OpenTX - Application Note 20
Altitude Limiter Using a Vario
Create an altitude limiter for electric powered gliders which re-enables power at a lower altitude.
(This application was contributed by Danny)
The limiter cuts the motor off when the glider reaches the target altitude and enables the motor again when the altitude drops below a lower preset altitude. This enables multiple ascents to the target altitude without having to land.
This limiter simulates some of the features of altitude limiters used for altitude limited electric soaring (ALES) competition. (The 30 second motor run limit is not implemented here.) The target altitude and resumption altitude may be set as required but this example uses 100m and 15m respectively.
Switch SB↑ turns altitude limiting OFF.
Switch SB- and SB↓ turn altitude limiting ON.
The ladder diagrams that represent these lines are as follows.
L14 is now used to disable the throttle.
Throttle Disable without Sticky Throttle Option.
Add the following line as the last line in the Mixer screen throttle channel.
Throttle Disable with Sticky Throttle Option
Add the following line as the last line in the Mixer screen supplementary ‘Sticky’ channel.
Refer to Application Note 3 for further details.
Create the following audio files and transfer them to the [SOUNDS]/[en] folder of the SD card
Create the following two special function lines. In this example, SF8 and SF9 are used.
Confirm It Works
With switch SB up (altitude limiting OFF), check that switch SF enables and disables the throttle as described in Application Note 9.
With switch SB down (altitude limiting ON), at ground level, check that the throttle is enabled. Ascend and confirm the throttle is disabled at 100m. Descend below 15m and confirm that the throttle becomes enabled.
Again ascend until the throttle disables at 100m. Before descending below 15m, set switch SB up (turning OFF altitude limiting) and confirm that the throttle is enabled. Confirm that the aircraft can ascend above 100m.
Refer to Application Note 9 for information about the Vario.
Refer to Application Note 3 for throttle disabling control and sticky throttle control.
AMA ALES regulations http://www.modelaircraft.org/files/RCE13-2-2Kallevang.pdf