+- HP Forums (https://www.hpmuseum.org/forum)
+-- Forum: HP Software Libraries (/forum-10.html)
+--- Forum: General Software Library (/forum-13.html)
+--- Thread: (42S) Solvers: Automobiles (/thread-13205.html)
(42S) Solvers: Automobiles - Eddie W. Shore - 06-29-2019 03:29 PM
Blog Entry: http://edspi31415.blogspot.com/2019/06/hp-42sdm42free-42-auto-solvers.html
Download files for Free42/DM42: https://drive.google.com/file/d/1N4wpO9Q-Mhyp51kdubAh5guf2xZhp8Tc/view?usp=sharing
1. Displacement, Bore, Strokes (File: displacement.raw)
Code:
00 { 79-Byte Prgm }
01▸LBL "DISPMNT"
02 MVAR "DISPMNT"
03 MVAR "BORE"
04 MVAR "STROKE"
05 MVAR "#CYLIN"
06 PI
07 4
08 ÷
09 RCL "BORE"
10 X↑2
11 ×
12 RCL× "STROKE"
13 RCL× "#CYLIN"
14 RCL- "DISPMNT"
15 .END.Variables:
(DISPM): displacement of the a cylinder (cubic inches)
(BORE): diameter of the cylinder (inches)
(STRO): distance traveled by the piston (inches)
(#CYLI): number of cylinders
Equation:
π/4 * bore^2 * stroke * #cylinders - displacement = 0
Example:
Bore = 4 in
Stroke = 3.5 in
4-cylinder engine
Result: Displacement = 175.9292 in^3
2. Gear Ratio, MPH, RPM (File: gearratio.raw)
Code:
00 { 74-Byte Prgm }
01▸LBL "GEARRTO"
02 MVAR "RPM"
03 MVAR "MPH"
04 MVAR "TIREDIA"
05 MVAR "GEARRAT"
06 PI
07 RCL× "RPM"
08 RCL× "TIREDIA"
09 RCL÷ "MPH"
10 1056
11 ÷
12 RCL- "GEARRAT"
13 .END.Variables:
(RPM): the tire's revolution per minute
(MPH): speed of the vehicle (miles/hour)
(TIREDI): diameter of the tire (inches)
(GEAR): gear ratio = transmission ratio * final drive ratio
Equation:
(RPM * π * tire_diameter) / (MPH * 1056) - gear_ratio = 0
Example:
RPM = 3,400 rpm
Tire Diameter = 28 in
Gear Ratio = 3.85
Result: MPH = 73.5635 mph
3. Quarter Mile Estimation: Elapsed Time, Car's Weight, Horsepower
(File: quartermile.raw)
Code:
00 { 52-Byte Prgm }
01 ▸ LBL "QRTMI"
02 MVAR "ET"
03 MVAR "WEIGHT"
04 MVAR "HP"
05 5.825
06 RCL "WEIGHT"
07 RCL÷ "HP"
08 3
09 1/X
10 Y↑X
11 ×
12 RCL- "ET"
13 .END.Variables:
(ET): elapsed time for the car to travel 1/4 mile (seconds)
(WEIG): weight of the car including passengers, drivers, fuel, and other items carried (pounds)
(HP): horsepower
Equation:
(weight/horsepower)^(1/3) * 5.825 - elapsed_time = 0
Note: MPH = (horsepower/weight)^(1/3) * 234 = 1363.05/elapsed_time
Example:
Weight: 3,540 lb
HP: 215 hp
Result:
ET: 14.8190
(MPH = 91.9802 mph, [SHIFT] (TOP.FCN) ( 1/X ) 1363.05 [ * ])
4. Tire Sizes (file name: tiresize.raw)
Code:
00 { 87-Byte Prgm }
01 ▸ LBL "TIRESZE"
02 MVAR "SECWDTH"
03 MVAR "RIMDIA"
04 MVAR "ASPECT"
05 MVAR "TIREDIA"
06 2
07 RCL× "SECWDTH"
08 RCL× "ASPECT"
09 2540
10 ÷
11 RCL+ "RIMDIA"
12 RCL- "TIREDIA"
13 .END.Variable:
(SECW): section width (millimeter)
(RIMDI): rim diameter (inches)
(ASEPC): aspect ratio
(TIREDI): tire diameter (inches)
On a side of a tire, we can get three of the four values by from a code that looks like this:
P235 / 75R17
P: passenger car (L for light trucks)
235: section width
75: aspect ratio
R: radial tire
17: rim diameter
Equation:
(2 * section_width * aspect_ratio) / 2540 + rim_diameter - tire_diameter = 0
Example: Use the stats of the tire above to calculate tire diameter.
Result: 30.8780 in