Linear actuators for heat control

Considering going to the actuators vs cables for the heat control and an Avery oil cooler valve. Wondering if the acuators being fire wall forward is too harsh for them. At 170 dollars an actuator, failures could add up. Also, how they would hold up in the Florida heat and humidity. Oh, and just to keep the "cabin heat and Florida" jokes to a minimum, we travel and back pack in those places that acually get colder then 70

What actuators are you considering?

The only one Iam aware of is from TCW

KISS

For all the reasons mentioned in the above linked thread,
I would not "pimp" the heater actuation mechanism.

Actuating the old fashion heater control cables is an exceedingly simple and
intuitive pilot action.

Spend the money for electrically actuating the overhead air inlets.

Try this

http://store.firgelli.com/mobile/Category.aspx?id=1821

These are great and are exceptionally easy to control. You need not do something just because "that's the way it has always been done". I am using these actuators for the oil cooler butterfly and probably the heater valves. There are many others doing the same. Do the cables work? Yes. Do the actuators work? Yes. Pick one and run with it!

Consider how the actuator will be used. There are two kinds of applications. The first applies strain to the actuator when it is static, as well as when it is asked to move an attached device. The other app only loads the actuator when it is in motion. The static load case will probably be more prone to heat related problems related to plastic gearing or adhesives, in particular if the load is significant.

Someone noted that inability to close a heater door in the firewall could be a serious problem. Ahh, yep. I'd always recommend a stainless heater control valve, and if you want to use an actuator, keep it behind the firewall. An engine compartment fire is going to kill a hot-side actuator very quickly.

The oil cooler supply duct valve is non-critical.

I've been using the TCW heat valve actuators on my RV10 with no problems.
The kit is complete with variable control.
http://www.tcwtech.com/control_valve_servo_kit.html

After having a locked elevator trim on my Rv8 I installed their safety trim also on th -10.

Greg...

I did a hybrid solution with both push/pulls and high torque RC servos. I ran the push/pulls to a location under the panel, where they are both out of the way, but in the event of a servo failure, I can reach them (barely).

The servos are powered by an RC BEC (basically a 12v to 6v transformer) and potentiometer knobs on the lower panel are wired to an Arduino that controls the position of the servo. It gives me very precise control of the servos. This is handy in the 10, because it's a very narrow margin between frosty toes, and feeling like your legs are ready to melt!

It also allowed me to put the heater control knob for the rear seat heat in reach of the rear passengers, on the back of the center console.

Here is what the servo bracket I made looks like. It's mounted on the bottom of the subpanel flange on the far right side:



Video of it hooked up to a servo tester:
https://picasaweb.google.com/104915858356518723094/RV106FWF#6097277199384733234

That said, doing this did take a few iterations to get it working reliably, and I bet I have 30-40 hours invested in it. Push/pulls alone would have saved me 95% of that time and effort.

I have the TCW servo on my oil cooler baffle valve on my RV10. Very happy with it so far. 100 hours on it so far and no troubles.

NovaBandit said:

I did a hybrid solution with both push/pulls and high torque RC servos. I ran the push/pulls to a location under the panel, where they are both out of the way, but in the event of a servo failure, I can reach them (barely).

The servos are powered by an RC BEC (basically a 12v to 6v transformer) and potentiometer knobs on the lower panel are wired to an Arduino that controls the position of the servo. It gives me very precise control of the servos. This is handy in the 10, because it's a very narrow margin between frosty toes, and feeling like your legs are ready to melt!

It also allowed me to put the heater control knob for the rear seat heat in reach of the rear passengers, on the back of the center console.

Here is what the servo bracket I made looks like. It's mounted on the bottom of the subpanel flange on the far right side:

Video of it hooked up to a servo tester:
https://picasaweb.google.com/104915858356518723094/RV106FWF#6097277199384733234

That said, doing this did take a few iterations to get it working reliably, and I bet I have 30-40 hours invested in it. Push/pulls alone would have saved me 95% of that time and effort.

Click to expand...

Cool! I also had the idea to use an Arduino for various non critical controls such as cabin temp and lighting. It's nice to see someone else has made it work.

For more critical stuff, have you had any experience using multiple Arduinos tied together to detect a failed or malfunctioning controller? Seems that muxing/demuxing the signals between the controllers would get fairly complex. I guess one could use serial connections between the redundant controllers and a supervisory controller to allow it to monitor the states of the sub units.

1001001 said:

Cool! I also had the idea to use an Arduino for various non critical controls such as cabin temp and lighting. It's nice to see someone else has made it work.

For more critical stuff, have you had any experience using multiple Arduinos tied together to detect a failed or malfunctioning controller? Seems that muxing/demuxing the signals between the controllers would get fairly complex. I guess one could use serial connections between the redundant controllers and a supervisory controller to allow it to monitor the states of the sub units.

Click to expand...

As compared to, say, just pulling the knob?

DanH said:

As compared to, say, just pulling the knob?

Click to expand...

Spoilsport.

He could use the arduino to automatically control the oil temp... I was thinking of something like that hooked up to a cowl flap to control chts. Yes it's nerdy but I think it would be a fun project.

Hi,

I'm working on several Arduino projects for my Jurca Sperocco (all wood tandem low wing, Lyco 300hp) in France:

1- Fuel transfer system: 4 aux tanks to the main one. 4.3" TFT touch screen with Arduino Mega. Relays for the electrical pumps, optical sensors for "empty tank" notification and capacitive gauge for the main tank supervision. The idea is to feed automatically the main tank when its level reaches down 80% and bring it back to 95%. Also taking into consideration the solo/tandem for a better balance. Aux switches as backup.

2- Heating management: Mixing warm/cold air before crossing the firewall. LCD 20x4 char screen. 3 RC servos: one to open/close the firewall access (flame detector and switch), one to mix warm/cold air to reach a target temp and one to make the flow going down (feet) or up (panel). A relay to manage a 48mm axial fan, forcing air while on the ground, and another for windshield demist.

3- Landing gear supervision: Displaying Up/Down gear position (red/green) and real time hydraulique pressure. 4.3" TFT touch screen. 1000 and 1600 PSI pressure probes (5V linear, $35 on eBay!). The gear switch remains autonomous with its pressure switches to manage the hydraulique pump.

4- Alarm system: A LCD 40x2 char screen to display alerts on top of the panel. This to replace the classical leds. Same Arduino as the gear supervision. Considering to add an Oil Temp management too.

5- Rear electrical canopy management + basic instruments: Sequencing the lock/unlock then close/open process. 4.3" TFT touch screen displaying the canopy process and, when closed, a set of basic instruments for the passenger (air speed, altitude, vario, etc.) based on a set of nini probes (pressure, magnetometer, accelerometer).

This geek's stuff will fit well next to the G3XTouch...

Just to share ideas for the long winter evenings

Happy building!

Linear servo pics - mounting & bowden cable connection?

I have a controller that I made using a Raspberry Pi Pico, a Kitronix servo board for the Pico, and a 6v regulator board.

https://www.robotshop.com/products/kitronik-simply-servos-board-for-raspberry-pi-pico

NOYITO Three Terminal Voltage Regulator Module LM7805 LM7806 LM7809 LM7812 DC or AC to DC 6V 9V 12V Output 1.2A Max Power Supply Module Terminal and 5x2 Pins Output （Pack of 2） (LM7806 DC6V) https://a.co/d/j8HSGVm

I'm looking for pictures of how people have mounted their Firgelli or Actuonix linear servo actuators & how they have connected them to the heater flapper and an oil cooler shutter. My plan is to keep both servos behind the firewall & use a bowden cable connection for the oil cooler shutter & probably also for the heater.

Thanks,
David

After one replacement under warranty and a second failure, I literally gave away my servo controllers (oil and heat, per plans), and retrofitted Bowden cables per mothership's plans.

Now I have a cable creep problem with the heater valve wanting to drift closed in flight. Should have gone with a ratcheting knob on that side but didn't know it would be an issue.

Simple is almost always better in terms of more reliable and reduced weight. The cables are simple. The hybrid approach offers the worst of both solutions.

The best part is the one you can eliminate.

In their defense, apart from the cool/wow factor, the servo controls are lighter than the Bowden cable. The longer the run (wires vs steel cable) the greater the weight savings.

Per ounce saved, it's an expensive way to shed weight. Plus you get much reduced reliability in the bargain.

I'm sorry I ever messed with them, but I was in an all-glass-philosophy mode at the time, and wanted as clean and hi-tech a panel as possible. Now I am beyond caring about such things, and want heat (and control of the oil temp) reliably when I pull the knob.

Temp rating ??

I installed an Actuonix linear servo on my oil cooler mimicking the method TCW does there's. It worked fine for the first 150 hours. During my testing phase for the unit I would partially close the cooler in flight to warm up my oil temps in the cool Ohio winters. From that I knew that closing the oil cooler in flight could quickly produce some very high oil temps. I set up my EFIS so that I received a yellow alert anything over 50% closed and a red anything above 80% closed. I found even on the coldest days at altitude in Ohio there was no reason to use more than 50% in flight. I would use it on the ground to warm up the oil quicker and exceed 50% but always opened it before flight. (Hince the EFIS warnings so not to forget) Last year after start-up I partially closed it and it failed. After taking it back to the hangar, removing it and inspection I found the 2 half's of the case had separated. After some research I saw that Actuonix operating temp is rated at 50 C max while TCW (Who I believe uses the same linear servo, it anyone has better info please provide input) operating limitation is 70 C. Since I have Earth X batteries, I installed a ring thermocouple down the side of both batteries. My co-pilot side battery on the 14 is near the oil cooler and see temps on the ground in the 120 range so the 50 C limitation is marginal. If the TCW linear servo is truly rated at 70 C that would provide a better buffer for FWF applications, but I am not sure. Just be careful on mission critical applications if using a system that could fail and stick close. I have also installed a blast tube on the servo to help cool it.

I used the TCW on my oil cooler and it failed at around 75h.
In hindsight it was unnecessary and I wouldn’t recommend it.
If you need warmer oil in the winter it’s safer to fit a blanking plate.
Or a manual actuation if the butterfly.

More data

200+ hours on my -10.

TCW oil cooler actuator - No issues, Works great

Actuonix Linear actuators for both heat valves - No issues, Works great

Not sure how my installation is any different than anyone else's but there you have it.

All good data.
I doubt there’s anything that different between installations.
My issue is that this sort of thing really should just last the life of the airframe. No ifs or buts. No question a manual cable would. It’s an important piece of hardware.
A failure in the summer that closes it off inadvertently could have you in a paddock.
So if the hardware can’t reliably deal with 200+F continuously I think it has no place sitting on top of the oil cooler.
I doubt there’s that many installations tbh. Maybe 100 total?
Sounds like the failure rate could be significant.
Cheers

Richard Connell said:

All good data.
I doubt there’s anything that different between installations.
My issue is that this sort of thing really should just last the life of the airframe. No ifs or buts. No question a manual cable would. It’s an important piece of hardware.
A failure in the summer that closes it off inadvertently could have you in a paddock.
So if the hardware can’t reliably deal with 200+F continuously I think it has no place sitting on top of the oil cooler.
I doubt there’s that many installations tbh. Maybe 100 total?
Sounds like the failure rate could be significant.
Cheers

Click to expand...

I question your faith in a manual cable; I have had many seize or break, the most memorable being a throttle cable in a 172…

The good news is we all can decide what level of perceived risk is acceptable for ourselves…

Bill Boyd said:

After one replacement under warranty and a second failure, I literally gave away my servo controllers (oil and heat, per plans), and retrofitted Bowden cables per mothership's plans.

Now I have a cable creep problem with the heater valve wanting to drift closed in flight. Should have gone with a ratcheting knob on that side but didn't know it would be an issue.

Click to expand...

The handle can be changed to a nice black round from ACE Hardware...

AMAZON.....

Anti Splat Aero also sells a similar Bowden cable for $24.95, or you can also now choose the option of a ratcheting cable for $80...designed to prevent cable creep due to vibration or whatever.

https://antisplataero.com/products/bowden-cable-assembly

Has anyone tried some type of heat shield materials to keep the direct heat away?

Why do I feel this discussion is about installing an actuator and computer controller to flip a light switch?

To each his own. Someday soon they'll completely eliminate my job with some servos and computers, and I'll be able to sit quietly on the porch and talk about how we "flew them planes with cables and switches, looking right out a big glass winda..."

Do whatever you enjoy, this is all about being happy with your creation.

Build on!

Wow. I feel like I kicked the hornet's nest by resurrecting this thread!

It seems that everyone missed (or chose to ignore) what I was proposing to do & what I was asking for.

David Carter said:

I'm looking for pictures of how people have mounted their Firgelli or Actuonix linear servo actuators & how they have connected them to the heater flapper and an oil cooler shutter. My plan is to keep both servos behind the firewall & use a bowden cable connection for the oil cooler shutter & probably also for the heater.

Click to expand...

Lots of responses about failures due to putting these servos FWF. That's a complete "No Duh!" based on the temperature ratings of those servos. They are rated for 50C / 122F. No way I'd consider putting that FWF. (https://www.actuonix.com/assets/images/datasheets/ActuonixL12Datasheet.pdf)

As to the costs of replacing servos, they are $70 each from Actuonix. I have less in a pair of servos (heater & oil cooler shutter) than what TCW charges for a single servo & controller setup. And my controller setup could control another 6 servos if I had uses for them.