Computers not allowed in dating
But the older “whiz wheel” type of flight computers can solve it almost as easily, and at the same time provide you with a picture of what’s going on.
I’ll use the following example problem to show how each type of flight computer is used to solve it: I’ll show the E6-B solution first, because it illustrates more of the entire wind triangle than the CR solution.
Like the E6-B, the reverse side of the CR-3 is used to solve wind triangles, but in a very different way.
Jeppesen’s design, dating from 1955, provides a wind solution that doesn’t require any sliding parts.
The wind solution involves a rotating compass ring with a transparent screen and a sliding plate imprinted with diverging lines that intersect a series of concentric arcs.
One literally “draws” the wind triangle on the computer and reads off the solution.
Unlike weight-and-balance or speed-time-distance calculations which are just simple arithmetic, the wind triangle requires trigonometry.
The arrow tail is on our right, so our wind correction will be to the right, meaning we have to add the 11.5° to our desired 240° course, giving a 251.5° heading (this is a heading, so don’t forget to correct for magnetic variation before setting off).
The arc appearing within the grommet gives our ground speed.
This in turn affects the time it will take to get where we’re going, and thus also the amount of fuel needed.
Given the speed and direction of the wind (from forecasts), our desired course, and our true airspeed (from the airplane’s flight manual), the wind triangle solution tells us the necessary heading to use, and what our groundspeed will be.
It takes about the same number of steps, but they are quite different than those performed on the E6-B.