Rescue Mode in Heliflight

Rescue mode is implemented in Heliflight using the "ANGLE" mode of Betaflight. The ANGLE mode has not been renamed yet, as we are still using the Betaflight Configurator tool until someone wants to modify it to better support Heliflight's functionality and provide a GUI setup tailored to helicopters.

To enable Rescue mode, simply assign a button (preferably) or a switch on your transmitter to the "ANGLE" mode in the Mode window of Configurator. If you assign it to a switch instead of a button, do not enable this switch during take-off, otherwise in the best case your helicopter will take off straight up as it spools up (or in the worst case the angle mode will go haywire while spooling up and instantly crash the helicopter). You should always do a quick function check of the sticks before spooling up to ensure the swashplate is moving correctly. This function check would reveal if the swashplate is not responding to the collective stick on your transmitter because the Rescue mode is accidentally enabled.

Currently, Heliflight's Rescue mode will level the helicopter to the nearest orientation, either up-right or inverted. If you are not used to inverted flight this can be extremely chaotic and disorienting, as when you let off of the Rescue mode button the collective pitch will instantly return to the setting on your transmitter stick. Eventually Heliflight will have a configuration parameter to allow the user to require it to return to up-right orientation. Additionally, we may implement a version of Rescue mode that initially levels to the fastest orientation, and then after a second or two flips the helicopter back up-right if it was inverted.

Collective pitch is overridden by Helflight in Rescue mode. Rescue mode varies from zero collective pitch when initiated in a vertical orientation, to a maximum of the rescue_collective setting when level (either inverted or up-right). The collective pitch will change the instant the Rescue mode is enabled, and then will increase smoothly as the helicopter returns to a level orientation. If the helicopter needs to climb faster after leveling, just increase the rescue_collective setting.

set angle_level_strength = 75

• This setting determines how aggressively Rescue mode will attempt to return the helicopter to a level orientation. The higher the strength, the larger the setpoint change that will be given to the PID controller for it to execute.

set rescue_collective = 375

• This setting determines the maximum collective pitch setting when the helicopter is in a level orientation (either upright or inverted). The amount of collective pitch will scale smoothly from zero collective when the helicopter is vertical to maximum collective when the helicopter is level. A setting of 500 would typically achieve the maximum collective pitch of the helicopter if the servo configuration and scaling has been done according to the Heliflight setup instructions.