efficiency) and there is a 43% loss (57% efficiency) of power to the rear wheel, which leaves 39.5hp, then the transformation from gasoline to movenemt has an efficiency of about 5.1%.
Of course these numbers are too low, because while the clutch is being operated, power is NOT being transmitted, but time continues to elapse, lowering the average power.
But still,
Astounding. :ugeek:
-Clam
But i got to thinking. 70 hp at the rear wheel, how is this possible, from a physics standpoint. So, i whipped out my calculator, and did some math.
520 lbs + 180 lbs rider =700 lbs, or 317.5kg
60mph=26.82m/s
if V(final)=V(initial) +AT, then 26.82=0+3.9A, acceleration = 6.8776 m/s^2. (That's about 2/3 of a G force laterally)
Distance=.5*A*T^2 so the distance traveled in 3.9s is 52.3m. So total joules = 52.3*317.5*6.8776, =114207.3J,
spread over 3.9s is 29283.9 joules/second (watts)
1hp is 740 watts, so that's an average of 39.5 hp. Basically, only 57% the energy measured at the rear on a dyno wheel turns into actual motion in this instance.
I know a tremendous amount of energy goes to squat the suspension, there's a slight delay for shifting gears and starting off, and the tires flex a lot, and some wind resistance towards the end. But are these things really THAT inefficient?
Just to put things into perspective. If the engine is running at 10% efficiency (90% loss) through the drag, there is a 10% loss in the drive train, (90% efficiency) and there is a 43% loss (57% efficiency) of power to the rear wheel, which leaves 39.5hp, then the transformation from gasoline to movenemt has an efficiency of about 5.1%.
Of course these numbers are too low, because while the clutch is being operated, power is NOT being transmitted, but time continues to elapse, lowering the average power.
But still,
Astounding. :ugeek:
-Clam