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Climate Control

raabs

Well Known Member
Ed Kranz documented an interesting setup for controlling cabin heat via an Arduino controller. In his setup he uses RC servos to control butterfly valves. I was wondering if any knew (maybe Ed himself?) how the setup worked out.

Did the servos get mounted in the tunnel in the final setup and have they survived the heat?
Have the two firewall mounted servos survived the environment?

Thanks!
 
I have 2 "RC servos" mounted in the tunnel controlling the heat. So far they have over 1400 hrs on them. I may have had to change one of them but I don't think it was from heat. However my controller only powers the servo when adjusting the position so most of the time they are off.
 
Heater Control

Like Weasel, I also used R/C servos to control the heater valves. Concerned about the heat in the engine bay, I wanted to keep them on the cabin side of the firewall, so they're attached to Bowden cables routed as per the plans. Works OK but in hindsight, I think the Firghelli linear servos like those from TCW are a better design, are probably lighter and seem to have proven reliable in the firewall forward environment. As an aside, I've never experienced any unwanted heat inside the tunnel. I believe this may be the result of the stainless heater valves being held tightly closed by a little residual tension when the servo is turned off.

i-L4sh65F-S.jpg
i-CgXprJn-S.jpg


The servos in the pictures above were changed out for high torque versions before final assembly, those old ones didn't have enough grunt to reliably manage the friction in the Bowden cables.
 
Thanks guys! I have been playing around with the servos and think ill take a look at the actuators also.

What controllers are you all using, particularly one that shuts power off except when positioning them? Is it just a standard 10k pot?

Thanks!
 
Servo Drivers

An R/C servo is driven by a PWM signal. A pot by itself won't work. I used servo controllers from Perihelion Design. They're nice and small and include trim for endpoint and sweep, as well as an "off" detent, which I think is important. They're $50 each.
 
servos

I decided to go with the Actuonix (firgelli) linear actuators. They are available in a multitude of lengths, and gear ratios. Also, there are different ways to control them.

As was posted, servos use PWM and require a specific controller. There are linear actuators available that are servo replacements. They also have a Linear Actuator Control board available. It is a really nice board and allows many adjustments. Buy it with the actuator and get a discount.

I also used one for my electric rudder trim...and it has a BUILT IN position sensor...

Highly recommended!
 
I decided to go with the Actuonix (firgelli) linear actuators. They are available in a multitude of lengths, and gear ratios. Also, there are different ways to control them.

As was posted, servos use PWM and require a specific controller. There are linear actuators available that are servo replacements. They also have a Linear Actuator Control board available. It is a really nice board and allows many adjustments. Buy it with the actuator and get a discount.

I also used one for my electric rudder trim...and it has a BUILT IN position sensor...

Highly recommended!

Any chance you could provide the model numbers of the ones you're using? I'm interested in the rudder trim application; I have a trim tab servo that needs to go in the rudder but it it big and heavy. I'd love to find something smaller, lighter, and with position feedback!

And are you using them under the cowl or just in the cabin environment?
 
servos

I am using them on the heat valves, oil cooler butterfly, and rudder trim.

I looked at the TCW oil cooler butterfly valve and played with it at OSH a couple of years ago. I decided to do something similar. They are using their actuator FWF and so am I. I am also using the actuators for the heat valves FWF.

The rudder trim is based on the spring bias system that Aerosport sells. I replaced the drum-and-cable manual knob with an actuator and bell crank.

electric%20rudder%20trim_zpsduqvpxxu.jpg


The rudder trim actuator with position was this one. I also purchased the LAC board at the same time. Very easy to control with a potentiometer and position indicator wiring is a breeze.

https://s3.amazonaws.com/actuonix/Actuonix+P16+Datasheet.pdf

The heat valve actuators I used do not have position, and they are set up to act like regular PWM servos. If I did it again, I would just use the LAC board for each actuator instead of messing around with trying to control a PWM servo. The LAC board makes the 12v actuators basically plug and play with a potentiometer, switch, or button...

https://s3.amazonaws.com/actuonix/Actuonix+L16+Datasheet.pdf

For the rudder trim, I was concerned about back driving the actuator. I went with the 256:1 ratio. I think it would work with a lower ratio, and be a bit faster.
 
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