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#1
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On May 13, 6:21*pm, Dan wrote:
wrote: I learned a great deal from this thread, especially all the references cited. Thanks to everyone for contributing. I think I may build the Jeff Shultz circuit, with 8 segments if bar LED, plus a red and yellow bar-like LED. However, I am not quite sure Shulz's logic of the lights is what I want. The display logic that makes sense to me is this: in cruise many green LED are lit *(could be 5-8), All greens at this point, no yellow or red lit. *These progressively go out as the nose is lifted. *Then the yellow comes on...with no greens lit then the red comes on. *I guess the yellow can stay on when the red is lit. might want to make the red flash. a job for a PIC? -Jeff * * If you make your own bar graph you can use a flashing red LED. Either that or use a yellow bar graph with separate flashing red LED. I think Radio Shaft carries them. I'd wire the yellow such that they remain lit as they climb until all are lit just before red illuminates. * *There are commercial systems available to the homebuilder. Look at their displays for ideas. If you find an array you like it shouldn't be too difficult to make one similar. * *I have the feeling no two people will agree on what's best. Dan, U.S. Air Force, retired The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. |
#2
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![]() "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. Bill, I tatally agree! It would also be nice to have the AOA measure units instead of degrees and be calibrated so to give the same readings for max L/D and Min Sink at all flap settings. When I was flying A-6 Intruders 21 units of AOA was the Max Range value (best L/D) at all flap settings. I don't believe you can develop an effective unit for aircraft with flaps without integrating the flap setting into the system. This requires knowing the performance curve for each setting in order to calculate a single Max L/D (Max Range) indicator reading and a single Min Sink (Max endurance) indicator reading. This isn't as simple of a problem as some seem to think it is. Wayne HP-14 with flap settings from -5 to +90. http://www.soaridaho.com/Schreder |
#3
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On May 14, 7:30*pm, "Wayne Paul" wrote:
"bildan" wrote in ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. *The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. *The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. *Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. Bill, I tatally agree! *It would also be nice to have the AOA measure units instead of degrees and be calibrated so to give the same readings for max L/D and Min Sink at all flap settings. * When I was flying A-6 Intruders 21 units of AOA was the Max Range value (best L/D) at all flap settings. *I don't believe you can develop an effective unit for aircraft with flaps without integrating the flap setting into the system. *This requires knowing the performance curve for each setting in order to calculate a single Max L/D (Max Range) indicator reading and a single Min Sink (Max endurance) indicator reading. This isn't as simple of a problem as some seem to think it is. Wayne HP-14 with flap settings from -5 to +90.http://www.soaridaho.com/Schreder Yes, there would have to be additional hardware/software to do it with flaps. But, as long as the AOA system knew what flap setting was being used, it could still display AOA data for that flap polar. Of course, a continuously variable system like yours could be complicated. To simplify the system, min sink is only of interest at thermalling flap settings and best L/D only at zero flap. (I'm guessing if you are in negative flap, you're not interested in flying at best L/D.) Also, the newer airfoils have made non-flapped gliders just about as good as flapped ones so the flap issue may be becoming moot anyway. It could be that a glider without flaps but flown with the precision possible with an AOA indicator might not be at much of a disadvantage. |
#4
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![]() "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. ----begin new post--------OE got confused again----------- Presuming that a moving/rotating vane system would work for you, you might consider an all mechanical system. One possibility might involve canibalizing an old VW fuel guage assembly for some of the parts--the 1965, and possibly the 1964, VW "Beetles" had a mechanical fuel guage activated through a push/pull cable that was similar to the throttles on lawnmowers and the hand brakes on bicycles. Actually, with a little thought and considering that the vane could be located on the side(s) of the forward cockpit area, it should be possible to devise a system that would be lighter, simpler, and also having less friction. You could even make the indicating needle move vertically--which would seem to me to be more intuitive. By the way, a pair of "pitch strings" mounted on the lower portion of the canopy sides would possibly work as well and would be a trivial installation; but I suspect that they could be difficult and distracting to read unless they happened to fit well with your use of peripheral vision. That issue greatly exceeds my "human factors" knowledge. Peter PS: I was an electronic technician, and occasionally design technician, for many years and I am confident that I could devise an electronic "lift reserve" or similar indicator with two or three angles marked for reference; but I strongly suspect that a simple mechanical system would be simpler and equally functional on a glider--where there should be no ice and no tractor propeller. |
#5
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![]() "Peter Dohm" wrote in message .. . "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... |
#6
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"Dan D" wrote in message
... "Peter Dohm" wrote in message .. . "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... Someone's trimming of messages needs work! My post, immediately above yours, included the following: "By the way, a pair of "pitch strings" mounted on the lower portion of the canopy sides would possibly work as well and would be a trivial installation; but I suspect that they could be difficult and distracting to read unless they happened to fit well with your use of peripheral vision. That issue greatly exceeds my "human factors" knowledge." That seems similar, except that I had suggested a string on each side. |
#7
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![]() "Peter Dohm" wrote in message .. . "Dan D" wrote in message ... "Peter Dohm" wrote in message .. . "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... Someone's trimming of messages needs work! My post, immediately above yours, included the following: "By the way, a pair of "pitch strings" mounted on the lower portion of the canopy sides would possibly work as well and would be a trivial installation; but I suspect that they could be difficult and distracting to read unless they happened to fit well with your use of peripheral vision. That issue greatly exceeds my "human factors" knowledge." That seems similar, except that I had suggested a string on each side. Sorry, didn't see it...it does seem great minds think alike! |
#8
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![]() "Dan D" wrote in message ... "Peter Dohm" wrote in message .. . "Dan D" wrote in message ... "Peter Dohm" wrote in message .. . "bildan" wrote in message ... The interest for me is a sailplane installation where AOA is a performance issue in addition to a safety issue. My glider can be flown at 1000 pounds up to 1433 pounds gross weight and spends a lot of time in 2G turns thermalling. The AOA for minimum sink is always the same but the airspeed at which that happens changes a lot. The same thing with best L/D. A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... Someone's trimming of messages needs work! My post, immediately above yours, included the following: "By the way, a pair of "pitch strings" mounted on the lower portion of the canopy sides would possibly work as well and would be a trivial installation; but I suspect that they could be difficult and distracting to read unless they happened to fit well with your use of peripheral vision. That issue greatly exceeds my "human factors" knowledge." That seems similar, except that I had suggested a string on each side. Sorry, didn't see it...it does seem great minds think alike! No problem, and I'm glad to have a second on a simple solution. |
#9
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![]() "Dan D" wrote in message ... A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... It isn't that simple. The string will show the angle of flow relative to the fuselage, not the airfoil. The fuselage angle of max L/D and minimum sink change with the flap setting. (Thermal at 15 degrees, cruise between zero and -10 degrees.) A true AOA would supply a single given Max L/D indication no mater what the flap setting. The software to do this isn't difficult if you know the airflow relative to the fuselage, the angle of incidence of the wing, and the wing's performance curves for various flap setting. From my perspective a reliable low-drag encoding vane is the tall pole in the tent. The airfoil performance/angle of incidence can be derived from sailplane's handbook. The cockpit indicator can be the designer's/owner's choice. Wayne HP-14 N990 Flap range -10 to +90. http://www.soaridaho.com/Schreder/HP-14/N990/N990.html |
#10
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![]() "Wayne Paul" wrote in message m... "Dan D" wrote in message ... A very 'slippery' glider takes a while for the airspeed to settle down after a pitch change. Flying to an exact AOA would be easier than chasing airspeed. An AOA indicator that shows minimum sink and maximum L/D as well as stall would be quite useful. The glider solution could be a simple as the piece of yarn along the side of the canopy... It isn't that simple. The string will show the angle of flow relative to the fuselage, not the airfoil. The fuselage angle of max L/D and minimum sink change with the flap setting. (Thermal at 15 degrees, cruise between zero and -10 degrees.) A true AOA would supply a single given Max L/D indication no mater what the flap setting. The software to do this isn't difficult if you know the airflow relative to the fuselage, the angle of incidence of the wing, and the wing's performance curves for various flap setting. From my perspective a reliable low-drag encoding vane is the tall pole in the tent. The airfoil performance/angle of incidence can be derived from sailplane's handbook. The cockpit indicator can be the designer's/owner's choice. Wayne HP-14 N990 Flap range -10 to +90. http://www.soaridaho.com/Schreder/HP-14/N990/N990.html The idea of the string, or the string on each side, is not that that it is a true angle; but, if the canopy sides are at a promising height and also an adiquate distance from the wing, that the positions can be marked as calibration points for the particular angles of interest--such as best L/D and minimum sink. |
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