How To Make Your Own Four Engine Throttles For FS2002

By Rob Barendregt

f you are interested in making your own 4-engine throttles for less than US $20 worth of material, please read on. All you need is a free (analog) game controller port on your PC and some easy-to-get parts, six hours of spare time and be a little handy with tools. If you don't have a free game port, you can use a gameport-to-USB convertor to connect them to a free USB port.

Features:

• 4 independant throttle levers.
• With Reverser blocking.
• 3 switches, that you can assign to any FS2002 function.

Note: For using the Reverse Thrust function with these throttles, you need to install Peter Dowson's FSUIPC module, which is a freeware add-on for FS2002; the latest version can be downloaded from: http://www.schiratti.com/dowson.html

Introduction

After the previous article of my rudder pedals, I had so many positive responses (and dozens of pictures from people all over the world that made them) I decided to spend the effort again in describing this throttle quadrant.

As I explained in my previous article, the operation of these throttles is based on the principle of an analog joystick: a joystick axis is just a variable resistor (called a potentiometer).

The main other components are K'NEX gear wheels. K'NEX, a construction 'toy', is available in a lot of countries, and is very robust and easy to work with. If you don't know where to get them: usually the K'NEX distributor sells individual components as well. And if you want to know more about K'NEX, partnumbers, etc.: look at www.knex.com. (for the USA/Canada: you can buy on-line as well) The other parts you can buy in any hardware and electronics hobby shop.

What Is Needed?

The main components you need, and how they are used:

• Plate material for the box (fig 1). I used plywood, 18mm thick. The baseplate is 15*15 cm.
• A piece of 9 mm multiplex wood, as top plate.
• K'NEX gear wheels, 4 small, 4 large. (fig 2A,C). The orange connector is mounted on the large wheel with two 4mm bolts; cut off the end of the bolt that sticks out of the nut.
• 4 Potentiometers (fig. 2B), value 100 KiloOhm LINEAR (not logarithmic), preferably with an plastic shaft. The small wheel is fixed onto the potmeter shaft with a small parker screw. Cut off the part of the shaft that sticks out of the wheel.
• 4 aluminium strips (fig. 2E): 10*3 cm, 3 mm thick. Drill two holes (6.5 mm for the K'NEX rod 2H, 10 mm for the potmeter). The distance between the hole centers is 37mm (a critical measure, for proper transmission between the wheels).
• 4 steel hooks (fig. 2D): 2*2 cm, to mount the strips onto the base plate.
• 3 mini switches (fig 2F, 1D): these are 'make' contacts (contact when pressed).
• A number of 6mm rings (fig. 2G), used to close up the wheels between the alu. strips.
• 1.5 meter of shielded computer cable (minimum 9 wires plus shield). An old (serial) modem cable will do fine.
• A 15-pin gameport connector (fig 7). if you don't have a free gameport: a gameport-to-USB convertor. Most computer shops sell them, cost about US $14. They usually have a 4-position switch: use position "Joystick-A".

Assembly Instructions

• Mount the potentiometer with small wheel onto the aluminum strip.
• Mount the hook onto the strip with 5mm bolts/nuts.
• Mount the strips onto the base plate. The distance between strips should be as small as possible (i.e. the large wheel should fit between them), so you can operate the four levers with one hand. In my construction: 3 cm (fig. 3A); depends on the thickness of your pots.
• Mount the large gear wheels with rings onto the grey K'NEX rod (fig. 3 B,C). Check that the transmission between the wheels is smooth. Some arithmatic: the transmission factor between the wheels is 2.5. This means when the large wheel rotates 90 degrees, the small wheel rotates 2.5*90 = 235 degrees (the potentiometer can rotate maximum 270 degrees).
• Fix the small wheel onto the pot shaft with a small screw: when the pot is centered, the yellow rod in the wheel should point straight up.
• Make 4 slots in the top plate: 7 mm wide, 12 cm long (fig. 1A). The yellow rod should slide smoothly in these slots.
• The side plates of the box should be such that the distance between the bottom of the top plate and the large wheels is about 1 cm. If done properly, the 12 cm slots limit the rotation of the large wheels to 90 degrees.
• Mount the switches onto the top plate.
• Make the construction for the reverser blocking (fig 1C). When the grey rod is rotated forward, it should block the throttle movement for the lower 20% (see fig 1B). This is the reverse thrust zone, that will be set with FSUIPC.

Electrical wiring

See fig. 5 and 6 for a schematic diagram. Note: you can connect a 4th switch (pin 14), but then you need a cable with an additional wire.

Solder the shielded cable to pots and switches according to the diagram and solder a 15-pin gameport connector to the other end of the cable. Solder the shield of the cable (thick light-grey line) to the 15-pin connector and pot housings. This will reduce 'jitter' on the controller axis resulting from electrical interference. Note for the pot connections: use the center contacts and the botton contacts: when the throttles are in fully reversed position (pointing towards you), the resistance between two pot contacts should be < 5 KOhm.

Installation Of The Throttles As A Windows Game Controller

I can only make the description for Windows98, but it should be possible to get it working under WindowsME/2000/XP as well. If you have a free gameport:

• Connect the cable to the PC game controller port.
• Click Start - Settings - Control Panel - Game Controllers.
• Add a new Controller: Click Add, and select '3-axis 4-button joystick', with the option 'rudder/pedals' checked.
• Back in the Controller list the '3-axis 4-button joystick' should have status OK now.
• Click tab 'Advanced' and organise the Controllers such, that the throttle "joystick" has Id-1 (a gameport controller should always have Id-1 for correct operation).
• Click the General tab, and click Settings - Calibrate to calibrate the throttle:
  • Simulate the 'circle' motion of the X/Y axis by moving the left 2 throttles alternately.
  • Calibrate the right 2 throttles by sliding them all the way forward and backward several times.
• Click Properties, and observe the axis indicators in the Test tab for full swing.

If you use the USB convertor:

• Set the throttles to max. (IMPORTANT!)
• Connect the cable to convertor, set the convertor switch in position 'Joystick-A' and the plug the convertor cable into a free USB port.
• Windows should detect the new USB device, and install it automatically as a Human Interface Device. You can check that with Start -Settings - Control Panel - System, tab Device Manager.
• Click Start - Settings - Control Panel - Game Controllers. Windows should have added a new controller called "USB adaptor"
• Now calibrate the throttles are described above.

Installation Of The Throttles In FS2002

Start FS2002 and go into the Options - Controls - Assignments window.

• Set the throttles to fully reversed.
• Select the '3 axis...' or 'USB Adaptor' under 'joystick type', and remove any default assignment (if applicable).
• Assign the 4 axis to 'Engine x Throttle axis', with option Reverse selected. See fig 8.
• Click tab Events/Buttons for the new controller, and assign Button-1,2 and 3 to any function you like.
• Select Options - Controls - Sensitivities, and select the new controller.
• Set the Sensitivity slider for all axis to MAX, and the Null zone to MIN.

Calibrating The Throttles With FSUIPC

Make sure you have FSUIPC installed (easy...just copy the file fsuipc.dll to the ..\FS2002\Modules folder). See the user guide.

Now you can set the lower part of throttle range as reverse thrust zone.

• Select Modules - FSUIPC, tab Joystick, subtab "seperate throttles per engine". Per throttle:
• Set the throttle to min. (fully Reversed), and click Set (Reverse)
• Set the throttle to max. and click Set (Max)
• Set the throttle at idle position (against the Reverse block) and click Set (Idle)

You should also create a dead zone around the Idle position. Tip: the simplest way of doing that:

• Close FS2002.
• Go to the folder FS2002\modules, and open file FSUIPC.ini with Notepad.
• At the bottom of the file, you should see something like:
  Throttle1=-15685,-12000,-11200,16192
  Throttle2=-16193,-12500,-11700,16192
  Throttle3=-16193,-12900,-12100,16192
  Throttle4=-16193,-12900,-12100,16192
• Edit the middle 2 values, to create a proper deadzone (typically 1000 - 2000 wide)

Observe correct operation of the throttles, specifically the reversers, in e.g. the default B747. If necessary, adjust the deadzone.

A Final Word

I know these throttles may not look very professional, but they work great. I'am not using the throttle on my CH Yoke anymore (use it as mixture axis now).

Needless to say, I do not accept any responsibility if it shouldn't work or if my description messes up something in your PC or FS2002 configuration. But, if you have any comments, questions, suggestions or need support, feel free to send me an email (please: no large attachments!).

Happy flying...