Curly Posted yesterday at 12:06 AM Posted yesterday at 12:06 AM (edited) Requested Change: Move the position of the spring stop to 80% of the aileron axis. Problem: On the DCS F-5E, the aileron limiter / the spring stop, is located at 50 % of the aileron axis. Placement of the Spring Stop here is inaccurate and makes the F-5 difficult to accurately control laterally. To be clear, I am not calling for the removal of the spring stop, only that it moved to 80% of the joystick axis. While it is true that the spring stop limits the total aileron deflection by more than 50%, as is stated in the F-5E flight manual: Examination of more detailed descriptions of the flight control contained in official Northrop documentation Indicates that aileron deflection per control stick movement (the aileron gearing) is not linear and that the spring stop should be located at 80% of the roll stick travel. With the landing gear down: Stick Travel is = +- 4.0 inches, and the max aileron angle is 35 degrees Up, 25 degrees Down. For a total Aileron Angle of 60 degrees When the landing gear is up, the aileron limiter / spring stop is active. The Stick Travel is limited to: +- 3.2 inches. Thus the spring stop is located +- 3.2 inches from the center. +-3.2 being equivalent to 80% of the total Stick Travel (4 inches). As (3.2 / 4) = %80 At 80% stick travel; the aileron angle is limited to 18.5 degrees Up, 14 degrees down. The spring stop therefore limits total aileron angle by more than 50%. As (18.5+14) / (35 +25) = 54% While the details of the Northrop Technical Manual match the description of the Aileron Limiter from the Pilots Manual, “Limits the Aileron travel to one half”. Neither sources state that the flight controls are limited to 50% / half travel when the landing gear is raised. Plotting the aileron angles and stick position from the Technical Description, and connecting these points by the appropriate slope. We constructed a diagram depicting the aileron angle as a function of the stick position, often called the aileron gearing ratio. This chart indicates that the aileron limiter in the landing gear up (aileron limited) config, cannot be located at 50% position of the total control stick travel (+-2 inches) like in DCS. As the location of the points which coincide with Landing Gear Down (aileron limited) Config, like (3.2,18.5) are not located half way from the points which coincide with Gear Up Cofing, like (4.0, 35), along the slope of Gear Up Config. It is likely that the aileron gearing ratio is not linear. Rather it is constructed of two distinct gradients. Connected at the location of the Spring Stop, +-3.2 inches from the center of the control stick. This point being = to 80% of the total control travel (4 inches) Simply stated the Spring Stop has to be located where max aileron is achieved in Gear Up Config. Which means that the Spring Stop can only be located at +- 3.2 inches of stick travel, 80 % of the total stick travel. The aileron flight control system seems to be designed to provide linear response of the ailerons to control stick inputs up to the Spring Stop. The steep gradient beyond the Spring Stop would provide feedback to the pilot that the critical range of operation had been exceeded. As compared to the DCS 50 % the spring stop implementation The Northrop implementation of the Spring Stop (At 80%, +--3.2 inches stick travel) would result in improved lateral control (roll rate / bank angle) of the DCS F-5E. Moving the spring stop from 50% to 80% of the stick travel range, increases the range of motion of the player's joystick by 30% in the roll axis. The result would be a 1.6 times increase in the gearing ratio of the player's Joystick position to the F-5E’s aileron angle. Making the DCS much more precise and controllable about the roll axis. And may reduce inadvertent wing destruction caused by unintentionally high roll rates. Placing the spring stop at 80% of the stick travel, should be considered as it is realistic and would match the description in both the Pilot’s Manual and the Northrop Technical Description. While also improving the lateral flying qualities of the F-5E The derived non linear / multi / gradient aileron implementation also appears to be valid. Given the similar approach used by Northrop in the longitudinal flight controls. Consider the implementation of the tri-gradient feel spring in the pitch axis. Designed to linear relation between tail deflection and Load Factor (g’s). Aileron Limiter Track F-5E Roll Coupling .trk Edited yesterday at 12:49 AM by Curly Format and Images 1
Recommended Posts