Motorised Trim Wheel for Flight Simulators

 

NOW AVAILABLE!

 

STL files for the 3D Printed parts are available here (updated Sept 17)

 

(Feb 21 - Customer contributed Cessna style wheel .stl file as option)

 

This GA aircraft style trim wheel is manually operated to set trim in normal flight, then when auto-pilot is active it automatically rotates to follow the A/P pitch control actions (stepper motor driven).

 

IMPORTANT: As with most projects on the site this is a DIY build project. The driver card and 3D printed parts are available to buy, but to complete the project you will need to source yourself the other parts such as stepper motor, feedback pot, indicator servo etc. See the purchase information page for more details.

 

TRIM WHEEL FEATURES

• Integrates directly with FSX/P3D/X-Plane as standalone unit, or can be used with the BFF Control Loader system
   

• Turn by hand to set trim manually
   

• Automatically follows FS trim movements when A/P is active or when electrical trim buttons operated
   

• 180mm trim wheel dia, 4.5 Revs working range (5 revs hard stop to hard stop - set by potentiometer rotational range)
   

• Working range adjustable in settings (soft stops)
   

• Built in RC Servo driven trim position indicator
   

• Built-in potentiometer provides trim position feed to FS via FSUIPC or XPUIPC.
   

• Base or side mounted
   

• Left or right hand mounting (trim wheel and indicator direction reversible)
   

• Full supporting BFF Trim Wheel software
   

• 3D Printed parts throughout (.STL files are available if you want to try your own)

 

STPDRV-2 card TECHNICAL DETAILS

• Drives bi-polar steppers with 2 phase sinusoidal voltage drive for smooth operation

• Input voltage: 24V

• Stepper output voltage adjustable from 2.4V to 24V to suit motor. Default is 12V for specified trim wheel motor

• TI DRV8432 drive chip will drive most small steppers without heat sinking, output currents can be increased with additional heat sinking to drive larger motors

• Includes over-temperature and other chip fault protection

• Potentiometer input, electric trim buttons, servo power in and servo out connections

• Indicator servo output electrically isolated from USB and stepper drive circuits

• Separate 5V servo power required (approx 500mA)

• USB Mini-B Connection - no virtual COM port required

• Status LED's and full card status reporting to software

MECHANICAL ARRANGEMENT

BFF Motorised Trim Wheel Assy - exploded view

 

The trim wheel assembly can be base or side mounted in your cockpit. It can also be mounted in a right or left hand orientation to allow location on the left or right side of a centre pedestal (the nose-up/down direction of travel of the trim wheel and of the position indicator can be reversed to suit). The unit can also be rotated for attachment to hide the body of the stand behind the wheel.

 

The trim position indicator and cover can be rotated about the wheel axis to customise the indicator location. 

 

The mechanical components of the trim wheel are 3D printed. I use a Zortrax M200 printer with Z-HIPS material which gives good dimensional accuracy and a good surface finish to the parts.

 

A full set of printed components available to buy.

 

I have also made the STL files available if you wish to try printing the parts yourself.

 

The STL files for the 3D printed components are here.

 

Good dimensional reproduction is needed on the geared parts (the trim wheel hub, and the pot and servo gears) to ensure smooth meshing. In addition the centre holes on the hub and pot gears will need to be drilled through accurately to give good press fit location on the motor and pot shafts (5 mm on motor, 6.35 mm (1/4") on pot). This is a better way to produce the required accuracy of fit as opposed to trying to print to the required shaft hole diameters. Please check the readme documents in the zip for more information.

 

The bought components used in the trim wheel assembly are:

• Stepper Motor: Mercury Motor SM-42BYG011-25, see
  
  https://www.sparkfun.com/products/9238
   

• Position feedback potentiometer: Vishay Spectrol Model 534 (10 turn, 10KOhm, Linear)
  
  http://www.vishay.com/ppg?57065
   

• Indicator Servo: Any good quality 9g micro-servo, for example:
  
  https://www.servoshop.co.uk/index.php?srch=SG92R
  
  Check it can handle the 0.8ms to 2.2ms pulse length range output by the STPDRV-1 card. You may also want to buy an extension cable for the servo if you wish to mount the STPDRV-1 card a bit further away from the trim wheel - the lead length on the 9g servo will not be much.

 

SYSTEM CONFIGURATION (Shows older STPDRV-1 card)

 

 

Please see the STPDRV-2 card datasheet for details of the connections.

 

The card provides connections for the stepper motor, position reporting pot, indicator servo, USB/TTL cable, electric trim buttons and 24V and 5V (servo) power inputs. The logic side of the card is powered directly from USB, and the 24V power input supplies the main drive chip and stepper motor. The indicator servo drive is electrically isolated from the rest of the card and requires a separate 5V supply. For full isolation the 5V supply should not share the same ground as the main 24V supply. If your servo is electrically quiet the card may still operate properly with shared grounds.

 

The current draw by the stepper motor and servo are low - so power supplies with approx 1 amp capacity should be sufficient. If the card is used to drive larger steppers or servos then the power supplies should be sized to suit and additional heat sinking should be added to the drive chip..

 

SOFTWARE

 

The trim wheel is operated and controlled using the BFF Trim Wheel software. This provides control and monitoring facilities for the wheel and card.

 

The software controls the power-up initialisation of the wheel, provides manual control of the stepper and servo drives, provides settings and wheel and card status monitoring.

 

On power-up initialisation the wheel will rotate automatically to determine drive sense and working range. When this is completed the operation is largely automatic - the wheel can be turned manually to adjust trim position in normal flight. When A/P becomes active the wheel  will  automatically follow the trim position.

 

The software will display wheel positions and card status to allow operation to be monitored, otherwise it can be left to its own devices.....

 

The window expands to display the settings area. User settings include stepper output voltage, wheel working range, position following response sensitivity, manual stepping speed, direction inversion etc.

 

The app can also be run when FS/X-Plane is not available. In this mode the manual motor and servo control is active. This is particularly useful during the wheel build and set up stages.

 

 

 

The software also supports operation of the trim wheel with the BFF Control Loader system. In this mode the wheel operation is fully integrated with the CL system. Manual adjustment of trim wheel position adjusts trim tab position and hence trim force level. And when A/P is active the trim wheel will move automatically to simulate minimising the stick force when the main elevator axis is following the A/P pitch control actions.

To enable trim wheel integration the CL system must be configured accordingly. See the CL system Configuration Manager (V1.16+) Tab 7 Item 25.

 

For use with X-Plane XPUIPC is required. If you can't get to the XPUIPC website here's DropBox links for XPUIPC - V1.9 and V2.0

 

 

 

 

 

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