We have started on the Instrument Panel and things are coming along nicely 🙂
The panel consists of a main panel and the “Blind Flying Panel” or six-pack. We have placed the magneto switches and had a very interesting time researching the clocks that were installed in the Spitfire.
The earlier marks of Spitfire did not generally have a cutout for a clock and it is apparent that many different types of clocks were employed from various manufacturers. It would seem most of the clocks utilised called for an 8 Day life after a full wind.
The DCS World Spitfire Mk.IX’s manual notes that the clock employed in their model is a Mk.IV (106A/322) Aviation Watch. “The watch is designed to display the current time in hours, minutes and seconds. It has a crown at the bottom of the device. The pendulum is used as the operating principle. The construction is of a common spring pendulum clock with a round-balancer. Power reserve is good for 8 days.”
We have thus based our clock on this design, using the internal face of a Longines WITTNAUER US TYPE A-11. This model is the 7 jeweled A-11 with 2 barrels for 8 days reserve power.
Remembering that this is to be used in VR, there is no need to model the actual internals and a decal has been placed on the faceplate. That is covered by a disc of 1mm clear acrylic.
The knurled crown can be rotated to either side to send a signal to the simulator to increase or decrease the time setting. This is achieved by means of a lever at the rear depressing one of two micro pushbuttons.
We have also taken the opportunity to refine the design of the starter and booster coil button covers. A clip has been incorporated to ensure the cover remains in place when closed. The intricate detail that can be incorporated in 3D Printed designs at no extra cost never ceases to amaze.
For those of you who may have suspected that nothing was happening over the last two weeks think again 🙂
We have been hard at work on doing the distribution drawings for the Presentation Throttle Quadrant, ordering materials, placing orders for waterjet cutting and the 3D printing of the handles etc.
The latter was ordered from Shapeways in the USA and arrived here in South Africa a week later. We were very impressed with:
the amount of information available on each component throughout the manufacturing process and
The great quality of the prints
The components were all printed in “Black, Strong and Flexible” Nylon through the SLS process.
We were very pleased with the way the coarse threads on the throttle handle had come out, and it provides a very strong neat connection while giving easy access to the bomb release button installation.
Throttle Handle assembled
Throttle Handle threads
We had the airscrew handle printed in Premium finish. This entails polishing of the part to reduce the graininess normally associated with SLS. The results, which admittedly are nice, however do not justify the significant extra cost in our minds.
There are many mysteries in aircraft building, secrets that have gotten lost in the mists of time. One of these must surely be the Dunlop Crackle….
Dunlop manufactured many of the RAF spade grips, including those of the Spitfire and the Hurricane. The grips had a non-slip covering with a very particular pattern applied and was known as the Dunlop Crackle finish.
The knowledge on how this was made or applied has now seemingly been lost. As a result, many replicas and restored originals now carry a variety of coverings, including tape, string, leather and numerous others. None of these solutions regrettably reflect the look of the original Dunlop Crackle.
Many hours of texturing on the Heritage Flight Simulation Spitfire Spade Grip have now rendered a satisfactory finish which closely resembles that of the original. We like it, we hope you do too 🙂
The Spitfire Mk.IX Engine Hand Control has turned out to be such a thing of beauty that we have decided to release it as a Desktop Display Model.
This will have many advantages.
It provides the hobbyist with a fantastic working desktop display model.
It provides a glimpse of what is to come for prospective Spitfire Simulator builders.
To aircraft home builders, it provides a full scale working throttle quadrant that can be adapted to their own requirements. (A modification to the Mixture Control will be made for this, currently it works through the triggering of 2 microswitches at the travel extremes. An extension to the lever will provide for an additional control rod)
Those who are contemplating the purchase of the full set of drawings, cutting patterns and 3D components when they become available (target end of 2018), will get the opportunity to assess the quality of the information provided and of the 3D printed components.
The display model will cover the full ambit of information to be provided for the complete build, amongst others:
Waterjet cutting patterns for plywood, aluminium and steel plate
We aim to release the plans for the desktop display and have the components ready for purchase from our Shapeways shop by the end of April.
I am very pleased to say that the throttle quadrant is nearing completion. In the process much has been learnt about the operation of the unit.
For the Rotol (Airscrew Control/Prop Speed) control box we had to deviate from the original, taking the approach instead followed by DCS World. As far as I could discern, the original mechanism operated a vernier cable which was wrapped internally in the box. Operation of the lever in our case will move a control rod, similar in operation to the throttle lever.
The throttle incorporates a gate in the form of a plate which stops forward movement of the lever. Full power at this point is delivered for take-off and climb. By moving the lever to the left then forward the plate is bypassed and the power set in combat mode, which was available for a limited period (5 minutes?) before the engine would call it a day.
The throttle lever when pushed forward activates a toggle switch which powers the circuit to the gear position indicator light. Operators need to remember to switch this off again when shutting down.
Replicating the design of an historical aircraft is a little like playing detective. It requires many painstaking hours of pouring over drawings and doing comparisons with photos of the particular series and model. Nowhere is this more the case than with the Spitfire. While we have some 3400 drawings at our disposal, representing everything that is publicly available, there are many more drawings which may now have been destroyed or are laying in some forgotten filing cabinet.
During the war much of the Spitfire’s production was decentralised, hived off to different smaller fabrication and manufacturing facilities.
These facilities would have been heavily affected by the bombings; even if not destroyed there were power, water and other service disruptions. It’s a wonder that people were able to produce any aircraft at all during this chaos. It speaks volumes to the courage and determination that went into making this great aircraft.
There were also components supplied on a turnkey basis, like the Dunlop Spade Grip, for which there are no formal drawings to be found. In those cases we have to rely on actual measurements taken from surviving equipment.
The basic series of drawings starts with the Mk.I and then variations to these designs were added. There are 38 different prefix codes listed below, signifying some of this variety:
All of this adds immense complexity to the task of recreating the designs. This week we were reminded of this while working on the throttle quadrant.
In keeping with our design philosophy, we are recreating the original Mk.IX quadrant before redesigning to accommodate rapid fabrication, reduced cost and simulator functionality. It’s been hard work but great fun, giving one a sense of what it must have been like in those anxious pre-war years slaving away at a drawing board, trying to get out a design as rapidly and effectively as possible while the spectre of the coming war loomed large.
Buttons are on the schedule, and buttons we shall have!
Finished the starter and booster buttons which are mounted on the panel. These are 16mm pushbuttons as opposed to the port side pushbuttons, which are 22mm. The shape of the cover is is also different. Well, that completes all the covered (dual action) buttons!
Now work will commence on the engine control cluster.
Modeling a historic aircraft cockpit one soon finds out that there is as much work in accurately recreating a small object as a large one. The three covered pushbuttons on the port side being a case in point. the original covers were beautifully crafted and we have been able to recreate these true to form. The functionality of these replicas is in fact more complex that the original. In order to inform the software that the switch cover has been opened, a second microswitch is clicked by the action of opening the cover.
The three pushbutton switches are shown below:
A rendition of the switch clusters on the port side: