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#81
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Building an electronic Angle of Attack indicator
"Peter Dohm" wrote in message .. . 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. I understand the process. I currently have a yaw string on my glider. The other canopy strings might be somewhat effective; however, I'm spoiled. I flew 13 years in the US Navy with "real" AOA systems. I am not looking for a crude substitute. I'm looking for the real thing. Wayne http://www.soaridaho.com/ |
#82
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Building an electronic Angle of Attack indicator
"Wayne Paul" wrote in message ... "Peter Dohm" wrote in message .. . 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. I understand the process. I currently have a yaw string on my glider. The other canopy strings might be somewhat effective; however, I'm spoiled. I flew 13 years in the US Navy with "real" AOA systems. I am not looking for a crude substitute. I'm looking for the real thing. Wayne http://www.soaridaho.com/ I can certainly understand that, and there is no question about which is "better". Also, the issue of whether the string(s) can be easily, accurately and safely read in flight is open to question--and certainly must be resolved under conditions other than ridge lift. IIRC, you were amoung the participants, a number of months ago, in a human factors discussion regarding the effects of head movement while circling and the relationship of that to an otherwise unexplained glider crash into a mountain side. The issue is not one that I would take lightly, and anything that requires a head movement up or down while also turning the head to either side should probably be avoided; but a cheap and dirty solution could conceivably work if peripheral vision, or an eyes only glance, is truly sufficient. OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Peter |
#83
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Building an electronic Angle of Attack indicator
"Peter Dohm" wrote in message news Also, the issue of whether the string(s) can be easily, accurately and safely read in flight is open to question--and certainly must be resolved under conditions other than ridge lift. IIRC, you were amoung the participants, a number of months ago, in a human factors discussion regarding the effects of head movement while circling and the relationship of that to an otherwise unexplained glider crash into a mountain side. The issue is not one that I would take lightly, and anything that requires a head movement up or down while also turning the head to either side should probably be avoided; but a cheap and dirty solution could conceivably work if peripheral vision, or an eyes only glance, is truly sufficient. OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Peter The old A-3D and A-6A AOA required a lot of maintenance in order to keep them calibrated. Speaking of ridge soaring, there is a current video on YouTube that may be enlightening to those who have not explored soaring flight. Most of my soaring is thermal flight; however, once a year a group of us head to Logan, UT to fly the ridge up into Southern Idaho. The YouTube video is from near the Idaho border heading south toward Logan. Here is the link. (http://www.youtube.com/watch?v=2Xo6N6_9rNQ) Wayne http://www.soaridaho.com/ |
#84
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Building an electronic Angle of Attack indicator
"Wayne Paul" wrote in message
m... "Peter Dohm" wrote in message news Also, the issue of whether the string(s) can be easily, accurately and safely read in flight is open to question--and certainly must be resolved under conditions other than ridge lift. IIRC, you were amoung the participants, a number of months ago, in a human factors discussion regarding the effects of head movement while circling and the relationship of that to an otherwise unexplained glider crash into a mountain side. The issue is not one that I would take lightly, and anything that requires a head movement up or down while also turning the head to either side should probably be avoided; but a cheap and dirty solution could conceivably work if peripheral vision, or an eyes only glance, is truly sufficient. OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Peter The old A-3D and A-6A AOA required a lot of maintenance in order to keep them calibrated. Speaking of ridge soaring, there is a current video on YouTube that may be enlightening to those who have not explored soaring flight. Most of my soaring is thermal flight; however, once a year a group of us head to Logan, UT to fly the ridge up into Southern Idaho. The YouTube video is from near the Idaho border heading south toward Logan. Here is the link. (http://www.youtube.com/watch?v=2Xo6N6_9rNQ) Wayne http://www.soaridaho.com/ Very cool indeed! Perhaps, someday, I'll get to try my hand at that. Peter |
#85
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Building an electronic Angle of Attack indicator
Peter Dohm wrote:
"Wayne Paul" wrote in message ... "Peter Dohm" wrote in message .. . 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. I understand the process. I currently have a yaw string on my glider. The other canopy strings might be somewhat effective; however, I'm spoiled. I flew 13 years in the US Navy with "real" AOA systems. I am not looking for a crude substitute. I'm looking for the real thing. Wayne http://www.soaridaho.com/ I can certainly understand that, and there is no question about which is "better". Also, the issue of whether the string(s) can be easily, accurately and safely read in flight is open to question--and certainly must be resolved under conditions other than ridge lift. IIRC, you were amoung the participants, a number of months ago, in a human factors discussion regarding the effects of head movement while circling and the relationship of that to an otherwise unexplained glider crash into a mountain side. The issue is not one that I would take lightly, and anything that requires a head movement up or down while also turning the head to either side should probably be avoided; but a cheap and dirty solution could conceivably work if peripheral vision, or an eyes only glance, is truly sufficient. OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Peter I would think a simple solution would be to have an indicator with range marks for common flap settings. It's not perfect, but if you usually use one setting for take off, one for landing and clean for flight you should be able to SWAG other settings based on those range marks. Dan, U.S. Air Force, retired |
#86
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Building an electronic Angle of Attack indicator
"Peter Dohm" wrote OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Should not be a big deal. I have in mind how to do the whole thing (with angles of attack and stall angles with and without flaps) mechanically. No electronics involved, other than some switches, linkages and led lights. -- Jim in NC |
#87
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Building an electronic Angle of Attack indicator
"Dan" wrote in message ... I would think a simple solution would be to have an indicator with range marks for common flap settings. It's not perfect, but if you usually use one setting for take off, one for landing and clean for flight you should be able to SWAG other settings based on those range marks. Dan, U.S. Air Force, retired A thought just crossed my mind. When you change the flap setting the angle between the fuselage and the effective chord of the airfoil (angle of incidence) changes. At the optimum L/D speed at various flap setting, I bet there is little change in airflow relative to the fuselage. If you are flying with the fuselage nose down, or nose up relative to the airflow, drag is created. So my guess is that a well designed sailplane fuselage flies at an angle of 0 degrees to the airflow at best L/D regardless of flap setting. This is just a gut feeling. I'll have to tape a string to my canopy and mark its' location at best L/D with a zero flap setting and see what speed I achieve maintaining that mark at various flap setting. Wayne http://www.soaridaho.com/ |
#88
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Building an electronic Angle of Attack indicator
On May 17, 6:30*pm, "Peter Dohm" wrote:
"Wayne Paul" wrote in message ... "Peter Dohm" wrote in message .. . 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. I understand the process. *I currently have a yaw string on my glider. *The other canopy strings might be somewhat effective; however, I'm spoiled. *I flew 13 years in the US Navy with "real" AOA systems. *I am not looking for a crude substitute. *I'm looking for the real thing. Waynehttp://www.soaridaho.com/ I can certainly understand that, and there is no question about which is "better". Also, the issue of whether the string(s) can be easily, accurately and safely read in flight is open to question--and certainly must be resolved under conditions other than ridge lift. *IIRC, you were amoung the participants, a number of months ago, in a human factors discussion regarding the effects of head movement while circling and the relationship of that to an otherwise unexplained glider crash into a mountain side. *The issue is not one that I would take lightly, and anything that requires a head movement up or down while also turning the head to either side should probably be avoided; but a cheap and dirty solution could conceivably work if peripheral vision, or an eyes only glance, is truly sufficient. OTOH, a true AOA system that can be calibrated over the full reasonable range of angles is far from trivial--and probably well beyond my design capabilities. Peter Having used "pitch strings" on several gliders, I can assure there are no 'human factors' issues whatsoever. The "pitch strings" are in easy view and not any more distracting than a yaw string which they complement. It would be equally absurd to claim that an airspeed indicator is 'distracting'. In fact, the indications are so intuitive that all pilots who have used them feel they had a much better understanding of what the glider and the atmosphere was doing. Think of them together as a "3D yaw string" They actually help with thermalling reacting 3 seconds or so ahead of a vario indication. The strings flick upward as you enter a thermal. One pilot told me that the strings "got him home" by improving his 'dolphin flying' technique. Let me add that if a pilot DOES find them distracting, he would fail that part of the Practical Test Standards dealing with pilot distractions. AOA indicators are 100% a good thing. There are no downsides to having one. There is nothing "open to question". While there are many crashes that are arguably due to the pilot NOT having AOA information, there are probably NONE where having that knowledge was a contributing factor. |
#89
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Building an electronic Angle of Attack indicator
"Wayne Paul" wrote in message ... "Dan" wrote in message ... I would think a simple solution would be to have an indicator with range marks for common flap settings. It's not perfect, but if you usually use one setting for take off, one for landing and clean for flight you should be able to SWAG other settings based on those range marks. Dan, U.S. Air Force, retired A thought just crossed my mind. When you change the flap setting the angle between the fuselage and the effective chord of the airfoil (angle of incidence) changes. At the optimum L/D speed at various flap setting, I bet there is little change in airflow relative to the fuselage. If you are flying with the fuselage nose down, or nose up relative to the airflow, drag is created. So my guess is that a well designed sailplane fuselage flies at an angle of 0 degrees to the airflow at best L/D regardless of flap setting. This is just a gut feeling. I'll have to tape a string to my canopy and mark its' location at best L/D with a zero flap setting and see what speed I achieve maintaining that mark at various flap setting. Wayne http://www.soaridaho.com/ That is where I was hoping this would go...a little experimentation. ;-) |
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