B. Jensen wrote:
: Cory,

: The ring gear was ruined because the starter gear stayed extended too
: long after the engine started. Thus the starter gear broke off the ring
: gear teeth.

: This mod (bypass) is only for experimental aircraft usage only.
: Basically the jumper wire retains residual power for a second or two
: after the start switch is released, and cases the starter to stay
: engaged. If the jumper wire is removed, then all power is removed
: immediately from the starter when the ignition switch is released. I

Cory, it sounds like this is the 2 starter contactor situation like I
mentioned. The jumper wire he's referring to goes between the solenoid and
the PM motor itself.

I liked your idea about a freewheeling diode, but you'd need a series diode
on the input to the PM motor too (to keep the voltage in the PM motor to
freewheeling diode circuit). I wouldn't worry about the current handling
capacity here, 600 A diodes are easy to get, but the Vf of the diode would
probably be like 1.0V. When cranking the voltage at the PM motor is probably
only about 6 or 7 V (piper uses a 6V contactor for the starter) so 1V
lost in the diode is a large fraction of the available power!
--
Aaron Coolidge