[simpits-tech] 737 sim elevator control design

[David C. Allen]

Hello Everyone
Here is a 737 sim elevator control design that uses a basic cam and 
follower centering system.  This is a general outline of how the 
simple system is changed to evolve to a more complex and dynamic 
system that will actually move the control column during autoflight.

Step 1, the basic cam and follower system. A VW Steering damper is 
used to dampen large changes in control column position.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e1.pdf

This image is the same as the one above, but the cam and follower 
neutral position is rotated 90 degrees.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e2.pdf

An electric linear actuator is added to replace the spring to frame 
attachment point. This electric linear actuator is a low speed high 
torque actuator . The linear actuator allows the dynamic adjustment 
of the spring force on the follower which increases or decreases the 
forces trying to center the cam, which centers the control column.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e3.pdf

This shows the electric linear actuator in the retracted position, 
the centering forces on the control column will be at their highest 
with the electric linear actuator in this position.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e4.pdf

A mounting support is added for the cam follower and the feel 
pressure linear actuator. This allows the follower and electric 
linear actuator to rotate around the cam axis. in this image it is 
attaches to a frame mounting point to keep it from rotating.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e5.pdf

The neutral shift electric linear actuator is added, replacing the 
frame mounting point of mounting support. The linear actuator 
controls the rotation of the mounting support around the cam axis. 
This allows the neutral position of the control column to be shifted 
forward or aft. The neutral shift electric linear actuator is 
controlled by a PWM motor speed controller. This electric linear 
actuator is a "high speed" device that is operated at a reduces speed 
for manual stabilizer trimming.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e6.pdf

The neutral shift linear actuator is shown in the nose down, neutral 
and nose up positions.
This linear actuator can be controlled by the auto pilot and the 
control column will move in the proper direction, and the pilot can 
always over-ride the autopilot!

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e7.pdf

Control column travel stops added to prevent cam over-travel.

http://www.737flightsim.com/Misc/SimpleElev_Center_Position1e8.pdf

The proposed system accomplishes the following:
A) Dynamic feel based on airspeed and system A & B hydraulic system pressure.
B) Neutral control column shift for stabilizer trim position
C) Auto-pilot control column movement, with pilot over-ride
D) Control column neutral position that can dynamically be re-positioned
E) The cam can be made "Non-Symmetrical" so the nose up force can be 
less than the nose down force.
F) The neutral shift electric linear actuator speed is controlled by 
a PWM motor speed controller.

Thoughts ?

David
www.737FlightSim.com