The prop related accident rate of clutched machines appears to be no
better than that of non-clutched. Although the prop may not spin at
idle, at high throttle settings it will spin up just as fast as other
machines as evidenced by the accident record. Further, the fact that a
unit is clutch equipped may lure pilots into a more casual approach to
their machine while its running. That trust is misplaced.
Francesco DeSantis came up with this safety improvement for clutched
machines, the Prop-Stopper ropeóan easy-to-build device that prevents
the prop from spinning while you start the machine. Even at full power
it would stop the prop. Yes, that would obviously be hard on the clutch,
but a clutch is cheaper to replace than a hand. And much less messy.
This piece of rope with a short tube attaches to the prop in such a
way that it can't spin, even if the throttle were at full. Then the
pilot gets buckled in and removes the rope while seated, nearly
eliminating the possibility of an accidental prop strike during startup.
The safest way to start a machine is with it on your
back like Miniplane maker, Diego is doing here. But reality means that
sometimes we have to putz with our machines to get them going. When a
motor is being difficult to start, that is a likely time for it to surprise
you with above-idle power.