737 Dual Control Developments

Last week was school half term and the children returned home for the week. I have also switched to standard working days which leaves very little time for the sim. I would rush home late in the evening and the children would want me to watch them, play their computer games. Something I greatly enjoy! Sadly progress this particular week on the sim was lacking.

It really didn't help when I was filming the final part to the dual controls, the weekend before and realised there was a huge flaw in the roll channel. I sat there pondering for a little while and thinking this is going to beat me. The issue was that past 35 degrees of roll, the centring pressure/ force feedback became less. This was solved with a 2:1 ratio gear, but the 3d printed gears could not handle those loads. So I switched back to a 1:1 gear ratio. At 35 degrees rotation, it became very ineffective. At 80 degrees it would try to push the controls all the way around. ALAS, ANOTHER FAIL!

It was at this point Helen my wife came out said, "it works, for now, move on and come back to it". I took this advice and thought yes it does. That night I awoke at 3:07 am and thought what about if I tried a multi-cam and pinion support. I got up out of bed in the early hours of Saturday morning to draw it on CAD. I then got to the computer and realised there were several hundred emails to answer! That took forever! and I think daylight may have arisen.

This is what I thought might work:

737 3D Printed Yoke Centering Mechanism
737 Dual Controls Centering Mechanism

The unit is based on a multi roller cam, as the shaft is rotated 30 degrees left or right, it comes into contact with a second finger, which progressively adds more force. As the unit passes 60 degrees, the 3rd finger comes into contact and adds its force to the controls. At no point does the force get less or becomes mechanically locked out like the previous version.

How progressive force is achieved on the Boeing 737 Roll channel with 3d printing
737DIYSIM mutli cam centering mechanism for the yoke

The two centring fingers have adjustable screws with offset the centre position. The rest of the fingers also have adjustment screws to adjust the point at which they become effective. On the opposite side are the tension fingers which can be adjusted to crank up the pressure on the springs.

The 3d printers are now busy at work! All 3 are going in order to test the design. While this happens I now hope to switch to updating the yoke design while the printing finishes.

Kind Regards


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