AeroElectric-List Digest Archive

Sun 02/02/14


Total Messages Posted: 13



Today's Message Index:
----------------------
 
     1. 08:13 AM - Re: Essential Bus question (Robert L. Nuckolls, III)
     2. 08:42 AM - Re: Essential Bus question (Robert L. Nuckolls, III)
     3. 08:49 AM - Re: 12V to 9V converter (Robert L. Nuckolls, III)
     4. 09:32 AM - Re: Essential Bus question (Tim Andres)
     5. 10:47 AM - Re: Essential Bus question (Robert L. Nuckolls, III)
     6. 02:34 PM - Re: Essential Bus question (Jeff Luckey)
     7. 03:39 PM - Analyze This (Jeff Luckey)
     8. 03:39 PM - Re: Essential Bus question (Robert L. Nuckolls, III)
     9. 04:14 PM - Re: Essential Bus question (Tim Andres)
    10. 04:14 PM - Re: Essential Bus question (Kelly McMullen)
    11. 05:11 PM - Re: Essential Bus question (Robert L. Nuckolls, III)
    12. 05:57 PM - Re: Analyze This (Robert L. Nuckolls, III)
    13. 07:44 PM - Re: Analyze This (Jeff Luckey)
 
 
 


Message 1


  • INDEX
  • Back to Main INDEX
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 08:13:49 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Essential Bus question
    At 08:25 PM 1/31/2014, you wrote: My first question would be why add the complexity of a second electrical system, when virtually all situations . . . Define "all situations" . . . the term is non- quantified/qualified. When we're designing a TC aircraft, EVERY situation needs to be articulated in the design documents along with the plan-B, C, . . . or Z that mitigates that situation. Then we have to go TEST every one of those plans to demonstrate compliance with design goals. . . . can be handled by either backup battery for EFIS, ship's battery or just plain old magnetos. For OBAM aircraft it's a function of design goals built upon the pilot's skills, maintenance protocols, airplane capabilities and anticipated missions. Obviously, the manner in which one might outfit a Kitfox can depart greatly from the way you would craft an LAIV-P. At the same time, the builder of an RV-6 in the Pacific NW (Lots of clouds all the time) who travels a lot might have a more sophisticated system than another builder who intends to use is LAIV only in day VMC but wants the speed, ability to hop the occasional mountain range and air conditioning. This litany of potential "situations" offers a brief peek into the value of having design goals synchronized to the end-use. Production aircraft tend to have cookie-cutter approaches to system architecture . . . because the designers can only hypothesize greatest risk situations for the targeted customer then address those hypotheses within the framework of the impediments to creativity imposed by the FARS. We on the List have a clean sheet of paper for the beginning of every project. The Z-figures are intended to offer a sort of "Cliff's Notes" on architectures that span the spectrum of possibilities. Some builders have put Z-14 into their 2 place RV's at no small penalty for cost and weight . . . but find comfort in not having to go through the very non- trivial exercise of optimizing their decision. There ARE LAIV-P aircraft flying with one battery, one alternator, and backup batteries sprinkled over the panel and perhaps some more in the flight bag. Its unlikely that either builder has tested available failure response plans against his/her perceptions of capability in the Plan-B hardware. Given the decreasing failure rates of modern electro-whizzies, it's unlikely that either of the pilots in the last two examples will have a 'dark-n-stormy night' story to write up for Flying Magazine. Bob . . .


    Message 2


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 08:42:04 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Essential Bus question
    At 01:53 PM 1/31/2014, you wrote: > >My RV-6 has been flying 12 years now with an electrical system based >on the Z diagrams. Now I am assisting my wife complete her RV-7 >electrical system. She has chosen to use the VPX Pro unit and wants >to incorporate a "backup" source of power for clearances, engine >start, and "endurance" (if the VPX box were to quit). Okay, you're plagued with the same litany of concerns that arise from lack of confidence in your present 'vision' for how this system should evolve. > >The circuit that we are considering uses a bridge diode that would >allow the main battery to supplement the "backup" battery for >increased endurance. Since I have not seen this variation before, >there must be a "gotcha" that I haven't found. Attached is a >picture of the basic circuit. Any suggestions and/or comments would >be appreciated. Read through the posting I made a few minutes ago and then consider a list of design goals that are based on . . . (1) How will this airplane be used? Do you anticipate long legs of travel at night over unfriendly terrain? (2) Are you anticipating more than a tiny percentage of approaches to landing to be in IMC? (3) Do you plan to carry the ultimate in backup reliability in your flight bag? http://tinyurl.com/d5mrjgh This is the stuff I recommend for folks like me who only rent airplanes . . . but if it were my airplane, those items would still be with me. In fact, I've not turned on a VOR or ADF in 15 years . . . nor have I used a panel mounted GPS . . . but that's another story. (4) Are your skill sets going to be honed to the levels necessary for low risk implementation of the hardware you plan to install? It's entirely possible to have an airplane decked out to the window-sills with goodies only to have A pilot become the weak link in the chain. http://tinyurl.com/kb2zr8m I've flown with pilots who were quite proud of all those dials, switches and knobs on the panel who never flew more IFR than to keep their ticket current. The greatest risk for bending their airplane was not rooted failure of hardware. Keep in mind that 2x the hardware is 2x the probability of failure. Got some more batteries scattered around the airplane . . . guess what . . . now you're running a clinic for batteries upon which you believe you're building a 'dependable' system. Commodity items like batteries are like house plants. Just because you have two of them does not mitigate the need for knowledgeable preventative maintenance but it DOES double the maintenance $time$. So before we spend a lot of time refining the work-arounds for hypothesized failures, let's look at the big picture and size the solutions to realistic risks having the greatest probability of presentation. Then you're ready to sift solutions for those having the lowest cost of ownership, weight penalties on the aircraft and taxation of your skill sets. Bob . . .


    Message 3


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 08:49:46 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: 12V to 9V converter
    >Bob, I have an old (30+ years) Hall variometer that I want to put in >my trike. It's powered by 9V batteries so it seems an easy enough >project to use a converter to power it off the dynamo on the HKS >engine. 2 amps should be more than enough output. There are quite a >few vendors on eBay that offer them for $2 or so. Do you have any >favorite vendors for this kind of thing? > >Rick Girard What kind of 9v batteries? These things? Emacs! More than one? How many and do you KNOW they are in parallel and not series for +/- supply to the electronics? Bob . . .


    Message 4


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 09:32:00 AM PST US
    Subject: Re: Essential Bus question
    From: Tim Andres <tim2542@sbcglobal.net>
    I would just add a simple Brown out 7ah Alarm battery/Aux bus charged thru a Schottky diode and maybe a resistor is very simple & cheap to do. A lot of equipment now comes with multiple diode isolated power inputs making it easy. This allows flight plan entry and clearance requests before start up without draining the main battery, keeps the GPS/NAV/COM and EFIS from rebooting when cranking the engine, and provides maybe 20-30 minutes of extra time to get back on the ground. Weight/cost is about $35 and 5 lbs. cheaper than a factory backup, which only powers one item. Tim > On Feb 2, 2014, at 8:39 AM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com> wrote: > > > At 01:53 PM 1/31/2014, you wrote: >> >> My RV-6 has been flying 12 years now with an electrical system based on the Z diagrams. Now I am assisting my wife complete her RV-7 electrical system. She has chosen to use the VPX Pro unit and wants to incorporate a "backup" source of power for clearances, engine start, and "endurance" (if the VPX box were to quit). > > Okay, you're plagued with the same litany of concerns > that arise from lack of confidence in your present > 'vision' for how this system should evolve. >> >> The circuit that we are considering uses a bridge diode that would allow the main battery to supplement the "backup" battery for increased endurance. Since I have not seen this variation before, there must be a "gotcha" that I haven't found. Attached is a picture of the basic circuit. Any suggestions and/or comments would be appreciated. > > Read through the posting I made a few minutes ago > and then consider a list of design goals that are > based on . . . > > (1) How will this airplane be used? Do you > anticipate long legs of travel at night over > unfriendly terrain? > > (2) Are you anticipating more than a tiny > percentage of approaches to landing to be > in IMC? > > (3) Do you plan to carry the ultimate in > backup reliability in your flight bag? > > http://tinyurl.com/d5mrjgh > > This is the stuff I recommend for folks like > me who only rent airplanes . . . but if > it were my airplane, those items would still > be with me. In fact, I've not turned on a > VOR or ADF in 15 years . . . nor have I used > a panel mounted GPS . . . but that's another > story. > > (4) Are your skill sets going to be honed > to the levels necessary for low risk > implementation of the hardware you plan to install? > It's entirely possible to have an airplane > decked out to the window-sills with goodies > only to have A pilot become the weak link > in the chain. > > http://tinyurl.com/kb2zr8m > > I've flown with pilots who were quite proud > of all those dials, switches and knobs on > the panel who never flew more IFR than to > keep their ticket current. The greatest > risk for bending their airplane was not > rooted failure of hardware. > > Keep in mind that 2x the hardware is 2x > the probability of failure. Got some more > batteries scattered around the airplane > . . . guess what . . . now you're running > a clinic for batteries upon which you believe > you're building a 'dependable' system. > > Commodity items like batteries are like house plants. > Just because you have two of them does not mitigate > the need for knowledgeable preventative > maintenance but it DOES double the maintenance > $time$. > > So before we spend a lot of time refining > the work-arounds for hypothesized failures, > let's look at the big picture and size the > solutions to realistic risks having the > greatest probability of presentation. > > Then you're ready to sift solutions for those > having the lowest cost of ownership, weight > penalties on the aircraft and taxation of > your skill sets. > > > Bob . . . > > > >


    Message 5


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 10:47:56 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Essential Bus question
    At 11:31 AM 2/2/2014, you wrote: > >I would just add a simple Brown out 7ah Alarm battery/Aux bus >charged thru a Schottky diode and maybe a resistor is very simple & >cheap to do. A lot of equipment now comes with multiple diode >isolated power inputs making it easy. >This allows flight plan entry and clearance requests before start up >without draining the main battery, keeps the GPS/NAV/COM and EFIS >from rebooting when cranking the engine, and provides maybe 20-30 >minutes of extra time to get back on the ground. >Weight/cost is about $35 and 5 lbs. cheaper than a factory backup, >which only powers one item. > >Tim Good data points. Let us consider the premises underlying the evolution of Figure Z-07 http://tinyurl.com/my9u3ud this shows a two battery/single alternator system for an electrically dependent engine. This exercise in 'electron gazing' grew out of Fred's project already fitted with a EXP-Bus. I could see a way to accommodate Fred's initial design goals for two batteries with a simple mod to the EXP-Bus . . . but I could see an alternative to Z-19 evolving from the deliberations . . . hence Z-07. Off in the distance, I think I see a single-battery variant of this architecture but that's possible only after we get real energy requirements data . . . and further refine the operating philosophy for the system. Tim's words raise useful questions that go directly to deliberations for sizing risks in a single-battery design. Where is it written or demonstrated that having the ship's processors 'reboot' is a bad thing? Under what operating scenarios is it useful/necessary minimize the time between the glass being awake and reaching the end of the runway just prior to engine run-up? I recall some stories about the Blue-Mountain systems (hard drives?) taking perhaps 90 seconds to wake up . . . but when was the last time you were ready to check mags less than, say 3-4 minutes after engine startup? I've reviewed as many of the airports I've visited that I can remember. I cannot recall any departure where engine run-up was accomplished for before the oil was warmed up a bit and I had taxied from parking to the run-up stand, certainly 4 minutes, sometimes 10. I think it took 15 minutes to get out of KCI once. . . . the check list belongs to YOU . . . you can adjust sequences of events to fit hardware. Let us consider "draining the main battery" for the purposes of gathering the ATIS data and getting a clearance delivery. Suppose the e-bus runs 5A and the exercise takes 3 minutes. 12v x 5a x 60s x 3m = 10,800 watt-seconds. Cranking the engine 12v x 200a x 10s = 24,000 watt-seconds. What does the battery hold? 12v x 5a x 60s x 120m = 432,000 watt-seconds. Okay, you used up 34,800 watt-seconds before the engine was lit for 35K/432K or 8 percent of the battery's capacity. If you're targeting 80% of new capacity for banishing your battery to kiddie-car duty, then the last flight will tax the battery to 10% of available capacity. The above analysis is a first order estimate and does not take into account vagaries of temperature and internal impedances of the battery but it's in the right church if not in the right pew. Whats is the return on investment for 5 more pounds of battery and two batteries to maintain instead of one? The value of this . . . or even more detailed analysis presumes that you KNOW what the drains are and what the battery's capabilities are after accounting for aforementioned vagaries AND targeted end of life decisions. Bob . . .


    Message 6


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 02:34:16 PM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: Essential Bus question
    my comments in larger font...=0A=0A-Jeff=0A=0A=0A=0A_______________________ _________=0A From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com >=0ATo: aeroelectric-list@matronics.com =0ASent: Sunday, February 2, 2014 1 0:47 AM=0ASubject: Re: AeroElectric-List: Essential Bus question=0A =0A=0A- .bob@aeroelectric.com>=0A=0AAt 11:31 AM 2/2/2014, you wrote:=0A> --> AeroEl ectric-List message posted by: Tim Andres <tim2542@sbcglobal.net>=0A> =0A> I would just add a simple Brown out 7ah Alarm battery/Aux bus charged thru a Schottky diode and maybe a resistor is very simple & cheap to do. A lot o f equipment now comes with multiple diode isolated power inputs making it e asy.=0A> This allows flight plan entry and clearance requests before start up without draining the main battery,- keeps the GPS/NAV/COM and EFIS fro m rebooting when cranking the engine, and provides maybe 20-30 minutes of e xtra time to get back on the ground.=0A> Weight/cost is about $35 and 5 lbs . cheaper than a factory backup, which only powers one item.=0A> =0A> Tim =0A=0A- Good data points. Let us consider the premises=0A- underlying the evolution of Figure Z-07=0A=0Ahttp://tinyurl.com/my9u3ud=0A=0A- thi s shows a two battery/single alternator system=0A- for an electrically d ependent engine. This=0A- exercise in 'electron gazing' grew out of Fred 's=0A- project already fitted with a EXP-Bus. I could=0A- see a way t o accommodate Fred's initial design=0A- goals for two batteries with a s imple mod to=0A- the EXP-Bus . . . but I could see an alternative=0A- to Z-19 evolving from the deliberations . . .=0A- hence Z-07.=0A=0A- Off in the distance, I think I see a single-battery=0A- variant of this architecture but that's possible=0A- only after we get real energy requ irements data=0A- . . . and further refine the operating philosophy=0A - for the system. Tim's words raise useful questions=0A- that go dire ctly to deliberations for sizing risks=0A- in a single-battery design. =0A=0A- Where is it written or demonstrated that having=0A- the ship' s processors 'reboot' is a bad thing?=0A=0AOK, let me write it here:=0AWatc hing the Garmin 430 in my Cherokee re-boot after engine start is very incon venient. Is it catastrophic? No.- Are there work-arounds? Certainly.- I t's just a pain in the @ss.- In an experimental w/ all glass, it would be even more annoying.=0A=0ANow that I'm designing the electrical system for my RV-7A, I'm certainly want a design where that does not happen.- This i s one of the reasons people like us build our own airplanes - we get to eng ineer-out those little annoyances that we just have to put up with in certi fied airplanes.=0A=0A=0A- Under what operating scenarios is it useful/ne cessary=0A- minimize the time between the glass being awake=0A- and r eaching the end of the runway just prior=0A- to engine run-up?=0A=0A- I recall some stories about the Blue-Mountain=0A- systems (hard drives? ) taking perhaps 90=0A- seconds to wake up . . . but when was the=0A- last time you were ready to check mags less=0A- than, say 3-4 minutes a fter engine startup?=0A=0A- I've reviewed as many of the airports I've =0A- visited that I can remember. I cannot recall=0A- any departure w here engine run-up was accomplished=0A- for before the oil was warmed up a bit and I=0A- had taxied from parking to the run-up stand,=0A- cer tainly 4 minutes, sometimes 10. I think=0A- it took 15 minutes to get ou t of KCI once.=0A=0AAll true but, there are also thousands of quiet little airports where you can depart as quickly as you want to=0A=0A- . . . the check list belongs to YOU . . . you=0A- can adjust sequences of events to fit hardware.=0A=0A- Let us consider "draining the main battery"=0A - for the purposes of gathering the ATIS data=0A- and getting a clear ance delivery. Suppose the=0A- e-bus runs 5A and the exercise takes 3 mi nutes.=0A- 12v x 5a x 60s x 3m = 10,800 watt-seconds.=0A- Cranking the engine 12v x 200a x 10s = 24,000=0A- watt-seconds. What does the b attery hold?=0A- 12v x 5a x 60s x 120m = 432,000 watt-seconds.=0A=0A - Okay, you used up 34,800 watt-seconds before=0A- the engine was lit for 35K/432K or 8 percent=0A- of the battery's capacity. If you're targ eting=0A- 80% of new capacity for banishing your battery=0A- to kiddi e-car duty, then the last flight=0A- will tax the battery to 10% of avai lable=0A- capacity.=0A=0A- The above analysis is a first order estima te=0A- and does not take into account vagaries of=0A- temperature and internal impedances of the=0A- battery but it's in the right church if not=0A- in the right pew.=0A=0A- Whats is the return on investment fo r 5 more=0A- pounds of battery and two batteries to maintain=0A- inst ead of one?=0A=0A- The value of this . . . or even more detailed=0A- analysis presumes that you KNOW what the=0A- drains are and what the bat tery's capabilities=0A- are after accounting for aforementioned=0A- v =================


    Message 7


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 03:39:51 PM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Analyze This
    Listers,=0A=0AAttached find a schematic (some people call them ladder diagr ams) of a design for the electrical system for my RV-7A.- Below is a list of design goals, pros and cons. Please take a look and provide engineering feedback.=0A=0ATIA=0A=0A=0AElectrical Systems Design Goals:=0A1. fault tol erant - able to tolerate failure of any single component and fly for 45 min .=0A2. easy to operate=0A3. no avionics brown-out on engine start=0A4. easy to repair=0A5. comprised of standard, readily-available components =0A6. c ost effective=0A=0A=0APros:=0A1. simplified operation - only 2 master switc hes=0A2. simplified design - single buss=0A=0A3. no brown-out on engine sta rt=0A4. automatic fail-over - no pilot interaction required; avionics won't reset=0A=0A--- In the event a battery system suffers a failure, eith er an open circuit or a ground fault, the faulty=0A--- system simply stops providing power to the buss and the remaining good system continues t o =0A=0A--- provide electricity without interruption.=0A=0A=0ACons: =0A1. buss-isolation power diodes may require heat sinks=0A2. some energy w asted as heat thru power diodes


    Message 8


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 03:39:52 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Essential Bus question
    OK, let me write it here: Watching the Garmin 430 in my Cherokee re-boot after engine start is very inconvenient. Stop-watch that for me some time. I'd really like to have a number on this widely discussed but never quantified driver of design goals. Is it catastrophic? No. Are there work-arounds? Certainly. It's just a pain in the @ss. In an experimental w/all glass, it would be even more annoying. Now that I'm designing the electrical system for my RV-7A, I'm certainly want a design where that does not happen. This is one of the reasons people like us build our own airplanes - we get to engineer-out those little annoyances that we just have to put up with in certified airplanes. Then by all means do so. It's your airplane and your design goals. The question wasn't whether or not you wanted to do a particular thing, it was an invitation explore why you wanted to do it . . . hopefully for reasons firmly of your own choosing and not 'just because' hangar lore and legacy traditions dictated it. Brownout batteries have been discussed her on the list often for several years an even illustrated one approach in Z-10/8 http://tinyurl.com/7ro5yuc All true but, there are also thousands of quiet little airports where you can depart as quickly as you want to Yup . . . there are. If a significant percentage of your departures are so expeditious that boot time on the glass becomes an impediment, then you have an element of fact that drives a different design goal. I'm trying head off any notions that just because one is considering a glass cockpit that a brownout battery is recommended . . . it comes with a price in weight and costs of ownership that may add little or no value. Bob . . .


    Message 9


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 04:14:47 PM PST US
    Subject: Re: Essential Bus question
    From: Tim Andres <tim2542@sbcglobal.net>
    Not to argue your points Bob, and I agree simple is often better, but I would just add that I don't want to wait 20 seconds for the screens to reboot after engine start as my engine data is there also and I want see oil pressure etc right away. And I much prefer to enter a lengthy flight plan with the prop off as my attention will be focused inside the plane, I'll admit on occasion I've looked up from the panel and discovered the plane moving. My flight plan will then be lost when I then crank the engine, unless I save it to memory, which I won't unless I'm using it again. And sometimes I take off with a hot engine, I'd rather not sit with the already hot engine running in the summer heat while I enter several waypoints in the Garmin. To me it's worth the 5lbs for the convenience, and the cost is easily overcome in fuel not burned. The beauty of EAB, built what you want, then live with your decisions. Tim > On Feb 2, 2014, at 10:47 AM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com> wrote: > > > At 11:31 AM 2/2/2014, you wrote: >> >> I would just add a simple Brown out 7ah Alarm battery/Aux bus charged thru a Schottky diode and maybe a resistor is very simple & cheap to do. A lot of equipment now comes with multiple diode isolated power inputs making it easy. >> This allows flight plan entry and clearance requests before start up without draining the main battery, keeps the GPS/NAV/COM and EFIS from rebooting when cranking the engine, and provides maybe 20-30 minutes of extra time to get back on the ground. >> Weight/cost is about $35 and 5 lbs. cheaper than a factory backup, which only powers one item. >> >> Tim > > Good data points. Let us consider the premises > underlying the evolution of Figure Z-07 > > http://tinyurl.com/my9u3ud > > this shows a two battery/single alternator system > for an electrically dependent engine. This > exercise in 'electron gazing' grew out of Fred's > project already fitted with a EXP-Bus. I could > see a way to accommodate Fred's initial design > goals for two batteries with a simple mod to > the EXP-Bus . . . but I could see an alternative > to Z-19 evolving from the deliberations . . . > hence Z-07. > > Off in the distance, I think I see a single-battery > variant of this architecture but that's possible > only after we get real energy requirements data > . . . and further refine the operating philosophy > for the system. Tim's words raise useful questions > that go directly to deliberations for sizing risks > in a single-battery design. > > Where is it written or demonstrated that having > the ship's processors 'reboot' is a bad thing? > Under what operating scenarios is it useful/necessary > minimize the time between the glass being awake > and reaching the end of the runway just prior > to engine run-up? > > I recall some stories about the Blue-Mountain > systems (hard drives?) taking perhaps 90 > seconds to wake up . . . but when was the > last time you were ready to check mags less > than, say 3-4 minutes after engine startup? > > I've reviewed as many of the airports I've > visited that I can remember. I cannot recall > any departure where engine run-up was accomplished > for before the oil was warmed up a bit and I > had taxied from parking to the run-up stand, > certainly 4 minutes, sometimes 10. I think > it took 15 minutes to get out of KCI once. > > . . . the check list belongs to YOU . . . you > can adjust sequences of events to fit hardware. > > Let us consider "draining the main battery" > for the purposes of gathering the ATIS data > and getting a clearance delivery. Suppose the > e-bus runs 5A and the exercise takes 3 minutes. > 12v x 5a x 60s x 3m = 10,800 watt-seconds. > Cranking the engine 12v x 200a x 10s = 24,000 > watt-seconds. What does the battery hold? > 12v x 5a x 60s x 120m = 432,000 watt-seconds. > > Okay, you used up 34,800 watt-seconds before > the engine was lit for 35K/432K or 8 percent > of the battery's capacity. If you're targeting > 80% of new capacity for banishing your battery > to kiddie-car duty, then the last flight > will tax the battery to 10% of available > capacity. > > The above analysis is a first order estimate > and does not take into account vagaries of > temperature and internal impedances of the > battery but it's in the right church if not > in the right pew. > > Whats is the return on investment for 5 more > pounds of battery and two batteries to maintain > instead of one? > > The value of this . . . or even more detailed > analysis presumes that you KNOW what the > drains are and what the battery's capabilities > are after accounting for aforementioned > vagaries AND targeted end of life decisions. > > > Bob . . . > > > >


    Message 10


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 04:14:55 PM PST US
    From: Kelly McMullen <kellym@aviating.com>
    Subject: Re: Essential Bus question
    Virtually all glass have their own light weight backup batteries so do not have startup brown out issues unless no backup battery is installed. I see very little value in being able to turn on GPS prior to start. While one needs engine instrumentation prior to and during start, one does not need avionics on. Of course newer avionics that allow faster input of flight plans than the 430 help, if that is the reason for turning on 430 before start. On 2/2/2014 4:39 PM, Robert L. Nuckolls, III wrote: > > > Brownout batteries have been discussed her on the list often > for several years an even illustrated one approach > in Z-10/8 > > http://tinyurl.com/7ro5yuc > > > All true but, there are also thousands of quiet little airports where > you can > depart as quickly as you want to > > Yup . . . there are. If a significant percentage > of your departures are so expeditious that > boot time on the glass becomes an impediment, > then you have an element of fact that drives > a different design goal. > > I'm trying head off any notions that just because > one is considering a glass cockpit that a brownout > battery is recommended . . . it comes with a price in > weight and costs of ownership that may add little > or no value. > > > Bob . . . > >


    Message 11


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 05:11:08 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Essential Bus question
    At 06:14 PM 2/2/2014, you wrote: > >Not to argue your points Bob, and I agree simple is often better, >but I would just add that I don't want to wait 20 seconds for the >screens to reboot after engine start as my engine data is there also >and I want see oil pressure etc right away. Yeah . . . that's an old saw that has been around since the Curtis Jenny . . . when sheared oil pump shafts were relatively common . . . along with a host of other ills associated with vintage engines. I've never encountered a pilot who's oil pump died at startup. I've flown lots of airplanes in cold weather that didn't show any pressure for 30-45 seconds after start. >And I much prefer to enter a lengthy flight plan with the prop off >as my attention will be focused inside the plane, I'll admit on >occasion I've looked up from the panel and discovered the plane >moving. My flight plan will then be lost when I then crank the >engine, unless I save it to memory, which I won't unless I'm using it again. >And sometimes I take off with a hot engine, I'd rather not sit with >the already hot engine running in the summer heat while I enter >several waypoints in the Garmin. You mean its stored waypoints go away during reboot? > >To me it's worth the 5lbs for the convenience, and the cost is >easily overcome in fuel not burned. >The beauty of EAB, built what you want, then live with your decisions. Absolutely. But why 5#? What did Eric decide about his brown-out eliminator? Perhaps we still need to refine the electronic bus-booster idea . . . it weights a few ounces and has no periodic maintenance requirements. Of course, a battery used only for brownout protection can be run until it dies . . . as long as the pilot doesn't included it in his/her calculations for battery only endurance. Bob . . .


    Message 12


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 05:57:48 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Analyze This
    At 05:38 PM 2/2/2014, you wrote: >Listers, > >Attached find a schematic (some people call them ladder diagrams) of >a design for the electrical system for my RV-7A. Below is a list of >design goals, pros and cons. Please take a look and provide >engineering feedback. The alternator's b-lead is two diode-drops removed from the regulator bus sense lead so expect the b-lead to run 2-drops higher voltage than the regulator's set-point. With the battery tapped in between the two diodes, you'll want to adjust the regulator for a BATTERY voltage of 14.2V This will peg the b-lead at 14.2+diodeV and the bus at 14.2-diodeV. Current limiters are not generally recommended or demonstrated as useful in battery feeders. Bob . . .


    Message 13


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 07:44:22 PM PST US
    From: Jeff Luckey <jluckey@pacbell.net>
    Subject: Re: Analyze This
    =0A=0A=0A=0A________________________________=0A From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroelectric-list@matronics.com =0ASent: Sunday, February 2, 2014 5:56 PM=0ASubject: Re: AeroElectric-List: Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0A=0AAt 05:38 PM 2/2/2014, y ou wrote:=0A> Listers,=0A> =0A> Attached find a schematic (some people call them ladder diagrams) of a design for the electrical system for my RV-7A. - Below is a list of design goals, pros and cons. Please take a look and provide engineering feedback.=0A=0A- The alternator's b-lead is two diode -drops=0A- removed from the regulator bus sense lead so=0A- expect the b-lead to run 2-drops higher voltage=0A- than the regulator's set-point. With the battery=0A- tapped in between the two diodes, you'll want to=0A - adjust the regulator for a BATTERY voltage of=0A- 14.2V=0A=0A- This will peg the b-lead at 14.2+diodeV and=0A- the bus at 14.2-diodeV.=0A=0A Roger that=0A=0A- Current limiters are not generally recommended=0A- or demonstrated as useful in battery feeders.=0A=0AIf the prove to be problem atic, it is very easy to bypass them=0A=0Athanks bob=0A=0A=0A- Bob . . . =========================0A ===================




    Other Matronics Email List Services

  • Post A New Message
  •   aeroelectric-list@matronics.com
  • UN/SUBSCRIBE
  •   http://www.matronics.com/subscription
  • List FAQ
  •   http://www.matronics.com/FAQ/AeroElectric-List.htm
  • Web Forum Interface To Lists
  •   http://forums.matronics.com
  • Matronics List Wiki
  •   http://wiki.matronics.com
  • 7-Day List Browse
  •   http://www.matronics.com/browse/aeroelectric-list
  • Browse AeroElectric-List Digests
  •   http://www.matronics.com/digest/aeroelectric-list
  • Browse Other Lists
  •   http://www.matronics.com/browse
  • Live Online Chat!
  •   http://www.matronics.com/chat
  • Archive Downloading
  •   http://www.matronics.com/archives
  • Photo Share
  •   http://www.matronics.com/photoshare
  • Other Email Lists
  •   http://www.matronics.com/emaillists
  • Contributions
  •   http://www.matronics.com/contribution

    These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.

    -- Please support this service by making your Contribution today! --