A Strobex blade tracker permits blade track-
ing from inside the helicopter in flight or on the
ground. See figure 7-21. The system uses a highly
concentrated stroboscopic light beam flashing in
sequence with the rotation of the rotary wing
blades. When aimed at a fixed target on the blade
tips, the tips appear to stop.
To synchronize the strobe light and rotary
wing rotation, a soft iron sweep attached to the
rotating swashplate passes close to a magnetic
pickup on the stationary swashplate. This causes
a once-per-revolution pulse used for synchroniza-
tion. Each blade has a retroreflective target
number attached under the blade in a uniform
location. Blade tracking is then determined by the
relative vertical position of the fixed target
Figure 7-22.-Electronic tracking.
Figure 7-21.-Strobex blade tracker.