Plane: Allow lower speeds in landing final #29265
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Relaxed target airspeed constraints in navigation.cpp to allow for target airspeeds as low as the AIRSPEED_STALL if set. The TECS will still further constrain the target airspeed as appropriate.
Introduced the is_on_final public method, which determines if the landing is at the pre-flare stage or later, so the aircraft is on final for landing. Similar to the existing is_flaring and is_on_approach methods.
Previously the TECS never allowed for a speed demand outside of the navigation airspeed range (AIRSPEED_MIN to AIRSPEED_MAX), even on landing final. This can be too fast for touchdown if a conservative AIRSPEED_MIN is used, which might be preferable for other phases of flight. This commit lowers the min. airspeed to AIRSPEED_STALL, if set, during landing final only. Using a value of TECS_LAND_ARSPD or LAND_PF_ARSPD lower than AIRSPEED_MIN, it enables slower touchdowns while ensuring the rest of the flight remains safely at or above AIRSPEED_MIN.
Corrected the AIRSPEED_STALL parameter description, which stated that it was an indicated airspeed. More accurately, according to its TECS implementation and in line with the other airspeed parameters, it is a true airspeed (or an indicated airspeed at sea level).
Updated the AIRSPEED_STALL parameter description to explain its effects on the landing final
Hwurzburg
requested changes
Feb 10, 2025
It could be added to LAND_OPTIONS, but currently you need to have AIRSPEED_STALL specified, and TECS_LAND_ARSPD or LAND_PF_ARSPD set to a value lower than AIRSPEED_MIN for this to do anything different than the current behavior. What do you think? |
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Up to @tridge ...many set airspeed_stall, but default for landing airspeed is 1/2 way between min and cruise....so probably not a big deal... |
Hwurzburg
approved these changes
Feb 13, 2025
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Plane: Allow lower speeds in landing final
Description
This PR allows for lower airspeeds during the landing final while maintaining appropriate limits during other phases of the flight, including the landing approach phase, if AIRSPEED_STALL is set. This enables smoother/slower landings when a conservative AIRSPEED_MIN is used, which previously resulted in fast touchdowns.
Changes