Replica Spitfire flying controls recap July 2018

Because of the growing interest in this project and enquiries to purchase a kit, I felt it would be useful to recapitulate what the current version of the kit offers in the way of controls and to highlight what is under development.

The kit was re-designed in 3D from Supermarine Aviation Works engineering drawings. Most of the parts are 3D printed in PLA plastic with the use of standard PVC tube for the column, aluminium tubing for axes and cockpit support and plywood for the cockpit panel and base plate. This keeps the whole assembly light for shipping. The kit was designed to be easily installed and removed so that the spare room can be used for its real function when required. It is also worthy to note that the re-design closely follows the original in that assembly and dis-assembly is possible. This is particularly true of the throttle quadrant and access is also given to the accessory boxes. While I do not expect users to fiddle around with the innards, this does allow parts and PCB connections to be checked and replaced if required.

The objective of the first version of the kit was to improve immersion when flying WWII simulators by accurately reproducing the position and movements of the flying and engine controls. A secondary objective of the project is to build a more complete cockpit by including add-ons of the lower instrument panel and the right hand cockpit panel. This will leave an open space where the blind flying panel and gunsight are located for users who need a video screen, keyboard & mousepad. The final objective will be to develop a full VR cockpit with a complete instrument panel based on the DCS Spitfire with about 80 operable controls, switches, levers, buttons, pumps & handles. Note that to keep things simple the dials will only be for “feel” for those who want to tap the glass !

 

In parallel to the development of the kit and the add-ons for sim pilots, I am also developing a full cockpit section for hire at airshows, museums and promotional events. This cockpit will start off with the basic controls already developed, combined with track IR technology and as the other controls are developed it will progressively evolve into a full VR cockpit.

The first version of the kit, currently in production, comprises of two main assemblies, a portion of the port cockpit wall and a floor mounted control column.

IMG_1720

The cockpit panel assembly houses three main units ;

  • A Throttle Quadrant with Fuel Cut Off, Throttle, Airscrew Control and friction wheel levers. The fuel cut off is often referred to as the mixture lever. In the kit it operates an electro-optical switch mid course, as in most sims this is a toggle function. The throttle is the early production MkIX Spitfire type, with a pushbutton on the grip which was normally used as the bomb release switch. Late production MkIX’s had the gyro gunsight (an option in the IL2 Spitfire MkIXe) with a twist grip type throttle handle, which was used for ranging the gunsight (This is not currently available in our kit). The throttle and airscrew levers operate geared potentio-meters. To allow the throttle to be used in sims featuring earlier marks of Spitfire with the WEP function, the gate design is that of an early mark in order to offer this feature. By pushing the throttle lever left and forward at the initial stop (max take-off setting) it goes further forward and operates another electro-optical switch to toggle WEP on, and off when the throttle is reduced. The outer friction wheel & lever is mated to a screw thread allowing the pilot to adjust the stiffness of the levers in the gate, as in the real aircraft.
  • A Trim Wheel Unit with both elevator and rudder trim wheels. The box unit, representing the chain guards in the real aircraft, allows the correct positioning of the trim wheels in relation to the throttle quadrant. The Spitfire is quite trim sensitive and any change in airspeed, prop pitch, or engine R.P.M. requires adjustment of trim settings. With Hotas type controls trim is easily and almost unwittingly controlled using the stick mounted micro switches, but in our kit the pilot needs to move the left hand around the cockpit to adjust the wheels in true WWII style.

IMG_1338

  • A VHF Radio Remote Controller Unit (RCU). The replica unit in the kit offers seven programmable buttons. All the buttons activate a light (LED) when pressed, except for the OFF button. The selector lever at the bottom of the unit normally has three positions Transmit, Receive and REMote. In the kit only the T & REM positions operate micro-pushbuttons. In DCS all these buttons can be programmed to their true functions, ie for selecting the various radio channels. In practice most of us use them for more handy functions like toggling gear, flaps, canopy, map, rads, bailout, etc… For those used to low light or night flying, the light filter slider also works.

 

IMG_1713

The floor mounted control column has the following features ;

  • A low pitch axis. The Spitfire does not have a cockpit floor and the real column pitch axis is below the floor height of a modern office chair.  The column length has therefore been adapted to give the correct height for the spade grip when sitting in front of a desk or worktop. The Spitfire control column is angled back by 11° in the neutral position. To achieve this in the kit a spring loaded strut has been added, which simulates the elevator link rod in the real aircraft. This strut has opposing springs which hold the column at the correct rest angle and which allow and limit appropriate forward and aft column mouvement. There is no hard centre point and the column does not always come back to exactly the same neutral point. However by coming hands off and adjusting elevator trim the aircraft is easily stabilized. I did test a central notch in the strut, but I abandoned this as it didn’t feel realistic – I had the impression that the desire for a fixed hard point was more due to the prolonged use of hard centering joysticks than realistically simulating natural aerodynamic control centering forces.
  • Articulated roll axis. As in the real aircraft the roll axis control is just above the pilot’s knees. This is because the cockpit is quite narrow and there is no room to move the whole column left & right. The roll command is operated by a geared chain in the real aircraft. In our kit the oily greased chain & guard have been replaced by a simple plastic strap, which operates a slider in an accessory box at the base of the column. There are no springs on the roll axis, however top axis friction can be adjusted by a winged nut. Again there is no hard centre point, so the aircraft can be trimmed out by adding a little friction and simply leaving the spade grip in the desired position. Springs could be added to simulate increasing aileron resistance, but this effect only sets on with high airspeeds and most good simulators simulate this by progressively reducing roll rates as airspeed increases.
  • A realistic firing button assembly. The firing button is of the mixed armement type found on b, c and e winged Spitfires, offering a top, bottom or both firing button system. This allows separate or combined use of canons and machine guns. The micro-switches inside are operated by a spring loaded paddle, as in the real unit. The firing unit also features a safety catch. In our kit the operation of the safety catch is both mechanical and electronic. The catch operates an electro-optical switch to toggle the safety on and off, as required in some simulators. In the safe position the paddle is mechanically blocked and the guns cannot be fired. When selecting a new plane in DCS, one has to remember to set the catch to “safe” before spawning in, as forgetting this can cause some embarrassing moments.
  • Spade grip mounted brakes lever. This operates as in the real aircraft and is linked to a slider. Directional control of the aircraft is made via the rudder pedals with combined light use of the brakes. Because the brake lever in the kit operates a slider, this makes taxying the aircraft really easy (and realistic).
  • Realistic spade grip finish. Thanks to one of my first customers we now use a self vulcanizing rubber tape over a twisted wire base and this gives a good non slip appearance and feel to the spade grip.

 

Re-design of some original parts based on customer feedback

  • Control column strut. On the prototype model the free end was anchored to the base plate. This meant that the strut was not perpendicular to the column in the “rest” position. Because the tension of the springs in the strut can be adjusted by moving the strut’s control column end fitting up or down on the column, the excessive angle began to impair the “throw” angles of the column. This was overcome by adding a block to raise the anchor end of the strut.
  • Pitch axis gearing. On the prototype the pitch axis was directly linked to a potentiometer, however since the column only rotates 11° forward and 13.5° aft this gave insufficient throw on the potentiometer and caused spiking. The remedy was to add gearing so that the potentiometer can rotate through a greater angle. In the photos you can see this gearbox at the base of the column on the left hand side.
  • Trim wheel gearing. These gears were introduced as a modification because the original un-geared version was overly sensitive in some sims, which often show the elevator trim wheel making several rotations. This elevator wheel is now geared to give almost two revolutions and the rudder trim was also geared to give a finer adjustment capacity.
  • Throttle and Airscrew Control levers. PLA plastic has the benefit of being very light, but it is not very robust in some planes especially when printed with honeycomb filling. While the initial prototype model has stood up to over a year of constant use, being trundled around at airshows and exhibitions for use by the public, the throttle and airscrew control levers have proved to be too fragile for shipping and I have willingly had to replace breakages. The redesign of these items has been more on their internal structures, ensuring that there are no butt joints in the original 3D drawings and in how the parts are prepared for printing. We no longer use honeycomb on these parts and we ensure that the print lines are unbroken from end to end. This has vastly improved their mechanical resistance at the expense of using more plastic and a longer printing time. Existing customers will be sent upgraded levers free of charge as they become available.

 

Developments currently under way

 

As posted previously work has already started on the right hand cockpit panel with the Chassis Control unit. The plan is to design controls that will use up the remaining free slots on the two Arduino game controllers in the initial kit so that customers can have add-ons to the basic kit. These will include, in addition to the chassis unit, the wobble pump, drop tank cock and jettison handle, fuel tank pressure selector, ki-gas pump, main fuel cock, starter & booster coil buttons and covers, cockpit light rheostats, magneto switches, flap operating lever & nav lights switch. The work is not too complicated compared to what has already been produced, but it does take time to conceive 3D models and to conduct printing and use tests.

I also plan to make a new proper video of the kit in use, as the original version showing the unfinished prototype is not truly representative of the production version. It will be posted here when available.

In the meantime I live and work near Paris (France), so if any of you are passing through you are welcome to come and visit my tiny workshop and try out the gear for yourselves. Use the Contact Form to ask me for further details.

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