MAVLINKHUD

Overview

The FLAP parameter group configures the deployment behavior for aircraft Flaps. Flaps increase lift and drag, allowing for slower landing and takeoff speeds.

ArduPlane manages the deployment of flaps based on pilot switch position and, optionally, automatic flight stages (e.g., auto-landing).

Key Concepts

1. Deployment Stages (FLAP_n_PERCNT)

Defines the percentage of servo travel for each switch position.

  • Stage 1: Partial flaps (often used for takeoff or loiter).
  • Stage 2: Full flaps (used for final approach and landing).

2. Deployment Speed (FLAP_SLEWRATE)

Prevents the flaps from "snapping" into position, which could cause a sudden ballooning effect (rapid increase in lift).

  • Slew Rate: Limits the degrees per second the servo can move.

Parameter Breakdown

  • FLAP_1_PERCNT: Percentage for first stage (0-100%).
  • FLAP_2_PERCNT: Percentage for second stage.
  • FLAP_SLEWRATE: Maximum movement speed (% per second).

Integration Guide

  1. Outputs: Map a servo output to Flap (Function 3).
  2. Config: Set the percentages based on your airframe manufacturer's recommendations.
  3. Mixing: Flaps often require a corresponding Elevator-to-Flap mix (see TKOFF_FLAP_ELEV) to counter the pitching moment they create.

Developer Notes

  • Library: ArduPlane/servos.cpp.
  • Context: Only relevant for ArduPlane.

FLAP_1_PERCNT

%
Default 0
Range 0 100

Automatic Flap Percentage (Stage 1) (FLAP_1_PERCNT)

Description

FLAP_1_PERCNT automates the first stage of flap deployment for fixed-wing aircraft.

Flaps are used to increase lift at low airspeeds. ArduPilot can automatically lower the flaps based on the current airspeed. This parameter sets how far the flaps should move (from 0% retracted to 100% full flaps) when the plane slows down below the FLAP_1_SPEED.

Tuning & Behavior

  • 0: Disables automatic flaps.
  • Value (%): The target deflection. For example, setting this to 30 will lower the flaps 30% of their total range when the plane is slow.
  • Logic Link: Used primarily in CRUISE, FBWB, and AUTO modes.

FLAP_1_SPEED

m/s
Default 0
Range 0 100

Flap 1 Speed (FLAP_1_SPEED)

Description

Defines the airspeed threshold for automatically deploying the first stage (FLAP_1_PERCNT) of wing flaps.

Tuning & Behavior

  • Default Value: 0 (Disabled)
  • Should be set higher than or equal to FLAP_2_SPEED.

FLAP_2_PERCNT

%
Default 0
Range 0 100

Automatic Flap Percentage (Stage 2) (FLAP_2_PERCNT)

Description

FLAP_2_PERCNT defines the "Full Flaps" or secondary deployment stage.

When the plane slows down even further (below FLAP_2_SPEED), the autopilot will increase the flap deflection to this value.

FLAP_2_SPEED

m/s
Default 0
Range 0 100

Flap 2 Speed (FLAP_2_SPEED)

Description

Defines the airspeed threshold for automatically deploying the second stage (FLAP_2_PERCNT) of wing flaps.

FLAP_SLEWRATE

%/s
Default 75
Range 0 100

Flap Slew Rate (FLAP_SLEWRATE)

Description

Limits how quickly the flaps move from one position to another. This prevents sudden changes in lift and pitch when the flaps are deployed or retracted.