more mower

[John S Gwynne]

--------

   In message <199411030301.VAA17699 at mail.utexas.edu> , you write:
 
| > By the way, that scheme of one pulse per revolution isn't accurate on any
| > engine that can rev very quickly.  I read somewhere that Ford had trouble
| > with the controllers for the Taurus SHO because that motor can rev at
| > 20000 rpm / second which was too fast for their systems to keep up with.

My 350 SBC seems to be about 11000 rpm/sec with no load near the
(estimated) peak torque RPM (based on the graph in counter.ps).

Let see...

velocity = acceleration * time;

velocity_error = acceleration * delta_time;  delta_time=time between
						RPM measurements

time_spark = 60/RPM/4;	for a 4-cycle 8 cyl

Now,

degrees_error_crank = (1/2)*acceleration_degs*time_spark^2+
	+velocity_error_deg*time_spark
		; acceleration_degs=360*acceleration/60
		; velocity_error_deg=acceleration_deg*delta_time

degrees_error_crank = acceleration*(360/60)*( 1/2*time_spark^2 + 
	+delta_time*time_spark

degrees_error_crank = acceleration*( 6/2*(60/4/RPM)^2 + 6*60/4/RPM*delta_time)

degrees_error_crank = acceleration*( 675/RPM^2 + 90/RPM*delta_time )

	;worst case acceleration = 11k RPM/S

degrees_error_crank = 11k * ( 675/RPM^2 + 90/RPM*delta_time );

	;worst case RPM is just off idle, say 1000 RPM
	;assume RPM measurement every 10mS.

degrees_error_crank = 17.3 deg. (yea, but this acceleration at this
				 RPM is not realistic; even at no-load)

degrees_error_crank(RPM=4000) = 2.9 deg. (much better :) )




We need some realistic data (RPM-vs-time over the usable RPM range) for 
both no-load and loaded conditions. It could take a couple a days 
for me to get it. Does anyone else have this?


                                       John S Gwynne
                                          Gwynne.1 at osu.edu
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