Brake Toggle Bungees
Nov 26, 2007 by John Fetz
A brake toggle entangling the prop can be fatal. Two
fatalities have been caused by it, one captured on video. It's most likely to happen right after launch, when
thrust is pushing the motor towards the riser, and you let go of the
brakes. It's far more likely with low
attachment machines because their geometry puts the top cage close to
your risers and brake toggles. If you fly such a machine, it is best
that the space between your first and second (or inner and outer) hoop
have netting to reduce the possibility.
Normally, air friction against the long brake line
(between pulley and trailing edge) pulls the brake toggles against their
stops. But in some cases, letting go of a toggle without carefully
putting it at the pulley, can allow it to flail and be sucked into the
prop. Usually it just breaks the toggle off and you face the lesser
emergency of having no brake on that side. However, if it wraps into the
prop, you're doomed into an irrecoverable spiral.
One possible fix is John Fetz idea with a lightweight
bungee cord that prevents the toggle from going too far while allowing
full brake travel.
This should only be done by experienced pilots
or instructors who can anticipate possible side effects. Be
extremely careful not to introduce more risk than you mitigate. For
example, attaching a 2nd brake line to lower hand position, adds
more material that can foul the prop.
The Mod
Put a ring around your brake toggle, it may require
untying the brake. A thick round ring would be best so the line doesn't
abrade. Run a 1/8" bungee from the hook-in
loop for the slip ring. If you incorporate a 2nd brake toggle (like in
the diagram at right), rin The slip ring allows the primary
brake to easily overpower the light bungee while still pulling the brake
away from the prop.. |
