---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 08/31/06: 25 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:18 AM - in-rush limiters (Erich_Weaver@URSCorp.com) 2. 04:06 AM - Re: in-rush limiters (Robert L. Nuckolls, III) 3. 04:14 AM - Re: Is EFIS vulnerable at engine start? (FLYaDIVE@aol.com) 4. 04:15 AM - Re: in-rush limiters (Oops!) (Robert L. Nuckolls, III) 5. 05:03 AM - Re: in-rush limiters (FLYaDIVE@aol.com) 6. 05:23 AM - Paralleled microphone circuits? (Robert L. Nuckolls, III) 7. 05:33 AM - Re: Is EFIS vulnerable at engine start? (gert) 8. 05:43 AM - Re: Dynon D10 AOA Boom (Ernest Christley) 9. 05:50 AM - Re: in-rush limiters (Robert L. Nuckolls, III) 10. 06:39 AM - Static port on Dynon AoA probe (Ernest Christley) 11. 07:15 AM - Lex (glen matejcek) 12. 07:51 AM - Re: Is EFIS vulnerable at engine start? (Greg Campbell) 13. 07:58 AM - Re: Paralleled microphone circuits? (FLYaDIVE@aol.com) 14. 08:20 AM - Re: Is EFIS vulnerable at engine start? (Doug Windhorn) 15. 11:59 AM - downside of manual battery disconnects? (D Wysong) 16. 12:14 PM - Re: GRT Wx Impressions (gyoung) 17. 01:07 PM - Re: Static port on Dynon AoA probe (Brian Lloyd) 18. 01:44 PM - Re: Static port on Dynon AoA probe (Kevin Horton) 19. 02:27 PM - Re: Is EFIS vulnerable at engine start? (Carlos Trigo) 20. 02:43 PM - Re: downside of manual battery disconnects? () 21. 02:58 PM - Re: Re: Alternator Switching (Kelly McMullen) 22. 03:34 PM - Re: Is EFIS vulnerable at engine start? (Nancy Ghertner) 23. 04:51 PM - Re: in-rush limiters (Hopperdhh@aol.com) 24. 05:21 PM - Re: in-rush limiters (Hopperdhh@aol.com) 25. 08:10 PM - Re: Is EFIS vulnerable at engine start? (glaesers) ________________________________ Message 1 _____________________________________ Time: 01:18:46 AM PST US Subject: AeroElectric-List: in-rush limiters From: Erich_Weaver@URSCorp.com --> AeroElectric-List message posted by: Erich_Weaver@URSCorp.com I am considering installing in-rush limiters for my landing lights. Can in-rush limiters be used effectively in conjunction with a wig-wag flasher? My understanding is that the in-rush limiters do their job through their odd property of providing decreasing resistance with increasing heat. That would imply that they would need time to cool down before being able to do their job the next time the power is turned on. With the flasher however, the power is being turned on and off very quickly. On the other hand, the bulb filament is probably not cooling off a lot either between flashes, so maybe the in-rush limiters do not need to be effective when the wig-wag is wigging and wagging. Did I just answer my own question? If so, can someone recommend an appropriate in-rush limiter for my 12V, 75W halogen lights thanks Erich Weaver ________________________________ Message 2 _____________________________________ Time: 04:06:44 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: in-rush limiters --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 05:06 PM 8/30/2006 -0700, you wrote: >--> AeroElectric-List message posted by: Erich_Weaver@URSCorp.com > > >I am considering installing in-rush limiters for my landing lights. Can >in-rush limiters be used effectively in conjunction with a wig-wag flasher? > >My understanding is that the in-rush limiters do their job through their >odd property of providing decreasing resistance with increasing heat. That >would imply that they would need time to cool down before being able to do >their job the next time the power is turned on. With the flasher however, >the power is being turned on and off very quickly. On the other hand, the >bulb filament is probably not cooling off a lot either between flashes, so >maybe the in-rush limiters do not need to be effective when the wig-wag is >wigging and wagging. > >Did I just answer my own question? If so, can someone recommend an >appropriate in-rush limiter for my 12V, 75W halogen lights The inrush limiters are, as you've already guessed, slow to respond. They have to cool down for perhaps a minute or more to be an effective inrush limiter for the next turn-on event. At the same time, filaments in lamps . . . especially the halogens have a cooling time constant so long as to eliminate the need for current limiting between flashes of a wig-wag system I did some measurements on the bench a few years ago to flash an automotive halogen headlamp bulb. The first turn-on transient was what you would have expected . . . light up transient from cold start was about a 10x running current. However, sufficient heat was retained between flashes that subsequent turn-on events were perhaps 1.2x running current. Before halogens, the notion of installing inrush limiters or adding some kind of keepwarm circuit had some appeal. With the proliferation of the much more rugged halogens, the old life-enhancing techniques are less useful. The next revision of the 'Connection's lighting chapter will only mention these techniques as ideas with historical significance but not recommended for new design. Bob . . . --------------------------------------------------------- < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > --------------------------------------------------------- ________________________________ Message 3 _____________________________________ Time: 04:14:40 AM PST US From: FLYaDIVE@aol.com Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? --> AeroElectric-List message posted by: FLYaDIVE@aol.com In a message dated 8/30/06 9:15:25 PM Eastern Daylight Time, gert.v@sbcglobal.net writes: > begs the question, what about the current crop of electronic engine > instruments, ya all keep them off till u engine is running. > What good are they if u can't have them on during engine start ;-) > so u wait till the engine is running, switch u electronic instruments on > to discover u have no oil pressure, oops....somehow i don't think i want > Blue Mountain to check my oil pressure if i have to have their system > off during engine start. ===================== I do not know if Blue Mountain (BMA) has an EIS. What I was mentioning was the EFIS system. There is also a huge difference between the electronics of an EFIS or Com radio and a simple sending unit and gage used for fuel quantity, oil temp & pressure and the like. Now, Grand Rapids states KEEP THE UNIT ON. So there is a difference in electrical design between the two or at least their thinking! Barry "Chop'd Liver" "Show them the first time, correct them the second time, kick them the third time." Yamashiada ________________________________ Message 4 _____________________________________ Time: 04:15:20 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: in-rush limiters (Oops!) --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 05:06 PM 8/30/2006 -0700, you wrote: >--> AeroElectric-List message posted by: Erich_Weaver@URSCorp.com > >Did I just answer my own question? If so, can someone recommend an >appropriate in-rush limiter for my 12V, 75W halogen lights P.S. If you would like to include an in-rush limiter in your design, consider the KC003L on http://dkc3.digikey.com/PDF/T062/1405.pdf Bob . . . ________________________________ Message 5 _____________________________________ Time: 05:03:02 AM PST US From: FLYaDIVE@aol.com Subject: Re: AeroElectric-List: in-rush limiters --> AeroElectric-List message posted by: FLYaDIVE@aol.com In a message dated 8/31/06 4:20:49 AM Eastern Daylight Time, Erich_Weaver@URSCorp.com writes: > I am considering installing in-rush limiters for my landing lights. Can > in-rush limiters be used effectively in conjunction with a wig-wag flasher? > > My understanding is that the in-rush limiters do their job through their > odd property of providing decreasing resistance with increasing heat. That > would imply that they would need time to cool down before being able to do > their job the next time the power is turned on. With the flasher however, > the power is being turned on and off very quickly. On the other hand, the > bulb filament is probably not cooling off a lot either between flashes, so > maybe the in-rush limiters do not need to be effective when the wig-wag is > wigging and wagging. > > Did I just answer my own question? If so, can someone recommend an > appropriate in-rush limiter for my 12V, 75W halogen lights > > thanks > > Erich Weaver ================================== Erich: I am familiar with two types of inrush limiters. Neither of them work off of heat (I would like to learn more about this heat type). The simplest "limiter" you can build yourself. It is nothing more than a coil. The coil can be made around either a dowel or a ferrite slug. The wire size is chosen to handle the current of the load and the basic size is about 1/2" ID, 1" OD and 2" Long. The type of wire is SOLID single strand and is what is known as Transformer Wire. After wrapping the wire coils TIGHT you can use heat shrink tubing over them. If you want to get fancy and I would; before you heat shrink tube them dip them in varnish. They should be located close to the load device. Oh! When choosing the wire size, do NOT go by the Mil-Spec wire size used in wiring the plane. I would DOUBLE that wire size. Barry "Chop'd Liver" "Show them the first time, correct them the second time, kick them the third time." Yamashiada ________________________________ Message 6 _____________________________________ Time: 05:23:18 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Paralleled microphone circuits? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" >Hi Bob, > >I am a homebuilder (Midget Mustang, very small single seat) now doing the >wiring. My radio stack will contain one comm/nav radio and I plan to >include a small handheld mounted elsewhere in the cockpit. If needed due >to a failure of the #1 radio, it will interface to my headphones via your >isolation amplifier. > >My question is, "Can I connect my mike to both radios concurrently. I will >have seperate PTT switches, so only one radio will transmit. I am not sure >if the 2nd radio will load the mike too much, or will there be some other >gotcha out there? Connecting the mic circuits as you've suggested offers an unknown probability of success . . . I would guess not a good one. A transmitter selector switch is suggested. See: Figure 18-11 of: http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf >I use your website lots. Thanks for all your work in that area. You're most welcome sir! Bob . . . ----------------------------------------- ( Experience and common sense cannot be ) ( replaced with policy and procedures. ) ( R. L. Nuckolls III ) ----------------------------------------- ________________________________ Message 7 _____________________________________ Time: 05:33:54 AM PST US From: gert Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? --> AeroElectric-List message posted by: gert for the record, I am NOT worried about it, but it stands to reason that many an EIS are build on the same platform as the accompanying EFIS, if a company recommends to not turn on the EFIS and the EIS is on the same platform, should it then not follow to have that switched off too?? I just think it is funny that u want to buy a $$$$ EIS but the mfg recommends to have it off at a important time. Yes, i know, u can always add another switch to u stick to switch it on el-pronto when the engine catches ;-) Robert L. Nuckolls, III wrote: > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > > At 08:10 PM 8/30/2006 -0500, you wrote: > >> --> AeroElectric-List message posted by: gert >> >> begs the question, what about the current crop of electronic engine >> instruments, ya all keep them off till u engine is running. >> What good are they if u can't have them on during engine start ;-) >> so u wait till the engine is running, switch u electronic instruments >> on to discover u have no oil pressure, oops....somehow i don't think >> i want Blue Mountain to check my oil pressure if i have to have their >> system off during engine start. > > The risks are exceedingly low. I suppose there are > folks who tell tales of having lost an engine when a pump > shaft sheared on startup . . . but think about it. Just > how highly stressed are the oil pump parts? If one is > really worried about a bullet proof oil pressure indication > at startup, perhaps a pressure switch and "OIL P WARN" light > in the annunciator panel is called for. > > I wouldn't put engine instrumentation on the e-bus. 99.999% of > the time, engine instruments show the same things they said > the last time you looked at them. Loss of some engine functionality > in addition to loss of alternator on same tank of fuel is exceedingly > remote. Or, one could install an SD-8 for unlimited endurance on > an 8 Amp e-bus and flip the instrumentation on from time to time. > > Bob . . . > > -- ------------------------------------------------------------------- Pursuant to US Code, Title 47, Chapter 5, Subchapter II, '227, any and all nonsolicited commercial E-mail sent to this address is subject to a download and archival fee in the amount of $500 US. E-mailing denotes acceptance of these terms. -------------------------------------------------------------------- ________________________________ Message 8 _____________________________________ Time: 05:43:05 AM PST US From: Ernest Christley Subject: AeroElectric-List: Re: Dynon D10 AOA Boom --> AeroElectric-List message posted by: Ernest Christley Take a peek at http://www.ch601.org/resources/aoa/aoa.htm The Dynon AOA function requires calibration, just like this instrument will need. Ed described how it works. The calibration technique is to go up and do a few stalls, noting where the gauge is at the stall point. > > >>--> AeroElectric-List message posted by: >> >>I have a Dynon D10A. Would be nice to use the AOA feature. Already have a >>pitot/static under wing of my Europa. >> >>I am thinking a probe high up on the rudder may work and not complicate >>rigging the wings or hurting anything when wings go on trailer. >> >>Dynon sells a boom mount AOA/pitot, part number is 100532-000 but it is 1" >>in diameter and has a pitot. >> >>I am thinking something like a thin wall 5/16" or 1/4" tube, with 1" of >>the tip turned up, flattened, and plugged up and a hole drilled. >> >>Has anyone mounted a AOA on rudder? >> >>Know where to buy one? >> >>Made one? >> >>Thx. >>Ron Parigoris >> >> >> >> >> -- ,|"|"|, Ernest Christley | ----===<{{(oQo)}}>===---- Dyke Delta Builder | o| d |o http://ernest.isa-geek.org | ________________________________ Message 9 _____________________________________ Time: 05:50:16 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: in-rush limiters --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 08:01 AM 8/31/2006 -0400, you wrote: >--> AeroElectric-List message posted by: FLYaDIVE@aol.com > >In a message dated 8/31/06 4:20:49 AM Eastern Daylight Time, >Erich_Weaver@URSCorp.com writes: > > > I am considering installing in-rush limiters for my landing lights. Can > > in-rush limiters be used effectively in conjunction with a wig-wag > flasher? > > > > My understanding is that the in-rush limiters do their job through their > > odd property of providing decreasing resistance with increasing > heat. That > > would imply that they would need time to cool down before being able to do > > their job the next time the power is turned on. With the flasher however, > > the power is being turned on and off very quickly. On the other hand, the > > bulb filament is probably not cooling off a lot either between flashes, so > > maybe the in-rush limiters do not need to be effective when the wig-wag is > > wigging and wagging. > > > > Did I just answer my own question? If so, can someone recommend an > > appropriate in-rush limiter for my 12V, 75W halogen lights > > > > thanks > > > > Erich Weaver >================================== >Erich: > >I am familiar with two types of inrush limiters. Neither of them work off of >heat (I would like to learn more about this heat type). See http://www.gesensing.com/products/resources/datasheets/cl.pdf >The simplest "limiter" you can build yourself. It is nothing more than a >coil. The coil can be made around either a dowel or a ferrite slug. The >wire >size is chosen to handle the current of the load and the basic size is about >1/2" ID, 1" OD and 2" Long. The type of wire is SOLID single strand and >is what >is known as Transformer Wire. After wrapping the wire coils TIGHT you can >use >heat shrink tubing over them. If you want to get fancy and I would; before >you heat shrink tube them dip them in varnish. They should be located >close to >the load device. Adding inductance in series with a load does have an effect of softening an inrush current event. However, the time constant of an inductive circuit is (t=L/R) and the inductance of a 1" x 2" wood core inductor with 30T of wire on it is about 10 microhenries. Assuming one finds a suitable hunk of ferrite and assuming also a permeability of about 10, the inductance goes up to about 100 microhenries. Cold closed loop resistance for a 75 watt lamp circuit will be on the order of 0.3 ohms yielding a max time constant on the order of .0001/0.3 or about 1/3 millisecond for a ferrite core device. A wood core device yields about a 1/30 millisecond - rather short compared to the time constant of a part like the KC003L NTC current limiter that will be in the neighborhood of 10-100 milliseconds. An inductive current limiter would be so fast compared to the inrush time for a lamp filament as to offer little assistance in mitigating the magnitude of inrush current. >Oh! When choosing the wire size, do NOT go by the Mil-Spec wire size used in >wiring the plane. I would DOUBLE that wire size. Don't understand why. The current ratings for choosing wire size from charts like those found in AC43-13 or chapter 8 of the 'Connection are already de-rated for 10C temperature rise. The 6A lamp cited in the original post would not seriously warm an inductor wound with 22AWG (5A rated) wire. Bob . . . ________________________________ Message 10 ____________________________________ Time: 06:39:32 AM PST US From: Ernest Christley Subject: AeroElectric-List: Static port on Dynon AoA probe --> AeroElectric-List message posted by: Ernest Christley This only has a cursory connection to electronics in airplanes, but I still thought it would be the best place to ask. The Dynon AoA probe doesn't have provisions for a static port. It was designed with the expectation that the ports would be located on the sides of the fuselage. That's not such a good location in a Delta. The only flat space to put a port would be along the turtleback, aft of the cockpit, which would put them deep inside of the wing's wake. The readings would be all over the place. The plans location is for the static probe to be low on the front leading edge, along with the pitot. I have to build a mounting post for the Dynon probe (again, the available mounting kits are designed for RVs, and don't match up to the Delta's curves and angles) which is basically a streamline tube flaring into the wing. I can see two options: 1) build another tube into the streamlined mounting post pointing forward 2) design ports into the side of the streamlined tube mounting post The second option would look nicer and be aerodynamically cleaner (for a sufficiently small value of aerodynamically clean). The question is, where along the streamline crossection would I put the port in order to reliably pick up static pressure? Would it be better to have a length of flat section to put the ports in, and if so, how big would a flat spot need to be? I'm making this mounting post from composite, so complex shape isn't an issue. -- ,|"|"|, Ernest Christley | ----===<{{(oQo)}}>===---- Dyke Delta Builder | o| d |o http://ernest.isa-geek.org | ________________________________ Message 11 ____________________________________ Time: 07:15:32 AM PST US From: "glen matejcek" Subject: AeroElectric-List: Lex --> AeroElectric-List message posted by: "glen matejcek" B&B- >...causing him to abort and go off the end of the runway (I'm sure his >accelerate/stop distance was more than the runway length). If he had kept >going on the takeoff he probably would have been able to rotate and get off >the ground in the 3,500 feet he had. Bad day for all. As I understand it, the plane did roll off the end of the rwy, became airborne, and came down a mile off the end of the rwy. >> He was probably still a little below V1 >But did he reach or pass Vrto? You're probably thinking of V1. If memory serves, the 2 rwys at LEX cross at about the highest point on the field. That point is about mid field for the short rwy. The T/O roll would climb about six feet to the apex of that rwy, which would decrease normal accelleration, and then descend nine feet to the other end. In pre-dawn dark, with light rain, one could not see the other end of either rwy. One could speculate that once one was far enough down the rwy to see the far end, and had enough time to go through the 'what the...' process, there was no way to stop in the rwy remaining. Also, that particular rwy is restricted to day vmc ops, and there seems to have been only one controller on duty vs the 2 required by FAA policy. There's no telling what other factors might be in the error chain. A very sad day, indeed. glen matejcek aerobubba@earthlink.net ________________________________ Message 12 ____________________________________ Time: 07:51:48 AM PST US From: "Greg Campbell" Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? I don't have a Dynon yet - but based on my experience with the Chelton Sport: I would say "yes" you do want a separate power switch (for each screen), and "no" you don't want it on during engine start (if the voltage causes it to reboot). My original design had the EFIS screens fused directly to the E-Bus as I couldn't see a time when I would ever want to turn them off. Turning the EFIS screens off is no big deal, but turning the AHRS off and getting an in-flight restart was a big deal when I had the Crossbow NAV425. If I start with just one battery, the EFIS would stay on just fine. If I cross-connect both batteries for the start, the starter would spin a little faster, but both EFIS screens would usually reboot. If the batteries were low - then using both batteries and not having two EFIS screens drawing a couple of extra amps each would be a nice option. The Chelton doesn't have an ON/OFF switch on the EFIS, (or I haven't found it ;-) The other place it would be nice is if you're trying to shed some load. I have two screens, but I can easily get by with one. Turning one off in flight wasn't an option before. And those screens DO put out the heat. And finally - if one of the screens acted up & did something weird, it would be nice to be able to shut it off to avoid the distraction. So... for all these reasons, I plan on adding a power switch to each EFIS screen. My current plan is to continue using fuses, but add a DPDT ON-OFF-ON switch, possibly with a "guard". With the guard down, it would be in the "normal ON" position and connected to a fuse in the E-Bus. In the "center OFF" position the screen would be off. In the "alternate ON" position with the guard up, it would be connected to a different fuse directly on the main bus. This gives me the ability to: 1) reboot just one screen 2) turn off one screen (to save power, heat, etc..) 3) take a "second shot" if the first fuse pops, by switching to the "alternate ON" 4) gain back the voltage lost through the diode to the E-Bus (the second fuse goes direclty to Bus1) IF the battery is ever getting really, really, low - that last 0.4v might make a difference. The Chelton "small screens" run considerably warmer than the Dynon. I've been flying with the Chelton's for over a year and my system is still evolving. One other thing I discovered is that my Grand Rapids EIS "fades out" long before the other screens stop running in a low voltage situation. It continues to put out valid engine data to the Chelton, but you won't be able to see it on the EIS. Consider what you would do if you smelled electrical smoke in the cockpit !? Reaching over and shutting off the master switch might be overkill, or it could be your first choice. The airlines teach that once you've made the situation "survivable" you should usually stop troubleshooting. Turning off the master switch in-flight needn't leave you clueless, so my backup instruments include mechanical gages for: airspeed, altimeter, VSI, compass, and MP. A battery backed Dynon wouldn't be bad either! Greg ________________________________ Message 13 ____________________________________ Time: 07:58:55 AM PST US From: FLYaDIVE@aol.com Subject: Re: AeroElectric-List: Paralleled microphone circuits? --> AeroElectric-List message posted by: FLYaDIVE@aol.com >My question is, "Can I connect my mike to both radios concurrently. I will >have seperate PTT switches, so only one radio will transmit. I am not sure >if the 2nd radio will load the mike too much, or will there be some other >gotcha out there? ========================================= It depends on HOW you hook up the PTT switch. You do NOT want the MIC to be HOT in a parallel radio circuit. That would change the MIC matching impedance of both radios. But, if you switch in and out the MIC lines using a PTT switch that would work. In most cases the PTT switch ONLY keys ON the radio and does not switch in and out the MIC. You may have to go to a small relay ... Point of Failure. The problem as I see it is ... When you talk to yourself or yell at yourself (as needed) you will NOT have any sidetone in the headset. Lucky it is a single seater ;-) Barry "Chop'd Liver" "Show them the first time, correct them the second time, kick them the third time." Yamashiada ________________________________ Message 14 ____________________________________ Time: 08:20:39 AM PST US From: "Doug Windhorn" Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? FYI, the Dynon is set to come on when powered (mine is via fuse from the e-bus). If it were necessary to turn it off for starting (not), a simple push of the lower left button for 2 secs. turns it off. Doug Windhorn ----- Original Message ----- From: Greg Campbell To: aeroelectric-list@matronics.com Sent: Thursday, 31 August, 2006 7:50 Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? I don't have a Dynon yet - but based on my experience with the Chelton Sport: I would say "yes" you do want a separate power switch (for each screen), and "no" you don't want it on during engine start (if the voltage causes it to reboot). My original design had the EFIS screens fused directly to the E-Bus as I couldn't see a time when I would ever want to turn them off. Turning the EFIS screens off is no big deal, but turning the AHRS off and getting an in-flight restart was a big deal when I had the Crossbow NAV425. If I start with just one battery, the EFIS would stay on just fine. If I cross-connect both batteries for the start, the starter would spin a little faster, but both EFIS screens would usually reboot. If the batteries were low - then using both batteries and not having two EFIS screens drawing a couple of extra amps each would be a nice option. The Chelton doesn't have an ON/OFF switch on the EFIS, (or I haven't found it ;-) The other place it would be nice is if you're trying to shed some load. I have two screens, but I can easily get by with one. Turning one off in flight wasn't an option before. And those screens DO put out the heat. And finally - if one of the screens acted up & did something weird, it would be nice to be able to shut it off to avoid the distraction. So... for all these reasons, I plan on adding a power switch to each EFIS screen. My current plan is to continue using fuses, but add a DPDT ON-OFF-ON switch, possibly with a "guard". With the guard down, it would be in the "normal ON" position and connected to a fuse in the E-Bus. In the "center OFF" position the screen would be off. In the "alternate ON" position with the guard up, it would be connected to a different fuse directly on the main bus. This gives me the ability to: 1) reboot just one screen 2) turn off one screen (to save power, heat, etc..) 3) take a "second shot" if the first fuse pops, by switching to the "alternate ON" 4) gain back the voltage lost through the diode to the E-Bus (the second fuse goes direclty to Bus1) IF the battery is ever getting really, really, low - that last 0.4v might make a difference. The Chelton "small screens" run considerably warmer than the Dynon. I've been flying with the Chelton's for over a year and my system is still evolving. One other thing I discovered is that my Grand Rapids EIS "fades out" long before the other screens stop running in a low voltage situation. It continues to put out valid engine data to the Chelton, but you won't be able to see it on the EIS. Consider what you would do if you smelled electrical smoke in the cockpit !? Reaching over and shutting off the master switch might be overkill, or it could be your first choice. The airlines teach that once you've made the situation "survivable" you should usually stop troubleshooting. Turning off the master switch in-flight needn't leave you clueless, so my backup instruments include mechanical gages for: airspeed, altimeter, VSI, compass, and MP. A battery backed Dynon wouldn't be bad either! Greg ________________________________ Message 15 ____________________________________ Time: 11:59:49 AM PST US From: D Wysong Subject: AeroElectric-List: downside of manual battery disconnects? --> AeroElectric-List message posted by: D Wysong Does anyone have any experience with the manual battery disconnects that the hot rod folks use? Has anyone heard any issues with corrosion or failures or horror stories floating around about these things? Are certain brands better than others? Are any (for whatever reason) more suitable for aircraft use than others? Thanks for the insight! D ________________________________ Message 16 ____________________________________ Time: 12:14:36 PM PST US Subject: AeroElectric-List: Re: GRT Wx Impressions From: "gyoung" --> AeroElectric-List message posted by: "gyoung" Has anyone opened up the 396 power (cig lighter) cord to see if there are wires in it for the data connections? I know I can buy a cord with bare wires that has the power and serial connections but I'd like to maintain the cig lighter plug for power. If the wires are in the one I have, I'll splice into them. Any other alternatives? Regards, Greg Young james(at)berkut13.com wrote: > Thanks for the report Mike, > > Unfortunately, your friend must not have had the Garmin 430 and 396 > connected by the serial data line. The two units, if properly connected, > will transfer the flight plans requiring only a single data entry in the > 430. They also connect to the SL-30 radios to pre-select the frequencies as > the flight progresses. > > Of course, if it's not plugged in...it will never work. ;-) > > James Redmon > Berkut #013 N97TX > http://www.berkut13.com > > --- Read this topic online here: http://forums.matronics.com/viewtopic.php?p=58764#58764 ________________________________ Message 17 ____________________________________ Time: 01:07:10 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Static port on Dynon AoA probe --> AeroElectric-List message posted by: Brian Lloyd Ernest Christley wrote: > 1) build another tube into the streamlined mounting post pointing forward > 2) design ports into the side of the streamlined tube mounting post If you examine the pitot tube on a Yak-52 or CJ6A you will find that the static ports are in a ring around the pitot tube about 1" back from the front. The whole assembly sticks out of the leading edge of the wing by about 16". It works just peachy and the errors are minimal. Brian ________________________________ Message 18 ____________________________________ Time: 01:44:27 PM PST US From: Kevin Horton Subject: Re: AeroElectric-List: Static port on Dynon AoA probe --> AeroElectric-List message posted by: Kevin Horton On 31 Aug 2006, at 09:38, Ernest Christley wrote: > --> AeroElectric-List message posted by: Ernest Christley > > > This only has a cursory connection to electronics in airplanes, but > I still thought it would be the best place to ask. > The Dynon AoA probe doesn't have provisions for a static port. It > was designed with the expectation that the ports would be located > on the sides of the fuselage. That's not such a good location in a > Delta. The only flat space to put a port would be along the > turtleback, aft of the cockpit, which would put them deep inside of > the wing's wake. The readings would be all over the place. The > plans location is for the static probe to be low on the front > leading edge, along with the pitot. > I have to build a mounting post for the Dynon probe (again, the > available mounting kits are designed for RVs, and don't match up to > the Delta's curves and angles) which is basically a streamline tube > flaring into the wing. I can see two options: > > 1) build another tube into the streamlined mounting post pointing > forward > 2) design ports into the side of the streamlined tube mounting post > > The second option would look nicer and be aerodynamically cleaner > (for a sufficiently small value of aerodynamically clean). The > question is, where along the streamline crossection would I put the > port in order to reliably pick up static pressure? Would it be > better to have a length of flat section to put the ports in, and if > so, how big would a flat spot need to be? I'm making this mounting > post from composite, so complex shape isn't an issue. There is no reliable way to predict an exact probe profile and location that will give an acceptable static source. I have been involved with two projects that tried to chose locations for static pressure ports. One project, on a type-certificated light aircraft, used engineering analysis and experience to chose a static port location. The chosen location had large errors, and the easiest solution was to launch into a fly, fix, fly approach, using a modified Piper pitot-static port. They kept on changing the angle on the bottom of the Piper port until they found an acceptable compromise. I recall that there were at least four configurations tested, maybe more. The other project, on a large business jet, had a much larger budget. They used computational flow dynamics (CFD) computer predictions to chose a static port location. The chosen location produced such large errors at high angle of attack that the indicated airspeed would stagnate as you approached the stall, then it would start increasing as you got closer to the stall. It was fixed by putting a very complicated correction curve in an air data computer. Bottom line - the best bet is to copy exactly what someone else has done, assuming they have a successful installation with acceptable errors. If you start experimenting, the best chance of success is to get the static port as far ahead of the wing as possible. Any location near the wing is a recipe for trouble, as the wing's purpose is to modify the local pressures to create lift, and a static port needs to see the far-field ambient pressure. If you put a "roll your own" system near the wing, expect to find large errors. If you enjoy flight testing, this is a good thing, as it will keep you busy for months doing fly, fix, fly. Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://www.kilohotel.com/rv8 ________________________________ Message 19 ____________________________________ Time: 02:27:03 PM PST US From: "Carlos Trigo" Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? So... for all these reasons, I plan on adding a power switch to each EFIS screen. My current plan is to continue using fuses, but add a DPDT ON-OFF-ON switch, possibly with a "guard". With the guard down, it would be in the "normal ON" position and connected to a fuse in the E-Bus. In the "center OFF" position the screen would be off. In the "alternate ON" position with the guard up, it would be connected to a different fuse directly on the main bus. This gives me the ability to: 1) reboot just one screen 2) turn off one screen (to save power, heat, etc..) 3) take a "second shot" if the first fuse pops, by switching to the "alternate ON" 4) gain back the voltage lost through the diode to the E-Bus (the second fuse goes direclty to Bus1) Greg I am planning something similar, but some time ago I realized that when one wants to go from "normal ON" to "alternate ON", or backwards, it is not possible without rebooting the unit, since you will have to pass by the central OFF position of the DPDT switch, which will cut power to unit. How can this be solved? I looked for a OFF - ON - ON switch but didn't find it. Does it exist? Carlos ________________________________ Message 20 ____________________________________ Time: 02:43:44 PM PST US From: Subject: Re: AeroElectric-List: downside of manual battery disconnects? --> AeroElectric-List message posted by: ---- D Wysong wrote: > --> AeroElectric-List message posted by: D Wysong > > Does anyone have any experience with the manual battery > disconnects that the hot rod folks use? > > Has anyone heard any issues with corrosion or failures or > horror stories floating around about these things? > > Are certain brands better than others? > > Are any (for whatever reason) more suitable for aircraft use > than others? > > Thanks for the insight! > > D D I would suggest getting a brand name unit. The German made Hella brand is very good quality. You can find them at your local marine supply store. Charlie Kuss ________________________________ Message 21 ____________________________________ Time: 02:58:48 PM PST US From: Kelly McMullen Subject: Re: AeroElectric-List: Re: Alternator Switching --> AeroElectric-List message posted by: Kelly McMullen Your 1960 Mooney came with a generator and a single master switch, so there was no choice but to have the whole bus active during start. Generators could care less whether the master is on or off. Of course, it didn't have an avionics master either. Do Not Archive Quoting Dave N6030X : > --> AeroElectric-List message posted by: Dave N6030X > > My scratch-built Dragonfly did not come with a POH. And my 1960 Mooney > POH doesn't tell me what order to switch them on either. I suspect > most of the people on this list are building experimentals and will be > WRITING the POH. > > Dave > > At 09:08 AM 8/30/2006, you wrote: >> Repeat: FOLLOW THE CHECKLIST AS DESIGNED BY A TEAM >> OF ENGINEER'S (who have covered all bases) AND IS APPROVED >> BY THE FAA. If experimental try to follow industry standards, which >> is: ALT on before start, ALT off after shutdown. Simple. > > ________________________________ Message 22 ____________________________________ Time: 03:34:14 PM PST US From: Nancy Ghertner Subject: Re: AeroElectric-List: Is EFIS vulnerable at engine start? --> AeroElectric-List message posted by: Nancy Ghertner On 8/30/06 9:10 PM, "gert" wrote: > --> AeroElectric-List message posted by: gert > > begs the question, what about the current crop of electronic engine > instruments, ya all keep them off till u engine is running. > What good are they if u can't have them on during engine start ;-) > so u wait till the engine is running, switch u electronic instruments on > to discover u have no oil pressure, oops....somehow i don't think i want > Blue Mountain to check my oil pressure if i have to have their system > off during engine start. > > A DeMarzo wrote: >> And I think that I would spring for a $10 switch as just a tiny bit >> more protection on my $3000 instrument. >> >> Spikes Happen >> >> Al >> General Aviation - Pricing People Out Daily >> >> >> >> On 08/30/2006 7:56:01 AM, Bill Denton (bdenton@bdenton.com >> ) wrote: >>> Dynon disagrees... >>> >>> The following exchange came from >>> Dynon's message board: >>> >>> Question: "I've just installed my D10A and as >>> advised in the instructions wired it through a 2 amp fuse. Since I >>> didn't order the internal battery, I did not connect the "stay >> alive" wire and also did not install a separate power switch. The unit >> comes on when I turn on the master switch without my pressing the unit's >>> power button. I assume this in normal, but can I have problems with >> power >>> spikes during engine start? Should I install a separate power switch in >>> the Dynon circuit? If not, should I turn off the EFIS before engine >>> start?" >>> >>> >>> Answer, from Dynon Support: >>> >>> "The EFIS is indeed >>> designed to come alive when power is applied. >>> >>> Many customers install the EFIS in exactly the same electrical >>> configuration you have set up. The unit will not be damaged by having it >>> on during engine start, but it may reboot if the voltage momentarily >> drops >>> below 10V. >>> >>> Also, since you did not purchase the internal battery, you may want to >>> connect the keep alive wire to power the clock when your master >> switch is >>> off. Otherwise it will reset after every power >> * >> >> >> * You can hook up a back up battery either for the Blue Mountain alone with a diode in the circuit available on their website, or as I am doing use the back up battery for the emergency bus to power up the efis before start up. Lory Ghertner ________________________________ Message 23 ____________________________________ Time: 04:51:56 PM PST US From: Hopperdhh@aol.com Subject: Re: AeroElectric-List: in-rush limiters In a message dated 8/31/2006 8:53:53 A.M. Eastern Daylight Time, nuckollsr@cox.net writes: Don't understand why. The current ratings for choosing wire size from charts like those found in AC43-13 or chapter 8 of the 'Connection are already de-rated for 10C temperature rise. The 6A lamp cited in the original post would not seriously warm an inductor wound with 22AWG (5A rated) wire. Bob . . . Bob, When wire is wound in a transformer or choke, the density of the power loss is much greater than even in a bundle of wires. A typical design value is 500 to 1000 circular mils per amp. Solid number 22 wire is 25.3 mils in diameter and has about 643 circular mils. Therefore it is only rated for about 1 amp when wound in a multi layered coil. Operating a number 22 enamel wire at 5 amps continuously when it is tightly surrounded by more number 22 enamel wire also carrying 5 amps would cause it to overheat. Dan Hopper Retired electrical engineer and transformer nut. ________________________________ Message 24 ____________________________________ Time: 05:21:48 PM PST US From: Hopperdhh@aol.com Subject: Re: AeroElectric-List: in-rush limiters Bob, Sorry, after rereading all the posts on this subject, I made a wrong assumption in writing the reply below. The reply still is correct, but probably not applicable. Dan In a message dated 8/31/2006 7:54:57 P.M. Eastern Daylight Time, Hopperdhh@aol.com writes: In a message dated 8/31/2006 8:53:53 A.M. Eastern Daylight Time, nuckollsr@cox.net writes: Don't understand why. The current ratings for choosing wire size from charts like those found in AC43-13 or chapter 8 of the 'Connection are already de-rated for 10C temperature rise. The 6A lamp cited in the original post would not seriously warm an inductor wound with 22AWG (5A rated) wire. Bob . . . Bob, When wire is wound in a transformer or choke, the density of the power loss is much greater than even in a bundle of wires. A typical design value is 500 to 1000 circular mils per amp. Solid number 22 wire is 25.3 mils in diameter and has about 643 circular mils. Therefore it is only rated for about 1 amp when wound in a multi layered coil. Operating a number 22 enamel wire at 5 amps continuously when it is tightly surrounded by more number 22 enamel wire also carrying 5 amps would cause it to overheat. Dan Hopper Retired electrical engineer and transformer nut. (http://www.matronics.com/Navigator?AeroElectric-List) (http://www.matronics.com/contribution) ________________________________ Message 25 ____________________________________ Time: 08:10:16 PM PST US From: "glaesers" Subject: AeroElectric-List: Re: Is EFIS vulnerable at engine start? --> AeroElectric-List message posted by: "glaesers" ---------------------------------------------------------------------------- ---------------------------- I am planning something similar, but some time ago I realized that when one wants to go from "normal ON" to "alternate ON", or backwards, it is not possible without rebooting the unit, since you will have to pass by the central OFF position of the DPDT switch, which will cut power to unit. How can this be solved? I looked for a OFF - ON - ON switch but didn't find it. Does it exist? Carlos ---------------------------------------------------------------------------- --------------------------- The switch you are looking for is the Master Switch that B&C sells (the S-10 - $19.50). See: http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?11X358218#s700-2-10 This is a double-pole switch, which may be more than you need, but getting a single pole version will be a $pecial order item from someplace like Digikey or Mouser or OnlineComponents and probably take a while to get. Dennis Glaeser