It is an advanced level project and requires good mechanical and electrical build skills. This is a project for the flight sim enthusiast; as a working estimate the project will cost about UKŁ800 (+ control wheel) to complete (depending on motor, encoder and other component prices).

The project follows the same pattern as other flight sim projects on the site - you will find detailed plans, essential software and key bits of electronics below. Obtaining the other parts and materials needed for the project is up to you.

The main project elements are:

The force response of the yoke varies with flight conditions so that changes in airspeed, trim settings etc cause the feel of the controls to change - similar to the behaviour of real aircraft controls.... This makes for force feel much more like real flight controls.

The force levels produced are also much higher than on conventional FFB joysticks. The default system set up will produce single handed aileron control forces up to 4.25 kgf (~9 lbf) and elevator forces up to 9 kgf (~20 lbf). Larger forces can be generated but may require forced air cooling of  the control cards and motors to prevent overheating.

The yoke's range of travel is +/- 90 Deg on the aileron axis and 155 mm on the elevator axis.

The force components generated by the control loader system include:

• Airspeed dependent aerodynamic loading (centring forces proportional to control surface displacement and airspeed)

• Adjustable aerodynamic force gains (equivalent to adjustable control surface area)

• Angle of attack (alpha and beta) effects (eg for longitudinal stability response)

• More realistic trim behaviour (independent of simulator trim system, controls can be force trimmed in any position)

• Control surface static & dynamic weight effects (aircraft acceleration effects)

• Prop-wash effects

• Engine vibrations (vary with power & rpm)

• Runway vibration effects (vary with runway speed)

• Stall buffeting effects (frequency and amplitude definable - eg stick vibration type behaviour)

• Damping and friction adjustments (-ve gains definable)

• Auto Pilot following (when used with BLDRV-12/24 drivers)

Note that the plans do not include the control wheel (yoke) - choice of which is likely to be a matter of personal preference or dictated by the particular cockpit build. The plans show a 25mm outside diameter hollow tube to which you must secure your wheel. Please make sure your choice of wheel is strong enough to carry the forces (some plastic yokes designed for light spring loading may struggle with the force levels).

The yoke construction is fairly simple in principal - but needs to be built accurately. The aileron drive motor, wheel tube and control wheel (not included) are mounted on a travelling carriage, which itself is mounted on low friction linear guides and linear ball bushings. The control wheel tube is mounted in needle roller bearings on the carriage. The carriage is driven by the elevator motor via a toothed belt loop. The elevator motor is mounted on the base structure of the yoke at the rear.

Each movement axis is loaded by a single 3 phase BLDC motor (fitted with 360 cpr quadrature encoder). The motors are specified in the drawings. An important characteristic is their sinusoidal back EMF which enables very smooth response to the sinusoidal commutation voltages from the purpose designed BFF BLDRV-12/24 drivers.

The BLDC motors are sized to allow simple toothed belt torque transmissions to be used whilst still providing good levels of force output. These belt drives are easier to build than spur gearing and are fairly tolerant of slight misalignments and positioning errors likely to be found in DIY constructions.

The force levels are such that at the higher levels one handed operation of the yoke becomes quite uncomfortable quite quickly if the control is displaced or untrimmed. The yoke needs to be secured to a fixed base otherwise it will move under the generated loading. At full load with 12V supply the elevator loading is about 9 kgf (20 lbs), one handed aileron operation at full load requires about 4.25 kgf (9 lbs). These forces are typically with the controls fully displaced during a flight manoeuvre, force levels during normal flying conditions are much lower than this off course.

Provision is made for fitting potentiometers to report the control position.

NOTE the plans do NOT include details of the control wheel - builders must source their own. The hollow yoke tube shown in the design is 25mm outside diameter. Wiring for any buttons on the wheel can be routed through the yoke tube.

A number of videos clips of the prototype in operation are on Page 2.

MOVIE CLIPS ON PAGE 2

Drawing Set Revision History

29/9/11 - Sheet S001-2 raised to R2 - corrected item 2 (front plate) width.

19/9/11 - Sheet A004-1 raised to R2 - corrected item 24 (belt) length.

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