Introducing the update of the Cessna 337 Skymaster

[captainjack]

Hello,
I am writing in November of 2016.
It seems that the last post in this thread was in 2014.
Is there still any interest in discussion about the 337?
Is anyone still here?
I love this aircraft, it is so skilfully created, exceptionally elegant in all of its presentation and behavior, and I hope to find others who are still interested in talking about it.
cj

[danten66]

I have to say that I love this plane and have a great time with it. If a paintkit was available I would probably make use of it

Thanks for putting this one together.

Dan

[Necolatis]

Found this by chance, dont know if it has useful info: https://ntrs.nasa.gov/archive/nasa/casi ... 010159.pdf

[FlyingHigh]

Hello,
I enjoy this aircraft very much, and I have made some updates to it.
I am wondering where to send my files and request for updates.

[wlbragg]

Can you provide a list of the updates?
If the original or current maintainer doesn't volunteer, I will volunteer to review the work and commit it to fgaddon.

[Catalanoic]

He was on the now offline ViveFG! spanish community, you can still reach him by mail, PM me if interested.

[FlyingHigh]

Can you provide a list of the updates?
If the original or current maintainer doesn't volunteer, I will volunteer to review the work and commit it to fgaddon.

Thank you.

I had contact with Nando a couple of weeks ago and he asked me if I could be a developer and I told him I could not be a developer because I do not know how to develop or program anything. I told him I only found a basic fix for the bus voltage bug that I hoped would be implemented as an update to the aircraft in the official hangar.

But since then I heard no response.

About the list of updates I propose:

If you run the Cessna 337G, you will notice a problem with the electrical system.
Bus zero and bus 1 voltages do not represent accurately the states of master switch, or alternator switche[s] (if engine[s]) are running). Of course, this bug propagates problems throughout the entire electrical system.

I propose a fix for that fundamental problem.

Before going any further, I hope you will run the aircraft and see if you notice the problem itself. Watch bus voltage properties especially in relation to the states of the master switch and the avionics master switch. Also watch the " volts" property in relation to the same.

If you can also see the problem, then I will be able to talk more about my proposed fix.

Thank you wlbragg!

FlyingHigh

[wlbragg]

Thanks FlyingHigh, I will take a look at this and see if I can verify your observations.

[wlbragg]

I'm not sure I am seeing what you are.
This is what I see when switching from bat to alt



The gauges correspond to the properties. Can you be a little more specific? By buss 1 and 2 are you referring to bat and alt?

I re-read your post and it is true the "avionics" switch appears to have no effect on the amp flow. It appears to only be tied to the radio stack as well.

None of the breakers are active so I assume this electrical buss is still a work in progress.

[wlbragg]

I looked at the electrical code and I am curious to know what you have in mind. I am not totally familiar with how this all works internally. But I have worked on the c173p electrical which is more advanced than the 337 so I am guessing I could get around in this.
I don't know if these electrical connections and linkages are finished or complete. They appear to be missing some components or I think you would at least see the amp meter respond to power needs.
I see no nasal or system xml that is manipulating all the inputs and outputs. So again, it appears to me this was a work in progress.

Code: Select all

<?xml version="1.0"?>
 
   <!-- 28 Volt electrical system -->

<PropertyList>

   <!-- SUPPLIERS -->

<supplier>
   <name>Battery 1</name>
   <prop>/systems/electrical/suppliers/battery[0]</prop>
   <kind>battery</kind>
   <volts>28</volts>
   <amps>17</amps>
</supplier>

<supplier>
   <name>Alternator 1</name>
   <prop>/systems/electrical/suppliers/alternator[0]</prop>
   <kind>alternator</kind>
   <rpm-source>/engines/engine[0]/rpm</rpm-source>
   <volts>28</volts>
   <amps>60</amps>
</supplier>

<supplier>
   <name>Alternator 2</name>
   <prop>/systems/electrical/suppliers/alternator[1]</prop>
   <kind>alternator</kind>
   <rpm-source>/engines/engine[1]/rpm</rpm-source>
   <volts>28</volts>
   <amps>60</amps>
</supplier>

<supplier>
   <name>External 1</name>
   <prop>/systems/electrical/suppliers/external[0]</prop>
   <kind>external</kind>
   <volts>0</volts>
   <amps>0</amps>
</supplier>

   <!-- BUSSES -->

<bus>
    <name>Main Bus</name>
    <prop>/systems/electrical/outputs/bus[0]</prop>
</bus>

<bus>
    <name>Avionics Bus</name>
    <prop>/systems/electrical/outputs/bus[1]</prop>
</bus>

   <!-- OUTPUTS -->

<output>
   <name>Starter 1 Power</name>
   <prop>/systems/electrical/outputs/starter[0]</prop>
</output>

<output>
   <name>Starter 2 Power</name>
   <prop>/systems/electrical/outputs/starter[1]</prop>
</output>

<output>
   <name>Cabin Lights Power</name>
   <prop>/systems/electrical/outputs/cabin-lights</prop>
</output>

<output>
   <name>Instrument Power</name>
   <prop>/systems/electrical/outputs/instr-ignition-switch</prop>
</output>

<output>
   <name>Fuel Pump Power 1</name>
   <prop>/systems/electrical/outputs/fuel-pump[0]</prop>
</output>

<output>
   <name>Fuel Pump Power 2</name>
   <prop>/systems/electrical/outputs/fuel-pump[1]</prop>
</output>

<output>
   <name>Landing Light Power</name>
   <prop>/systems/electrical/outputs/landing-light</prop>
</output>

<output>
   <name>Beacon Power</name>
   <prop>/systems/electrical/outputs/beacon</prop>
</output>

<output>
   <name>Flaps Power</name>
   <prop>/systems/electrical/outputs/flaps</prop>
</output>

<output>
   <name>Turn Coordinator Power</name>
   <prop>/systems/electrical/outputs/turn-coordinator</prop>
</output>

<output>
   <name>Map Lights Power</name>
   <prop>/systems/electrical/outputs/map-lights</prop>
</output>

<output>
   <name>Instrument Lights Power</name>
   <prop>/systems/electrical/outputs/instrument-lights</prop>
</output>

<output>
   <name>Strobe Lights Power</name>
   <prop>/systems/electrical/outputs/strobe-lights</prop>
</output>

<output>
   <name>Taxi Lights Power</name>
   <prop>/systems/electrical/outputs/taxi-lights</prop>
</output>

<output>
   <name>Pitot Heat Power</name>
   <prop>/systems/electrical/outputs/pitot-heat</prop>
</output>

   <!-- AVIONICS OUTPUTS -->

<output>
   <name>ADF Power</name>
   <prop>/systems/electrical/outputs/adf</prop>
</output>

<output>
   <name>Audio Panel 0 Power</name>
   <prop>/systems/electrical/outputs/audio-panel[0]</prop>
</output>

<output>
   <name>Audio Panel 1 Power</name>
   <prop>/systems/electrical/outputs/audio-panel[1]</prop>
</output>

<output>
   <name>Autopilot Power</name>
   <prop>/systems/electrical/outputs/autopilot</prop>
</output>

<output>
   <name>Avionics Fan Power</name>
   <prop>/systems/electrical/outputs/avionics-fan</prop>
</output>

<output>
   <name>DME Power</name>
   <prop>/systems/electrical/outputs/dme</prop>
</output>

<output>
   <name>HSI Power</name>
   <prop>/systems/electrical/outputs/hsi</prop>
</output>

<output>
   <name>NAV 0 Power</name>
   <prop>/systems/electrical/outputs/nav[0]</prop>
</output>

<output>
   <name>NAV 1 Power</name>
   <prop>/systems/electrical/outputs/nav[1]</prop>
</output>

<output>
   <name>Transponder Power</name>
   <prop>/systems/electrical/outputs/transponder</prop>
</output>

   <!-- GENERAL CONNECTIONS -->

<connector>
   <input>Battery 1</input>
   <output>Main Bus</output>
   <switch>
      <prop>/controls/engines/engine[0]/master-bat</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Alternator 1</input>
   <output>Main Bus</output>   
   <switch>
      <prop>/controls/engines/engine[0]/master-alt</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Alternator 2</input>
   <output>Main Bus</output>
   <switch>
      <prop>/controls/engines/engine[1]/master-alt</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>
<!--
<connector>
   <input>External 1</input>
   <output>Main Bus</output>
</connector>
-->

   <!-- MAIN/AVIONICS BUS CONNECTION (AVIONICS POWER) -->

<connector>
   <input>Main Bus</input>
   <output>Avionics Bus</output>
   <switch>
      <prop>/controls/switches/master-avionics</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

   <!-- MAIN BUS CONNECTIONS -->

<connector>
   <input>Main Bus</input>
   <output>Starter 1 Power</output>
   <switch>
      <prop>/controls/engines/engine[0]/starter</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Starter 2 Power</output>
   <switch>
      <prop>/controls/engines/engine[1]/starter</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Cabin Lights Power</output>
   <switch>
      <prop>/controls/circuit-breakers/cabin-lights-pwr</prop>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Fuel Pump Power 1</output>
   <switch>
      <prop>/controls/engines/engine[0]/fuel-pump</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Fuel Pump Power 2</output>
   <switch>
      <prop>/controls/engines/engine[1]/fuel-pump</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Landing Light Power</output>
   <switch>
      <prop>/controls/switches/landing-light</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Beacon Power</output>
   <switch>
      <prop>/controls/switches/flashing-beacon</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Flaps Power</output>
   <switch>
      <prop>/controls/circuit-breakers/flaps</prop>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Turn Coordinator Power</output>
   <switch>
      <prop>/controls/circuit-breakers/turn-coordinator</prop>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Map Lights Power</output>
   <switch>
      <prop>/controls/switches/nav-lights</prop>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Instrument Lights Power</output>
   <switch>
      <prop>/controls/circuit-breakers/instrument-lights</prop>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Strobe Lights Power</output>
   <switch>
      <prop>/controls/switches/strobe-lights</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Taxi Lights Power</output>
   <switch>
      <prop>/controls/switches/taxi-lights</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

<connector>
   <input>Main Bus</input>
   <output>Pitot Heat Power</output>
   <switch>
      <prop>/controls/switches/pitot-heat</prop>
      <initial-state>off</initial-state>
   </switch>
</connector>

   <!-- AVIONICS CONNECTIONS -->

<connector>
   <input>Avionics Bus</input>
   <output>ADF Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>Audio Panel 0 Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>Audio Panel 1 Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>Autopilot Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>Avionics Fan Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>DME Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>HSI Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>NAV 0 Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>NAV 1 Power</output>
</connector>

<connector>
   <input>Avionics Bus</input>
   <output>Transponder Power</output>
</connector>

</PropertyList>

[FlyingHigh]

Hello Wlbragg and happy new year, thank you for looking into the problem.
I was inaccurate in my description, this post is more specific. I tried to add images but I don't know how to do that yet.

You are correct, "systems/electrical" does not show any problems, my error.

The problem can be seen in "systems/electrical/outputs/".
There are 2 buses listed there, "bus" is the main bus and "bus[1]" is the avionics bus.

If you watch the two bus voltages under "systems/electrical/outputs" and follow these steps, you should be able to see the problem:

1. At cold start, all is well. Master switch and avionics master are off, the buses show no voltage.
2. Turn on the master switch, all is well, main bus shows voltage, avionics bus does not.
3. Turn on the avionics master switch, all is well, the avionics bus shows voltage and the avionics stack comes alive.
4. Here is where the problem begins to appear. Turn off the master switch, both buses should return to zero volts, yet both buses still show voltage, and the avionics stack stays on.
5. Turn off the avionics master switch, the avionics bus voltage stays on, but the avionics radios turn off.
6. Turn on the avionics master switch again, nothing changes, the avionics stack stays off yet the avionics bus still carries voltage.
7. Turn on the master switch. The avionics stack radios turn on.
8. You are now back at step 4.

I'm interested to see if you notice the same and to hear any thoughts about it.

FlyingHigh

edit to add p.s.: I looked through the xml code you posted, it seems the avionics bus is connected properly to the main bus by the avionics master switch. I think this is a work in progress too, it does not attempt to model battery drain or recharge, etc.
But even without that modeling, the bus voltage should respond properly to the states of the master and avionics master switches, yet they don't. I'd like to try to fix that so I can then fix some other difficulties with the electrical system. This problem here seems to be a root level problem. Thanks again!

[wlbragg]

Yes, I see the same. I would like to know what your fix is?
Beware, turning the master "bat" off and leaving an alternator in-line should also cause the power to not be turned off. But the fact is even when you turn off both the front and rear alternator circuits and the bat, you still get power, which is not correct

[FlyingHigh]

Right, the buses stay alive even when they shouldn't. I'm not even considering the alternators yet, because at this point the problem is evident even with the engines off/alternator switches off.

I tried to fix this in nasal with simple listeners and setprops, but it didn't fix anything.

My solution that fixed everything at once was not my solution at all, but the electrical system of Gary Neely (aka 'Buckaroo'). I didn't understand his nasal code at all, but once I installed his system per his instructions, the problem was solved immediately and I could move on to other issues in the 337G.

His system does not simulate battery drain or recharge, given, but it is not designed to do that. And anyway, neither does the current 337G system simulate those things.

If Neely's system is installed as a stop-gap measure, at least the root problem is fixed until a different solution can be discovered and programmed.

As for me, I would like to try to make the 337G's electrical system from scratch, but I am already stuck at this root problem.

For the life of me, I cannot figure out why these buses continue to cary voltage when their controlling switches are off.

Thoughts?

[wkitty42]

obviously whatever is supplying the voltage is not monitoring those switch properties like it should be... you need to find where that voltage is being put into the system and make it follow the switches instead of being "true" all the time...

[FlyingHigh]

Hello Wkitty, thanks. I'm searching for the source of that voltage.
From the xml file I see that the battery is properly declared and attached to the main bus by the master switch.
That seems correct to me.
What is odd is that the master switch, if turned on, pass voltage to the bus. But if turned off, it will not cut the voltage.
That is what is so strange. It is as if the master switch is being honored only halfway.
I tried using simple nasal to get the buses to behave according to the switches, but it did not work.
It's still a mystery to me, still searching for the answer.