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+--- Thread: (42S) Rate of Climb and Descent, Head and Cross Winds (/thread-14345.html)
(42S) Rate of Climb and Descent, Head and Cross Winds - Eddie W. Shore - 01-11-2020 03:35 PM
Rate of Climb and Descent
The solver CLIMB creates a solver of the equation:
ROC = TAS * ALT / √(DIST^2 + ALT^2)
ROC: rate of climb, usually in ft/min
TAS: true airspeed of the airplane, usually in knots
ALT: (vertical distance) the change in elevation, take into the account the height of your airplane, the height of the mountain or obstacle to be cleared plus desired clearance height, usually in feet
DIST: (horizontal distance) distance to the mountain or obstacle to be cleared
For the solver to accurate, you must keep the units consistent (feet or nautical miles for distance, ft/min or knots for speed and rate of climb)
Conversion factors:
1 knot = 101.269 ft/min
1 nautical mile = 6076.12 ft
HP 42S/DM42/Free42 Solver program CLIMB
Code:
00 { 61-Byte Prgm }
01▸LBL "CLIMB"
02 MVAR "TAS"
03 MVAR "ALT"
04 MVAR "DIST"
05 MVAR "ROC"
06 RCL "TAS"
07 RCL× "ALT"
08 RCL "DIST"
09 X↑2
10 RCL "ALT"
11 X↑2
12 +
13 SQRT
14 ÷
15 RCL- "ROC"
16 .END.Example:
TAS = 90 knots = 9114.21 ft/min
ALT = 5000 ft
DIST = 16 nautical miles = 97217.92 ft
Solve for ROC: 468.1328 ft/min
Link to download (climb_solver.raw): https://drive.google.com/open?id=1Zd_Gyj8RJ_ehaozjBB9hfP5Gj_s1QBAS
Head Winds and Cross Winds
The program WINDS calculates the head wind and cross wind (right is positive, left is negative) given the following inputs:
D: reported wind direction
HDG: heading of the aircraft
V: compass magnetic variation, if any
The directions are entered in degrees, measured from true north, clockwise
K: reported wind velocity
Head wind:
HW = K cos(D - HDG - V)
Cross wind:
CW = K sin(D - HDG - V)
We can use the polar to rectangular conversion function with the following convention:
θ = D - HDG - V
r = K
HP 42S/DM42/Free42 Program WINDS
Code:
00 { 79-Byte Prgm }
01▸LBL "WINDS"
02 DEG
03 "WIND DIR?"
04 PROMPT
05 "HEADING?"
06 PROMPT
07 -
08 "COMP VAR?"
09 PROMPT
10 -
11 "WIND VELOCITY?"
12 PROMPT
13 →REC
14 "Y:CROSS X:HEAD"
15 AVIEW
16 STOP
17 RTN
18 .END.Example:
Wind Direction: 30°
Heading of Aircraft: 350°
No compass adjustment
Wind Velocity: 20 knots
Results:
Y: cross winds: 12.8558 knots (from the right)
X: head winds: 15.3209 knots
Link to download (winds_head_and_cross.raw): https://drive.google.com/open?id=1RoIKgbnAWmT36pLn6MHMqKXmUw19e3wh
Source:
"Rate of Climb and Descent" and "Head Winds and Cross Winds" HP 65 Aviation Pac 1. Hewlett Packard, 1974
Blog link: http://edspi31415.blogspot.com/2020/01/hp-42sdm42free42-rate-of-climb-and.html