Version 1. - May 2006
= 700 divided by 3 multiplied by 11 = 2567 feet
A more complex calculation is usually just a few steps; the system above can often be used for each step. The ‘square’ system is shown for the following calculations.
Ground speed and fuel use
To calculate wind speed in knots (ie how many nautical miles in one hour)
Question: You launch at 0830, and at 0840 you fix your position 2NM away. What is the wind speed?
Set up the square:
10 minutes is the time from 0830 to 0840.
= 2 divided by 10 multiplied by 60 = 12 NM (in one hour) ie 12 knots.
To convert this to km/hour, you can set up another square for the next step, using the conversion 1NM = 1.85km.
= 12 divided by 1 multiplied by 1.85 = 22.2 km
So a speed of 12 knots will be the same as 22.2 km/hr.
© Australian Ballooning Federation Inc
ABF Pilot Training Manual Part 8