Here is an explanation of the design work that goes into our models regarding the flight controls setup. It gives you an idea of how much thoughts go into making a new model and releasing it for production.
We have currently 3 prototypes at different stages.
The first one is being extensively test flown by our team in France.
The second one is in Houston with Scott and is being built right now.
#3 is the first production unit test airframe and is in my workshop. This is the one you're seeing on this thread.
I will test fly it at 4000 ft density altitude to validate all the modifications that have been implemented after the test phase of #1.
The Diamond is an airframe capable of 300 mph top speed with the JB-220 ( remember to use a pitot tube telemetry system to stay below the 200 mph AMA limit ). I have computed the flight controls accordingly.
One first consideration that came to me is that due to the aerodynamics design, the flight controls require very little deflection for the flight. 10 to 15 degrees is the maximum deflection required. This is unusually low and requires a specific geometry design to avoid using the servo at a low ATV rates and stall them due to overstress ( bad mechanical advantage ).
To setup the controls there are two options; use the provided ABS/ carbon covers or make integrated control links. Both methods work fine. We have used the ABS covers in all our planes for 15 years and they perform very well at speeds up to 300 mph with the appropriate geometry. The pushrod force transferred to the cover should not exceed 20 lbf though.
Each method will require a different setup for each flight control. This is because the covers place the servo high in the surface, whereas the integrated controls method would require to place the servo low in the surface on a glued servo tray.
The ABS covers require to have a fairly long control horn to place the pushrod in the appropriate angle relative the cover opening. You will also notice on the sheet that the servo offset is entered accordingly.
Elevator:
The control horn length is 45 mm and the servo arm 9 mm.
A 100 oz.in servo is enough on this control due to the specific geometry.
The pushrod force is less than 8 lbf, which makes the ABS covers suitable for the job as well as Gold Clevises from Sullivan in 4-40.
Aileron:
The control horn length is 45 mm and the servo arm 12 mm.
A 170 oz.in servo is enough on this control.
The pushrod force is less than 9 lbf, which makes the ABS covers suitable for the job as well as Gold Clevises from Sullivan in 4-40.
Rudder:
Note that the rudder is the main control that requires the highest torque due to the size and deflection.
The control horn length is 4 mm and the servo arm 11 mm.
A 220 oz.in servo is required on this control.
The pushrod force is 14 lbf, which makes the ABS covers suitable for the job as well as Gold Clevisses from Sullivan in 4-40.
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Flaps:
Flaps require a very careful setup. They are very large and need to be deflected to 70 degrees for landing to provide enough drag.
That make the control need a lot of torque for the landing position.
Here is the simulation of the maximum torque required to extend the flaps to 15 degrees at 126 mph. Max extended speed is 116 mph with the recommended servo.
The control horn length is 40 mm and the servo arm 26 mm.
A 300 oz.in servo is enough on this control due to the specific geometry.
The pushrod force is 32 lbf. The ABS covers are not suitable for the job, neither are the Gold Clevisses from Sullivan.
Large ball links with dual horn required on this setup.
The maximum speed for the landing position with a 300 oz.in servo is 70 mph:
I am making specific full carbon fiber servo covers/ support for this setup.
I recommend the excellent Futaba S9156 for this setup, or higher.