Translation by Christian Girardet
After building the main blocks of the cockpit, let’s make the Overhead and Pedestal panels. These are called V.U. by Airbus which stands for “Visual Unit”. Once all of them are cut, lay them on the floor, keeping a 2mm gap between each panel. The resulting measurements will give us the precise dimensions of the metal frame onto which they will be installed. Once this frame is eventually made, we will be able to check if the original dimensions of our wooden structures match and, if needed, to make required adjustments. By doing it in this order we are less likely to end up with V.U. panels being too large (or too small) than planned. Once the actual measurements are done, it will be time to finish cutting all the remaining cockpit’s wood parts (see details in “Debit du bois” Excel file)
You can obviously go for the commercially available laser cut and engraved panels. These are likely to look nicer than what you could build yourself, but more expensive, of course.
I decided to buy the panels available at Opencockpits, especially those difficult to make by myself such as the MCDU (the holes cannot be done using a file), or some difficult smaller panels such as Flaps and Spoilers.
Opencockpits panels are remarquably well manufactured , the paint is a real RAL 7011 and back-lighting is possible and efficient. Most of the panels have 2 layers: one transparent plexiglass panel inside, painted RAL grey on the sides and in the screw holes and the upper external panel with all the engravings. Each panel is 3.2 mm thick and assembly is done by screws. The MCDU (more later on that piece) is a complex ensemble of various panels and comprises all the engraved keys. Optionally, you can also order a package with all the switches included. If a purchase from a commercial supplier is a matter of debate for the smaller panels, this is not even a question when dealing with complex pieces such as the MCDU whose price is fortunately quite reasonable. Cockpitsonic panels are built more or less the same way and are of nearly equivalent quality.
Opencockpit panels have a total thickness of 6.5mm (8 mm for Cockpitsonic products).
Airbus V.U. panels’ paint has often changed over time. On the samples I had, the closest paint hue seems to be RAL 7011.
This is equivalent to Pantone 5477 or to 69 56 47 25 for CMJN, or for those of you using RGB, R84, G101 and B105.
These references will be needed to print the outside layer of the V.U.
Why does Opencockpit provide 2 plexi sheets for one panel? Among various reasons, it enables you to imitate the slots for the fastening screws such as Dzus fasteners, which adds a lot to the realism of your project. The same result can be obtained by drilling 2 identical panels for the various components while the slots for the screws are only cut out in the upper panel. Another approach would be to use a thicker panel (5 to 6mm), drill all holes required for the components and drill the slots only half way down into the thickness of the panel. This is more complex with an identical end visual result.
Cutting the panels:
“Plexi”, actually PMMA (Plexiglass or Altuglass), polycarbonate, Lexan or more commonly polystyrene can be easily cut with a circular saw (small teeth blade) or with a jig saw with thin blade and at the slowest speed setting
In both cases, first put some masking tape where the cut will be made: your markings will be much easier to see compared to using a marker directly on the Plexi. The tape will not interfere with the cut. Make the cut a bit wider than you mark, clamp the panel and use an electric planer with a very small depth of cut setting. This will be hard (quite hard actually) on your planer, but it gives you a very straight edge and very accurate final dimensions. Last, use a cutter blade at 90 degrees of the cut side and scrape to smooth and even out the edge. Same process on the edge of the cut to bevel it a bit. This should produce a constant screech while scraping and you should get a nice regular shaving. Final step is sanding with 500 sanding paper. Each V.U. panel is then identified by a number written on the masking tape.
The total Overhead and Pedestal V.U. surface is 0.8 square meter (8.61 sq. ft.), not including the MCDUs. With the glare-shield and the waste, estimate 1square meter (11 sq. ft.).
|# VU||Name of VU||Dimensions|
|Overhead||see the Overhead chapter||mm|
|23VU||Left FLT CTRL||145x45|
|Blank 2 ***||324x65|
|Blank 3 ***||145x109|
see the Pedestal chapter
|408VU||Trim + Pkg Brk||202x95|
|Blank 1 ***||145x48|
|Blank 2 ***||145x170|
*Not an official Airbus designation
** Opencockpit dimensions, Actually 145 mm wide instead of 155mm
*** Blank panels without any component or engraving can be cut out from particle board.
**** Important: these panels have to be reduced to 202 mm if you use the Opencockpit MCDU.
Once everything has been cut, lay all panels on the floor, keeping a 2mm gap between panels edges and add another 2 mm on the outside: this gives you the exact dimension of the aluminum frame to build.
This is one of the main problems to solve when making your own panels. When I built my previous cockpit, I developed a method providing good results and all the panels to be backlit could fit into a A4 format. This is obviously not the case for the A320, as the Overhead panels must be printed on a A3 format. This means you will have to use a professional printer. Luckily the price remains minimal.
Take one Plexi V.U. panel with the Dzus slots already completed. Paint the edge of the panel (thickness) with some grey glycerin paint, as well as all screws slots and holes. These surfaces, once painted, must be opaque to the LED back-lighting. Try not to bleed on the outer surfaces of the panel.
From the above links, you get 3 files (drawings) for each V.U. panel: one in black and white positive, one black and white negative and the same for the engraving surface in RAL 7011.
We will use the inverted file for the “front” face (the engraved/upper face of the panel). By inverted, understand blacks are white and reciprocally. Why to invert the picture? Simply to save on black ink… Print it on an adhesive sheet available in any office supplies store. This sheet will be used as a drilling template for the round and the square holes once applied to the panel. Most panels will fit on a A4 sheet, but 7 of the Overhead panels would require an A3 sheet. For these, use two A4 sheets.
Carefully tape these two A4 sheets together with a piece of tape along the whole length of the edge between the two sheets. Put the tape on the peel-off side and make sure there is none on the “print” side. It will go through an A3 printer without jamming. Print the black and white picture and let it dry.
Now, very importantly, put a piece of transparent tape ON THE PRINT SIDE of the sheets, as before, along the separation edge between the sheets. Once done, if possible, remove the piece of tape we had put on the peel-off side. The tape on the printed side could be removed without damage to the ink, but this will not be necessary: it is just a drilling template.
Now glue this big A3 size sticker to the Plexi. You really should use a light table for this: a simple box with some fluorescent light bulbs inside, covered with a translucent Plexiglass sheet. Put some weight on one end of the sticker, remove the peel-off backing one band at a time and smooth out the surface with your finger. Try not to let too many air bubbles trapped between the sticker and the Plexi. Most importantly make sure that the vertical lines are perfectly parallel to the edges of the Plexi.
Center the holes and drill through. Remove the sticker (now useless) and wipe-off any glue residue with some solvent.
The end goal is to make a label with perfectly transparent text and completely opaque space between the letters, even with a bright white LED close behind the label. This cannot be achieved with any printer, whether ink or laser. Your best bet is to go to a print shop with the file of the panel front (preferably in CMJN or TIFF) and ask them to “flash” it. The result is a black and white film with a perfectly opaque black, exactly what we need. A3 sheet flashing is no problem and costs about 8 Euros. An A3 sheet will usually cover several V.U. panels.
This will be the first layer to block the light between the text letters.
At the same time you have your film flashed, ask the printer to print the same file, but this time in color using a 100 gr paper and with a laser printer. Usually the black and white print and the color one are should perfectly stackable, but sometimes as these are made on 2 different printers, there is a slight difference. Not really noticeable on small panels (A4 or smaller) but it can be off by a few pixels on a large sheet, which will slightly blur the letters. Try to align the 2 sheets as best as possible, starting in the center and lining up the ends as best as you can.
To precisely glue these two sheets together, you will need some neoprene contact glue: the gel version, not the liquid one. The latter has a tendency to produce small lumps which will be noticeable under the paper. Gel is easy to apply with the small notched spatula it comes with and does not dissolve BW or color films. In transparency, the glue is slightly yellowish. This is actually great as white LEDs will produce a “cold” white light. So how can we glue the 2 films together precisely while this type of glue does not allow any placing adjustment?
Cut the flash film with a 2 cm margin around the image, then the color print, this time with a 1 cm margin (at least on one of the long sides).
Turn your light table on and stack your sheets very precisely and gently place some weights on the 2 sheets. Check that nothing moved! Using a length of tape equal to the longest side of the sheets, tape them together, straddling the tape on the edge of the color sheet: that’s why we had different margins width for the black and white and the color sheets! It is best to put the tape parallel to the edge of one of the pictures (but not on it) as a guide. There should be enough room for that. The tape will act as a hinge between the 2 sheets keeping them perfectly aligned even when you close them.
Open your “booklet”, quickly apply you contact glue with a large brush (keep it even), wait 5 to 10 minutes for the solvents to evaporate, put everything back on the light table and gently apply the color print sheet onto the black and white film, starting from the hinge and making sure no air bubbles are trapped. Rub gently as you go, so to avoid these bubbles.
That’s what the end product looks like: a film, black on the underside and grey on the top, with perfectly aligned letters. Leave it alone as is for now; do not trim the margins.
Keep in mind that as the top sheet is in color, it is possible to print the green lines found on some of the panels, as they will stay green in transparency. If the green is not green enough for you, apply some green paint on the underside of the film using transparent stain glass paint (available in hobby stores). Use a small watercolor brush for the job. It works pretty well!
The Plexi panel has been drilled and sanded with 500 sand paper to diffuse the light and to clean up the edges of the holes.
As our film (flashed film + color print) is really opaque, it is not possible to see the Plexi through the film. Flip the film and put it on the light table. Spread neoprene gel glue on the rear side of the film and on the top side of Plexi panel. Carefully put the Plexi on the film aiming precisely as you will not be able to adjust the positon once both faces are in contact. Most importantly, make sure that no hole (Korry switch hole for instance) overlaps any text or letters. Once in place, flip the Plexi upright and rub to help spreading the glue.
Cut the excess film and the taped hinges with a cutter blade.
Using the same small cutter, open the square and round holes, make a series of successive small cuts from the outside inward.
You now have a V.U. pretty close to the original.
Note: on the pictures you can see online (Airliners.net for instance) the color of the back-lighting varies greatly from one pic to another. This is because of different speed settings of the cameras used. A320 pilots have confirmed that the back-lighting color is actually light orange. Here too, it varies quite a bit, based on the light intensity setting chosen by the pilots. You can emulate this color by putting a filter in front of the LED lights by stacking 2 yellow gelatin filter sheets with an orange one. The yellow will provide a green dominant hue and the orange a pinkish one. Put together, this is perfect and does not absorb much light from the LEDs. These gelatin filter sheets are very thin colored Plexi sheets used for theater stage lighting and can be found in music equipment stores. The same result can be achieved using stain glass paints as described in the Overhead chapter.
1 - After the color print has been made, do not delay too long before gluing it on the flashed film. A3 size paper dimensions can fluctuate significantly with humidity levels and there is a risk of a slight offset with the film. If the color print is warping due to humidity, use a hair dryer or wait for better weather conditions!
2- As mentioned earlier, check the alignments at the printer’s on one set of films before launching your whole order. Potential slight differences between the flashed film and the color print are a problem mainly for the large V.U. panels. For the smaller panels, this is not really an issue as they are cut-off from their sheet and then adjusted on a much smaller surface.
3- For the back-lighting, you can use either 15,000 mcd large angle individual LEDs, or even better, use those LEDs ribbons or rolls.
4- These LED bands are powered with 12votls DC and can be cut in group of 3. Very useful for the Overhead back-lighting as they provide a very uniform light for the V.U. panels.
5- V.U.s made this way look really good and are perfectly opaque. The upper surface is strong enough that no anti-glare glass is needed as protection. The surface is mat/satin as they can be put next to those made by Opencockpit without noticing a great difference between the two types. The key is to adjust perfectly the grey color to get a true RAL 7011: this depends by and large on the printer and on the paper you will use. In my case, the values for my A3 printer are R=84, G=101 and B=105 to get a RAL 7011. To help you adjust your colors, you can download the "seeking for RAL 7011" file providing you with color samples and their RGB values. First have that sheet printed by the print shop and then select the values closest to RAL. Then change the color values using Photoshop and an equivalent software. Only after that you will be able to have the A3 sheets laser printed.
Panel wiring, Korries and other switches installation is in chapter 16.