By Christian Behne on Sunday, 30 October 2022
Category: Tutorials

Tutorial - Cockpit Ventilation System

In a closed cockpit, the air can get a bit stuffy. Especially when several pilots are working in it for a long time with strenuous approach training. VIER IM POTT offers a suitable product for this. But we thought that the topic is also interesting for the many cockpit builders among you.

Goal

We aim to build a simple multi-stage controllable ventilation system for the cockpit that is fully integrated into the logic of the A320. The fans of the ventilation system are controlled by two relays depending on the aircraft logic. In other words, the control is done in overhead and accordingly only works if the parameters required for it are met.

Components​

Y​ou will need the following or similatr parts:

4x Fans
Axial-Fan, 12V DC, 120x120x38mm, rpm: ~2900, volume flow: max. 178 m³/h

4x  Protective grille
120x120mm
e.g. SUNON LGP120

4x Fan connection cable
1m for 230 volts
e.g. SUNON LFTK01

1x Mega2560R3
Arduino compatible board
e.g. JOY-IT ARD-MEGA2560R3

1x Arduino Shield - Relais V3
With 4 relais for 220 VAC
Arduino compatible board
​e.g. SEEED HLS8L-DC5V-S-C

1x USB cable
max. 3m recommended

1x Box for Arduino Mega,
for the installation of Arduino board and relay shield
e.g. KKSB 7350001160849

1x DIN-Top-hat rail clip for box
for mounting the box on a top-hat rail (switch box recommended)
e.g. KKSB 7350001160962

2x Junction box
Ø20, 80x80x45mm
Cables and small parts

Hardware installation​

 We have chosen the rear and lower corner of the cockpit as the installation location for the fans. We aim to make the installation as unobtrusive as possible. At the same time, we want to prevent an unpleasant draught in the cockpit.

By installing it at the rear, we achieve a continuous air flow from the rear to the front. By installing it on the floor, the coolest possible air is pumped into the cockpit. We want to switch the fans in two stages. In stage 1, only one of the two fans per side rotates. In stage 2 both are switched on.

After measuring, we remove the side panels of the simulator for better machining. We use a drill and a simple jigsaw to make the necessary cut-outs.​

The cables are all brought together in an installation box. The box itself is then connected to the distribution box via a min. 4-core cable. Make sure that the distribution box can be reached with a USB cable. We use a USB cable with a length of 3m. Longer distances may require an active USB cable.

Software installation​
We decided to use MobiFlight for the software control. 

This enables a very simple and logical configuration of commands in interaction with the relays of the Arduino board.​

MobiFlight + Arduino + Your Favorite Flight Simulator = Your Home Cockpit!

After installing and connecting the Arduino board, the switching outputs must first be configured. This is relatively simple. The relays have outputs 4, 5, 6 and 7, but it doesn't hurt to take a look at the operating instructions.

Now we create an output mapping for the two switching states. Aircon Pack 1 only switches the relay to which the first two fans are connected. Aircon Pack 2 also switches the second relay.

Now it gets a bit technical. Our installation requires FSUIPC (http://www.fsuipc.com/). This must be installed and configured for the simulator. That's all you need to know about it. Don't worry, we'll keep it very simply.

We want to switch the relay when the necessary conditions are met. In our case, this is a functioning Pack Flow. 

The logic will be the following:

  • PACK FLOW LOW = all fans off
  • PACK FLOW NORM = two fans are running
  • PACK FLOW HIGH = all fans are running

For this we use the so-called FSUIPC offsets. The principle is simple. The simulator writes to a certain memory address whether PACK FLOW LOW, NORM or HIGH is active. With the help of Mobiflight, we look at this address and switch the relay accordingly.​

This address is 0x5526.0 and 0x5526.1​

Sounds a bit complicated? It is, but to be honest we don't need to delve deeper into this matter.

This completes the setting of AirconPack1. Now we have to tell the simulator software to write the state to the corresponding address. In the case of ProSimA320 it looks like this. With other simulation software, this can probably be set similarly.

We now do the same again with AirconPack2. I'm sure you can figure out how to do this on your own. After that, Mobiflight only has to be started and we can test the result.

Result

 If you thought that all you had to do was turn the knob in the overhead to start the ventilation, you were wrong. It's not that simple in a real aircraft. Without compressed air from the engines or from outside, there is no ventilation. Why should it be easier in the simulator?

We move on to aircraft logic, which until now had no real meaning. For ventilation to work, at least the following conditions must be met:

  1. the APU must have started, or
  2. an engine must have started, or
  3. compressed air is supplied from outside
  4. the packs must be switched on.

This also means that if we switch off the packs for take-off, the ventilation in the cockpit will also go out. Cool, isn't it?​

PACK FLOW NORM 

PACK FLOW HIGH 

We hope we were able to give you some suggestions and, with the help of the tutorial, show you a way to make your simulator even more realistic. 

Officially, we can't give you any support for the installation, but if you have any questions, just write to us and we'll try to help you. Of course we will gladly accept suggestions, maybe you have even better ideas.

You will find more information about our A320 back wall system here:

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