Every day that is asked, the answer is "2 weeks".
Let me say some things about failsafes.
- there are 2: one in the RC and the other in the FC
- the RC failsafe works differently in different brands, and even works differently depending on whether the transmitter has been switched on since the receiver was powered up
- you need to research and test your RC failsafe to make sure you understand it
- it is required that you understand both failsafe systems
- the FC failsafe only takes over if the RC system stops sending pulses (or generally stops sending signal to the FC)
- the default for the FC failsafe is to stop motors and drop from the sky
- the FC failsafe can be set to go to any flight mode switch position AND ALSO has an associated set of control stick positions.
- RC failsafe may do any of these depending on brand and setting:
-- none (always stops the signal so the FC failsafe always takes over, safe, use FC failsafe)
-- go to previously selected position (if the receiver has "seen" the transmitter to get these values, and then the transmitter goes away for some reason, else don't send pulses, generally this RC failsafe needs to be programmed to go to a specific flight mode switch position and the FC failsafe is unused)
-- always maintain the last set of received stick positions (unsafe, this one is a fly-away waiting to happen as you can imagine)