---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 07/22/09: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:19 AM - Re: Wild flights... 22 hr trip in an LSA over the Atlantic... (Werner Schneider) 2. 08:09 AM - differences in fuses versus circuit breakers (Dj Merrill) 3. 09:33 AM - EV200 (al38kit) 4. 09:47 AM - Re: transorbs (nuckollsr) 5. 04:31 PM - Re: EV200 (Robert L. Nuckolls, III) 6. 04:31 PM - Re: differences in fuses versus circuit breakers (Robert L. Nuckolls, III) 7. 05:55 PM - Re: EV200 (al38kit) 8. 06:10 PM - Re: EV200 (Richard E. Tasker) 9. 06:40 PM - Re: differences in fuses versus circuit breakers (Dj Merrill) 10. 07:11 PM - Re: Autopilots vs. "The Right Stuff" (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:19:49 AM PST US From: Werner Schneider Subject: Re: AeroElectric-List: Wild flights... 22 hr trip in an LSA over the Atlantic... Jay, I wish them luck, but when I look at their route they can only depart when very favourable winds are around as the last leg to this Island in the Atlantic took a bit more then they expected I guess, as with that GS they will not make it to Brazil! Good luck and hopefully a proper flight planning! Werner do not archive ________________________________ Message 2 _____________________________________ Time: 08:09:47 AM PST US Subject: AeroElectric-List: differences in fuses versus circuit breakers From: Dj Merrill Hi Bob, For the 12v/24v DC circuits typically used in our aircraft, is there any difference in the rating one would select if using a fuse versus a circuit breaker? In other words, a hypothetical example, if one arrived at a value of 15 amps to protect a wire, would a 15 amp fuse be interchangeable with a 15 amp circuit breaker for protecting the wire? I ask for two reasons - in a discussion on another mailing list, someone has said that fuses and circuit breakers of the same rated value are not interchangeable, and AC43.13-1B table 11-3 on page 11-15 in Section 4 shows a 15 amp CB or a 10 amp fuse to protect a 16 gauge copper wire (picture attached). If there is a difference, do you know and can you explain in simple terms why? Thanks, -Dj -- Dj Merrill - N1JOV Glastar Sportsman 2+2 Builder #7118 N421DJ http://deej.net/sportsman/ "Many things that are unexplainable happen during the construction of an airplane." --Dave Prizio, 30 Aug 2005 ________________________________ Message 3 _____________________________________ Time: 09:33:35 AM PST US Subject: AeroElectric-List: EV200 From: "al38kit" It appears the EV200 is a good master relay...anyone know why it should not be used as a starter relay...also...? Al Read this topic online here: http://forums.matronics.com/viewtopic.php?p=254326#254326 ________________________________ Message 4 _____________________________________ Time: 09:47:02 AM PST US Subject: AeroElectric-List: Re: transorbs From: "nuckollsr" Yes I still have it and I'd be happy to send it to Bob if he wants to take a look. It's in heat shrink with lead wires sticking out. I haven't molested it yet - just checked it with a meter. A transorb is basicaly two zeners back to back and one in this is shorted. It measures a standard diode drop one way and open the other. Yes, I'd like to look at it. Please send to Bob Nuckolls, P.O. Box 130, Medicine Lodge, KS 67104-0130. Bob . . . Read this topic online here: http://forums.matronics.com/viewtopic.php?p=254333#254333 ________________________________ Message 5 _____________________________________ Time: 04:31:12 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EV200 At 11:31 AM 7/22/2009, you wrote: > >It appears the EV200 is a good master relay...anyone know why it >should not be used as a starter relay...also...? To what advantage? This is a contactor that operates for a few seconds per flight cycle. The el-cheeso parts have performed well and demonstrated good value. The EV200 may function well too . . . but what's the expected return on investment for the more expensive purchase? Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 6 _____________________________________ Time: 04:31:22 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: differences in fuses versus circuit breakers At 10:06 AM 7/22/2009, you wrote: >Hi Bob, > For the 12v/24v DC circuits typically used in our aircraft, is there >any difference in the rating one would select if using a fuse versus a >circuit breaker? In other words, a hypothetical example, if one arrived >at a value of 15 amps to protect a wire, would a 15 amp fuse be >interchangeable with a 15 amp circuit breaker for protecting the wire? This is a classic example of how AC43.13 offers advice that is not explained and makes no sense based on the physics. For example, AC43.13 says their table applies to fuses per Mil-F-15160. Here . . . http://www.dscc.dla.mil/Programs/MilSpec/ListDocs.asp?BasicDoc=MIL-PRF-15160 we see that the general spec covers a couple dozen types of fast acting fuses (1 hour trip at 135%, seconds to few minutes at 200%). The spec called out is constellation of FORM/FIT/FUNCTION specs for a variety of fuses. Now we go look at Mil-C-5806G . . . http://www.aeroelectric.com/Reference_Docs/Circuit_Breaker/Mil-C-5806G.pdf This is a QUALIFICATION TEST spec for circuit breakers of unspecified performance. The poor sap who takes AC43.13 table 11-13, and the specifications called out (gee the talked about Mil-W-5088 wire too!) will be pretty much in the dark as to how a considered selection can be made. MOST readers will simply check to see that the sales brochure for each part under consideration simply cites these specs . . . without a clue as to how the part performs to design goals. > I ask for two reasons - in a discussion on another mailing list, >someone has said that fuses and circuit breakers of the same rated value >are not interchangeable, and AC43.13-1B table 11-3 on page 11-15 in >Section 4 shows a 15 amp CB or a 10 amp fuse to protect a 16 gauge >copper wire (picture attached). For our purposes, breakers and fuses are size-for-size interchangeable. The table cited from AC43.13 is but one of many examples of poor and/or senseless advice. Please consider running section 11 through the shredder and come here to the AeroElectric List for advice based on experience and proven recipes for success. The article at http://www.aeroelectric.com/articles/wiresize.pdf speaks to the practical aspects of wire sizing and selection of circuit protection. For the airplanes we're building, it DOESN'T need to be complicated. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 7 _____________________________________ Time: 05:55:11 PM PST US Subject: AeroElectric-List: Re: EV200 From: "al38kit" If I could get the parts cheap enough, the benefit for me, with two planes, would be interchangeability...or just having one spare on the shelf. Thanks for the initial lead, it looks like a great relay, but like you say, can be pricey...I think I can get them at a little over $40. Cheers, Al Read this topic online here: http://forums.matronics.com/viewtopic.php?p=254422#254422 ________________________________ Message 8 _____________________________________ Time: 06:10:56 PM PST US From: "Richard E. Tasker" Subject: Re: AeroElectric-List: EV200 Uuuh... Because a much cheaper and perfectly adequate solution is available - the normal el-cheapo starter relay. The only reason I can see for ever using the EV200 is that it uses less current when it is energized which might be justifiable for the master relay. But for the starter relay - how long would it be on when starting - 2-5 seconds? Save the money and spend it on gas... My $0.02 Dick Tasker al38kit wrote: > > It appears the EV200 is a good master relay...anyone know why it should not be used as a starter relay...also...? > > Al ________________________________ Message 9 _____________________________________ Time: 06:40:43 PM PST US Subject: Re: AeroElectric-List: differences in fuses versus circuit breakers From: Dj Merrill On 7/22/2009 7:25 PM, Robert L. Nuckolls, III wrote: > For our purposes, breakers and fuses are size-for-size interchangeable. Thanks! :-) -Dj ________________________________ Message 10 ____________________________________ Time: 07:11:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Autopilots vs. "The Right Stuff" At 11:21 AM 7/21/2009, you wrote: >Yes, with the wondrous capabilities and reliability of today's >computer controlled machines, be assured that nothing can go >wrong...go wrong...go wrong....go........ > >I seem to recall reading about several accidents caused by the >erroneous actions of computer controlled servo systems; actions that >couldn't be detected nor corrected by the pilots. Admittedly, these >were the result of faulty assumptions being built into the >computer's database by humans. I guess it comes down to "who (or >what) do you trust?" Or designing for failure tolerance. Accidents that follow servo system failures are generally situations where the pilot did not have his/her hand on the stick while too close to the ground. I've had a/p systems hiccup . . . and it's never pleasant. I wouldn't shoot a coupled approach without having a hand on the wheel and a thumb on the disconnect switch. You need to unhook the autopilot to land so you can be ready to punch it off when you break out and/or punch it off when and if it strays. I worked a FMEA on a Baron accident where the pilot was in a climb and punched altitude hold as he approached his assigned level. The autopilot immediately grabbed pitch and held the desired altitude. At the same time, it started driving trim to take force out of the pitch servo. Unfortunately, the down-pitch relay stuck and continued to trim down while the a/p servo worked to keep pitch level. When the pitch servo ran out of authority, the aircraft nosed down. The pilot was then aware of a problem. He correctly deduced a difficulty in the automatic flight control system and punched the a/p disconnect button. The pitch servo relaxed and the airplane was now trimmed nearly full nose down trim. Forces on the wheel needed to keep the airplane level would have been high. He was so busy trying to fly the airplane that he probably didn't notice the trim situation. This was a smoking hole event where all of the wreckage ended up in a single divot. In years since we've installed pitch authority limiters in servos (no reason for the a/p to be more capable than a robust pilot), trim in motion annunciation signals, and software based monitors that watch for diverging forces. The accident was a simple, analog, single channel autopilot that had a connection to the standard factory electric trim. The a/p had no way to spot the stuck relay but was capable of standing off the effects of divergent forces until they were too large for the pilot to physically handle when he told the autopilot to buzz off. Microprocessors, highly integrated flight control systems, and lessons-learned have largely eliminated such events. The forces and rates in a stepper motor implemented wing leveler can never over-stress a pilot or an airframe. Bob . . . ------------------------------------------------------------------------------------- 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 Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse 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.