X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3673079 for flyrotary@lancaironline.net; Fri, 05 Jun 2009 14:04:13 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta02.mail.rr.com with ESMTP id <20090605180333556.FHBT14139@cdptpa-omta02.mail.rr.com> for ; Fri, 5 Jun 2009 18:03:33 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Ed's Electrical System was Incident 5119 Date: Fri, 5 Jun 2009 14:03:33 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01C9E5E6.69E00E60" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: Acnl/6S8qQOyH03SSv2YMwNFqgN62AABS/Ug In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090605180333556.FHBT14139@cdptpa-omta02.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_000C_01C9E5E6.69E00E60 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi David, You ever hear that old saying ".it seemed like a good idea at the time." ? {:>) I agree that Bob's stuff is a good place to start. I also realized exactly what you point out. While I could isolate my battery from a failed (or good for that matter {:>)) alternator - with my design, I could do nothing to isolate my essential bus from a bad battery. The only reason I can give you (10+ years later) is that I apparently viewed the alternator as the likely cause of a problem, since I swap my batteries out every two years. But, clearly a new battery short - an open circuit would not likely pose a real problem - an no essential bus power. Along those same lines of thinking, is probably why I had the battery voltage holding the master relay closed. Clearly pilot played major role in this incident from one 10 year point to the next 10 year point. Regarding the "fancy" voltmeter switch, at the time since I had two batteries and an alternator, it seemed like a good idea to be able to know the state of the three power devices. Having it just to the main circuit did not seem to provide any information on the voltage state of each battery. I like, it did not case the problem, so I'll leave it in there. No amp meter. I agree there is some rewiring in the very near future. I do find it sort of Ironic that the very thing I put in to permit me to have sufficient time (battery time) to get to an airfield - showed that it could do just that {:>). The two year old 17AH battery showed it could easily provide 30 minutes of quality voltage. It did not start to get really nasty until approx 50 minutes after launch (with two EFI and boost pumps running - I turn one EFI and boost pump off at cruise altitude). Past 50 minutes, things were clearly going to Hades in a hand basket, my EFISM showed the EC2 was still sending the correct pulse duration to injectors (based on my fuel flow reading), however, there was simply not enough voltage/power to pull the injectors completely open or for long enough. All in all I was pleased how long things did stay functional. Based on the measured voltage later on the ground (where it might have a chance to recovery some) the battery was reading six volts. So things probably continue to work/more or less down to around 7-8 volts. Some good suggestions David. One of the reasons for providing these incidents is so that folks can learn from them (self included). Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard Sent: Friday, June 05, 2009 1:03 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Ed's Electrical System was Incident 5119 Hi Ed, Great job handling the emergency! Very nice write up. I do have to admit that you made some unusual decisions in the electrical system. None of that stuff is new, electric Bob's advice is pretty sound. I think that the "master" solenoid is often called the "battery" master for a reason - it only isolates the battery. If you want to have another battery, have another battery master that truly isolates that battery. In your system, if either battery becomes a dead short - you have just taken out your essential buss with no way to recover in flight! All your buses (essential or not) should be on the other side of the 'master' solenoids. If you want to be able to isolate the alternator, that is a separate system. (crow-bar/solenoid/field switch/fuse link/breaker/whatever). I have come to the opinion that sudden over-voltage that frys your avionics is exceedingly unlikely. I have decided to only "isolate" my alternator with a fusible link. - nice and simple that way. The alternator also connects to the buss side of the battery master solenoids. To make one of the buses 'essential' provide an alternate path around any perceived possible points of failure. Batteries fail. I have seen it in cars, I'm sure you have too. Sure, it's mostly the older type, but a good solid short across a SLA could fail it as well. I also find it unusual that your voltmeter is not simply reading the main buss voltage - no fancy switch. That way, you know what you are getting, if you know what I mean. If you want to see how one or another power source is doing, isolate the other sources from the master buss. Lastly, what about you ammeter? Does it not measure current directly from either the battery or the alternator? I'm not sure that a diode is the solution you are looking for. I think what you really need is to re-do the big wires in your system altogether. If you have settled on a one-battery system, get rid of all that extra weight and do it according to the book. From what I know, you would use a diode to 1) re-route field decay spikes back to the battery, or 2) provide alternate path from a battery to an essential (always hot) buss. (i.e. If you wanted to use a diodes, your essential buss would be connected to the other side of the master contactors via diodes, and you would use a diode from each battery to the essential buss.) So at a minimum you would want 2 diodes, one from the alternator and another from your single battery to the essential buss. I know you are a WAY better gEEk than me (i cant even spell AC). So I suspect that you already know what I am saying and you just need a kick in the arse to bite the bullet and re-do the system. Highest regards as always, -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Fri, Jun 5, 2009 at 4:47 AM, Ed Anderson wrote: Jim Maher was kind enough to convert the large DXF files of my electrical system to JPG so perhaps more of you can examine it. Recall I have removed the 2nd battery stuff - so ignore that on the diagrams. Also the diagram does not show any of the detailed EC2/injector/ignition wiring - follow Tracy's recommendations on that. As you will note there is no "isolation" diode between alternator and battery and also that the battery voltage holds the master relay closed. That is another change I must make. I must have decided (10+ years ago) that the battery would never fail - only the alternator. Clearly (now), without battery voltage (in my design) to hold the master relay closed - when the battery voltage fall to around 6-7 volts (in my case) the relay opens and all that good electrical power being produced by the perfectly good alternator - can not reach any part of the electrical system. Clearly NOT good as I could have continued to fly perfectly well with just the alternator juice. Your design is not going to be any better than the accuracy of your assumptions. Clearly some of my assumptions make 10 years ago definitely need revising. Ed The message is ready to be sent with the following file or link attachments: DIAG_3B.jpg DIAG_2B.jpg DIAG_1B.jpg Note: To protect against computer viruses, e-mail programs may prevent sending or receiving certain types of file attachments. Check your e-mail security settings to determine how attachments are handled. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_000C_01C9E5E6.69E00E60 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi = David,

 

You ever hear that old saying = “…it seemed like a good idea at the time…” ? {:>)   = I agree that Bob’s stuff is a good place to start.  I also realized = exactly what you point out.  While I could isolate my battery from a failed = (or good for that matter {:>)) alternator – with my design, I could = do nothing to isolate my essential bus from a bad battery.  The only = reason I can give you (10+ years later) is that I apparently viewed the = alternator as the likely cause of a problem, since I swap my batteries out every two = years.  But, clearly a new battery short – an open circuit would not likely = pose a real problem – an no essential bus power.

 

Along those same lines of thinking, = is probably why I had the battery voltage holding the master relay = closed. 

 

Clearly pilot played major role in = this incident from one 10 year point to the next 10 year = point.

 

 

Regarding the “fancy” voltmeter switch, at the time since I had two batteries and an = alternator, it seemed like a good idea to be able to know the state of the three power devices.  Having it just to the main circuit did not seem to = provide any information on the voltage state of each battery.  I like, it did = not case the problem, so I’ll leave it in there.  No amp = meter.

 

I agree there is some rewiring in = the very near future.  I do find it sort of Ironic that the very thing I put = in to permit me to have sufficient time (battery time) to get to an airfield = – showed that it could do just that {:>).  The two year old 17AH = battery showed it could easily provide 30 minutes of quality voltage.  It = did not start to get really nasty until approx 50 minutes after launch (with two = EFI and boost pumps running – I turn one EFI and boost pump off at = cruise altitude).

 

 Past 50 minutes, things were = clearly going to Hades in a hand basket, my EFISM showed the EC2 was still = sending the correct pulse duration to injectors (based on my fuel flow reading), = however, there was simply not enough voltage/power to pull the  injectors = completely open or for long enough.  All in all I was pleased how long things = did stay functional.  Based on the measured voltage later on the ground = (where it might have a chance to recovery some) the battery was reading six volts.  So things probably continue to work/more or less down to = around 7-8 volts.

 

 

Some good suggestions David.  = One of the reasons for providing these incidents is so that folks can learn = from them (self included).

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Friday, June 05, = 2009 1:03 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Ed's Electrical System was Incident 5119

 

Hi Ed,

 

Great job handling the emergency!  Very nice write = up.   I do have to admit that you made some unusual decisions in the = electrical system.  None of that stuff is new, electric Bob's advice is pretty sound.  I think that the "master" solenoid is often = called the "battery" master for a reason - it only isolates the = battery.  If you want to have another battery, have another battery master that = truly isolates that battery.  In your system, if either battery becomes a = dead short - you have just taken out your essential buss with no way to = recover in flight!  All your buses (essential or not) should be on the = other side of the 'master' solenoids.    If you want to be = able to isolate the alternator, that is a separate system. = (crow-bar/solenoid/field switch/fuse link/breaker/whatever).  I have come to the opinion = that sudden over-voltage that frys your avionics is exceedingly = unlikely.  I have decided to only "isolate" my alternator with a = fusible link. - nice and simple that way.  The alternator also connects to = the buss side of the battery master solenoids.  To make one of the buses 'essential' provide an alternate path around any perceived = possible points of failure. Batteries fail.  I have seen it in cars, I'm = sure you have too.  Sure, it's mostly the older type, but a good solid short = across a SLA could fail it as = well.

 

I also find it unusual that your voltmeter is not simply reading = the main buss voltage - no fancy switch.  That way, you know what you = are getting, if you know what I mean.  If you want to see how one = or another power source is doing, isolate the other sources from the master buss.    Lastly, what about you = ammeter?  Does it not measure current directly from either the battery or the alternator?  

 

I'm not sure that a diode is the solution you are looking for.   I think what you really need is to re-do the big wires = in your system altogether.  If you have settled on a one-battery system, = get rid of all that extra weight and do it according to the book.  From = what I know, you would use a diode to 1) re-route field decay spikes back to = the battery, or 2) provide alternate path from a battery to an = essential (always hot) buss.  (i.e. If you wanted to use a diodes, your essential buss would be connected to the other side of the master = contactors via diodes, and you would use a diode from each battery to the essential buss.)  So at a minimum you would want 2 diodes, one from the = alternator and another from your single battery to the essential = buss.

 

I know you are a WAY better gEEk than me (i cant even spell = AC).  So I suspect that you already know what I am saying and you just need a = kick in the arse to bite the bullet and re-do the system.  =

 

Highest regards as always,

 

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net

On Fri, Jun 5, 2009 at 4:47 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:



Jim Maher was kind enough to convert the large DXF files of my = electrical
system to JPG so perhaps more of you can examine it.  Recall I have removed
the 2nd battery stuff - so ignore that on the diagrams.  Also the = diagram
does not show any of the detailed EC2/injector/ignition wiring - = follow
Tracy's recommendations on that.

As you will note there is no "isolation" diode between = alternator and
battery and also that the battery voltage holds the master relay = closed.
That is another change I must make.  I must have decided (10+ years = ago)
that the battery would never fail - only the alternator.  Clearly = (now),
without battery voltage (in my design) to hold the master relay =  closed -
when the battery voltage fall to around 6-7 volts (in my case) the = relay
opens and all that good electrical power being produced by the = perfectly
good alternator - can not reach any part of the electrical system.  Clearly
NOT good as I could have continued to fly perfectly well with just = the
alternator juice.

Your design is not going to be any better than the accuracy of your
assumptions.  Clearly some of my assumptions make 10 years ago = definitely
need revising.

Ed


The message is ready to be sent with the following file or link = attachments:

DIAG_3B.jpg
DIAG_2B.jpg
DIAG_1B.jpg


Note: To protect against computer viruses, e-mail programs may = prevent
sending or receiving certain types of file attachments.  Check your = e-mail
security settings to determine how attachments are handled.


__________ Information from ESET NOD32 Antivirus, version of virus = signature
database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.



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