How To Build Your Own Cockpit

Parts 22 - 24

by Kev Saker

Part 22

Part 22 shows how a simple manual stab trim gauge is made and linked mechanically to the stab trim lever, the working of the manual stab trim lever is described in part 8. It should be remembered that the main trim facility in Flight sim is a simulated electric trim activated from the three-position yoke trim switch.

Below this is the panel I use to control the view selections, I use 5 solenoids to provide 5 possible window views, Forward including panel, left front, left, right front, right.

Finally for this section there is a drawing of the parking brake switch. You will see it uses the same methods as already described, but to run through it, the handle is attached to a piece of aluminium bar which slides through a aluminium tube fitted onto the centre panel. At the bottom of the tube there is a toggle switch which provides the on/ off action of the handle and also controls the parking brake warning light. You will also see two micro switches that connect to the solenoids that activate the parking brake function in Flight sim. As you pull the handle up to activate the brake the micros are pushed momentarily to switch the function. The same thing happens when you push the handle in to release the park brake.

Part 23

Now we come to the radio pedestal and its functions. A plan view of this can be seen on drawing 17. All the radio panels are made of plasticard sheet; I begin by cutting the panel to size then cutting another piece the same. These are glued together, but first I cut the corners of the top piece as in diagram 23 this produces a panel that is strong and has recessed screw points as on the real plane. The next thing to do is drill the holes for the rotary knobs and momentary switches if required. At this point I would paint the panel and mark it up with Lettereset dry transfers.

Finally I fit the micro switches and momentary buttons as in the drawing. All the radio panels can be built using this method. The panels in the middle of the plan that have toggle switches are simply wired in series with the momentary buttons on the radio panels and are master switches for each radio panel. Also on this panel there are three momentary buttons which are connected to solenoids that activate the Morse code ident functions in Flight sim. Finally on this drawing you can see the wooden frame built into the top of the pedestal box. These wooden rails are where all the radio panels are attached.

Part 24

This next section covers the building of the solenoid computer interface. I first built this over ten years ago for the Phantom. Today there are several choices available to the cockpit builder. I believe it is possible to hard wire a keyboard running wires directly to the various switches. I myself did consider this but I was not happy with the fact that you would be using the computers power supply, and running wires all over the sim would create the risk of a voltage drop as the computer keyboard only uses very low voltage. There are also some commercially available, programmable switch pads that it may be possible to use on a home built sim.

The best solution available to us at present is a device called an EPIC card. This fits into your computer and allows you to program many switched functions into your cockpit. I believe it is possible to get additional EPIC cards to control digital displays too, so this represents what is probably the best way of building a cockpit at this time provided off course you are prepared to pay for it. Some people have asked me which is the best method to use, my solenoid system or the EPIC. The simple answer is I built my system a long time ago, long before the EPIC appeared. Perhaps if it had been around then I would have used it.

My system has a couple of things I like. Firstly provided you can find a cheap source of small low voltage solenoids, you can build it for very little cost, secondly it has absolutely nothing to do with the computer and does not require a slot on your motherboard, finally it is very reliable and when up and running requires no attention at all. I use about 30 solenoids which may not sound like a lot of functions, however by using the SHIFT and CTRL keys you can double the no of functions. For example I mentioned that the heading hold function used the CTRL and H key, so if you assign the H key on its own to another function you will see that you can get more than one item controlled by each solenoid. The choice is yours.

As for the construction of the interface it is very simple, cut two plastic plates, one for the top, and one for the bottom, use a piece of clear Perspex to obtain a keyboard map. This is done by placing the clear Perspex over the keyboard and marking out with a permanent marker pen the position of all the keys, then using an electric drill cut all the holes to form a template. Tape the two plastic plates together and place the template over the plates, now drill out all the key positions.

When complete make a base from ply or chipboard and drill holes in each corner for the threaded rod supports. Then using aluminium tube threaded rod and nuts assemble the interface as in the drawing. The solenoids fit on the top plate. Using hollow plastic rods (again obtainable from good model shops) you can make simple self-adjusting connections between the solenoid pin and the plastic rods. This is done by cutting some very thin strips of rubber (cycle innertube is fine). Looking at drawing 24, bottom left you can see how easy it is to make the connection, by pushing the rubber into the hollow rod with the solenoid pin you get a tight fit that when the solenoid pushes the rod down on the key will self adjust the throw of the rod.

My drawing of the interface is rather poor, I would sooner build anything than try and draw it! If you look at the photo in the introduction to this article you will get a better idea.

One final word on solenoids, I have used three different types on my interface, some cost 6 pounds each while the others I obtained from a surplus electronics stall for 1 pound each. They are in use in many applications that require a small push or pull movement so they are worth searching out.

Finally for this module on drawing 25 you can see the layout of the two keyboards and how the data switcher controls them.

One other thing springs to mind about my system of two keyboards. This set-up offers the possibility of providing an instructors position on your simulator. For example if you wanted to simulate failing an engine on take off, all that would be needed is for the instructor to wait until you had started your take off run, and then quickly switch control of the sim back to the main keyboard, then he could shut down an engine and return control to you in the sim, all by the flick of one switch.

To take this a step further you could build a simple board at the instructor's station with a few toggle switches so you could illuminate the engine fire warning light after failing the engine. With some thought it can be seen that many failures could be simulated in this fashion, from the discreet drop out of an Autopilot hold to a dangerous trim runaway on final approach.

I believe this idea could introduce a hole new aspect of flight simming were you could not only simulate line flying but use checklists to practise dealing with the many faults and failures that pilots train for in multi million pound simulators.

My next and final module will feature the ejector seat and 757 seat construction, also the over head system panel and the seat motion system. (And anything else I can think up in the mean time!) Finally I would just like to say thanks to all the people that have taken the time to write, and their encouragement with this project.

Read other articles in this series