Douglas,
firstly can we ask what transmitter/receiver set are you using, the manufacturer's name and model please. If it's a 2.4Ghz set OF ANY MAKE it will have a failsafe (somewhere) guaranteed, and on the default throttle stick.
If its a 27 or 40 MHz set then yes, if you want a failsafe you can by a unit and plug it in line between the receiver and the ESC.
See other threads on this forum found by searching for "failsafe".
Kimmo