---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 12/08/09: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:51 AM - Re: Switchology Question (logansc) 2. 05:10 AM - Who Has Got The Time? () 3. 07:14 AM - Re: Who Has Got The Time? () 4. 07:39 AM - Re: Hobbs MeterHobbs Meter (Fran & Joe) 5. 09:02 AM - Re: Dual Battery Contactor (Robert L. Nuckolls, III) 6. 10:02 AM - Re: Dual Battery Contactor (P.S.) (Robert L. Nuckolls, III) 7. 10:11 AM - Re: Hobbs Meter (user9253) 8. 10:22 AM - Re: Dual Battery Contactor (Chris Stone) 9. 11:02 AM - Re: Switchology Question (Jeff Page) 10. 12:43 PM - Re: Dual Battery Contactor () 11. 01:34 PM - Re: Who Has Got The Time? (BobsV35B@aol.com) 12. 02:35 PM - Re: Who Has Got The Time? (ray) 13. 03:25 PM - Re: Who Has Got The Time? (Robert L. Nuckolls, III) 14. 04:11 PM - Re: Dual Battery Contactor (Robert L. Nuckolls, III) 15. 06:46 PM - Power Mizer (Bill Bradburry) 16. 07:29 PM - Re: Power Mizer (Matt Prather) 17. 08:57 PM - Re: Power Mizer (Robert L. Nuckolls, III) 18. 10:25 PM - Re: Lopresti HID claims (XeVision) ________________________________ Message 1 _____________________________________ Time: 04:51:10 AM PST US Subject: AeroElectric-List: Re: Switchology Question From: "logansc" Bob: Thanks for the response. I'll work out a "switchology" sequence today and try it this afternoon. Regards, Lee... Read this topic online here: http://forums.matronics.com/viewtopic.php?p=276676#276676 ________________________________ Message 2 _____________________________________ Time: 05:10:55 AM PST US From: Subject: AeroElectric-List: Who Has Got The Time? 12/6/2009 (and again on 11/8/2009) Hello Fellow Pilots and Builders, The aeroelectric list has been filled lately with discussions of hardware (meters) that keep track of time. Just exactly what time is being kept, and for what purpose, is unclear. To shed some light on the subject let's start by taking a look at what 14 CFR (FAR's) say about time. We'll take flight time first, then TIS (Time In Service): 1) Here is how pilot flight time is defined in section 1.1 of the FAR's : "Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing;" I am not aware of any meter that could keep accurate track of such time. You'll find many pilots, and airlines, that do not keep track of flight / pilot time in conformance with this definition. Standard compliance by all pilots with this definition is unlikely because there is room for interpretation. Does "moves under its own power for the purpose of flight" mean the instant the wheels start to roll as you leave the parking space in order to go flying? Then that XXX minutes plus that you spend taxiing, doing engine run up, and waiting for takeoff clearance at the end of the runway, would all be flight time. Considering the delays involved in operating at some airports one could become a multi thousand hour flight time pilot very quickly using that interpretation. On the other hand one is certainly exercising some very important PIC duties from the time he leaves the parking space until starting takeoff roll. Should all of that time be ignored and not recognized in some fashion? 2) Here is how section 1.1 of FAR's defines TIS (Time In Service): "Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing." I suppose that there is hardware that could record this exact time, but it certainly is not in common use in our category of airplanes. So let's take a look at three common timing devices: the Hobbs meter, the mechanical engine RPM based tachometer, and the software associated with electronic flight instrumentation or engine instrumentation: A) The Hobbs meter (you can look here for a quick review): http://en.wikipedia.org/wiki/Hobbs_meter It doesn't take very long to conclude that "Hobbs meter" has become a very generic term (like Kleenex or Scotch tape) and that Hobbs meters come in wide varieties and can be connected to record a wide variety of time. I guess it is possible for a Hobbs meter to be connected up so that it records one of the time definitions in the FAR's, but it doesn't seem easy. B) FAR 91.205 (a) and (b) require an engine tachometer to be installed in any powered standard category civil aircraft even for day VFR operations. By far the most common type of tachometer found is the mechanical RPM based tachometer. Presumably the purpose of the required tachometer is to inform the pilot of his engine's RPM at any given instant, but somewhere along the line these tachometers began including the total time of engine operation. This required someone to decide how to convert instantaneous RPM into total elapsed time of engine operation. If, say 2,000 RPM were chosen as the standard mechanical ratio to convert one minute at this RPM into one minute of elapsed engine operating time then any engine operation at less than 2,000 RPM generates less than one minute of elapsed engine operating time and any RPM greater than 2,000 generates more than one minute of elapsed engine operating time. See some of the tachometer conversion ratios between RPM and time available here: http://tghaviation.rtrk.com/?scid=387399&kw=3649251 In any case it does not appear that any mechanical engine tachometer can generate either of the elapsed times defined by the FAR's. C) There is such a huge variety of electronic flight and engine instrumentation systems and their associated software (and the ability of the operator to modify the software in some cases) that any accurate comparison of one airplane's / engine's / pilot's time to another airplane's / engine's / pilot's time would require some detailed examination of the processes used to generate that time. Again the probability that an electronic system would automatically generate elapsed time in exact compliance with either of the FAR time definitions is not likely. So what is the builder / pilot to do? My suggestions: a) Don't get all wrapped around the axle about generating time. Many people are not recording flight time or time in service the same way that you are. b) Pick some hardware and a system of documentation that seems to fit your needs and go with it. c) Be consistent in how you do things so that you can view and show the results with some confidence. d) Be wary of someone else's time claims, but don't make a big deal of time unless you are billing by the hour. 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." PS: My choice for my airplane was just to record "Tach time" from my engine electronic data system for both flight time and TIS. My engine data system generates zero tach time anytime the engine RPM is less than 1,500 RPM and constant equal running time in hours and tenths any time the engine RPM is above 1,500 RPM. Recording this time for both flight time and TIS short changes me on pilot flight time since a fair amount of time while practicing landings in the landing pattern the engine is below 1,500 RPM. On the other hand it will take much longer elapsed time for my engine to reach its 2,000 hour TIS to be due for overhaul. This approach greatly simplifies my bookkeeping. Back when I was flying rental aircraft I just went with the flow and used the FBO's Hobbs meter time for flight time -- I paid for it, I should be able to log it. ________________________________ Message 3 _____________________________________ Time: 07:14:13 AM PST US Subject: RE: AeroElectric-List: Who Has Got The Time? From: Couple of observations. 1. Regardless of all the wiz bang stuff out there, piloting is still very much a human engineered activity. The rolling time is what the pilot enters in his/her logbook and swears to it based on their signature. If the FAA had the resources (and they don't) they could easily match Hobbs with book entries to see how much you're cheating. Until they begin using biometrics which are fed wirelessly to the FBI database to log activity around and in aircraft, your word is good. I hope I don't give anyone at the FAA any ideas? 2. Have you ever seen or flown antique aircraft? They don't have spit for gauges. Ok, one airspeed dial and oil pressure. Again, pilot rules the books and the sky. 3. Hobbs are useful in rental aircraft for obvious reasons and yes, it's natural to log from them if you subtract the time the plane wasn't actually moving under its own power, but idling there trying to warm up, waiting for you etc. Someday we'll all have remote starters with automatic shutdown if there is a problem so we can spend more time drinking coffee by the window and BS'n in the pilot lounge while our climate controlled cabins warm up. 4. Like many I am more interested in how long to my next service interval than I am struggling to amass 10,000 hours in my log book. Accuracy is good at all plateaus. I have two Dynons of which each has more clocks and time settings than a Swiss train station. Glenn E. Long -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of bakerocb@cox.net Sent: Tuesday, December 08, 2009 8:07 AM Subject: AeroElectric-List: Who Has Got The Time? 12/6/2009 (and again on 11/8/2009) Hello Fellow Pilots and Builders, The aeroelectric list has been filled lately with discussions of hardware (meters) that keep track of time. Just exactly what time is being kept, and for what purpose, is unclear. To shed some light on the subject let's start by taking a look at what 14 CFR (FAR's) say about time. We'll take flight time first, then TIS (Time In Service): 1) Here is how pilot flight time is defined in section 1.1 of the FAR's : "Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing;" I am not aware of any meter that could keep accurate track of such time. You'll find many pilots, and airlines, that do not keep track of flight / pilot time in conformance with this definition. Standard compliance by all pilots with this definition is unlikely because there is room for interpretation. Does "moves under its own power for the purpose of flight" mean the instant the wheels start to roll as you leave the parking space in order to go flying? Then that XXX minutes plus that you spend taxiing, doing engine run up, and waiting for takeoff clearance at the end of the runway, would all be flight time. Considering the delays involved in operating at some airports one could become a multi thousand hour flight time pilot very quickly using that interpretation. On the other hand one is certainly exercising some very important PIC duties from the time he leaves the parking space until starting takeoff roll. Should all of that time be ignored and not recognized in some fashion? 2) Here is how section 1.1 of FAR's defines TIS (Time In Service): "Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing." I suppose that there is hardware that could record this exact time, but it certainly is not in common use in our category of airplanes. So let's take a look at three common timing devices: the Hobbs meter, the mechanical engine RPM based tachometer, and the software associated with electronic flight instrumentation or engine instrumentation: A) The Hobbs meter (you can look here for a quick review): http://en.wikipedia.org/wiki/Hobbs_meter It doesn't take very long to conclude that "Hobbs meter" has become a very generic term (like Kleenex or Scotch tape) and that Hobbs meters come in wide varieties and can be connected to record a wide variety of time. I guess it is possible for a Hobbs meter to be connected up so that it records one of the time definitions in the FAR's, but it doesn't seem easy. B) FAR 91.205 (a) and (b) require an engine tachometer to be installed in any powered standard category civil aircraft even for day VFR operations. By far the most common type of tachometer found is the mechanical RPM based tachometer. Presumably the purpose of the required tachometer is to inform the pilot of his engine's RPM at any given instant, but somewhere along the line these tachometers began including the total time of engine operation. This required someone to decide how to convert instantaneous RPM into total elapsed time of engine operation. If, say 2,000 RPM were chosen as the standard mechanical ratio to convert one minute at this RPM into one minute of elapsed engine operating time then any engine operation at less than 2,000 RPM generates less than one minute of elapsed engine operating time and any RPM greater than 2,000 generates more than one minute of elapsed engine operating time. See some of the tachometer conversion ratios between RPM and time available here: http://tghaviation.rtrk.com/?scid=387399&kw=3649251 In any case it does not appear that any mechanical engine tachometer can generate either of the elapsed times defined by the FAR's. C) There is such a huge variety of electronic flight and engine instrumentation systems and their associated software (and the ability of the operator to modify the software in some cases) that any accurate comparison of one airplane's / engine's / pilot's time to another airplane's / engine's / pilot's time would require some detailed examination of the processes used to generate that time. Again the probability that an electronic system would automatically generate elapsed time in exact compliance with either of the FAR time definitions is not likely. So what is the builder / pilot to do? My suggestions: a) Don't get all wrapped around the axle about generating time. Many people are not recording flight time or time in service the same way that you are. b) Pick some hardware and a system of documentation that seems to fit your needs and go with it. c) Be consistent in how you do things so that you can view and show the results with some confidence. d) Be wary of someone else's time claims, but don't make a big deal of time unless you are billing by the hour. 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." PS: My choice for my airplane was just to record "Tach time" from my engine electronic data system for both flight time and TIS. My engine data system generates zero tach time anytime the engine RPM is less than 1,500 RPM and constant equal running time in hours and tenths any time the engine RPM is above 1,500 RPM. Recording this time for both flight time and TIS short changes me on pilot flight time since a fair amount of time while practicing landings in the landing pattern the engine is below 1,500 RPM. On the other hand it will take much longer elapsed time for my engine to reach its 2,000 hour TIS to be due for overhaul. This approach greatly simplifies my bookkeeping. Back when I was flying rental aircraft I just went with the flow and used the FBO's Hobbs meter time for flight time -- I paid for it, I should be able to log it. ________________________________ Message 4 _____________________________________ Time: 07:39:50 AM PST US From: "Fran & Joe" Subject: Re: AeroElectric-List: Hobbs MeterHobbs Meter This link works: http://www.alliedelec.com/Search/ProductDetail.aspx?SKU 7-0077&gclid= CISGmb-Lx54CFQ_xDAodcwNRrA ________________________________ Message 5 _____________________________________ Time: 09:02:49 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dual Battery Contactor At 05:34 PM 12/7/2009, you wrote: Chris, Thanks for the tip and lead on a great solution for preserving alternators from high stress loads... Not sure there is "benefit" to be realized for shielding an alternator from "high stress" loads. As converters of mechanical to electrical energy, these devices have specifications. They also tend to be designed for a particular marketplace task. The prudent designers, manufacturers and installers of such devices understand the capabilities and limits. That understanding is factored into satisfaction of design goals and establishment of maintenance programs. Subscribing to the notion of "stress mitigation" on an alternator by programming the manner in which loads are applied to the machine suggests that design goals, capabilities and limits are suspect or perhaps known to be poorly married. The aux battery management module for OBAM aircraft was first proposed in an article I wrote for Sport Aviation many moons ago. The intent of this device was to provide automatic management of an auxiliary battery included to power flight critical electro-whizzies. The ABMM prevented connection of the aux battery to the system unless bus voltage was high enough to avoid discharging the battery (i.e. alternator on line). Hence the 13.0 volt switchpoint calibration for closing the contactor. The corollary idea was that the ABMM opens the contactor automatically during alternator shut down or failure thus isolating the aux battery and preserving contained energy for a specific task. The product being discussed appears to perform in precisely the same manner where it's desirable to isolate a RV vehicle battery from recreational electro-whizzies battery unless the alternator is available to service BOTH batteries. This is a PARTICULAR case where the recreational battery is EXPECTED to be deeply discharged. Now, if the vehicle battery has not been abused while parked, then the bus is expected to rise above 13.0 (or 13.2) volts seconds after the engine starts. This device would spare the alternator from "high stress" loads only if BOTH batteries are deeply discharged. But even then, I can't imagine that the bus will stay below 13.2 volts for very long even if the vehicle battery was drawn down completely and the engine was started with jumper cables. Finally, irrespective of number of batteries and no matter how you've abused the batteries, your alternator should be EXPECTED to happily deliver full rated output for an indefinite period of time. If not, there's something wrong with the selection of alternator or the manner in which it has been installed. Bob . . . ________________________________ Message 6 _____________________________________ Time: 10:02:33 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dual Battery Contactor (P.S.) At 05:34 PM 12/7/2009, you wrote: Chris, Thanks for the tip and lead on a great solution for preserving alternators from high stress loads... . . . . irrespective of number of batteries and no matter how you've abused the batteries, your alternator should be EXPECTED to happily deliver full rated output for an indefinite period of time. If not, there's something wrong with the selection of alternator or the manner in which it has been installed. P.S. There's another article I wrote in 1998 that speaks to the physics and operational considerations of diodes vs. contactors for battery management. See: http://www.aeroelectric.com/articles/bat_iso2.pdf Bob . . . ________________________________ Message 7 _____________________________________ Time: 10:11:18 AM PST US Subject: AeroElectric-List: Re: Hobbs Meter From: "user9253" The link in the previous post did not work, but this one should: Joe http://www.alliedelec.com/Search/ProductDetail.aspx?SKU 7-0077&gclid=CISGmb-Lx54CFQ_xDAodcwNRrA -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=276718#276718 ________________________________ Message 8 _____________________________________ Time: 10:22:42 AM PST US From: Chris Stone Subject: Re: AeroElectric-List: Dual Battery Contactor This brings to mind a question as to what happens to the alternator when the load placed on it exceeds it's output capacity? Will the output voltage start to drop as capacity is exceeded? If overload is continued are the diodes the weak link in the chain? Will the diodes fail before overheating of the stator windings? What is the common failure mode? Chris Stone RV-8 -----Original Message----- >From: "Robert L. Nuckolls, III" >Sent: Dec 8, 2009 11:55 AM >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: Dual Battery Contactor > > >At 05:34 PM 12/7/2009, you wrote: > >Chris, >Thanks for the tip and lead on a great solution for preserving >alternators from high stress loads... > > Not sure there is "benefit" to be realized for shielding > an alternator from "high stress" loads. > > As converters of mechanical to electrical energy, these > devices have specifications. They also tend to be designed > for a particular marketplace task. The prudent designers, > manufacturers and installers of such devices understand the > capabilities and limits. That understanding is factored > into satisfaction of design goals and establishment > of maintenance programs. > > Subscribing to the notion of "stress mitigation" on > an alternator by programming the manner in which loads > are applied to the machine suggests that design goals, > capabilities and limits are suspect or perhaps known > to be poorly married. > > The aux battery management module for OBAM aircraft was > first proposed in an article I wrote for Sport Aviation > many moons ago. The intent of this device was to provide > automatic management of an auxiliary battery included > to power flight critical electro-whizzies. The ABMM > prevented connection of the aux battery to the system > unless bus voltage was high enough to avoid discharging > the battery (i.e. alternator on line). Hence the 13.0 > volt switchpoint calibration for closing the contactor. > The corollary idea was that the ABMM opens the contactor > automatically during alternator shut down or failure > thus isolating the aux battery and preserving contained > energy for a specific task. > > The product being discussed appears to perform in > precisely the same manner where it's desirable > to isolate a RV vehicle battery from recreational > electro-whizzies battery unless the alternator > is available to service BOTH batteries. > > This is a PARTICULAR case where the recreational > battery is EXPECTED to be deeply discharged. Now, > if the vehicle battery has not been abused while > parked, then the bus is expected to rise above > 13.0 (or 13.2) volts seconds after the engine > starts. This device would spare the alternator > from "high stress" loads only if BOTH batteries are > deeply discharged. But even then, I can't imagine > that the bus will stay below 13.2 volts for very > long even if the vehicle battery was drawn down > completely and the engine was started with jumper cables. > > Finally, irrespective of number of batteries and > no matter how you've abused the batteries, your > alternator should be EXPECTED to happily deliver > full rated output for an indefinite period of time. > If not, there's something wrong with the selection > of alternator or the manner in which it has been > installed. > > Bob . . . > > ________________________________ Message 9 _____________________________________ Time: 11:02:18 AM PST US From: "Jeff Page" Subject: Re: AeroElectric-List: Switchology Question > You won't see any output from the SD-8 without being > well above 2000 rpm. This caught me off guard and triggered me to look at the specs on the B&C website. I often cruise at 2200rpm. Their web site says that for a Lycoming engine, the vacuum pad runs 1.3:1 compared to the crankshaft. So at 2200 rpm, the SD-8 is turning 2860 rpm. Interpolating their chart idicates about 6A at that speed. While idling, I will get a low voltage indication on my aux bus that I hadn't anticipated. Perhaps I should be considering an SD-20. Jeff Page Dream Aircraft Tundra #10 ________________________________ Message 10 ____________________________________ Time: 12:43:25 PM PST US Subject: RE: AeroElectric-List: Dual Battery Contactor From: Chris, As Bob noted, the alternator will continue to output at its rated capacity as long as the regulator is demanding it. Each alternator should be able to run at its rated capacity for N hours before failing (some calculus test performed at the factory). The bigger question is what are you doing in your cockpit while you are waiting for the alternator to explode and your bus architecture to melt down? Answer, you should be activating your fire gear. No, a diode won't immediately melt if you drop to 8 volts, but by then you should have your contingency plan in action. Should you experience 1 or more failures in any situation, you should start shedding load and if the alternator seems to be a problem, shut it down. Two heads are better than one and one good battery and two alternators are better than 2-3 batteries any day. Glenn -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Chris Stone Sent: Tuesday, December 08, 2009 1:20 PM Subject: Re: AeroElectric-List: Dual Battery Contactor This brings to mind a question as to what happens to the alternator when the load placed on it exceeds it's output capacity? Will the output voltage start to drop as capacity is exceeded? If overload is continued are the diodes the weak link in the chain? Will the diodes fail before overheating of the stator windings? What is the common failure mode? Chris Stone RV-8 -----Original Message----- >From: "Robert L. Nuckolls, III" >Sent: Dec 8, 2009 11:55 AM >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: Dual Battery Contactor > > >At 05:34 PM 12/7/2009, you wrote: > >Chris, >Thanks for the tip and lead on a great solution for preserving >alternators from high stress loads... > > Not sure there is "benefit" to be realized for shielding > an alternator from "high stress" loads. > > As converters of mechanical to electrical energy, these > devices have specifications. They also tend to be designed > for a particular marketplace task. The prudent designers, > manufacturers and installers of such devices understand the > capabilities and limits. That understanding is factored > into satisfaction of design goals and establishment > of maintenance programs. > > Subscribing to the notion of "stress mitigation" on > an alternator by programming the manner in which loads > are applied to the machine suggests that design goals, > capabilities and limits are suspect or perhaps known > to be poorly married. > > The aux battery management module for OBAM aircraft was > first proposed in an article I wrote for Sport Aviation > many moons ago. The intent of this device was to provide > automatic management of an auxiliary battery included > to power flight critical electro-whizzies. The ABMM > prevented connection of the aux battery to the system > unless bus voltage was high enough to avoid discharging > the battery (i.e. alternator on line). Hence the 13.0 > volt switchpoint calibration for closing the contactor. > The corollary idea was that the ABMM opens the contactor > automatically during alternator shut down or failure > thus isolating the aux battery and preserving contained > energy for a specific task. > > The product being discussed appears to perform in > precisely the same manner where it's desirable > to isolate a RV vehicle battery from recreational > electro-whizzies battery unless the alternator > is available to service BOTH batteries. > > This is a PARTICULAR case where the recreational > battery is EXPECTED to be deeply discharged. Now, > if the vehicle battery has not been abused while > parked, then the bus is expected to rise above > 13.0 (or 13.2) volts seconds after the engine > starts. This device would spare the alternator > from "high stress" loads only if BOTH batteries are > deeply discharged. But even then, I can't imagine > that the bus will stay below 13.2 volts for very > long even if the vehicle battery was drawn down > completely and the engine was started with jumper cables. > > Finally, irrespective of number of batteries and > no matter how you've abused the batteries, your > alternator should be EXPECTED to happily deliver > full rated output for an indefinite period of time. > If not, there's something wrong with the selection > of alternator or the manner in which it has been > installed. > > Bob . . . > > ________________________________ Message 11 ____________________________________ Time: 01:34:18 PM PST US From: BobsV35B@aol.com Subject: Re: AeroElectric-List: Who Has Got The Time? Good Afternoon OC, I tried to make the same point when this message first surfaced, but no one seems to care! Such is life. Happy Skies, Old Bob In a message dated 12/8/2009 7:11:53 A.M. Central Standard Time, bakerocb@cox.net writes: --> AeroElectric-List message posted by: 12/6/2009 (and again on 11/8/2009) Hello Fellow Pilots and Builders, The aeroelectric list has been filled lately with discussions of hardware (meters) that keep track of time. Just exactly what time is being kept, and for what purpose, is unclear. To shed some light on the subject let's start by taking a look at what 14 CFR (FAR's) say about time. We'll take flight time first, then TIS (Time In Service): 1) Here is how pilot flight time is defined in section 1.1 of the FAR's : "Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing;" I am not aware of any meter that could keep accurate track of such time. You'll find many pilots, and airlines, that do not keep track of flight / pilot time in conformance with this definition. Standard compliance by all pilots with this definition is unlikely because there is room for interpretation. Does "moves under its own power for the purpose of flight" mean the instant the wheels start to roll as you leave the parking space in order to go flying? Then that XXX minutes plus that you spend taxiing, doing engine run up, and waiting for takeoff clearance at the end of the runway, would all be flight time. Considering the delays involved in operating at some airports one could become a multi thousand hour flight time pilot very quickly using that interpretation. On the other hand one is certainly exercising some very important PIC duties from the time he leaves the parking space until starting takeoff roll. Should all of that time be ignored and not recognized in some fashion? 2) Here is how section 1.1 of FAR's defines TIS (Time In Service): "Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing." I suppose that there is hardware that could record this exact time, but it certainly is not in common use in our category of airplanes. So let's take a look at three common timing devices: the Hobbs meter, the mechanical engine RPM based tachometer, and the software associated with electronic flight instrumentation or engine instrumentation: A) The Hobbs meter (you can look here for a quick review): http://en.wikipedia.org/wiki/Hobbs_meter It doesn't take very long to conclude that "Hobbs meter" has become a very generic term (like Kleenex or Scotch tape) and that Hobbs meters come in wide varieties and can be connected to record a wide variety of time. I guess it is possible for a Hobbs meter to be connected up so that it records one of the time definitions in the FAR's, but it doesn't seem easy. B) FAR 91.205 (a) and (b) require an engine tachometer to be installed in any powered standard category civil aircraft even for day VFR operations. By far the most common type of tachometer found is the mechanical RPM based tachometer. Presumably the purpose of the required tachometer is to inform the pilot of his engine's RPM at any given instant, but somewhere along the line these tachometers began including the total time of engine operation. This required someone to decide how to convert instantaneous RPM into total elapsed time of engine operation. If, say 2,000 RPM were chosen as the standard mechanical ratio to convert one minute at this RPM into one minute of elapsed engine operating time then any engine operation at less than 2,000 RPM generates less than one minute of elapsed engine operating time and any RPM greater than 2,000 generates more than one minute of elapsed engine operating time. See some of the tachometer conversion ratios between RPM and time available here: http://tghaviation.rtrk.com/?scid=387399&kw=3649251 In any case it does not appear that any mechanical engine tachometer can generate either of the elapsed times defined by the FAR's. C) There is such a huge variety of electronic flight and engine instrumentation systems and their associated software (and the ability of the operator to modify the software in some cases) that any accurate comparison of one airplane's / engine's / pilot's time to another airplane's / engine's / pilot's time would require some detailed examination of the processes used to generate that time. Again the probability that an electronic system would automatically generate elapsed time in exact compliance with either of the FAR time definitions is not likely. So what is the builder / pilot to do? My suggestions: a) Don't get all wrapped around the axle about generating time. Many people are not recording flight time or time in service the same way that you are. b) Pick some hardware and a system of documentation that seems to fit your needs and go with it. c) Be consistent in how you do things so that you can view and show the results with some confidence. d) Be wary of someone else's time claims, but don't make a big deal of time unless you are billing by the hour. 'OC' Says: "The best investment we can make is the effort to gather and understand knowledge." PS: My choice for my airplane was just to record "Tach time" from my engine electronic data system for both flight time and TIS. My engine data system generates zero tach time anytime the engine RPM is less than 1,500 RPM and constant equal running time in hours and tenths any time the engine RPM is above 1,500 RPM. Recording this time for both flight time and TIS short changes me on pilot flight time since a fair amount of time while practicing landings in the landing pattern the engine is below 1,500 RPM. On the other hand it will take much longer elapsed time for my engine to reach its 2,000 hour TIS to be due for overhaul. This approach greatly simplifies my bookkeeping. Back when I was flying rental aircraft I just went with the flow and used the FBO's Hobbs meter time for flight time -- I paid for it, I should be able to log it. ________________________________ Message 12 ____________________________________ Time: 02:35:53 PM PST US From: ray Subject: Re: AeroElectric-List: Who Has Got The Time? Old Bob and OC, I read both your posts and appreciate the time spent to write them. Guess I should have said something. Problem is, then I'd have to write every day! This list is a great resource and I for one appreciate being able to lurk while others solve problems and present a variety of opinions and solutions. I'm sure I'm not the only one. Both of you and everyone else, PLEASE continue posting, there's a lot of us out here reading them. Raymond Julian Kettle River, MN. do not archive BobsV35B@aol.com wrote: > Good Afternoon OC, > > I tried to make the same point when this message first surfaced, but no > one seems to care! > > Such is life. > > Happy Skies, > > Old Bob > > In a message dated 12/8/2009 7:11:53 A.M. Central Standard Time, > bakerocb@cox.net writes: > > > 12/6/2009 (and again on 11/8/2009) > > Hello Fellow Pilots and Builders, The aeroelectric list has been filled > lately with discussions of hardware (meters) that keep track of > time. Just > exactly what time is being kept, and for what purpose, is unclear. > To shed > some light on the subject let's start by taking a look at what 14 CFR > (FAR's) say about time. > > We'll take flight time first, then TIS (Time In Service): > > 1) Here is how pilot flight time is defined in section 1.1 of the > FAR's : > > "Flight time means: Pilot time that commences when an aircraft moves > under > its own power for the purpose of flight and ends when the aircraft > comes to > rest after landing;" > > I am not aware of any meter that could keep accurate track of such time. > You'll find many pilots, and airlines, that do not keep track of > flight / > pilot time in conformance with this definition. Standard compliance > by all > pilots with this definition is unlikely because there is room for > interpretation. > > Does "moves under its own power for the purpose of flight" mean the > instant > the wheels start to roll as you leave the parking space in order to go > flying? Then that XXX minutes plus that you spend taxiing, doing > engine run > up, and waiting for takeoff clearance at the end of the runway, > would all be > flight time. Considering the delays involved in operating at some > airports > one could become a multi thousand hour flight time pilot very > quickly using > that interpretation. > > On the other hand one is certainly exercising some very important > PIC duties > from the time he leaves the parking space until starting takeoff roll. > Should all of that time be ignored and not recognized in some fashion? > > 2) Here is how section 1.1 of FAR's defines TIS (Time In Service): > > "Time in service, with respect to maintenance time records, means > the time > from the moment an aircraft leaves the surface of the earth until it > touches > it at the next point of landing." > > I suppose that there is hardware that could record this exact time, > but it > certainly is not in common use in our category of airplanes. > > So let's take a look at three common timing devices: the Hobbs > meter, the > mechanical engine RPM based tachometer, and the software associated with > electronic flight instrumentation or engine instrumentation: > > A) The Hobbs meter (you can look here for a quick review): > > http://en.wikipedia.org/wiki/Hobbs_meter > > It doesn't take very long to conclude that "Hobbs meter" has become > a very > generic term (like Kleenex or Scotch tape) and that Hobbs meters come in > wide varieties and can be connected to record a wide variety of time. I > guess it is possible for a Hobbs meter to be connected up so that it > records > one of the time definitions in the FAR's, but it doesn't seem easy. > > B) FAR 91.205 (a) and (b) require an engine tachometer to be > installed in > any powered standard category civil aircraft even for day VFR > operations. By > far the most common type of tachometer found is the mechanical RPM based > tachometer. Presumably the purpose of the required tachometer is to > inform > the pilot of his engine's RPM at any given instant, but somewhere > along the > line these tachometers began including the total time of engine > operation. > This required someone to decide how to convert instantaneous RPM > into total > elapsed time of engine operation. > > If, say 2,000 RPM were chosen as the standard mechanical ratio to > convert > one minute at this RPM into one minute of elapsed engine operating > time then > any engine operation at less than 2,000 RPM generates less than one > minute > of elapsed engine operating time and any RPM greater than 2,000 > generates > more than one minute of elapsed engine operating time. See some of the > tachometer conversion ratios between RPM and time available here: > > http://tghaviation.rtrk.com/?scid=387399&kw=3649251 > > In any case it does not appear that any mechanical engine tachometer can > generate either of the elapsed times defined by the FAR's. > > C) There is such a huge variety of electronic flight and engine > instrumentation systems and their associated software (and the > ability of > the operator to modify the software in some cases) that any accurate > comparison of one airplane's / engine's / pilot's time to another > airplane's > / engine's / pilot's time would require some detailed examination of the > processes used to generate that time. > > Again the probability that an electronic system would automatically > generate > elapsed time in exact compliance with either of the FAR time > definitions is > not likely. > > So what is the builder / pilot to do? My suggestions: > > a) Don't get all wrapped around the axle about generating time. Many > people > are not recording flight time or time in service the same way that > you are. > > b) Pick some hardware and a system of documentation that seems to > fit your > needs and go with it. > > c) Be consistent in how you do things so that you can view and show the > results with some confidence. > > d) Be wary of someone else's time claims, but don't make a big deal > of time > unless you are billing by the hour. > > 'OC' Says: "The best investment we can make is the effort to gather and > understand knowledge." > > PS: My choice for my airplane was just to record "Tach time" from my > engine > electronic data system for both flight time and TIS. My engine data > system > generates zero > tach time anytime the engine RPM is less than 1,500 RPM and constant > equal > running time in hours and tenths any time the engine RPM is above > 1,500 RPM. > > Recording this time for both flight time and TIS short changes me on > pilot > flight time since a fair amount of time while practicing landings in the > landing pattern the engine is below 1,500 RPM. On > the other hand it will take much longer elapsed time for my engine > to reach > its 2,000 hour TIS to be due for overhaul. This approach greatly > simplifies > my bookkeeping. > > Back when I was flying rental aircraft I just went with the flow and > used > the FBO's Hobbs meter time for flight time -- I paid for it, I should be > able to log ========================= nbsp; (And Get Some > AWESOME FREE to find Gifts tric re b k you for p; > -Matt Dralle, List ======================== = Use utilities Day > ================================================ - > MATRONICS WEB FORUMS ================================================= > > > > * > > > * ________________________________ Message 13 ____________________________________ Time: 03:25:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Who Has Got The Time? At 04:32 PM 12/8/2009, you wrote: > >Old Bob and OC, > >I read both your posts and appreciate the time spent to write them. >Guess I should have said something. Problem is, then I'd have to >write every day! This list is a great resource and I for one >appreciate being able to lurk while others solve problems and >present a variety of opinions and solutions. I'm sure I'm not the >only one. Both of you and everyone else, PLEASE continue posting, >there's a lot of us out here reading them. In our own self-interested way, we're participants and exploiters of what Thomas Friedman has identified as a constellation of forces that are "flattening the world". See: http://future.iftf.org/2006/05/thomas_friedman.html for a brief peek at his thinking. When EAA was but a gleam in Father Paul's eye, what we knew and could learn about this hobby we cherish came through narrow pipes of communication with barely enough content and clarity to get a VW powered Headwind flying. 35 years later we find ourselves members of a world wide community that successfully builds and flies aircraft that rival (if not surpasses) the cost- performance figures for the highly touted production machines. Mr. Friedman has astutely identified a combination of milestones in our planet's culture that made this all possible. Here on the Matronics lists and elsewhere, folks have an opportunity to tap the time, talents and resources of thousands of fellow travelers in the world of OBAM aviation. It grew up not by any particular grand plan but spontaneously as the Ten Great Flattenters evolved. We live in fascinating times of unprecedented opportunity. We would do well by ourselves and our children not to screw it up . . . or let anyone else screw it up either. Bob . . . ________________________________ Message 14 ____________________________________ Time: 04:11:57 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Dual Battery Contactor At 02:40 PM 12/8/2009, you wrote: > >Chris, > >As Bob noted, the alternator will continue to output at its rated >capacity as long as the regulator is demanding it. Each alternator >should be able to run at its rated capacity for N hours before >failing (some calculus test performed at the factory). In the aviation world we test alternators/generators/motors to rated loads and worst case temperatures to meet specifications. If the customer observes published limits, they have a high probability of seeing the laboratory experience repeated in the field. >The bigger question is what are you doing in your cockpit while you >are waiting for the alternator to explode and your bus architecture >to melt down? Answer, you should be activating your fire gear. No, a >diode won't immediately melt if you drop to 8 volts, but by then you >should have your contingency plan in action. Should you experience 1 >or more failures in any situation, you should start shedding load >and if the alternator seems to be a problem, shut it down. > >Two heads are better than one and one good battery and two >alternators are better than 2-3 batteries any day. Exactly. I'll re-enforce that idea with the notion that except for unanticipated failure, NOTHING that goes on in your electrical system should be a surprise. I've written often about failure mode effects analysis wherein all normal and abnormal operating conditions are deduced, studied for deleterious effect to be mitigated by design. The ONLY way you're going to beat the @#$@# out of your alternator is to jump-start with a DEAD battery and then launch into the blue with all your electro-whizzies turned on. Until the battery's recharge demands begin to taper, the alternator will be running flat-out. The duration of this event is generally a few tens of minutes at the most. All other times, I would hope that the builder has PREDICTED what loads can be serviced under any/all conditions and is operating the airplane accordingly. Chapter 17 in the 'Connection speaks to this process in detail. I've also suggested that the hierarchy of importance for surviving the flight experience stacks up like this:(a) airframe, (b) owner/builder/pilot (c) powerplant (d) all other things. The significance of the second item goes far beyond the knowledge and skills needed AFTER the wheels are up. There is a great deal that can be done in the craftsmanship, understanding and decisions made long before the airplane leaves the shop . . . like due diligence to the study of category (d). Bob . . . >Glenn > > >-----Original Message----- >From: owner-aeroelectric-list-server@matronics.com >[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Chris Stone >Sent: Tuesday, December 08, 2009 1:20 PM >To: aeroelectric-list@matronics.com >Subject: Re: AeroElectric-List: Dual Battery Contactor > > > >This brings to mind a question as to what happens to the alternator >when the load placed on it exceeds it's output capacity? Will the >output voltage start to drop as capacity is exceeded? If overload >is continued are the diodes the weak link in the chain? Will the >diodes fail before overheating of the stator windings? What is the >common failure mode? > >Chris Stone >RV-8 > >-----Original Message----- > >From: "Robert L. Nuckolls, III" > >Sent: Dec 8, 2009 11:55 AM > >To: aeroelectric-list@matronics.com > >Subject: Re: AeroElectric-List: Dual Battery Contactor > > > > > > >At 05:34 PM 12/7/2009, you wrote: > > > > >Chris, > >Thanks for the tip and lead on a great solution for preserving > >alternators from high stress loads... > > > > Not sure there is "benefit" to be realized for shielding > > an alternator from "high stress" loads. > > > > As converters of mechanical to electrical energy, these > > devices have specifications. They also tend to be designed > > for a particular marketplace task. The prudent designers, > > manufacturers and installers of such devices understand the > > capabilities and limits. That understanding is factored > > into satisfaction of design goals and establishment > > of maintenance programs. > > > > Subscribing to the notion of "stress mitigation" on > > an alternator by programming the manner in which loads > > are applied to the machine suggests that design goals, > > capabilities and limits are suspect or perhaps known > > to be poorly married. > > > > The aux battery management module for OBAM aircraft was > > first proposed in an article I wrote for Sport Aviation > > many moons ago. The intent of this device was to provide > > automatic management of an auxiliary battery included > > to power flight critical electro-whizzies. The ABMM > > prevented connection of the aux battery to the system > > unless bus voltage was high enough to avoid discharging > > the battery (i.e. alternator on line). Hence the 13.0 > > volt switchpoint calibration for closing the contactor. > > The corollary idea was that the ABMM opens the contactor > > automatically during alternator shut down or failure > > thus isolating the aux battery and preserving contained > > energy for a specific task. > > > > The product being discussed appears to perform in > > precisely the same manner where it's desirable > > to isolate a RV vehicle battery from recreational > > electro-whizzies battery unless the alternator > > is available to service BOTH batteries. > > > > This is a PARTICULAR case where the recreational > > battery is EXPECTED to be deeply discharged. Now, > > if the vehicle battery has not been abused while > > parked, then the bus is expected to rise above > > 13.0 (or 13.2) volts seconds after the engine > > starts. This device would spare the alternator > > from "high stress" loads only if BOTH batteries are > > deeply discharged. But even then, I can't imagine > > that the bus will stay below 13.2 volts for very > > long even if the vehicle battery was drawn down > > completely and the engine was started with jumper cables. > > > > Finally, irrespective of number of batteries and > > no matter how you've abused the batteries, your > > alternator should be EXPECTED to happily deliver > > full rated output for an indefinite period of time. > > If not, there's something wrong with the selection > > of alternator or the manner in which it has been > > installed. > > > > Bob . . . > > > > > > > > > > > > Bob . . . //// (o o) ===========o00o=(_)=o00o======== < Go ahead, make my day . . . > < show me where I'm wrong. > ================================ ________________________________ Message 15 ____________________________________ Time: 06:46:12 PM PST US From: "Bill Bradburry" Subject: AeroElectric-List: Power Mizer This is off the airplane subject, but concerns electricity and I don't know where to find a more knowledgeable group. I was shown a device today called the Power Mizer which is supposed to be a capacitor that will reduce the current draw of inductive devices. An electric motor pulled about 10A on startup and then settled down to about 6A without the device turned on. With it on, the start up draw dropped to about 5A and the steady state draw to about 2.4A. This makes no sense to me. I smell a rat. Check out this video and let me know if this is hogwash. You can contact me off line to keep the traffic down on the list. http://www.youtube.com/watch?v=YMZjWkbF9bQ&feature=related Thanks for the assistance. Bill B ________________________________ Message 16 ____________________________________ Time: 07:29:17 PM PST US Subject: Re: AeroElectric-List: Power Mizer From: "Matt Prather" I don't think this is a new idea.. Power factor correction is probably nearly as old as AC power distribution. There's a fairly good description of power factor correction on the Wikipedia page: http://en.wikipedia.org/wiki/Power_factor Regards, Matt- > > > This is off the airplane subject, but concerns electricity and I don't > know > where to find a more knowledgeable group. > I was shown a device today called the Power Mizer which is supposed to be > a > capacitor that will reduce the current draw of inductive devices. An > electric motor pulled about 10A on startup and then settled down to about > 6A > without the device turned on. With it on, the start up draw dropped to > about 5A and the steady state draw to about 2.4A. > This makes no sense to me. I smell a rat. Check out this video and let > me > know if this is hogwash. > > You can contact me off line to keep the traffic down on the list. > > http://www.youtube.com/watch?v=YMZjWkbF9bQ&feature=related > > Thanks for the assistance. > > Bill B > > ________________________________ Message 17 ____________________________________ Time: 08:57:53 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Power Mizer >I smell a rat. Check out this video and let me >know if this is hogwash. It depends . . . but your skepticism is not unwarranted. In the DC power world of our airplanes, the power system is very UNdynamic. I.e. relatively steady state levels of voltage and current. For our purposes, Watts of beneficial power is simply a matter of multiplying volts x amps. In the AC world, it doesn't HAVE to be more difficult. The lowly incandescent lamp and heaters in your water heater do not present a highly reactive load on the power source. As soon as you wrap wires around cores of magnetic materials, 'stuff' happens. The counter EMF of magnetic fields building in cores will lag behind the applied voltage thus causing current to no longer be in phase with the applied voltage. Apparent power is still volts x amps. But true power consumed is multiplied by the cosine of the difference in phase angles between current and voltage to produce a correction value or "power factor". The BIG downside of powering large loads of poor power factor is that the WIRE size in the motor, sizes of breakers, feeder wires, and wires in transformers must be rated for apparent current. The industry uses capacitors at judicious places throughout their distribution systems and large users will use capacitors in their installations to counteract the inductive components of low power factor loads. Watt-hour meters on the back of your house measure true power consumed. I.e. they're corrected for any differences between true and apparent power. Now, if your house is plagued with lots of continuous duty, low power factor loads, the overall system efficiency can be degraded due to increased heating in the wiring needed to supply the SAME amount of energy to the working task. The demonstration in the video was with an unloaded motor which has decidedly different characteristics compared with a motor that is loaded to name-plate rated horsepower. Hence the demonstration was bogus. Further, measurement of current alone is NOT a true indication of system efficiency. I've written to the company to see if they'll share a engineering report on the testing claimed in their promotional videos and literature. I'm betting that they won't. Bottom line is that while adding capacitors to a system with a lagging power factor will increase the ohmic efficiency (let you get the same energy out the other end of the wire at slightly less current . . . and I DO mean slightly) it won't have more than a similarly slight effect on your light bill. See: http://tinyurl.com/yln6gwv A few years back there was a big "gee whiz" promotion on devices that would "save you a gazillion dollars" that were inserted in a line between the wall plug and appliance. I've not seen those critters being hyped lately . . . I think they're out of fashion. Bob . . . ________________________________ Message 18 ____________________________________ Time: 10:25:08 PM PST US Subject: AeroElectric-List: Re: Lopresti HID claims From: "XeVision" Eric M. Jones wrote: > Thanks, > Photometric units contain plenty of traps for the unwary. > > BTW: "Cree Achieves 186 Lumens per Watt from a High-Power LED > High-performance chip and R&D package combine for record-setting efficacy" > > Amazing. Yes, I agree with your first comment. The 2nd is likely at lower drive levels, they (LED's) "droop" typically at higher drive levels. We are watching the LED technology very closely. We work with Cree high powered LED's in our flashlight offerings. LED can make a very good taxi light now, but to collimate it for a landing light is still a big hurdle. It still has a way to go to compete with HID for landing lights. Especially 50 watt or 75 watt HID as we now have, 5300 and 8300 Lumens output each respectively. 35 watt HID produces about 3200 lumens compared to ~1600 lumens from a 100 watt incandescent such as the well known GE4509, very common in light single and twins. Also the 24/28 volt version of the same 100 watt lamp, the same 1600 lumens. The 250 watt sealed beam incandescent aircraft lamps produce almost the same lumens as a 35 watt HID. -------- LED still has a long way to go to compete with HID as a landing light. This is true in terms of total lumens and reach (distance). 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