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  #31  
Old 08-12-2017, 12:57 PM
leok leok is offline
 
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Location: Clarkston, MI
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Default Thanks for the compliment

Quote:
Originally Posted by Carl Froehlich View Post
This is the single point failure risk you accept when using a VPX type approach, While this design takes great steps to add other means to mitigate this risk, it is still there.

This is a very through design if the builder insists on using a VPX. The wire harness design and fabrication is in a class all by itself. As with all such builder choices, decide on one that you most comfortable. I fly with what I consider a simplier, cheaper and more robust design. It has proven it value to me and other builders over the last 16 years or so.

Carl
Thanks for the compliment.

As for the VPX choice, I understand where you are coming from. Although I believe simple, cheaper and more robust can be argued from both sides with reasonable merit. It also depends on the specific installation and how well all of the design goals are supported.

As you kindly mentioned, I spent a lot of thought on how to mitigate the weaknesses I perceived in using the VPX. On the other side sales literature provides the benefits for anyone to see.
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  #32  
Old 08-12-2017, 05:24 PM
TFeeney TFeeney is offline
 
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Location: Lafayette, IN
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Very nice write up. I'm through the paper planning portion and I can attest to the many iterations in Excel/Powerpoint that you mentioned. Every time I look at it there's another mistake I find. You've done a ton of homework here that will really pay off - and definitely help others in the future as well.

At the end though, what has me the most nervous up to this point is the ribbon/tape layout you did on the bench. I've got a mockup of cardboard, but I wonder how accurate the measurements you took have to be?

After all the work to create a beautiful harness, I can see myself installing on the airplane and being 1/2 inch short on one connector. I understand the concept of service loops, but can you explain how you incorporated them - I think the slack in the system is my answer, but I can't visualize it in the picture below.

Quote:
Originally Posted by leok View Post
Wire Harness Fabrication

Using the diagrams and lists compiled I made full size foam replicas of each instrument and placed them with double stick tape in the plane where I wanted to mount them. I was particularly careful to place them where I could access the connectors for maintenance and there were no interferences.

I taped a flat ribbon to each box and along the routing I had determined for the main wire harness. I made sure each branch to an avionics box had a service loop as needed. Once completed, I removed, measured and made a diagram of the wire harness.



I used blue tape to lay out the harness on my work table. I placed a nail at each junction and corner to create the entire wire harness diagram in full scale. Next using spring clamps to hold the wire ends, I laid each wire from the pin out diagrams in place. I used blue tape to temporarily label both ends of each wire.



VERY IMPORTANT for a nice clean job… Once all wires are in place, lace the wires starting at the main trunk and working out each branch. The wires will move as they are laced. You only want to trim the ends to the same length once after everything is laced nice and tight. Lacing knots are available in several locations, so I will not cover them here.
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  #33  
Old 08-12-2017, 05:24 PM
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snopercod snopercod is offline
 
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Location: Asheville, NC
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I may have missed it, but your ELT will have a (2-cond?) cable to both an audio alert device (I mounted mine behind my head where I might be able to hear it), and a panel-mounted switch/light panel. Both of those need to be accessible because they contain batteries. The buttons/light on the panel are so you can test the unit every three months, and also activate it in case of impending doom.

Again, I may have missed it, but you'll definitely want some USB outlets for battery-powered "stuff".

You'll also want some way of charging your batteries if you're not going to be flying for a while. I have a Cigarette lighter plug for that purpose wired directly to the battery through a 20A 3AG fuse.
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  #34  
Old 08-12-2017, 06:33 PM
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Tommycat Tommycat is offline
 
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Location: North-western Illinois
Posts: 67
Default Helpful?

Hi leok,

Contactor/relay coil diodes required? (voltage spike drain.)

Termination location of the annunciator sensor wire at the starter contactor. (12VDC +)

Resistor in the annunciator sensor wire circuit? (Near the starter contactor.)


Best regards,
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  #35  
Old 08-12-2017, 07:06 PM
leok leok is offline
 
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Location: Clarkston, MI
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Quote:
Originally Posted by TFeeney View Post
At the end though, what has me the most nervous up to this point is the ribbon/tape layout you did on the bench. I've got a mockup of cardboard, but I wonder how accurate the measurements you took have to be?

After all the work to create a beautiful harness, I can see myself installing on the airplane and being 1/2 inch short on one connector. I understand the concept of service loops, but can you explain how you incorporated them - I think the slack in the system is my answer, but I can't visualize it in the picture below.
I used ribbon because it was at hand and easy to tape together. It is the 1/4" kind that makes curly decorations. I taped the ribbon in the location I wanted the main harness section first. That's the part where everything else branches off. Next I taped in position lengths of ribbon where I envisioned a branch coming off. For the service loop, as an example, I plan on servicing everything through the PFD/MFD hole. They will need to be easily removed. So I need a branch that not only reaches the device, but allows me to remove the PFD and put it away far enough to get at the connectors in the back. No crawling under the panel to disconnect the connectors.

Once I have enough length to reach the component, then I allow enough slack to move the component into a position to access the connectors. I then clipped the ribbon to length and taped it to the back of the mock device. I also taped the ribbon in the position I intended to route/fasten the harness permanently.

Some components needed service loops, some only comfortable slack to allow the connectors movement during service. Once I had the entire harness made of ribbon complete, I pulled it carefully out and measured it. What you see in the diagram is the actual length of the ribbon between branches and to each device including the service loop length.
I had tried to measure with a tape measure before I hit on this method, and well, it would have been an expensive mistake .... lots of incorrect measurements.

I also purposely went a little on the long side any time I wasn't positive of the position or routing. Easy to cut, impossible to lengthen. Everything fit well in the end
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  #36  
Old 08-12-2017, 07:31 PM
leok leok is offline
 
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Location: Clarkston, MI
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Quote:
Originally Posted by snopercod View Post
I may have missed it, but your ELT will have a (2-cond?) cable to both an audio alert device (I mounted mine behind my head where I might be able to hear it), and a panel-mounted switch/light panel. Both of those need to be accessible because they contain batteries. The buttons/light on the panel are so you can test the unit every three months, and also activate it in case of impending doom.

Again, I may have missed it, but you'll definitely want some USB outlets for battery-powered "stuff".

You'll also want some way of charging your batteries if you're not going to be flying for a while. I have a Cigarette lighter plug for that purpose wired directly to the battery through a 20A 3AG fuse.
Snooper,

I managed to leave off the ELT remote test and activation that is in the IP. So yup, got that covered. The ELT has RS232 into the GTN650 as well. No audio that I have been able to identify.

I have 6 USB ports, 3 front and 3 back. They don't show on the drawings because I have them on a sub-buss with direct battery feed. I'm not sure if I want to leave them there for two reasons 1) When on E Buss power they are another drain on the battery if not watched. 2) could be used too extensively when on the ground draining the battery. Still thinking on that one.

For external charging I have a 'power-let' plug. Basically a motorcycle power jack that will allow up to 20 amps in/out direct to the battery. I found it after the main power distribution drawing was complete and I forgot to add it in.

Thank you for the significant thought and great questions. I will add this stuff to the drawings. We used to call these "as Builts" in the old construction days.
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  #37  
Old 08-12-2017, 07:43 PM
leok leok is offline
 
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Location: Clarkston, MI
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Quote:
Originally Posted by Tommycat View Post
Hi leok,

Contactor/relay coil diodes required? (voltage spike drain.)

Diodes are installed. Wow, you guys are good at picking out details!! I will add them the the drawings

Termination location of the annunciator sensor wire at the starter contactor. (12VDC +)

VPX provides that with a wire from the starter relay direct to connector-pin, J2-11. Again I will add to the drawing.

Resistor in the annunciator sensor wire circuit? (Near the starter contactor.)

1 K ohm resistor is installed

Best regards,

Once again, I appreciate the comments and questions.
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  #38  
Old 08-13-2017, 05:27 AM
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snopercod snopercod is offline
 
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Quote:
Originally Posted by leok View Post
We used to call these "as Builts" in the old construction days.
I know all about those from my power plant days. Red to add and green delete...or was it the other way around

Regarding the USB ports, I use a plug-in USB charger to charge my Stratus 2 after I shut down. I plug the charger into my single Cigarette lighter plug. If I leave it overnight, there is no problem draining the battery. But if I leave it for several days, it does drain the battery a little. Also, I think if you are using built-in USB charger(s), they're going to draw some current even if nothing is plugged into them. I'm thinking you might want to run those directly from the battery through a normally-off switch. If you needed to charge something overnight, you would turn on the switch.

Edit: I used small 18V MOVs across all switches, and larger ones across the starter and master relays. I also used snubbing diodes across the relay coils.
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Last edited by snopercod : 08-13-2017 at 05:33 AM.
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  #39  
Old 08-14-2017, 07:26 PM
leok leok is offline
 
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Quote:
Originally Posted by snopercod View Post
Regarding the USB ports, I use a plug-in USB charger to charge my Stratus 2 after I shut down. I plug the charger into my single Cigarette lighter plug. If I leave it overnight, there is no problem draining the battery. But if I leave it for several days, it does drain the battery a little. Also, I think if you are using built-in USB charger(s), they're going to draw some current even if nothing is plugged into them. I'm thinking you might want to run those directly from the battery through a normally-off switch. If you needed to charge something overnight, you would turn on the switch.

Edit: I used small 18V MOVs across all switches, and larger ones across the starter and master relays. I also used snubbing diodes across the relay coils.
My thoughts are running along the same path for the USB outlets. I have two triple 2.4 amp outlets installed.
You had me on the MOVs. I had to google that term and read up (metal oxide varistor for those in the same boat as me) I did not know anything about how they functioned until I read up. I think you must have a background in electronics, or at least a hobby.

Thanks once again for helping me learn a bit!
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  #40  
Old Yesterday, 10:39 PM
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MCA MCA is offline
 
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Wow! Nice job with everything. You'll enjoy both the RV-10 and the VP-X!
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