User manual LORUS ROTARY SLIDE RULE

[. . . ] to form a utility bearing compass, and the inner circumference is provided with a logarithmic scale graduated from 10 to 100 and a distance conversion scale (KM, 1000 FT, NAUT, STAT). The outer circumference of the fixed dial ruler is marked with the same logarithmic scale (10 ­ 100) as the rotary bezel, and the inner circumference is graduated with a time s ca le . N 5 3455 60 NAUT . 15 0 33 50 55 70 30 ST A T. N W5 4 50 9:00 60 70 1:1 0 80 45 45 8:0 0 55 05 1:2 80 60 30 0 0 7:0 50 0 90 90 0 1:3 40 10 285 SPORTS 75 10 10 1:40 35 6:00 45 15 1:50 W 11 1 2:00 30 5:00 100 12 255 12 4:3 40 20 0 1 12 0 24 0 14 SW Time index (reference point for time conversion) Utility bearing compass scale Logarithmic scale on fixed scale* Logarithmic scale on rotary bezel* * Any value on the logarithmic scale is relative, for example, "19" assumes any values that are the n-th power of 10, multiplied by itself . . . 1. 9, 190, 1900 . . . s ORDINARY COMPUTATION [Multiplication, division and the rule-of-three calculation] A Multiplication [Pro ble m ] 30 x 40 = ?[S ol ut io n] 1) B r i n g 3 0 o n t h e r o t a r y b e z e l i n l i n e with 10 on the fixed scale. [. . . ] > z = x ­ y if a = b z = x ­ y ­ 1 if a < b s COMPUTATION FOR NAVIGATION [Calculation of time, speed and distance] All the examples here can be calculated according to the following formula: SPEED = DISTANCE/TIME A Time calculation [Pro ble m ] Ground speed : 200 MPH Distance to fly : 100 miles Time to fly :?[Sol ut io n] 1) A d j u s t 2 0 o n t h e r o t a r y b e z e l t o t h e time index 5 on the fixed scale. 2) Read the fixed scale at a position corresponding to 10 on the rotary bezel. 3) For the purpose of determining the number of digits, the same rule as with the division applies. [Answer] 30 (minutes) 5 mark at the 12 o'clock position B Speed calculation [Proble m] Ground speed : ?Distance to fly : 100 miles Time to fly : 30 minutes [Sol utio n] 1) Adjust 10 on the rotary bezel to 30 on the fixed scale. 2) T h e v a l u e o n t h e r o t a r y b e z e l c o r r e sponding to the time index 5 on the fixed scale is read to be 20. 3) For the purpose of determining the number of digits, the same rule as with the division applies. [Answer] 200 MPH 5 mark at the 12 o'clock position SE 15 0 15 16 15 2:3 0 16 165 17 17 18 3:00 18 19 19 20 21 20 3:30 195 21 22 22 210 23 23 24 4:0 2 05 24 14 25 C Distance calculation [Proble m] Ground speed : 200 MPH Distance to fly : ?Time to fly : 30 minutes [Sol utio n] 1) A d j u s t 2 0 o n t h e r o t a r y b e z e l t o t h e time index 5 on the fixed scale. 2) The value on the rotary bezel that corresponds to 30 on the fixed scale is 10. 3) For the purpose of determining the number of digits, the same rule as with the division applies. [Answer] 100 miles 5 mark at the 12 o'clock position A - 2) B - 1) C - 2) A - 1) B - 2) C - 1) [Calculation of climbing altitude, climbing rate, and climbing time] A Calculation of climbing altitude [Pro ble m ] Climbing rate : 430 FT/minute Climbing time : 18. 6 minutes Altitude to reach : ?[S ol ut io n] 1) Adjust 43 on the rotary bezel to 10 on the fixed scale. 2) Find the value on the rotary bezel corresponding to 18. 6 on the fixed scale. 3) For the purpose of determining the number of digits, the same rule as with the division applies. [Answer] 8000 FT B Calculation of climbing rate [Pro ble m ] Climbing rate :?Climbing time : 18. 6 minutes Altitude to reach : 8000 FT [Sol ut io n] 1) Adjust 80 on the rotary bezel to 18. 6 on the fixed scale. 2) Find the value on the rotary bezel corresponding to 10 on the fixed scale. 3) For the purpose of determining the number of digits, the same rule as with the division applies. [. . . ] 3) Find the value on the fixed scale corresponding to the KM index of the rotary bezel. [Answer] 35 nautical miles 64. 8 kilometers C Kilometers Statute miles Kilometers Nautical miles ?nautical miles [S ol ut io n] 1) Adjust the KM index on the rotary bezel to 64. 8 on the fixed scale. 2) Find the value on the fixed scale corresponding to the STAT index of the rotary bezel. [. . . ]