How To Build Your Own Cockpit

Parts 25 - 30

by Kev Saker

Part 25

Some exciting news starts this article on the building of my simulator. It would appear that a number of people who are constructing their own flight simulator have been having problems obtaining solenoids, as described in my last section.

There are a number of alternatives that folks can look at when they decide to build a sim. However, a good friend, Robert Prather who lives in Texas has come up with a simple way to build a computer interface. All you need is a second keyboard and a little patience.

I should mention that other people have used a similar system but Robert has taken the time to test this idea and lay it all out in print and diagrams for the rest of the flightsim community to enjoy. Well done, Robert, and thanks for the contribution. The rest of this section is devoted to Robert's article; read it here.

Part 26

As a footnote to Robert's article a thought springs to mind. If you have already started building your simulator with transformers, which means all your systems and keyboard functions are 12 volt powered, you can still use this idea by simply connecting all your functions to small relays, and then connect the keyboard connections to the relay. This will have the advantage of keeping the entire keyboard wiring very short. Relays are very cheap to obtain.

OK, the next thing to build is the seat. I have drawn the plans in such a way that you can build the seat as a heavy jet or an ejector seat depending what type of sim you are constructing.

If you look at the diagram BASIC SEAT STRUCTURE, you will see that the construction is really very simple. Start with a good sturdy base; use 6x4-inch timber and screw it together as in the plan. Add extra pieces at the front and back; try to ensure that the front of the seat is higher than the back so the seat pan has a comfortable slope back.

Next, using 1/4 inch plywood, cut two side pieces as shown. I have given sizes of my seat however you should make up your own mind if these sizes will suit you. I would suggest you cut a card template for the side panels so you can get the angle right before you cut the ply.

When you have these parts, screw them to the base already completed. Next add the top piece. This should be slightly narrower than the seat base. As for width, make it wide enough to drill a couple of holes so you can add a head rest if you wish (these can be obtained cheaply at your local car breakers yard). The next thing to cut is the seat back. You should use 1/2 inch ply or MDF board so it will give the seat the strength it will need when you start climbing all over it! Finally, cut a slot at the bottom of the seat back as shown. This is where the seat motion arm will exit.

Looking now at diagram SEAT PAN you will see the way to proceed. Basically, the motion system comprises of a piece of thick ply, which is attached to the seat base at the front of the seat. Use two door hinges so the pan will move up and down. If you look at the drawing you can see I have attached an arm under the seat pan (buy a length of angle iron for this and another job later on).

Bolt the arm to the seat pan so about 7 inches protrudes through the back of the seat as in the diagram. The next things to fit are the springs that the seat pan sits on. You can see where to fit them in the drawing. They should sit on the rear piece of 6x4 timber.

I used two car engine valve springs, as soft springs will not work. You can get a couple from the good old breakers yard for next to nothing. As for attaching them, the simple way is to get two pieces of steel plate with a hole drilled in the middle, slot this into the bottom of the spring then screw the plate to the 6x4 timber. Also on this drawing you will see two holes drilled in the sides of the seat for the folding arms. You can make these up from a couple of lengths of timber drilled and attached with two long nuts and bolts. Buy some covering material and a piece of foam and using two pieces of hardboard make up the padded arms using good material glue.

You will need to fit a couple of stops on the sides of your seat so when the arms are lowered they will rest on the stops.

Now at this point you should decide what type of seat you are building. If it's for the heavy jet then skip this part, if however you are making a fast jet then look at the diagram entitled FAST JET MODIFICATION. Basically, the seat needs a wooden box structure added to the back; this would contain the rocket motor and drogue chutes etc. You can make this up as drawn using ply or MDF board and screw it to the back of the seat. You may wish to change the shape and size of this part depending which type of ejector seat you are building. Mine was based on the Martin Baker MK4 seat used in the Phantom.

As mentioned before, excellent detailed plans and drawings of your seat can be found in books called DETAIL SCALE F-18 HORNET for example. Check out your local model shop.

An ejector seat is a fantastic project in itself, so take your time and build it up with lots of detail; it will be the centrepiece of your simulator. Finally, you can fit the ejection handles so they work!

Don't worry, you do not want to blow a hole in your roof, just fit a couple of micro switches that are pulled when you activate the handle, connect these to the EJECT key on your interface so you can see yourself floating down in your chute.

Part 27

Continuing with the seat motion system (both seats) see SEAT MOTION SYSTEM diagram.

This is a side view of the seat base. You can see the layout of the various parts. You can also see the seat pan is quite thick. You should use this to adjust the height to your preference. Moving back, the geared down 12 volt motor is seen attached to the angle iron bar. The motor needs to be able to turn a small flywheel with an off center lead weight attached. The motor can be fitted using large nylon ties. Also fit the motor with a piece of rubber between the motor and the bar as this will avoid noise and vibration. (Use an old piece of bicycle innertube.)

You may need to slow the flywheel down to produce the right effect. The best way to do this is fit a resistor speed controller. Yep it's back to the breakers yard--look for a car instruments light dimmer switch. This is usually a round coil with an arm that moves to vary the output. Fit this in line with the motor; you will be able to slow the flywheel right down to produce a nice bouncing up and down type motion. While you're at it try to get a few of these resistor controllers, as they are great when you fit the cockpit lighting system.

I have previously described the sound to light unit but just to recap, you can buy a disco type sound to light unit to activate your motion system. They are available at music shops or can be bought as electronics projects in kit form. We do not require the lighting effect so rather than a light fit a heavy-duty relay that will activate the seat motor instead. This should be placed near your bass speaker, as it will react to the low frequency sounds.

The overall effect this system produces is quite impressive. If you change the touchdown wav from a screech to a rumble you will feel every landing you make through the seat of your pants! You will get many other effects too. For example, when you raise or lower the gear you will get some turbulence, and of course if you crash heaven forbid!

Finally for the seat you will need to fix it to the floor. If you use that other piece of angle iron, cut and bolt it to the floor at the front of the seat, cut two lengths of threaded rod and drill two holes in the front of your seat, screw the rod into the wood base. You may wish to glue them as they need to be secure.

Now line up your seat with the angle iron and mark were the rods touch the angle iron; drill holes here so the rod will slide through. This will hold the seat in position and will also allow you to slide the seat forward and backwards for adjustment.

Another thing springs to mind--cover the parts of the seat frame you might touch with very thin Aluminium sheet so the seat feels right and will give a nice metal appearance when painted. You can use a cheap rivet gun to attach the Aluminium; this looks very good on the ejector seat.

The only thing remaining is to obtain two pieces of foam and some covers for the cushions, and don't forget the sheep skin fronts!

Part 28

That about covers the seat, etc. The next job, and quite a big one, is the overhead systems panel. The basic construction of the frame for the panel was covered in part 16. You will see that there are wooden rails where each panel can be attached using small self tapping screws. Each panel on my sim is made from Plasticard as in part 23. This takes some time but it is the best way to proceed because you can cut the panel and paint it, then drill all the holes necessary for fixing switches and knobs etc., and before you fit them it is easy to add the text using Lettereset transfers. Finally add the switches and screw the panel in place.

If you look at diagram OVERHEAD PANEL you will see that each panel is numbered from the left top corner down each column, so starting with panel 1 I will list what each panel is.

Now how many of these panels you wire up to work in your sim is up to you. Some are important where others you don't really need. For example, you will need the electrical panel and engine generators, but you may not need the cabin signs (seat belts). I tried to get them all working in some way.

Hydraulic pump switches can interrupt the joystick circuit. Cockpit pressurisation and pack control can simply be wired to a small fan providing a nice cool flow of air on your flight deck.

These days they use the "dark cockpit principle" which means there are no warning lights on if every thing is working normally, so you can wire many panels to show an off warning light.

Some panels are easy to simulate. The cabin temp panel can be a thermometer, the cockpit voice recorder can be a small tape deck, as far as functions that control keys in flight simulator.

Working from left to right, YAW DAMPERS, PANEL LIGHTS, ENGINE START, FUEL PUMPS, ANTI ICE, EXTERIOR LIGHTS can all be connected to the interface of your choice.

If you intend to fit the overhead circuit breaker panel then many of the switches can be included in the mentioned systems simply as an in line switch.

Some folks have asked were to get all these switches. You will find there is a mail order catalog that supplies all types of switch to electronics enthusiasts or look at surplus electronics stands at model railway shows etc. Also if you email Robert Prather he has an idea for homemade switches.

Part 29

Part 29 deals with the basic wiring of the generator control panel. See diagram panel 10 and BUS DIAGRAM.

I have used two model railway 12 volt transformers as the basis of my electrical system. Each transformer has a thermal cut out which means if you get a short circuit the switch will pop out and cut the power. If you copy my diagram when this happens you will get a GEN OFF warning light on the gen panel. Also there is a simple bus tie system which means that if you lose a gen the supply from the other engine gen will provide power for this bus. I have tried to keep this diagram as simple as possible. I think if you study it, it is self explanatory, however I will describe how it works.

At the bottom of the drawing you will see the two transformers. The power runs from these to the gen control panel. You could just switch these on to provide power to the bus at the top of the diagram, however this would not be very realistic.

First you need to start the engines so the engine driven generators will supply power, so you now as pilot have a choice: hook up to ground power or start the APU (auxiliary power unit). There are switches for APU and ground power. You will see on the diagram that it is possible to provide electrical power to the bus by activating the APU or the ground power. You then start the engines and switch on the Generator switches. When you have done this and the engines are supplying power the APU or ground power can be shut down.

If for some reason you switch a generator off, then a warning light should illuminate. You can do this two ways, using a six pole switch wired to illuminate the warning light when the bus is off, or a relay powered by the other bus to illuminate the light when the power is switched off.

As for the bus tie switches I have drawn one to keep the diagram simple. Basically this is a switched connection between the positive and negative sides of both buses, so if one drops of line the other will supply power to that bus.

The power bus are the two main power supplies for all the functions and circuits in your flight simulator. You can piggyback these supplies rather than have long cable runs going to one power supply. Just connect two wires and run them up to your overhead panel, for example, so you have a handy power source up there.

One final thought--remember to include suitable fuses between the transformers and the gen panels.

Part 30

For a quick look at my Auto Brakes system, see diagram AUTO BRAKES. This is an easy way to create automatic braking after touchdown or on a rejected takeoff. I wanted this to work from the auto brake panel with working warning light rather than use the mouse to select it.

It works like this: if you have built your simulator along the same lines as mine you will have working thrust reverses connected to a solenoid or relay switch. Looking at the diagram, you will see that the auto-brakes get their power from the thrust reverse solenoid or relay. Through the auto brake selector switch a relay and AUTO BRAKE ON light is activated. The relay is connected to the micro switch on the brake pedal. This means that after landing or on a rejected take-off if you pull reverse thrust and provided the auto brake panel is set to RTO 2 3 or 4 the auto brake on light will illuminate and the brakes will be applied until you cancel reverse thrust around 60 knots then revert to manual braking.

Well that about covers it for this section. I had intended to make this the last article however I have made a few modifications to my simulator including an extra computer with two graphics cards which now give me a working ECAS system and FMC / NAV display.

I have learned a lot about networking and running multiple monitors while doing this so I will write it all down before I forget it all! I have included an up to date photo of my simulator, hope you like it.

Finally if anybody needs any more info drop me a line, it's always nice to hear from fellow simmers.

Any problems, email me at Kevin.saker@virgin.net

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