---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 10/07/13: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:56 AM - Re: Electric System architecture (Robert L. Nuckolls, III) 2. 08:49 AM - Re: Electric System architecture (rayj) 3. 09:42 AM - Re: Electric System architecture (Peter Pengilly) 4. 12:11 PM - Perplexing problem??? (Charles Brame) 5. 05:15 PM - The dreaded downwind turn . . . (Robert L. Nuckolls, III) 6. 05:58 PM - Re: The dreaded downwind turn . . . (Jared Yates) 7. 06:09 PM - Re: Perplexing problem??? (Robert L. Nuckolls, III) 8. 06:17 PM - Re: De-Slumpifier, Voltage Buffer to Prevent Brownout (user9253) 9. 06:17 PM - Re: De-Slumpifier, Voltage Buffer to Prevent Brownout (user9253) 10. 07:25 PM - Re: The dreaded downwind turn . . . (rayj) 11. 08:12 PM - Ray Allen position sensors (Jeff Page) ________________________________ Message 1 _____________________________________ Time: 07:56:47 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Electric System architecture At 10:29 PM 10/6/2013, you wrote: >Speaking of SA, is the article on the downwind turn (page 12, Oct. >issue) as off the mark as I think, or do I need to study my physics? What side of the fence did the author argue? Bob . . . ________________________________ Message 2 _____________________________________ Time: 08:49:21 AM PST US From: rayj Subject: Re: AeroElectric-List: Electric System architecture When he started talking about the the wind accelerating to aircraft during the turn, he lost me. I hope the article gets attached. Raymond Julian Kettle River, MN. "And you know that I could have me a million more friends, and all I'd have to lose is my point of view." - John Prine On 10/07/2013 09:55 AM, Robert L. Nuckolls, III wrote: > At 10:29 PM 10/6/2013, you wrote: >> Speaking of SA, is the article on the downwind turn (page 12, Oct. >> issue) as off the mark as I think, or do I need to study my physics? > > What side of the fence did the author argue? > > > Bob . . . > > * > > > * ________________________________ Message 3 _____________________________________ Time: 09:42:09 AM PST US From: Peter Pengilly Subject: Re: AeroElectric-List: Electric System architecture I think he is correct - change in wind speed (ie gusts) is the cause of most low altitude downwind turn problems - answer is careful reference to the instruments (in my experience ASI is key) so not to get suckered by distracting cues from ground references. The physics lesson could be cut out without loss of meaning. Peter PS Here's another vote for Kitplanes over SA. Do not archive On 07/10/2013 04:29, rayj wrote: > Speaking of SA, is the article on the downwind turn (page 12, Oct. > issue) as off the mark as I think, or do I need to study my physics? > > do not archive > Raymond Julian > Kettle River, MN. > > "And you know that I could have me a million more friends, > and all I'd have to lose is my point of view." - John Prine > On 10/06/2013 09:25 PM, Robert L. Nuckolls, III wrote: >> >> >> At 08:23 PM 10/6/2013, you wrote: >>> Bob, Your first two articles for Kitplanes were just first rate. I >>> will look forward to the architecture article. >>> The people who produce Kitplanes continue to amaze me. I may not be >>> able to appreciate every article, but I never fail to read it cover >>> to cover. >>> Wish I could say the same for the EAA mag. Once I get past Mike >>> Busch's monthly contribution, I'm pretty much done. Perhaps someone >>> should make the suggestion to EAA that they offer members the option >>> of Kitplanes instead of Sport Aviation. SA is the better coffee >>> table magazine, but Kitplanes is the one that goes to the shop. >>> >>> Rick Girard >>> do not archive >> >> Thank you sir. I've had that discussion with the >> SA editors several times over the years dating back >> to the days of Jack and Golda Cox. They used to send me >> articles for critical review too. But the higher >> ups (In the warbirds faction I think) raised a fuss about >> some of my work-product and strong-armed them >> into publishing some bad stuff. That's what >> prompted this piece on my website. >> >> http://tinyurl.com/ltrhnr8 >> >> A year or two later I got a call from and >> SA editor. He'd seen my review and claimed to >> be appalled that this class of article had >> been printed in SA. He promised to do better. >> Even said he had a budget to pay for articles. >> >> A short time later, he called again asking if >> I had something to give him . . . seems somebody >> dropped a ball. I spent two hard evenings cranking >> out a 'filler' which did get published . . . but >> alas . . . no check was forthcoming. >> >> That was the last time I had any contact with >> the folks at SA. Paul Dye called me last spring >> and asked if I would write for KP. I said 'sure'. >> What's more, his checks don't bounce. >> >> Compared to SA I believe KP to be a class act. >> >> >> >> Bob . . . >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> > > * > > > * ________________________________ Message 4 _____________________________________ Time: 12:11:27 PM PST US From: Charles Brame Subject: AeroElectric-List: Perplexing problem??? Bob, et. al., The volts and amps on my RV-6 continually fluctuate in flight. The volts oscillate rapidly (about 2 - 3 seconds per cycle) and continuously between 13 and 14.5, sometimes as high as 14.9 and sometimes as low as 12.6. The amps stay a steady 27 after start, but once the battery is charged, the amps begin cycling between 4 and 22, sometimes reading 00 for brief periods. I've flown the bird for nearly 300 hours, and the fluctuations have been pretty continuous since the bird was new. I've not been able to isolate a problem system as turning on or off landing lights, strobes, radios, etc., doesn't seem to change the readings or vary the oscillations. The crowbar over voltage circuit has never tripped the circuit breaker and the 3 year old PC-680 battery is fully charged after a flight, reading about 13.2 volts when manually checked with a hand held multi-meter. I've checked all the wires and grounds connections throughout the electrical system and all appear tight with no signs of shorts and/or burns. My electrical system is based on Z-13, All Electric On a Budget, with a B&C alternator and a generic Ford regulator. The regulator is mounted high on the cockpit side of the firewall and shouldn't have any heat related issues. The indicator is a VicroVision VM-1000. The volts are sensed off of the endurance bus, and with the alternator off, reads a steady 12.6 battery voltage (about .7 volts lower than the actual battery voltage due to the diode between the main and endurance bus.) The amps are really an alternator load meter measured by a Hall sensor on the alternator supply line. Before I change regulators or pull the alternator for bench checking, I'm looking for solutions and/or recommendations or even confirmation that I have a problem. Charlie Brame RV-6A, N11CB San Antonio ________________________________ Message 5 _____________________________________ Time: 05:15:00 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: The dreaded downwind turn . . . At 10:48 AM 10/7/2013, you wrote: >When he started talking about the the wind accelerating to aircraft >during the turn, he lost me. As soon as he says "a lighter aircraft will accelerate faster than a heavier aircraft" and bases the statement on an analysis of "square feet of sail" . . . he blew it. I sat next to a guy for several years who wrote heavy duty software for autopilots that flew UAV's of all stripe from 80Kts to 500 Kts. He tapped simple-ideas to from my high school physics to describe how the airplane flies. I've been meaning to do an article on the physics of this maneuver and have some drawings done . . . somewhere on the hard drive. I'll see if I can dig them up and perhaps finish the article. But while you read the words of folks wrestling with the 'dreaded downwind turn' go to the POH data for your airplane and get one number. Target IAS for best glide angle. This is the speed at which your distance over the ground versus altitude lost is at a maximum. When folks are talking about the physics of flight, they're talking about airplanes that are being 'flown' . . . in other being controlled to conditions that maximize performance. This generally calls for a speed well above best rate of climb combined with a 270 degree turn at 45 degrees of bank into the crosswind to get pointed back toward the runway. When the engine quits with a runway close behind you, its easy for those performance numbers get obscured by other things running around in your head. It takes a Bob Hoover like attitude to first get the nose down to achieve best glide angle whether you are turning or not; stack in a 45-degree banked turn on top of really adds pucker factor. At speeds below best glide, lift/drag ratios can go into the toilet in a hurry. On of my most cherished flight instructors was checking me out in a Beech Flying Club A36 one day. After three or four by-the-book touch and goes he said "let me show you something." "Stay at pattern altitude until you're on final." "Uh, okay . . ." As I turned final I reached for the throttle . . . "Nope, not yet . . ." The runway disappeared under the nose and I reached for the throttle . . . "Nope, not yet . . . " A few seconds later he said, "Okay. Close the throttle and give me 75 MPH." I set it up and was amazed. Sink rate went to something around 1200 ft/min. A few seconds later I acquired a better short-final view of the runway and he said, "Power up to arrest your descent, push the nose down and give me 90 MPH over the numbers." After that, the landing proceeded normally. The point being that maneuvering around at speeds below best glide is where the airplane sinks fast even if you're not turning . . . faster still if you turn. Best glide is well above those speeds at which perturbations in IAS due to gusting can begin to eat into your energy margins for maneuvering. Best rate and particularly best angle of climb speeds have the nose really high with a commensurate boat-load of drag. Whether the airplane remains controllable just before contact with the ground isn't a matter of winds, it's a matter of altitude and the pilot's willingness/ability to EXCHANGE energy stored on that altitude for controllable airspeeds. Airspeeds that bring you to the ground with energy to flare and keep the wheels attached to the airplane. The alternative is a 1000+ feet per minute descent rate, no energy to flare and a probability of having to eat your wheels. There are two magic numbers that drive your decision to turn around best glide speed and ground clearance KNOWN to be sufficient to the airplane's demands as determined by experiment and practice. Barry Schiff tells us how in this article. http://tinyurl.com/mo8wux4 Note that Barry mentions nothing about controllability hazards for having made a downwind turn. That's because the target approach speed for greatest probability of success is well above that where perturbations in wind velocity make any difference at all. See: http://tinyurl.com/kzr95lk http://tinyurl.com/m29yg5y http://tinyurl.com/k9y3z4y http://tinyurl.com/mmgmojr It's all about lift/drag ratios and energy budgets. If your choice of pitch angle is poor (IAS) or your stored energy (altitude) is lacking then it's a bit specious to drag 'hazards of downwind turns' into the discussion . . . things were probably not going to go well anyhow. You become a passenger in your airplane doing experiments with the controls. Bottom line is that EAA, of ALL organizations, should have folks with talents on a par with the honorable Mr. Schiff to vet their articles. http://tinyurl.com/mtn32qf Bob . . . ________________________________ Message 6 _____________________________________ Time: 05:58:08 PM PST US Subject: Re: AeroElectric-List: The dreaded downwind turn . . . From: Jared Yates I don't think Barry Schiff is eligible to write for Sport Aviation, being that he has written mostly for AOPA Pilot and not Flying Magazine. To get articles into SA, it seems that one must come from writing about Bonanzas in Flying Magazine. I've been hoping that the editorial staff shakeup was a Hightower legacy, and that the new staff would bring us more like Brady Lane/Mike Busch and less like Mac McClellan, but so far, no dice. > Bottom line is that EAA, of ALL organizations, should > have folks with talents on a par with the honorable > Mr. Schiff to vet their articles. > do not archive ________________________________ Message 7 _____________________________________ Time: 06:09:12 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Perplexing problem??? At 02:10 PM 10/7/2013, you wrote: Bob, et. al., The volts and amps on my RV-6 continually fluctuate in flight. The volts oscillate rapidly (about 2 - 3 seconds per cycle) and continuously between 13 and 14.5, sometimes as high as 14.9 and sometimes as low as 12.6. The amps stay a steady 27 after start, but once the battery is charged, the amps begin cycling between 4 and 22, sometimes reading 00 for brief periods. I've flown the bird for nearly 300 hours, and the fluctuations have been pretty continuous since the bird was new. I've not been able to isolate a problem system as turning on or off landing lights, strobes, radios, etc., doesn't seem to change the readings or vary the oscillations. The crowbar over voltage circuit has never tripped the circuit breaker and the 3 year old PC-680 battery is fully charged after a flight, reading about 13.2 volts when manually checked with a hand held multi-meter. I've checked all the wires and grounds connections throughout the electrical system and all appear tight with no signs of shorts and/or burns. My electrical system is based on Z-13, All Electric On a Budget, with a B&C alternator and a generic Ford regulator. The regulator is mounted high on the cockpit side of the firewall and shouldn't have any heat related issues. The indicator is a VicroVision VM-1000. The volts are sensed off of the endurance bus, and with the alternator off, reads a steady 12.6 battery voltage (about .7 volts lower than the actual battery voltage due to the diode between the main and endurance bus.) The amps are really an alternator load meter measured by a Hall sensor on the alternator supply line. Before I change regulators or pull the alternator for bench checking, I'm looking for solutions and/or recommendations or even confirmation that I have a problem. =========================== Don't change the regulator . . . We've had several discussions on this phenomenon but they formatted badly in the archives. Let me repeat an exchange from last spring with some formatting. PostPosted: Mon Apr 08, 2013 8:46 pm Post subject: Charging System Debug steps and success... At 12:04 PM 4/8/2013, you wrote: Greetings All, From time-to-time people have posted assorted problems, and gotten answers to, charging system issues. Many of these are of the wandering or oscillating voltage nature. Yes. The "galloping ammeter" syndrome is almost exclusive to alternator/regulator systems wherein the wire with duties to sense bus voltage ALSO carries alternator field current. This is a VERY common configuration in tens of millions of cars and tens of thousands of airplanes. A typical at-risk system uses the legacy FORD regulator featured in many of my writings and schematics. As my charging system (LongEz, externally regulator "ford-style" charging with regulator and battery in the nose) developed an oscillating attitude I had the "opportunity" to collect, review and then apply the information Bob has generously provided and thought an overview might prove useful for the next guy down the road. I'll start with key summary points for those who don't have the current need or desire to read through the details. My symptoms were an oscillating (2 - 6 Hz maybe?) charging voltage visible with the old (WesTach) panel meter. It was sufficient to pop the over-voltage crowbar once. It might also be related to an transient undervoltage alarm I got once. After isolating the problem, I fixed it by replacing the store-bought regulator connector (which had pig-tails, the bad connection was on the factory-made regulator +V crimp) with good-quality Fast-ons direct to the regulator. This dropped the alternator B+ to regulator V+ resistance from 528mOhms to ~140mOhms which fixed the problem. btw: the 140 ohms, which is still higher than I would like, seems to be roughly evenly shared by the fuse-link, breaker and switch (and associated wiring). Of course the ideal supply loop resistance is zero ohms. However a Bode plot of the closed-loop response of the alternator-regulator-aircraft system usually shows that several hundred mOhms can be tolerated before control loop stability margin becomes risky. The details and references for "the next guy": The debug strategy was to start by checking the resistance (using techniques appropriate for milliohm measurments), without doing any disconnecting of the current loop path from alternator B+ to the regulator and then back from the regulator ground (i.e. case) to the alternator ground (i.e. case). My plan was to keep dividing the problem in half to minimize debug time (i.e. binary search). I wanted to do as much testing as I could without taking anything apart as I didn't want to inadvertently change the problem (i.e. wiggle something and have the problem go away...) In the case that no problems were uncovered via the milliohm measurements, I then planned to follow Bob's charging component problem isolation technique which is in chapter 3 of the Aeroelectric connection book. This involves making measurements while the engine is running but I didn't need go to that step and I certainly didn't want to start there. For lots of charging system background and debug information, search Bob's site (www.aeroelectric.com) for "charging" and ignore all the stuff on plug-in-the-wall battery chargers. Bob has written articles and has product related to making good milliohm measurements using an applied current. I prefer having the current source (whether a bench supply or other similar to Bob's milliohm probes) separate rather than combining it with the volt-meter probes. Also, as Bob has covered in his articles, you don't need a regulated-to-a-known-value current source. It suffices to have an unregulated current source (like a D-cell, in a pinch) if you are using a second meter to measure the current. For more information on accurate milliohm measurements, search Bob's site for "milliohm". I conceptually divided the loop in half (ground side vs power side) and picked the ground side first. I put a current source (bench supply with an accurate current limit set to 1A (and set the voltage limit to be 2V though I didn't expect it to ever run in voltage mode regulation)) between the alternator case and the regulator case (which, on my LongEz is the length of the entire aircraft). I then measured the voltage (using separate wires) between the two cases and got 33.9mV which, at one amp, means 33.9mOhms. This is well below the ~200mOhms threshold area of concern (per Bob's annotations contained in "Know_Your_Charging_System.pdf"). Therefore the problem is in the V+ side. I repeated this on the V+ side which is a little bit trickier to measure as the "master" progressive switch needs to be in the "Alternator on" position which can add more currents to deal with (though, it turns out, not much). With the switch on, I measured the voltage from alternator B+ to regulator V+ both with the current source connected, and not connected. The value I care about is the connected value minus the not connected value. (though it still applies, I won't repeat this detail from now on). I measured 528mV (=528mOhms) which is well above the 200mOhm area of concern. So I've identified one (but maybe only the first?, it turned out to be only) problem. I then listed all (well, sort of, I didn't list both side of each wire...) of the connections between Alternator B+ and regulator V+. For me, starting from B+: Near side of load-meter shunt, near side of ANL, near side of fuse-link, near side of over-voltage breaker, nearside of alternator switch, V+ at the regulator. I kept the current source running between B+ on the alternator and regulator V+ (no reason to move it) and picked the point in the middle (near side ANL), B+ to near side ANL was only 11mV (=11mOhms). I continued the divide (roughly in half) and conquer approach (continuing to measure from B+ to my point of interest) which led me quickly to the crimp at the regulator. In the future I *might* start by measuring any connections I didn't personally make (of which there are very very few) before switching to the more disciplined binary search approach. In this case I would have gotten lucky but, in truth, it would not have saved much time. The time was spent going through Bob's articles and developing a plan. The execution of the plan went very fast. Repair and run-up test showed success. Specific Bob articles I found helpful (in addition to those on milliohm measurement): Know_Your_Charging_System.pdf 03_Alternator_12A2.pdf (i.e. the current chapter 3 in the aeroelectric connection, start at page 3-7 for debug info) Happy debugging! The phenomenon we're exploring is the twin brother of a 'ground loop'. In a ground loop, a potential noise current shares a conduction path with a potential victim (audio system, radio, etc). In our 'buss-loop', a noisy current (field supply) shares a pathway with a potential victim (voltage regulator). Operating currents for the alternator field can be anywhere between a few hundred milliamps (very light load, high rpm) to 3 or 4 amps (low rpm, high, load). The number and kind of accessories turned on at the time have a second order effect on control loop stability. If you have 500 milliohms of field supply resistance feeding a moderately loaded alternator current of say 2 amps, then the 2 amp x 0.5 ohms or 1 volt 'modulation' of voltage at the regulator's A/S terminals presents as a 1 volt error in the desired regulation set point. This is not a guarantee for unstable operation but the risks are very high. Wire resistance in the rest of the system has very low to zero risk for setting up the same condition. This problem came to light early on for single engine Cessnas. I addition to conductors that ran from bus to regulator, there were ohmic joints, (crimped pins, engaged pins, fast-ons, switch saddles, switch contacts, etc). I forget the exact number but I think I recall something like 19 ohmic joints in the Cessnas, far more than any other TC aircraft. About once a year I get an email from a TC Cessna owner asking about fixes for the 'galloping ammeter". Quite often, replacing one item in the constellation of system components provides relief . . . but it is temporary. My advice is to start at the bus and replace EVERYTHING with ohmic joints starting with breaker, master switch and it's fast-on terminals, and crimped on pins in all the Mate-n-Lok connectors. This 'shotgun' approach will reduce total path resistance to a value close to factory original values. Assuming the modern regulators have similar stability models, this approach should set the system up for another 40 years of stable operation. Steve, thank you so much for the validation of the simple-ideas offered as to root cause and remedy for this unique phenomenon. Good work my friend! ===================== Charlie, Check all the components from the bus, through the breaker, switch, and all connections that lead up to the (A) and (S) terminals on the regulator. Do an experiment to confirm that the problem is in this pathway: Unhook the wiring from (A) and (S) to the rest of the airplane. Hook a temporary wire from (A) and (S) to the alternator's b-lead terminal. Fire up the engine and see how the regulator behaves. I think you'll find that it's stable and that you need to refurbish the field power path. Bob . . . ________________________________ Message 8 _____________________________________ Time: 06:17:37 PM PST US Subject: AeroElectric-List: Re: De-Slumpifier, Voltage Buffer to Prevent Brownout From: "user9253" Bob, I mailed the DC to DC converter today. You should have it in a few days. It works for intermittent duty but can not handle 1.5 amps continuously. And so it could be used for short term brownout protection, but not as part of the normal power supply circuit. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410040#410040 ________________________________ Message 9 _____________________________________ Time: 06:17:52 PM PST US Subject: AeroElectric-List: Re: De-Slumpifier, Voltage Buffer to Prevent Brownout From: "user9253" Bob, I mailed the DC to DC converter today. You should have it in a few days. It works for intermittent duty but can not handle 1.5 amps continuously. And so it could be used for short term brownout protection, but not as part of the normal power supply circuit. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410041#410041 ________________________________ Message 10 ____________________________________ Time: 07:25:41 PM PST US From: rayj Subject: Re: AeroElectric-List: The dreaded downwind turn . . . I was thinking the same thing: If you can't trust an article from the EAA... I'll be interested to see if/how they walk back the article in the next issue. Raymond Julian Kettle River, MN. "And you know that I could have me a million more friends, and all I'd have to lose is my point of view." - John Prine > > Bottom line is that EAA, of ALL organizations, should > have folks with talents on a par with the honorable > Mr. Schiff to vet their articles. > > http://tinyurl.com/mtn32qf > > > > Bob . . . > > * > > > * ________________________________ Message 11 ____________________________________ Time: 08:12:48 PM PST US From: Jeff Page Subject: AeroElectric-List: Ray Allen position sensors I would like the Dynon Skyview to record the position of my ailerons and elevators. Has anyone used the Ray Allen position sensors for this ? Are they suitable for the continuous movement, or will they wear out ? Do they provide mechanical resistance that would be felt as drag on the control stick ? How much off axis motion will the plunger accept before binding ? Alternatively, are there any automotive products that might be suitable, such as throttle position sensors ? The one used on my vehicle would be impractical to mount. Thanks, Jeff Page Dream Aircraft Tundra #10 ------------------------------------------------------------------------------------- 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.