User manual

XCSoar User Manual

Average climb

This method sets the MacCready to the average climb rate achieved

across all thermals in the current ﬂight. As such, it takes into ac-

count the time spent centering the thermal. The value is updated

after leaving a thermal.

Since MacCready theory is optimal if the MacCready setting is the

average climb rate of the next expected climb, this method may

give suboptimal performance (commanding speed too slow) if the

conditions are improving; and similarly may be non-conservative

if the conditions are deteriorating (commanding speed too high).

Similarly, if the pilot continues to climb in weak thermals, this

will reduce the average and may therefore encourage the pilot to

continue to select weak thermals.

As a result of these limitations, the pilot should be aware of how

the system operates and adjust his decision-making accordingly.

5.13 Analysis dialog

The analysis dialog can be used to check the glide polar. This is

accessed via the menu

INFO . Analysis

The polar page shows a graph of the glide polar at the current bugs

and ballast setting. It also shows the calculated best LD and the

speed at which it occurs, and the minimum sink and the speed at

which it occurs.