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prkaye

Well Known Member
Since I've never done anything more than replacing a battery in my car, I've been wondering how I'm going to obtain the knowledge required to design my RV electrical system. I've read most of "The Aeroelectric Connection" by Bob Nuckoll's, but this is mostly in-depth discussions about specific components (whole chapters on antennas, switches, batteries, etc).
I've examined electrical system diagrams of a couple of other builders, and much of what i see baffles me. I don't need another introduction to electricity... i know the basics of electronics theory (i know ohm's law, i know what resistors capacitors and inductors do, i know about reactance and resistance and impedance...), what I do need is a good introduction to how the overal system is laid out for a typical RV electrical system. What the main parts are and how they all fit together. Something maybe that goes through from the simplest electrical system diagram, to progressively more complex systems, explaining how to interpret the diagrams and what everything on them means and why all the components are where they are in the system.
Anybody have a good reference for this?
 
Phil, Get a copy of Tony Bingelis' "Firewall Forward", "Sportplane Construction Techniques" and "The Sportplane Builder". He goes through some good basic electrical systems. Bob Nuckolls has some good stuff, but in my opinion goes WAY overboard on emergency backup and redundant systems. There is no need for much of this in a basic homebuilt aircraft. KISS!
(Donning flame suit now.)
 
EAA SportAir Workshops

I took the SportAir workshop on Electrical and Avionics. It was a 2-day workshop, with about 20 builders. It was hands-on, and very worthwhile. I would highly recommend it.
 
Canada

Unfortunately, I live way up in Ottawa Canada, so most of these workshops aren't convenient to get to. The closest US city is Watertown NY (2.5 hour drive).
 
I second the idea of Tony Bingellis's books Phil - they show some very basic electrical systems that can help you think "from the ground up". Knuckool's book is good, but not really organized to help someone understand the systems in a building block fashion.

Paul
 
Mostly there!

Hi Phil,
It sounds like you are most of the way to where you want to get! If you understand all the basics, the only real trick is to understand the current demands of the equipment you are going to install and any interconnect wiring between radio's and indicators etc. The schematics at the back of Bob's book are pretty easy and they progress from the simplest to the more complicated. So... write down everything electrical that will be in your plane including lights, seat warmers, whatever. Start to draw simple interconnect drawings between the radio's and the indicators (localizer glideslope what ever you plan to use). Make the big decision on fuses or breakers (that usually will start a war of words but it is a personnal choice). Pay attention to any leads that need to be shielded for noise attenuation (ARINC OBS pots, mike audio etc. and never ground the shield at both ends!) Continue to refine your system drawing until you have a set of drawings that will lead you thru the wiring process. In my humble opinion, paying attention to grounding and shielding is the biggest part of the job. You can always ask for help here! If you have any other questions just ask!

Paul Czarapata (yes I'm an EE)
N694BP reserved
 
thanks

Thanks guys,

I do have the Bingellis books, so I'll take another look. I do recall I wasn't
satisfied with his book on engines. It seemed to be a collection of tips for installing various things, but not a good overview/introduction of how the engine and all it accessories work together.

I've been looking at electrical drawings of one builder. I understand that the "main bus" is basically to distribute power to everything. I gather that the "essential bus" is a separate strip for things that you can't afford to lose. Each instrument/light/radio/etc only gets powered off one of the buses, is that right? Or is the idea that only one of the buses is "on" at a given time, and essential things are normally powered by the main bus, but you switch to the essential bus if you need to conserve power?

Then, what is the "Battery hot bus" ?
 
Appendix

Actually, I just looked at Appendix Z of The Aeroelectric connection book, and this looks like it will help a lot! Curious that this is the appendix, and not an introductory chapter (after getting all the way through to the chapter on Antennas, I had basically given up that htis book would give me the bigger-picture overview stuff... but there it is in the appendix). I'm travelling for the rest of the week, so I'll read this appendix and look at the example schematics while i'm away and see where i get from there.
 
Read it cover to cover!!

Phil, Aerolectric Bob has written a very good book, it starts out explaining how, and what and why various things do what they do. Once you have the basics figured out, it becomes much easier to understand the whole system.

I almost answered your first post, because it sounded like you hadn't read the entire book, now after your last post, it seems like I was correct.

The book is quite amazing in the depth of information presented, and (in my opinion) is designed to get you up to speed on electrical stuff so you can take the examples provided, and make informed adaptions as needed to fit your particular need.

Of course, you can just pick a specific example of a system, and copy it, but it would be an incredible long shot if it was exactly what you actually need. There are just too many variables to try to make a "one size fits all" wiring diagram.

Good luck,
 
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was not slamming bobs book

Mike, I wasn't slamming Bob's book. Of course, it is a very good book. I have indeed read most of it - i just didn't read the appendix (appendices are often skipped by readers of books). I was merely asking for advice on what ELSE I could read to give me the big picture that I didn't get from the book. I've been looking at the schematics in the appendix, and there are still some things that I don't understand. I think these schematics could benefit from a more in-depth discussion accompianying them (more than just the numbered notes provided).
I have written a textbook myself ("An Introduction to Quantum Computing" - Oxford University Press), and so I know how big a challenge it is to write a good book. My own book could use MANY improvements, and as you say, it's impossible to write the perfect book for all audiences. That's why I was inquiring about other references to help fill the gaps for me.
 
I agree, Phil, that Bob Nuckoll's book is not the best at explaining things electrical to a novice, and I have read the entire book a couple times. (And this coming from someone with a PhD!) A couple experienced builders commented to me that there is far more in Nuckoll's than you'll ever need to build your plane, and to not get lost in all the extra things that are not entirely relevant to your a/c but will nonetheless confuse you. I also agree that Bingelis is a good primer upon which Nuckoll's becomes more useful. I know this goes against the conventional wisdom on this forum, where it seems like everyone worships Bob, and I'm not knocking his book, but just wanted to let you know that you're not alone in remaining confused after you read it.

BTW, Van's has a very good electrical diagram for a basic VFR ship that sometimes get's overlooked in our drive to make everything as complex, and "leading edge" as possible. It's worked on their planes. Whatever system you choose, make sure you understand it completely. I would argue that a simple system that you completely understand, whatever its limitations, is better than a system with all the bells and whistles that you don't understand. I think this is especially true for the pilot who is also the builder/maintainer.

Good luck.
 
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DVD may be coming

Hi,

You may want to contact SteinAir up in Minnesota. They are supposed to be coming out with a two or three part DVD series on how to wire an airplane (they hold classes from time to time, but this is for those who live far away from the area). It sounds like they'll start with the REAL basics and then go from there. I told them I'll buy it as soon as they get it out (which may be some time since they just got done with Oshkosh).

Like you, I was baffled by (no, not the baffles . . ) but wiring this beast. I've trudged through the learning process, using the same books you have, and agree with your thoughts on these books. Trust me, take it one step at a time, and it will start to make sense.

I'm convinced anyone who could write a good, "cut to the chase" book on wiring could make a bundle. Every book seems to come up short. I like Bob Knuckolls book, but think it goes WAY overboard into things most of us don't care about (like how to make testing gizmos). All the stuff is there, but you (in my opinion only) have to filter through a LOT of stuff to get the things we need. I'd rather have a really good description on how to terminate a COAX cable, as opposed to knowing the 50 year history and theory of same. To his credit, i think he has a great amount of basic "how to" procedures on the internet (In fact, I think I use these more than the book when it comes down to the "how to" aspect of wiring).

Hope this helps . . .
 
prkaye said:
Mike, I wasn't slamming Bob's book. Of course, it is a very good book.
Click to expand...

Phil, I wasnt saying you were slamming it-------sorry if it came over that way.

What I was trying to impart is the same as "alpinelakes---" said........"Whatever system you choose, make sure you understand it completely. I would argue that a simple system that you completely understand, whatever its limitations, is better than a system with all the bells and whistles that you don't understand."

Bobs book does get into stuff that is a bit out in left field, but it provides a really good foundation for someone trying to understand what is going on------and why.

IMHO, understanding is essential to creating a good system.

Good luck, eh
 
Quantum Computing for dummies???

Man, if the author of a book on Quantum Computing is intimidated by wiring an airplane, I don't feel so bad. I'm working my way through Aeroelectric Connection and find it difficult to know which details are relevant to my plans. In the mean time, I'm just focussing on the metal work that I used to think would be hard.

I thought that having done a bunch of wiring in my house might make me feel better, but then just the other day some lights I had installed a few years ago randomly turned off, then a few seconds later turned back on. I turned to my wife and said, "that's why wiring my plane freaks me out!"
 
intimidating

Everything, including quantum computing, is intimidating until you understand it! I'm sure once I figure out how the battery, alternator, buses, starter, voltage regulators etc etc all fit together, it'll seem like child's play. But until then, it's as mysterious as quantum mechanics!
 
My Heresy

I certainly support all the helpful suggestions others made above. I just have one more: consider purchasing the Van's wiring harness for your airplane. You get diagrams, too. I made small, inconsequential changes but kept the basics. It seems to work fine and a lot of terminals and labels were done quite well. It didn't even feel like cheating, much.
 
what is that exactly... "wire harness", in this context? In only familiar with the "wire harnesses" used to connect car stereos to the speaker and power wires. Do they just mean they provide all the wires with terminals already attached? They provide the strips for the buses and grounding as well?
 
Hi Phil.
Unfortunately, there is no substitute for figuring this out on your own. The cited references are useful, and local help (your EAA or RAA chapter) should be available.

There are only a couple of tables you need to master in AC43.13 -- the wire gauge chart and the fuse (cb) table. That will establish your wire sizes and breaker ratings. Review the grounding techniques as well (the ones with the types of washers called out).

All wires downstream of the cb must be the designated gauge or fatter. If you have more than one instrument or circuit feeding off of one cb, make sure you consider the failure scenario. You are better off feeding redundant circuits off seperate breakers (such as engine monitor and fuel gauges off different breakers).

You don't have to wire the avionics yourself... there are several good sources for panel wiring on the internet. You will have to wire the firewall-forward and main airframe circuits, however. Start with the battery-alternator-master bus wiring design. Then, figure out your big power consumers ( landing/taxi lights, nav lights, cabin lights, strobes, pitot heat etc, flaps, fuel pump.). Run the wires for all this stuff prior to closing up the wings/fuselage. Leave big service loops for now behind the panel area and wing roots for later connection. Don't forget the antenna wire (RG-400 coax).

Your avionics/panel supplier will ask you to provide the master bus wire (fat), and connections to all of the stuff mentioned above, plus you will probably need to connect in the engine sensors (egt, cht, amps, fuel p, oil p, oil t) that are provide by the engine monitor vendor.

If you are not comfortable with the basic airframe wiring, don't attempt to wire up your own panel. There a lot more wires on the panel with specific requirements that need you to digest a lot of manuals and perfect your wiring techniques. Leave this for the panel builders. Establish a relationship with one of the electrical component/tool suppliers (my favourite has been Steinair since it was an infant).

Finally, cheat: Copy someone else's design, modify it to taste. Do this before you ever run a wire, and have a local 'expert' review it with you. You will learn a lot this way.

You may be beyond the basics (you know Ohm's law), but I published a 3-part training program here that you can review. I can also send you a complete schematic for my RV-9A if you wish (in either pdf format or editable using expresspcb.) That way you can steal all of the ideas that you want, for free!

Vern
 
alpinelakespilot2000 said:
BTW, Van's has a very good electrical diagram for a basic VFR ship that sometimes get's overlooked in our drive to make everything as complex, and "leading edge" as possible.
Click to expand...

I'd like to see this wiring diagram...can you provide a link to it or tell me where to find it? I'm pretty sure it's not in the builder's manual. Thanks!
 
Here's a suggestion when trying to understand Bob's 'Z' diagrams. Get yourself about 5-6 highlighter pens and print out the diagrams (enlarged if possible). Use seperate colors to highlight different portions of the diagram. It then gets much easier to understand how it all works.

100_0825.jpg
 
lostpilot28 said:
I'd like to see this wiring diagram...can you provide a link to it or tell me where to find it? I'm pretty sure it's not in the builder's manual. Thanks!
Click to expand...
Check your preview plans, section 5 (building practices) I think. It's in there (or at least was back when I got mine in 2005). If for some reason your's doesn't have it, let me know and I can try to scan mine and send it to you.
 
one approach

I had some of the same concerns about how to go about the electrical and ended up doing the following:
1. Read Bob's book cover to cover
2. Picked the Z11 Drawing as the basic drawing, alos studied the Vans electrical schematic and the drawings on the F1 Rocket website
3. Selected the equipment fit for my plane (dual dynon, 496, SL30, GTX 327, 0-360 with dual mags, etc)
4. Scanned the Z11 into my computer and modified it based on my equipment fit, then had it blown up at Kinko's (multiple copies) and made lots of notes on the drawing
5. Downloaded or asked in this forum for copies of installation manuals for each piece of equipment
6. Copied all the connection diagrams and connector diagrams in the manuals and put them in a loose leaf binder, then built a spreadsheet and made a wirelist from each connector pin to its respective connector and pin
7. Ripped off Vern Littles electrical schematic (and others) to study and modify mine as necessary
8. Drew a few subsystem diagrams for such thing as wig-wag circuit to get the connections correct
9. Went for fuse blocks rather than CB's to simplify the wiring somewhat, ended up with a total of 8 switches and one CB on my panel (used some of the dual function switch layouts defined in the aeroelectric switch section for nav/strobe etc to reduce switch count)
9. Bought prefabbed harnesses for the avionics wherever possible
10. Asked a bunch of questions on this and other forums about layout and wiring runs etc

So far so good and interestingly enough as I went along more of the system started to make sense and I made small adjustments to my schematic to suit my preferences. I am not finished yet and i am sure I will have to make some changes but it is proving somewhat easier than I first thought.
Hope this helps.
 
Quick build wiring system

Take a look at the Vertical Power system. http://www.verticalpower.com

It simplifies the wiring - the bus architecture is much simpler, as well as the wiring itself. We're also here to help you through the installation, and there is some good info on the documents page http://www.verticalpower.com/documents.html - including generic information that should be helpful regardless of what approach you take. ;)
 
Good documents, worth checking out...

MCA said:
......
http://www.verticalpower.com/documents.html - including generic information that should be helpful regardless of what approach you take. ;)
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Marc,
These documents should be really useful and answer questions many new builders have.

All about contactors....
http://www.verticalpower.com/docs/Contactor_Wiring.pdf

How to connect connectors
http://www.verticalpower.com/docs/Connector_Service_Manual.pdf

Thanks for publishing them...

gil in Tucson
 
K.I.S.S. and basics

az_gila said:
Marc, These documents should be really useful and answer questions many new builders have.

All about contactors....
http://www.verticalpower.com/docs/Contactor_Wiring.pdf

How to connect connectors
http://www.verticalpower.com/docs/Connector_Service_Manual.pdf

Thanks for publishing them...gil in Tucson
Click to expand...
Yea these are excellent because it focuses on the basics:

Quality parts: wire, connectors, components
Quality tools: a crimp is only as good as the crimper
Basics: Good connections that will not fail or come un-done
Heart of System: Charge, Start, (one) Main Pos buss and GOOD Grounds

I'd rather have the most BASIC wiring architecture w/ solid connections than the most clever, fancy, redundant wiring scheme and one weak connection. The idea, make it so it never fails. Electrical systems can get close to 100% reliable with care.

Bob's Book has a zillion 'Z' drawings, but the basics as MTBehnke highlighted above really has not changed in 60 years. Extra's like the "essential buss" and extra switches are add on's to the basics. I agree with Mel, Aeroelectic's tends to go towards to more than less. Adding copper wire and switches does add weight. Every ounce counts. Consider if you really need it, before adding redundant paths, dual batteries & alternator's. If your basics are solid, you'll have a reliable system, lasting the life of the plane. More connections and 'stuff' decreases reliability.

Unique to Bob's book/philosophy and contribution to kit/home-built plane electrical systems is as follow. He's strong proponent of and items subject to debate and preference are:

Automotive blade (ATC) plastic fuse blocks. He explains in his book why he thinks this is better than CB's. Although certified planes still use CB's, fuses have some advantages over resettable CB's, light and cheap, while doing the job, protect the wiring. With fuses you can afford to protect every individual circuit with its own size fuse. There's nothing wrong with CB's. In fact its still the deluxe standard "aircraft" solution. However you need to buy expensive aircraft quality CB's. Bob also thinks accesses to the fuse is not needed in flight if you design properly. He has a point and its a design philosophy. Hidden fuses is Bob's legacy and a neat idea; its used extensively in automobiles, which have fuses under the hood and under the dash-board. Its a "philosophy".

Fast-On blade connectors. He explains they have less parts than ring terminals, no screw or washers. He makes a good argument for fast-on terminals. I use both lug & fast-on terminals where needed and compatible. There is nothing wrong with lug terminals, lock washer and screw, but torque is critical. Bob educated us all that blade / fast-on terminals have some cool advantages, less parts and reliable electrical connections. Nothing wrong with lug terminals if done right, but I like Bob's ideas when they save weight, cost while still maintain reliability. Fast one terminals do that.

Anti Avionics Master - I like an avionics master. Even today, manufactures of modern avionics recommended components be turned off during starting and stopping of engine. Bob is not a proponent of avionic master switches. Bob feels strongly about (not having) this feature, but I would defer to the manufacturers of the avionics that recommend it. You can always turn individual items on and off at each unit, but that's a pain.

OV relay on internally regulated (IR) alternators - Bob has a negative opinion of internally regulated alternators. His idea is to add extra OV relays on to the output of the alternator (B-lead). This is the main area that I disagree with from Bob's other wise sage advice. I'm against adding and OV relay primarily since there are better options; if you want additional protection to OV you have two better options: One option, get a Plane-Power IR alternator with a crow bar device added on. The 2nd option is to use an externally regulated alternator (Plane Power, B&C or Homemade). I like the Transpo V1200 (OV protected) external voltage regulator. Technically an add-on/band-aid OV device could work, but its not as elegant as the other options.

Part two of this is over voltage is an over rated of over blown fear in my opinion. Most failures are passive or benign that I have seen. The worse cases get hyped or are just stories, myths and faults rumors. However to be fair it can happen and has happened (over voltage). Having a back-up OV protection device or scheme could save the day, although I know of no documented case where a OV relay saved the day. Your single engine plane's crankshaft can fail. Your prop can fall off, so I guess we should all fly twins? You can take redundancy to a logical limit on a single engine plane (day/night/vfr/ifr) or a paranoid limit. In the end, you're in a single engine/pilot plane.

Internally regulated alternators are very reliable and unlikely to have a critical OV, historically and statistically. Adding up all the parts for a OV relay: crow bar ($35), contactor ($26) and CB ($18) and extra connectors you are looking at $80. Vans stock alternator kit cost $270. A plane power unit is $375 and does not need anything else. A $25 buck difference. If you don't "trust" the stock alternator than get the plane power unit. Putting a band-aid on an internally regulated alternator adds, weight, cost and complexity and creates other issues; it's a less than an optimal choice in my opinion; you have better options. Cutting the "B-lead" under load is death to a good alternator.

IFR/IMC with an all electric $20,000 panel, don't mess around, get the best; don't mess around with band-aids to save $25.

The ultimate electrical redundancy is to NOT need to rely on the electrical system at all, which was the 'philosophy' in the old days with mechanical gauges and vacumn, pitot/static powered flight instruments. However no one is rushing to out vacuum pumps again. So you do want the best electrical system. However if flying VFR with an engine that's not electrically dependant, super redundancy may not be needed. Also with EFIS, GPS and handheld radios with internal self contained battery power, the electrical system is less critical (VFR). Now if launching into min IFR with an all glass panel and an auto engine that needs electrical power to run the EFI and ignition than yes Bob's dual idea are probably justified.


When using a stock internally regulated alternator, I personally recommend: Using an in-panel CB (pull-able) on the B-lead (not a fuse); Do not cycle the ALT switch on/off while the engine is running; & Cool and shield the alternator from heat. The pull-able CB in the panel adds the option to isolate the alternator manually. Bob likes to wire the "B-lead" (alternator output) direct to the battery with an in-line fuse. His idea does save wiring length, but it takes the (pull-able) CB control away. I'm not criticising, just saying its not totally compatible w/ internally regulated ND alternators.

Stock ND alternator Advantage
Going with a stock ND alternator, has the advantage of getting a replacement at any auto store. Going with a special plane-power, B&C or modified alternator means repaired or replacement in the field, say on a X-C trip might not be possible. However a plane-power internally regulated unit (with auxiliary OV device), can be switched out with a stock units in a pinch.
 
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Phil:

I was in Ottawa yesterday. What is with the lack of connection between 5 and 417? Have to travel surface streets to connect between the freeways. Us Yanks are used to having our freeways connect.

I found the the many faces of the electrical system to be intriguing. First came the panic and terror followed by the welcome challenge of actually designing my own system. I'm not going to offfer technical advice but instead give you some moral support. I was trepid as I started the design process and this with 30 years of aviation maintenance experience, I can only assume your trepidation is real.

Read up and map out the functional flows and it will eventually click. Try thinking of the flow of current and not the specific connection of the wires. It helps to visualize the fucntional flow sort of like in UML or block diagrams.

Jekyll
 
Rod Machado's Water analogy for electrical system

If any of you want to really are not sure about how the juice flows. Rod rod Machado noted and popular aviation educator, author and speaker has written some excellent articles and books. One article I remember was of the electrical systems using water as an analogy. It makes so much sense. Here is my take but Rod explains it with graphics so much better.

-Volts is water pressure
-Amps is the flow (trickle or full blast)
-Small hose or large hose flows more water (electrons) w/ less pressure (volt) loss (bigger / smaller wire).
-The Battery is a reservoir tank of water. The deeper the water the more the pressure at the tap at the bottom of the tank.
-The alternator is a water pump.........(which fills the tank, ie battery)
-Surges in water pipes, flushing toilet makes shower water pressure drop (some times) like turning on high load electrical items makes the volts drop.

You can take the analogy as far as you want. One I making up right now is shutting the faucet off quickly makes a surge or "water hammer", clunk. Same with electrical (load dump)....... its really a great analogy, except one gets you wet the other will shock you. :D

Almost every thing you can say about electrons (holes) in wires, batteries and alternators can be explained with the water in pipe analogy.

Here is one of Rod's Book's on Pvt Pilot that has the water analogy. I know he wrote magazine articles as well on this.

edit: You can find it in his private pilot hand book: http://www.rodmachado.com/Product/Books/books.htm

Here's an excerpt of a much larger discussion..........(describing how an ampmeter and load meter works with the water analogy) http://www.rodmachado.com/Images/c4-06.pdf
 
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Radios vs engine

http://www.approach-systems.com/ (at botom of their page you will find the link to this URL)

http://www.approachfaststack.com/

I read and pretty well understood Tony and Bob's books but still was not comfortable with doing the radios. I used the link above that allowed me to successfully wire the radios in 3 hours. I was very fearful that no matter how carefully I tried I would smoke $5,000.00 or more. Approach systems is very user friendly and helpful. I highly recommend them. As for the engine and charging system........Tony and Bob will get you through them. Tony being the easiest read IMO.

Look at Approach Systems. They clear up the area that, to me, was of most concern. Once I separated the radios from the engine it was pretty easy to wire the engine and have experts do the expensive stuff. :)
 
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