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Assembly | Joystick connection

How I build my own cockpit ?

Assembling the pedals and the steering-column on the two bottom modules:

Last time we finished with the construction of the steering column.  Time has come now to put all the constructed parts on their definitive location and to assemble them.
Let’s have a memory fresh-up.  Perhaps most of you have forgotten that, about one year ago, I built some bottom modules, on which the whole cab of the cockpit has to find its place.  I discovered them under a layer of dust.  Perhaps you better remember the pedals.  At last there’s the steering column.

All these things have to be adapted a bit and have to be assembled together. 
We start linking the two bottom modules to each other and to  make one firm entity by means of the middle module.  Then it’s the pedals turn to be integrated in the whole.  Being constructed on a stable base the pedals are integrated in the bottom module without disassembling them.  That’s why you have to do an extreme intervention in the front of the modules.  Using the saw we remove the front part and then push the pedals via the front side in the unit; we fix it by means of six pullers.  They get completely stuck.  This is a must, because the feet give a lot of pressure.  Surely this counts when the force feedback will be installed. 
The pivoting point of the pedals is put in the middle on the raised part of the bottom module, there where the pedestal comes over and fixed to the strengthening beams of this raised part.  To this pivoting point we adjust a spring , which is temporary tightened by a wire-rail with handle.  The latter will be replaces later by a steered engine of 12V.  Depending the case, this engine will tighten or release the spring.

mont1 mont2 mont3 mont4

The third part is the assembling of the steering column.  We made two pivoting points to this aim; by means of screws we fixed them on the left and right sides of the bottom.  To increase the solidity we anchored (cramped)  them to the point of support on which the chairs will be put. 
Then came the most difficult part of the job.
How keep the stick in a fixed position while taking care that the necessary power could be exerted when moving the column backwards and forwards.  The normal power exerted in a DC3 is about 35 kg. Moreover one has to know that there isn’t much place at the foot of the column and the whole may not be seen.  The only place to hide something is behind the pedestal.  It took me three days and nights to find a good solution.  You won’t believe but it happened in the same way as it happened to the Greek Archimedes.  I was taking a bath quietly, suddenly I said EUREKA: I had found it.  I jumped out the bath tube, searched quickly for a sheet of paper and made a draft. 

It works as follows.  The pivoting point of the column isn’t exactly in the middle of the lower tube; it stands at the back of the tube.  When you move the column, the tube goes up and down, it traces the fourth of a circle.  Construct another hinge in the middle and fix a bar to the lower tube: the tube moves a little.  This little movement is turned over to a bigger one by a lever at the back of the pedestal.  At the top of this lever a tension spring is fixed; it is tightened by a wire-rail with handle; at the bottom we fix a push-spring , which neutralizes the strength of the tension spring at the top. 
As a result the column keeps standing correctly in the wished position. 
So we have made these things all completely moveable; later, in experimenting,  we were able to create the correct tractive power and give the column the correct angle.  So you have to exert pressure heavily  on the column; this power (pressure) increases as the stick is pushed to the back or to the front, as it works in a real plane.
Moreover when the top tension spring is steered by a dc engine, as done with the pedals, the tractive power on the steering column changes proportionately to the air resistance of the plane.  This allows us to have a perfect force feedback. 
A bit exertion is necessary to take off your plane now. 
I’m already longing for a trim on the elevator to diminish a bit the big tensions.  Flying really was a hard job.

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Joystick connection:

The last thing we’ve to do is making the link between the potentiometers of the pedals, column and steering-wheel with the joystick.  We need a 15 pins connector and a cable with fifteen cores.  Those potentiometers from 100kΩ and the possible switches are connected as follows.

schjoy
  1. + 5V DC out
  2. Button A in
  3. Analog A in
  4. GND
  5. GND
  6. Analog B in
  7. Button B in
  8. +5V DC out
  9. +5V DC out
  10. Button C in
  11. Analog C in
  12. GND
  13. Analog D in
  14. Button D in
  15. +5v DC out

 

 

 

 

 

 

 

 

When all this has been soldered well you can plug the 15 pins plug into the joystick entrance, this should work once the software has been reprogrammed.  As happened before, it didn’t work from the first time.  All was well soldered, but the software didn’t work.  It gave me some white nights.  I tried a lot of things and one night it worked.  Don’t ask me how it happened; till now, I haven’t found out how I got it to work.  But it does work now; remember: where there’s a will, there’s a way !

Remark: The technique mentioned above isn't up to date anymore in 2007. There are no PC's anymore with a sound card and a analog joystick connection. All this is replaced in my cockpit project with a self build joystick called Mjoy 16 from Mindaugas.
More information about this subject you can find in the article
Mjoy16

Then I installed the plane-chair on the bottom module, put the loudspeakers in the corners and sat behind the wheel for my first test flight.  I soon heard the noise of the engine and even felt the vibrations of the speakers in the steering column. 
Then I lined up to the 25 R  runway of Zaventem to make a short flight to Deurne.
Having controlled the engines I accelerated slowly and, indeed,  the tail wheel of the DC3 was lifted, a short run, pushing the stick – a bit force was needed – and the wheels were leaving the runway.  It was quite different from playing with the former joystick. 
A short curve via Mechelen and we were on the way to Deurne.  The landing was bad, but it was a pleasant surprise I could avoid a crash at the last minute.  The plane stood at the left side of the runway, but after all it wasn’t so bad for a first test flight.  

The week after assembling, I didn’t do anything else than flying.  It gave me kick and kept me going.  At the end of this exciting week I started longing for a pedestal with throttle,  pitch, mixture and the trim; indeed, my arms started feeling very tired from all that pulling at that flight column.  That pedestal would be the crowning glory of the construction.  After the pedals it will be the most difficult part of the DC3 to construct.  I’ll tell you about that in another article.

 

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© Verley Jan 2007-2017 original text from 2003 translation Joan Pacquets