Automatic throttle system in the aircraft simulator

From Flightdeck Solutions

Please describe your system/machine/project. What is the function of your application? Where is your application used?
Our application is a simulated throttle for a simulated 737 NG and 737MAX aircraft. The high pitch lead screws we selected are used to simulate the auto-throttle system in the real aircraft. This system allows the autopilot to automatically move the throttles to control the airspeed. At the same time, a manual control system is possible when the autothrottle is deactivated. The same applies to manual override when the autothrottle is activated but a manual control system is still required.

What are the end user's operating/environmental conditions like? What challenges did you have to solve?
The environmental conditions are typical indoor conditions worldwide. These can be very hot and humid places as well as very cold and dry areas and everything in between. The biggest challenge in replicating the automatic throttle system was to make it smaller while maintaining full functionality. The real aircraft system is connected with cables that run throughout the aircraft. We had to house the entire system in the part of the throttle that is above the floor. The next big challenge was to design a system that would allow both automatic and manual throttle control, as well as manual override of the automatic throttle system.

What requirements did the lead screws have to fulfil?
The lead screw nut and spindle had to be robust enough to be used in all climate zones around the world in the long term. And they had to be able to be driven in reverse so that the pilots could override the automatic throttle system and control the throttle manually.

What alternative solutions for the screw drives were considered? 
We considered options such as belt drives, standard bronze lead nuts and direct servo drive. All of these options were either too large, too expensive or could not be adequately backdriven.

What polymer bearing technology solutions do you use?
We used the dryspin® high helix lead screw and lead screw nut in 50 mm pitch, supported by 3/8" igus® high precision linear bearings.

In which areas? How could the products solve your problems?
The threaded spindles and bearings were used for the control system of the two throttle levers (one lever for each engine). The system worked so well that we also introduced a similar system to drive the speedbrake lever (to control the simulated air brakes), which is mounted in the same throttle module. The products were the perfect blend of low cost, high reliability and very simple feedback control. Thanks to the low cost, we were able to meet our price targets for the simulated throttle valves. The high reliability means we don't have to worry about the units wearing out or failing in the field. The high back control means that these screws are very easy to turn back, giving us the perfect feel and power on the levers.