There are many MakerPlane avionics modules that comprise our “System of Systems”. Each one can stand-alone, or can be integrated into the cockpit to perform functions as part of the environment. For example, the SWZL-1 haptic stick shaker can be connected to a stall vane for mechanical triggering, or integrated in with pyEFIS to provide feedback based on Angle of Attack and pending or actual stall. Also see the MakerPlane Store to see the systems available for purchase. Help keep this site going by purchasing from MakerPlane.

Here is an overview of a couple of these avionics components that are part of our system.

 

Stick Shaker

The SWZL-1A is an aircraft “stick shaker” controller system that provides a haptic pre-stall warning based on a stall vane switch or the Angle of Attack (AoA) information received from an EFIS serial data stream. 

 The SWZL-1A controller directly drives a small vibration motor that is clamped to the control stick or control yoke of the aircraft.  The device is compatible with EFIS systems from Dynon, Garmin, Grand Rapids Technology (GRT) and of course MakerPlane pyEFIS.

 

Haptic Stick Shaker Installed in RV-9

 In normal operation the stick shaker does not interfere with the aircraft controls.  As a stall is approached, the aircraft angle of attack increases to the point where the stick begins vibrating and pulsing.  As the angle of attack increases, the amplitude of the vibration and the frequency of the pulsing increase, providing a progressive indication of an impending stall.  For aircraft without an angle of attack sensor, a simple stall vane switch may be connected to the SWZL-1A controller to provide a single-level, non-progressive stall indication.

 The SWZL-1A controller is entirely contained in a standard d-subminiature connector backshell, providing a light weight, robust mechanical package that may be mounted anywhere in the aircraft.  The controller requires only four or five connections: Power, Ground, serial EFIS data or stall switch input and one or two motor connections.  The entire system, including the motor, draws less than 0.2A of current when the motor is active.  The motor is mounted directly to the control stick or control yoke using the provided clamps and hardware.  Two wires connect the motor to the controller.  No modifications to the airframe or primary control system are required.

 The stick shaker controller is preset at the factory with four levels of progressive AoA indication plus an activation airspeed setting.  The AoA (percent) settings and motor speeds (out of 255) are:

  • 65/195 (AOA/Speed) lowest vibration, lowest pulse frequency
  • 70/215
  • 78/235
  • 87/255 highest vibration, highest pulse frequency

 The activation airspeed setting is:

  • 40 Knots (set as 400 deciKnots)

Trim Motor Controller

The M-PWR-2 is a two-channel variable speed trim motor control device developed primarily for amateur-built aircraft applications.  The device features two all-electronic motor drive channels in one compact package, capable of controlling Ray Allen (RAC) or Firgelli servo motors directly.  Fast and slow motor speeds are independently adjustable for each channel and are selectable using an external sensor or EFIS serial airspeed information.

M-PWR-2 Trim Motor Controller

 Each motor channel is capable of driving up to 1.2 amps with input voltages from 8 to 18 volts.  Protection is provided against voltage surges and reversed polarity on all inputs. 

As an open source hardware design, the M-PWR-2 device is a platform for development.  Basic two-channel variable speed trim motor control is provided in the Baseline (X-suffix) version and users may develop their own firmware using the provided driver source code as a starting point.  The M-PWR-2 uses a Microchip PIC13KF22 CPU and is compatible with the readily available MPLAB IDE and PICKIT development tools.

An enhanced feature set is available at extra cost by upgrading to the A-suffix version microcontroller.  In this M-PWR-2A device, the on-board low-voltage RS-232 interface extracts serial airspeed information from Dynon SkyView, Garmin G3X EFIS or MakerPlane EFIS air data streams.  This information may be used to replace or augment physical airspeed or flaps sensor switches.  The airspeed threshold is easily set in flight by using an external pushbutton switch and indicator lamp.

A unique feature of the A-suffix upgrade is the ability to detect and correct a stuck input trim switch or wiring fault. When a fault is detected, a lamp is illuminated, the faulted input is ignored, and the external pushbutton switch is used to temporarily assume control of the input until the fault is corrected.  Since the lamp and switch are required for EFIS mode indication and airspeed threshold programming, there is no extra hardware cost in providing input fault detection and correction.