This week we have been auditing all the different controls and came up with the following statistics:
Pushbuttons: 30 Toggle switches: 32 Incremental Rotary Encoders: 7 Potentiometers: 5 Absolute Rotary Encoders: 4
We have also been assessing control options and intend providing guidelines as to how various different open source programs may be applied in conjunction with various low cost controllers such as the Arduino.
As far as possible we will be looking at substituting the potentiometers for absolute rotary encoders for simplicity, robustness and accuracy. While slightly more expensive than potentiometers they provide a lower life cycle cost and better performance in the long run.
Thus work continues with the refinement of these options.
SOME DESIGN DETAILS
We can share some of the last control elements which were finalised over the last two weeks.
Windscreen De-Ice System
The windscreen de-icing system consists of a reservoir containing a 50/50 mix of distilled water and glycerine glycol, which can be manually pumped to a perforated distribution tube positioned in front of the windscreen. A small regulator valve next to the pump regulates the amount of flow while a cut-off valve returns the fluid to the reservoir when placed in the OFF position. All in all the associated brass tubing gives a wonderful steam locomotive effect to the Spitfire cockpit, which is quite unlike any of the more modern layouts seen in say the Mustang or Focke Wolf 190.
Identification Friend or Foe
The Spitfire Mk.IX was fitted with a radio transmitter/responder (transponder) sending coded signals when interrogated. The advent of radar made it essential to identify whether aircraft were friendlies (the system is unable to confirm whether aircraft are unfriendly). Early in WWII there were a number of incidents on both the British and German sides where forces were attacked by their own. The depicted Mk.III transponders were designed by engineer Freddie Williams to cope with the new radar technology introduced after 1940. It responds to specific ‘interrogators’, rather than replying directly to received radar signals.
The model also has two pushbuttons which, when pressed simultaneously, will destroy the transmitter to prevent it from falling into enemy hands.
We were also able to modify a modern NKK rocker switch to resemble the Air Ministry standard toggle switch and will be applying these to other functions as appropriate. They are 3D printed units from SLS Nylon and will also be available with all the other printed items from Shapeways when the designs have been finalised.