Auxiliary Controls Redone

Happy to announce that all the controls, other than the flying controls (Pitch/Roll/Yaw) have been checked and redone where necessary. This in order to ensure that they operate correctly with DCS-BIOS and to increase their robustness.

The Rudder Trim falls in the latter category. The original Spitfire rudder trim system had one turn from end to end, whereas the elevator trim had four turns. The easy way then was to directly connect a potentiometer to the knob. The risk here however is that the potentiometer can easily be damaged in the heat of battle through over-enthusiastic application. The updated design now works through a gear with a positive stop.

Another component which has been updated is the Chassis Control Mechanism (undercarriage lever).

We are replicating the somewhat idiosyncratic pneumatic action of the undercarriage as accurately as possible by mechanical means. In order to raise the gear, the pilot was required to “in one deliberate movement”, pull the lever down and to the left to remove it from the gate and without pausing, move it up to the top of the movement. Here he had to hold it until the pnuematics took over and plonked the lever across to the right and back into the gate. We achieve this through a set of clever (we hope, still to be proven!) springs, scissor press-plates, traps and triggers. Thus the pilot will pull the lever down which depresses the press-plate, move it across to the left which sets the trap, move it up then hold it for a few seconds and then release the lever. This lets the lever jump to the right which in turn triggers the trap which pushes the lever back into the gate.

Thats all very interesting but how does that affect this particular update? Well, for the undercarriage action DCS-BIOS will accept a toggle switch, pushbutton or rotary encoder. The length of time that the action of working the lever takes, say 7 seconds or so, would require immediate triggering of the action in the simulator when you start moving the lever down out of the gate. It was not possible to achieve this with two microswitches, I tried in a number of combinations, normally open, normally closed, parallel, series etc. It would only signal at the end of the cycle, which was 7 seconds too late. So I then devised a geared system for a rotary encoder, attached to the shaft. The clever bit here was to allow initial movement in a reverse direction without triggering the action incorrectly, ie. when you move the lever down out of the gate you don’t want the sim to think you are moving the gear lever down. So the wheel attached to the shaft has a slot which allows free movement for the extremities and only moves the gear on the central 60 degrees of the movement. This solves the problem and gets the gear moving in the sim at the appropriate moment. 

The final update was to the Remote Radio Control unit. Here the internals were completed and the whole front face now incorporates the engravings and switch retaining mechanism. There are three switch units:

  • Power on/off
  • 4 interlinked latching switches for channel selection
  • a 3-way switch to select radio mode
View of Radio Remote internals

What remains now on the controls is to redesign the main flight controls. They currently work directly against spring tension, which is not the most elegant way of doing things and provides poor feedback and centering. I wish to change this to a cam action, potentially with in-flight adjustable spring tension to provide force-feedback. 

But that is the subject of a future post! 🙂

2 thoughts on “Auxiliary Controls Redone”

  1. Very well done the gear mechanism.

    Too bad that DCS Spitfire PTT radio operation are not correct programmed for 3 way lever switch in radio box, but is just “copy and past” of P-51 radio with PTT button in throttle knob, this operation don’t fit for Spit because there is the 3 ways lever in their left momentary position that make the PTT function.

    1. Thank you Sokol!
      Yes, there are a couple of things that need fixing in the DCS Spitfire, fortunately all relatively minor. The top button on the radio remote control should be on/off, they have made it interconnected with the other 4 channel buttons. Also as you point out, the PTT lever at the bottom of the control should be momentary, they have made it a 3 way switch. Overall though it is a stunningly accurate representation of the Mk.IX and way above anything else that is out there.

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