VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   Electrical Systems (https://vansairforce.net/community/forumdisplay.php?f=43)
-   -   Electrical System Design and Build (https://vansairforce.net/community/showthread.php?t=152279)

leok 08-11-2017 07:04 PM

Quote:

Originally Posted by snopercod (Post 1195368)
I like how you approached this problem. Your diagrams were excellent! You must have been an engineer on the Space Shuttle program :o

Engineer yes, space shuttle no....

A few more years to retirement and the wife and I will be moving into your neighborhood. We will base out of KFQD (Rutherfordton Co).

tspear 08-11-2017 09:17 PM

Quote:

Originally Posted by leok (Post 1195406)
The E Buss bypasses the Master Relay and the VPX. Switch the E Buss on and the flight critical components are powered direct from the battery

I noticed that after; but I forgot to delete my post :o
You only had the first post up when I was reading/typing...

Very nice design. Curious, did you consider the Vertical Power PPS?

Tim

snopercod 08-12-2017 04:37 AM

Quote:

Originally Posted by leok (Post 1195408)
We will base out of KFQD (Rutherfordton Co).

Cool! I fly over there once in a while for lunch at 57 Alpha.

leok 08-12-2017 04:59 AM

Quote:

Originally Posted by tspear (Post 1195432)
I Curious, did you consider the Vertical Power PPS?

Tim

I don't really recall. I went to the VPX pro because of the number of outputs available. I knew I was going to have a rather large number of circuits.

It took me a while to comprehend all of the features. One of my favorites is the ability to reconfigure with the software. If I decide one of the instruments needs to be on say Avionics 1 instead of two, I just need to reassign the switch.

BillL 08-12-2017 06:51 AM

Maybe a little more specific question
 
Quote:

Originally Posted by tspear (Post 1195342)
What happens is the VPX dies?

Tim

Quote:

Originally Posted by leok (Post 1195406)
The E Buss bypasses the Master Relay and the VPX. Switch the E Buss on and the flight critical components are powered direct from the battery

Would/could a VPX failure take out both alternators?

Beautiful plan, thinking and execution. Made my head hurt just looking at it. I like the wiring harness layout. You must have experience in that arena, I could not get the lengths figured to do that and make all the wires go through the holes. :eek:

rv7charlie 08-12-2017 06:53 AM

Just a quick scan through the images, so I might have missed pertinent details...

Comment: If you lose the VPX, you likely lose both alternators. Question: How long will the battery last in IFR conditions (I didn't see pitot heat listed anywhere)?

Comment: Ebus is fed by #16, then #18 wire (I assume that protection devices aren't detailed). Question: Will #18 wire feed all the loads on the Ebus (including pitot heat (IFR) )?

Comment: Protection devices are drawn next to both alternator B leads. Question: Were they simply drawn next to the alternators for illustration convenience? (B lead protection should be at the battery end.)

Beautifully detailed docs. I wish I could force myself to document my wiring that clearly; my docs are basically a spreadsheet showing wire source>destination.

Charlie

Carl Froehlich 08-12-2017 07:11 AM

Quote:

Originally Posted by tspear (Post 1195342)
What happens is the VPX dies?

Tim

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

Carl Froehlich 08-12-2017 07:59 AM

Quote:

Originally Posted by rv7charlie (Post 1195475)
. SNIP
Beautifully detailed docs. I wish I could force myself to document my wiring that clearly; my docs are basically a spreadsheet showing wire source>destination.

Charlie

But - by far the most useful and practical approach. Knowing what is on every pin of each plug or connector is what I use for all building, maintenance and panel modification work. I add some detail on the spreadsheet on what wires are in what conduits but that is a simple list, not a diagram.

Carl

leok 08-12-2017 08:03 AM

Quote:

Originally Posted by BillL (Post 1195473)
Would/could a VPX failure take out both alternators?

I like the wiring harness layout. You must have experience in that arena, I could not get the lengths figured to do that and make all the wires go through the holes. :eek:

A total VPX failure would take out both alternators. I could add an independent back up field lead, but think I would rather get on the ground. The VPX has two separate internal busses. The alternator fields are fed from each side. So to take out both, it would need to be a failure that knocks both sides down. That also goes for radios and screens.

The E Buss wire feed is sized and fused for a 15 amp draw. Total draw on the E Buss as I have it is around 10 amps. Also the G5 has it's own battery. I can also manually dump additional load one device at a time if needed Total functional time to get on the ground? All depends on the battery size and state. Like I mentioned I might add another battery for voltage support during starting. I would likely tie that to starting and emergency use only through the switching in place. That would add additional duration to the E buss.

Some experience in wiring. I built two sand buggies from scratch. The wire harness was more of a modification as I used the donor motorcycle harness and accessories. I also took the G3X installation class from AEA. The ribbon trick was my way of taking correct measurements. I actually pulled it through the plane and taped it in position for each device.

leok 08-12-2017 08:18 AM

Quote:

Originally Posted by rv7charlie (Post 1195475)
Question: How long will the battery last in IFR conditions (I didn't see pitot heat listed anywhere)?


I'm not sure how log as I haven't done the calculations. At a 15 amp max draw, it should be long enough to get on the ground. Pitot heat is a VPX direct feed. If I lost VPX, I will loose pitot heat. Something I will have to think about. I am not a hard IFR guy, since my mission is retired pleasure travel, I am unlikely to be in the soup with freezing conditions. Good question.

Comment: Ebus is fed by #16, then #18 wire (I assume that protection devices aren't detailed). Question: Will #18 wire feed all the loads on the Ebus (including pitot heat (IFR) )?

It seams there is always a correction to the drawing I missed. Both wires were up sized to #14 with inline 15 amp blade fuses. It will cover all of the instruments, not Pitot heat. Again, I will need to consider that possibility. Thanks for the question.

Comment: Protection devices are drawn next to both alternator B leads. Question: Were they simply drawn next to the alternators for illustration convenience? (B lead protection should be at the battery end.)

Short answer is yes. Not installed yet, so advice is always welcome.

Beautifully detailed docs. I wish I could force myself to document my wiring that clearly; my docs are basically a spreadsheet showing wire source>destination.

Charlie

My docks have been an evolutionary process. They are all in a Power Point file (28 pages). I have no problem sharing the file. It might make a good base for someone with a similar instrument roster, or at least pieces to cut and paste.


All times are GMT -6. The time now is 03:17 AM.