Brittain Autopilot Systems

[Browncbr1]

It is technically possible for the Brittain to be hooked up if you choose to do so using the drawings that Brittain supplies, which I attached earlier.   The way the Brittain functions is almost exactly same as AC Cessna 300 and 400 autopilots.   I am not a lawyer and not suggesting this is or is not legal in a certified aircraft.  However, I was told by Brittain and garmin that they were pending final paperwork that would add Brittain to the G5 stc.  

[MyNameIsNobody]

5 hours ago, flyboy0681 said:

Seems to me the certifications would come based on the number of planes in a particular fleet. Obviously the #1 spot would be reserved for the C-172 and derivatives,  then the Cherokee family and so on. Where does Mooney fit into the scheme in terms of number of airframes still flying?

No it is based on auto pilot being certified with the G5

[Hank]

5 hours ago, outermarker said:

I still have a AccuTrak and AccuFlite system I'd like to keep working.

 

Me, too!!

[MyNameIsNobody]

1 hour ago, Hank said:

Me, too!!

Me three

 

[Evan Amaya]

I have dual G5’s on my F and I just configured my Brittain autopilot to gpss and heading bug off the G5.  I am only using the TC100EVT turn coordinator connected directly to the GAD29b.  Pin 8 on gad to pin E on TC100EVT and pin 14 to pin F. Pin E and F are on the plug that went to the Brittain controll head and is now disconnected in my case. Pin F is the orange wire, pin E blue.  I have not test flown yet.  I will in the morning but ground check shows it working.  On the G5 I have third party autopilot set to Cessna DC scale 1:1.  Pin E and F control the torquer motor on the back of the TC100EVT.  0 volts is centered.  +10volts is one direction and -10volts the other.  With the engine 4.5 in-hg when I turn the heading bug on the G5 the yokes fallow.  I don’t think it will fly a true coupled approach but it should hold the straight line.  I will post the test flight results tomorrow.

[thinwing]

Thanks for posting...I'm not sure I would trust that for IMC or approach but for long distance Vfr why not?

[Evan Amaya]

I played with the gpss and heading mode in flight this morning and it did work well in heading but I need to play with the gpss gain to get it to fallow the line.  I’m an Avionics’s tech at a repair station and am just playing around.  I agree that approach in imc wouldn’t be a good idea.  This should hold me over while I wait for Garmin to hurry up and get the GFC 500 STCed for our planes!

[Yetti]

3 hours ago, Evan Amaya said:

I played with the gpss and heading mode in flight this morning and it did work well in heading but I need to play with the gpss gain to get it to fallow the line.  I’m an Avionics’s tech at a repair station and am just playing around.  I agree that approach in imc wouldn’t be a good idea.  This should hold me over while I wait for Garmin to hurry up and get the GFC 500 STCed for our planes!

Oooh ooh I want to talk to you.   Do you have a schematic of the Brttain system?    I have been building an autopilot that was going to use the Left Right input into the B-11 Accutrak II.     But best I could find the inputs would be max 300millivolts. I have a PWM output that I can get up to 5 volts out of, but it would be hard to do millivolts.     

This is a Raspberry PI GPS based autopilot.   The GPS is Digital GPS quality WAAS.  

[Evan Amaya]

Yesterday my wife and I flew from, South Carolina to East Texas. Did it in 4.5 hours with a 7kt head.  I turned on the autopilot at 500ft agl , flipped to gpss and never touched the yoke the entire trip except for landing/takeoff.  Very happy with the results.  ATC had me go off course twice for traffic and I ed the G5 to heading mode then when advised to turn back on course went back to gpss and the plane smoothly went back to my original course.  Right now I have the scale factor set at 2.  I may play with this some more but in route I can’t complain.

[N201MKTurbo]

On 6/8/2018 at 10:28 PM, Yetti said:

Oooh ooh I want to talk to you.   Do you have a schematic of the Brttain system?    I have been building an autopilot that was going to use the Left Right input into the B-11 Accutrak II.     But best I could find the inputs would be max 300millivolts. I have a PWM output that I can get up to 5 volts out of, but it would be hard to do millivolts.     

This is a Raspberry PI GPS based autopilot.   The GPS is Digital GPS quality WAAS.  

Just run your PWM through an RC integrator to get a DC voltage. You should be able to limit it through software or put a voltage divider in your integrator so 100% = 300mv

[FBV]

Just run your PWM through an RC integrator to get a DC voltage. You should be able to limit it through software or put a voltage divider in your integrator so 100% = 300mv

I’m working on something very similar. Heading hold for my Accutrak. I’m using arduino hardware. I’m sourcing a LDO as you need not only +300 mV but also -300mV. Without the negative voltage, you’ll have an autopilot than can only make left turns. So a PWM with RC filter will not get the job done, unless I’m missing something. Hence why I’m posting..



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[N201MKTurbo]

1 minute ago, FBV said:

I’m working on something very similar. Heading hold for my Accutrak. I’m using arduino hardware. I’m sourcing a LDO as you need not only +300 mV but also -300mV. Without the negative voltage, you’ll have an autopilot than can only make left turns. So a PWM with RC filter will not get the job done, unless I’m missing something. Hence why I’m posting..



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Most autopilots have a + left and + right inputs so they don’t need a negative input. If you are dealing with a Brittan valve that needs a bidirectional signal, just give it a virtual ground at +2.5 volts and shift your zero point to 2.5 in software.

[N601RX]

If you are going to use a pwm signal you basically need an H-Bridge driven at 50% duty cycle. This will set up a zero voltage point that half way between ground and supply voltage. From here you can increase or decrease the duty cycle slightly to generate a positive or negative voltage. The quieter way would be to use a DAC with an amplifier. For what it’s worth Brittain uses an oscillator and transformer with diodes to generate the positive and negative voltages. It’s output voltage is isolated from the input voltage. 

[N201MKTurbo]

1 hour ago, N601RX said:

If you are going to use a pwm signal you basically need an H-Bridge driven at 50% duty cycle. This will set up a zero voltage point that half way between ground and supply voltage. From here you can increase or decrease the duty cycle slightly to generate a positive or negative voltage. The quieter way would be to use a DAC with an amplifier. For what it’s worth Brittain uses an oscillator and transformer with diodes to generate the positive and negative voltages. It’s output voltage is isolated from the input voltage. 

While that would work, after all that is how most motor drives work, this is a very low level application that requires almost no power at all. There are much simpler ways to get there. 

[Yetti]

1 hour ago, N201MKTurbo said:

While that would work, after all that is how most motor drives work, this is a very low level application that requires almost no power at all. There are much simpler ways to get there. 

There is this to get the negative voltage.   https://electronics.stackexchange.com/questions/221398/negative-voltage-pwm

The raspberry PI GPIO only has 5 volts available for the PWM so it will be slow turns.  Have to check amperage for the TC.   Might have to drive an external PWM with the Rpi. with it's own circuit.

But if the Turn Coordinator receives +10 volts from the B11, it may make sense to just use a DPDT switch inline between the B11 and TC.   From above:   ( Pin 8 on gad to pin E on TC100EVT and pin 14 to pin F. Pin E and F are on the plug that went to the Brittain controll head and is now disconnected in my case. Pin F is the orange wire, pin E blue.  )

My biggest issue now is the "oncourse" from the GPS message does not update too often.  At least sitting on the table it does not.   Once I figure that code out, should be pretty fun to hook up to a battery and run around in the car with.

I started working on the Moving Map screen.   download free sectional charts from here.  http://www.chartbundle.com

Will probably just do a Direct to map function.   Probably the easier thing to do would be upload route from phone via bluetooth.  Why rewrite a bunch of code.

 

I also have ordered a couple of SDR for ADSB.  I wanted to make a radar screen that maps ADSB targets.  https://codepen.io/jackrugile/pen/wqLsn

 

 

 

 

[N201MKTurbo]

1 hour ago, Yetti said:

There is this to get the negative voltage.   https://electronics.stackexchange.com/questions/221398/negative-voltage-pwm

The raspberry PI GPIO only has 5 volts available for the PWM so it will be slow turns.  Have to check amperage for the TC.   Might have to drive an external PWM with the Rpi. with it's own circuit.

But if the Turn Coordinator receives +10 volts from the B11, it may make sense to just use a DPDT switch inline between the B11 and TC.   From above:   ( Pin 8 on gad to pin E on TC100EVT and pin 14 to pin F. Pin E and F are on the plug that went to the Brittain controll head and is now disconnected in my case. Pin F is the orange wire, pin E blue.  )

My biggest issue now is the "oncourse" from the GPS message does not update too often.  At least sitting on the table it does not.   Once I figure that code out, should be pretty fun to hook up to a battery and run around in the car with.

I started working on the Moving Map screen.   download free sectional charts from here.  http://www.chartbundle.com

Will probably just do a Direct to map function.   Probably the easier thing to do would be upload route from phone via bluetooth.  Why rewrite a bunch of code.

 

I also have ordered a couple of SDR for ADSB.  I wanted to make a radar screen that maps ADSB targets.  https://codepen.io/jackrugile/pen/wqLsn

 

 

 

 

Have fun. It sounds like you are on the right track.

[cliffy]

OK just a thought-

Where is the legality in all of the above "fun" :-)   

I would think your IA will have a heart attack when he sees what is now installed and flying. I don't think there is any way he could sign off the annual with that stuff installed. 

I know I'm throwing a wet towel on things but really, every flight with that stuff installed could be considered a separate violation as none of it has any approval basis. Unless I'm missing something like you've taken the airplane into full experimental status or something. 

What am I missing?

[Yetti]

We may have to take the Mooney to Experimental status to get the AML for the Skyview STC.

The GPS meets the TSO-129 requirements and can do RAIM

My day job is keeping small towns from getting blown off the map lots of DOT PHMSA regs in that too.

I can provide lots of other acronyms if you like. :-)

Edited June 16, 2018 by Yetti

[FBV]

My implementation would not be permanently installed. A single 2pin molex connector under the panel would be the only interface I need. VFR only. I would never trust this stuff with my life.


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[Yetti]

And even the "certified" Brittian B11 unit has a requirement to be turned off during take off and landing.

[HRM]

5 hours ago, cliffy said:

OK just a thought-

Where is the legality in all of the above "fun" :-)   

I would think your IA will have a heart attack when he sees what is now installed and flying. I don't think there is any way he could sign off the annual with that stuff installed. 

I know I'm throwing a wet towel on things but really, every flight with that stuff installed could be considered a separate violation as none of it has any approval basis. Unless I'm missing something like you've taken the airplane into full experimental status or something. 

What am I missing?

This is exactly why I am leaving the certified world for the experimental.

[Browncbr1]

Sorry, thought all this was documented in an old thread...  Haven't been too active on MS lately. 

 

set G5 to AC +/-15v signal  (.75 per degree, 3.75/5)

 

This works for the B-12 DG gain box and also for the B-818 HSI adapter box if you are upgrading to a G5 from an NSD360 or similar. 

Brittain G5 Dwg Rev A.pdf

Edited June 18, 2018 by Browncbr1

[Eric fddt]

I am planning to replace my attitude gyro with the G5 but would keep the DG so my Brittain autopilot would still work. Is this ok ?

If I was to have a DG malfunction in flight, can I expect to have my autopilot still running good with the GPS but not on the heading bug ?

[HRM]

29 minutes ago, Eric fddt said:

I am planning to replace my attitude gyro with the G5 but would keep the DG so my Brittain autopilot would still work. Is this ok ?

If I was to have a DG malfunction in flight, can I expect to have my autopilot still running good with the GPS but not on the heading bug ?

This is a good plan, but why not go dual G5's and eliminate vacuum instruments altogether? Just keep vac for the AP. If you lose it, it's just an inconvenience.

As for the DG connected to the AP, you need to look at the schematics to see how it connects. Because the AP has a separate HDG and TRK position, I'm inclined to think that the GPS would operate independent of the DG.

[Eric fddt]

1 minute ago, HRM said:

This is a good plan, but why not go dual G5's and eliminate vacuum instruments altogether? Just keep vac for the AP. If you lose it, it's just an inconvenience.

As for the DG connected to the AP, you need to look at the schematics to see how it connects. Because the AP has a separate HDG and TRK position, I'm inclined to think that the GPS would operate independent of the DG.

Since the G5 is not certified with the Brittain AP (from my understanding) I have to keep the DG connected to the AP in order for it to work on heading when I don't use the GPS.