RE: Please help with an investigation
Beeping can be anything. But our aircraft, be it fixed wing or rotory; fuel powered or electric, you are going to hear the sound of the rotor or propellers (motors or engines) more than the beeping. That is until the aircraft crashes or lands and all moving parts stop, then you will hear the lost model alarm.
Never dealt with a lost model alarm, so I am assuming on how loud they are.
Rafael