Help me find a Real Time Downlink -rpm's & head temp..

[Texas Buzzard]

Pardon me if this doesn't belong here.But lots of knowlegble fliers post here.

I e-mailed Eagletree a week ago asking if they could set me up with real time downlink for RPM's, Head Tempreature, Altitude and Air Speed. They didn't nswer me.

If someone can steer me in the right direction for sucha downlink I would appreciate it very much.

I am planning a 300 mile cross country flight from Mexico to San Antonio, Texas next April when I have a tailwind I am using a P.A.W. 0.60 diesel. As the diesel enters cooler air at altitude sometimes the engine cuts out. I have an air gate for cooling which can be closed when head cools. This is simply a door in the air intake.

Please suggest a system or pieces of a system that will #1 send head temp to me in real time. then #2 would be RPM's. Airspeed is #3. Thanks
from Deep South Texas.

[Brandano]

Hmm, that will likely weight a fair bit, having to carry the batteries for a transmitter with it. Perhaps you could just set up a microcontroller to sample the temperature and drive the servo directly? If the temperature is too high increase servo position, wait a couple of seconds and sample again, if it's too low decrease position, wait and sample again. Most RC telemetry solutions seem to be data loggers, and I imagine that actual telemetry setups send data back in bursts if weight is a concern. Perhaps you could build an interface to a cellphone and get the phone to text you the data back

[Texas Buzzard]

Brandano thanks for your input.

If I understand you correctly you suggested that a therman sensor can control the position of the servor automatically with no downlink to the ground.

This would be just what I want. If there is a way to interface a thermistor to the servo signal then with some calibration I could have "automatic" door closing. Am I correct?

This sounds like an upper level servo tech would have to be employed. It sounds like a $250 job.

A hand carried thermometer and the use of a multi-position pot for a flap control would do the job.

Of course when I see a 10 degree drop in air temp I could manually close the air duct a bit. Thanks

[Brandano]

No, it might be a fairly cheap job, depending on how accurate you want the temperature sensor to be. You can use a fairly cheap thermistor (http://en.wikipedia.org/wiki/Thermistor) ripped off an old PSU, or you can use a serially addressed temperature sensor that comes with its own analog to digital converter, like one of these (http://www.ti.com/corp/docs/landing/google/temperature05/index.htm?CMP=KNC-reprisegooglehpa&HBX_PK=Temp_Sensor/Temperature+Sensor&HBX_OU=50), or a transistor junction in diode mode used as a temperature sensor... or any of the sensors on this page (http://www.micro-examples.com/public/microex-navig/doc/098-temperature-sensor.html)! You still need a microcontroller to provide the signal to drive the servo, though, and since these usually come with their own ADC converter, unless you need to sense a few hundred spots, then using a thermistor, a diode or a transistor should be good enough. The most difficult part will probably be to find someone to program the controller for you.

[Texas Buzzard]

No, it might be a fairly cheap job, depending on how accurate you want the temperature sensor to be. You can use a fairly cheap thermistor (http://en.wikipedia.org/wiki/Thermistor) ripped off an old PSU, or you can use a serially addressed temperature sensor that comes with its own analog to digital converter, like one of these (http://www.ti.com/corp/docs/landing/google/temperature05/index.htm?CMP=KNC-reprisegooglehpa&HBX_PK=Temp_Sensor/Temperature+Sensor&HBX_OU=50), or a transistor junction in diode mode used as a temperature sensor... or any of the sensors on this page (http://www.micro-examples.com/public/microex-navig/doc/098-temperature-sensor.html)! You still need a microcontroller to provide the signal to drive the servo, though, and since these usually come with their own ADC converter, unless you need to sense a few hundred spots, then using a thermistor, a diode or a transistor should be good enough. The most difficult part will probably be to find someone to program the controller for you.
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I don't need a few hundred spots. As of now 5 spots would do what I want.
You have more knowledge than I do. What I get from your post is 1) I need a thermister to sense the temp. 2) I need a microcontroller to develop a signal for transfer to servo and of course a servo.
So is it O.K. to say the servo is "slaved" to the thermister via the microcontroller? Some how the word selsen pops up to me. In The B-29 selsen motors were slaved to a similar selsen motor in the gunsight.....thus the selsen motors in the gun turret "folowed" the motors in the gunsight.
How that happened is beyond me.
You are using abreviations that I don't recognise. what is a " PSU". Where and what kind of microcontroller are you thinking of? Is PSU = to Power Supply Unit?
Can you draw a schematic? THANKS Brandano.
BTW, If I had a device that would close the "air gate" ( the door that allows cooling air to blow on the engine) automatically - I would be in business.
The engine is enclosed except for a 1.5" dia. hole in the rear. An articulated "door" can be opened and closed ( not all the way) so the temp of the head can be roughly controlled. Temp is not critical but there is a Temp at which the head must not go below.

Last night I though of using a spring from a Toyota carburetor. It's the one that opend the choke when the engine heats up. One of the early automatic chokes. It is a strip of meteal that is wound several time (maybe 5 times). No to find one. That would be fool proof.

[Brandano]

Same setup, only electronically controlled rather than mechanically controlled. PSU is indeed a power supply unit, sometimes they use a thermistor as a temperature safety switch. The spring you are mentioning is probably a bimetallic strip, same thing as used in a thermostat, it might not be easy to fine-tune. Similar devices are used in the coolant circuit to block the flow when the engine is too cold

[mnowell129]

Take this project:
http://www.instructables.com/id/Use-a-PIC-Microcontroller-to-Control-a-Hobby-Servo/
Add a thermistor (using the PIC's A/D) or digital thermometer module, and
let the temperature value drive the servo position. A few tweaks to figure out just how much servo movement you need per degree temp change and you're in business.

another example:
http://www.best-microcontroller-projects.com/servo-motor.html

and another:
http://www.rc-cam.com/servotst.htm

[hul]

http://www.jetimodel.cz/eng/duplex_dopln_EN.html
temperature and a GPS module (for speed) will be available shortly, guess you could rig something to use a voltage sensor to show rpm.

Hans

[Texas Buzzard]

Take this project:
http://www.instructables.com/id/Use-a-PIC-Microcontroller-to-Control-a-Hobby-Servo/
Add a thermistor (using the PIC's A/D) or digital thermometer module, and
let the temperature value drive the servo position. A few tweaks to figure out just how much servo movement you need per degree temp change and you're in business.

another example:
http://www.best-microcontroller-projects.com/servo-motor.html

and another:
http://www.rc-cam.com/servotst.htm
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I am looking at the page displaying the 12F 675 Servo Motor Driver.
I am looking at the Solderless Breadboard.
In upper left I see what might be the input signal from the thermister.
is that where the thermister connects?

By the way this stuff looks good, does this come as a kit?

[mnowell129]

You connect the input signal to any of the A/D converter inputs AN0, for example.
Check out the data sheet
http://ww1.microchip.com/downloads/en/devicedoc/41190c.pdf
Don't know if this is available in kit form, you'd want to put this circuit on a circuit board instead of breadboard for aircraft use.
You may want to find someone local to you that can help with this project and give you pointers. Also there are many electronics forums like RCG for advice on electronic projects.

[Connexxion]

Dear Texas Buzzard,

what you need to control the air intake and thus the cilinderhead temperature,is the Carbsmart made by CSM ltd.

It monitors the headtemp by means of a sensor attached to the cilinderhead.
The Carbsmart was meant to control a servo that's attached to the mixture needle,but you could attach the servo to your intake hatch.

Review:

http://www.trextuning.com/carbsmart.php

Since you're in th US,you could purchase it here:

http://www.grandrc.com/inc/sdetail/103885

Why did you choose for the PAW diesel?

And how are you gonna follow the plane?

I wish you all the luck needed and keep us up-to-date.