Experimenting with landings today, and I can't figure out what this parameter does
It's for calculating the flare. See this diagram https://github.com/PX4/Firmware/blob/master/Documentation/fw_landing.pngUsed here - https://github.com/PX4/Firmware/blob/master/src/modules/fw_pos_control_l1/landingslope.cpp#L81
We could definitely do a better job with documentation here.
Interesting. I just tested it out in the field and figured out that smaller values appear to move the glideslope back from the land waypoint.