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#1
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Angle of attack
The threads on this subject has uncovered something that gives me chills.
Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing". http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels |
#2
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Angle of attack
I broached a subject on the http://soaringcanada.riq.ca/ The Round
Table but not with a direct question about A of A but more general, to see what the response was. I tought it was interesting and revealing. I ask "A question on minimizing stall accidents". I wanted to get a sense of how this critical phase was being taught, in light of an accident that happened just prior. If you want to see the answer you my want to read some of the comments. Udo On Dec 11, 9:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote: The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing".http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels |
#3
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Angle of attack
On Dec 11, 6:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing".http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels Bill, You are wasting your breath, in this case several strokes of keys. Jacek Pasco, WA |
#4
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Of course, it doesn't help that the AOA control is called an "elevator", leading one to believe that it makes you go up & down - I've also seen a zillion references in TV & the movies that reinforced this belief.
As far as I'm concerned, Stick & Rudder is the best book on piloting an aircraft ever written. I have a copy printed in 1944. |
#5
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Angle of attack
Udo wrote:
I broached a subject on the http://soaringcanada.riq.ca/ The Round Table but not with a direct question about A of A but more general, to see what the response was. I tought it was interesting and revealing. I ask "A question on minimizing stall accidents". I wanted to get a sense of how this critical phase was being taught, in light of an accident that happened just prior. If you want to see the answer you my want to read some of the comments. Udo On Dec 11, 9:27 pm, "Bill Daniels" bildan@comcast-dot-net wrote: The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. When I went to collich in the U.S. (1967-1972), even though aeronautical engineering (what I *really* wanted to major in) had morphed into aerospace engineering (crummy commies), one forlorn airplane-based course curricularly remained. Nonetheless, in that one (mostly a nearly incomprehensible stability and control) aircraft-dominant course, it became apparent to me that wings cared first about AoA, and only secondarily about velocity of oncoming air. This was long before I'd sat in a lightplane, seen a glider, or heard of (the very excellent) "Stick and Rudder." Soon after graduating, I bumbled into soaring, and the illness permanently altered my life. Regrettably, I can no longer remember if or how my instructor taught 'low speed flight' aspects. Can't remember if he mentioned AoA, or if he merely said 'maintain flying speed.' Doesn't matter, because the aforementioned course colored whatever my instructor also conveyed. In glider terms, if we assume compressibility isn't an issue (and it isn't, for glider airspeeds), the wing cares Zero what speed your ASI displays. Physically, it cares only about AoA of the oncoming air. Of course, both are (through the stick) inter-related, but one (easier to reliably measure) falls out in the wash, while the other (AoA), physically determines what the wing is going to do next. Now, (glider)pilot training reality demonstrably proves conceptual grasp of the importance of AoA to the wing's immediate future actions (and arguably, pilots' near-term lives) isn't required in order to obtain one's pilot's license. Whether or not that's a good thing leads to this thread's sort of 'religious arguments.' Fact is, cats can be skinned multiple ways... Personally, my brain is most comfortable understanding underlying physical principles, even if it must (in part) rely on indirect measurements (e.g. ASI, noise, 'feel,' etc.). I believe if a person really and truly grasps the underlying physical principles governing the consequences of his or her actions, s/he's more likely to do the physically correct thing in moments of crisis, than not. Further, s/he's less likely to (N.B. Key Word follows!) *inadvertently* go where no thoughtful risk taker inadvertently wishes to go. (Kids, can you spell "i*n-p*a*t*t*e*r*n s*t*a*l*l/s*p*i*n?") Furthermore personally, I'd love to have an AoA gauge in my (flapped) glider, even if NOT scientifically/numerically accurate. So long as it's repeatable, I wouldn't care whether it showed my ship stalled at 10-degrees or 30-degrees AoA for 'whatever' flap deflection. That's the difference between usable engineering accuracy, and scientific (e.g. wind-tunnel-comparative) accuracy. Absence of the latter doesn't rule out usefulness of the former. 'Reverently,' Bob W. |
#6
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Angle of attack
As far as I'm concerned, Stick & Rudder is the best book on piloting an aircraft ever written. I have a copy printed in 1944. I've heard (but not verified) that, next to the bible, Stick And Rudder has been in continuous publication longer than any other book. My 1972 edition has 40 pages on what it takes to turn an airplane - and it's 40 pages that you *want* to read. Get this book if don't have it already! Tony V. CFIG |
#7
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Angle of attack
Sorry Bill,
I don't know how you train your students, but the training I received, and the training I give, ALWAYS refers to the attitude of the nose in respect to the horizon, NEVER to ASI readings. Nose attitude is the onboard AoA, and it works. If in your environment the reference is ASI reading, then indeed this would be indeed chilling. On a winch launch, nose attitude does not work, but ASI reference does work. Limits need to be greatly corrected in respect to free flight, but if you don't get below this limit, you won't crash - because the limit is such that you simply can't reach critical AoA by staying above the limit. Bert "Bill Daniels" bildan@comcast-dot-net wrote in message . .. The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing". http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels |
#8
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Angle of attack
This is an interesting topic. How exactly does the horizon give you
angle of attack reference? I don't have much experience in gliders yet, but in powered airplanes, the horizon can be in a lot of different places with reference to the nose. For example, the nose might be slightly above the horizon at stall with engine at idle, a lot more above the horizon at stall with full power and the horizon might be straight above the cockpit while holding a stall in a spin. In a powered plane, the nose can be right on the horizon, but airspeed may be just above stall as you are "mushing" through the air (ie level attitude with reference to horizon, but sinking at a high rate). I was taught that angle of attack was the angular difference between the wing chord line and the wind flow direction. I would think a simple AoA indicator would be a string suspended below a wire about 1 to 2 feet out in front of the wing with a panel outboard of the string with lines drawn representing angles drawn with a protractor such as 0 degrees, 5 degrees, 12 degrees, etc. Scott Bert Willing wrote: Sorry Bill, I don't know how you train your students, but the training I received, and the training I give, ALWAYS refers to the attitude of the nose in respect to the horizon, NEVER to ASI readings. Nose attitude is the onboard AoA, and it works. If in your environment the reference is ASI reading, then indeed this would be indeed chilling. On a winch launch, nose attitude does not work, but ASI reference does work. Limits need to be greatly corrected in respect to free flight, but if you don't get below this limit, you won't crash - because the limit is such that you simply can't reach critical AoA by staying above the limit. Bert "Bill Daniels" bildan@comcast-dot-net wrote in message . .. The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing". http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels -- Scott http://corbenflyer.tripod.com/ Gotta Fly or Gonna Die Building RV-4 (Super Slow Build Version) |
#9
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Angle of attack
Exibit "A" below. I couldn't come up with a better example of what I'm
talking about. "Bert Willing" wrote in message ... Sorry Bill, I don't know how you train your students, but the training I received, and the training I give, ALWAYS refers to the attitude of the nose in respect to the horizon, NEVER to ASI readings. Nose attitude is the onboard AoA, and it works. If in your environment the reference is ASI reading, then indeed this would be indeed chilling. On a winch launch, nose attitude does not work, but ASI reference does work. Limits need to be greatly corrected in respect to free flight, but if you don't get below this limit, you won't crash - because the limit is such that you simply can't reach critical AoA by staying above the limit. Bert "Bill Daniels" bildan@comcast-dot-net wrote in message . .. The threads on this subject has uncovered something that gives me chills. Internationaly, gliding has an abominable safety record. Many fatal accidents have as their root cause, failure by the pilot to maintain flying speed or, stated more directly, control his angle of attack. Clearly, based on these r.a.s threads on the subject, some do not understand AOA in some fundamental way and that's chilling. Controlling airspeed is simply not good enough - it's too abstract, too easy to triviallize, too easy to misunderstand the significance of it. Safety committees and organizations need to take this to hart. Here is a root cause of our most dangerous accidents. The awareness of and understanding of AOA has somehow slipped through the cracks. Slay this dragon, and our accident numbers will look far better. If the concept and practice of controlling angle of attack is not absolutely ingrained in a pilot, the probability of an accident is non-trivial - in fact, sooner or later, it's a near certainty. Awareness of AOA should never be far from a pilots consiousness. Controlling angle of attack is so fundamental to being a pilot that it's staggering to think that it's possible to become one without it being hammered into them until it's as instinctive as walking. Flying an aircraft without this level of understanding is like being the captain of a ship without understanding what makes it float. As pilots, we do not fly the cockpit, the fuselage or the empenage - we fly the wing. The wing is really the only thing that does fly, the rest is just baggage. Read Jim Webb's truly excellent book "Fly the wing". http://www.amazon.com/Fly-Wing-James-Webb/dp/0813805414 Or equally good, Wolfgang Langewiesche's "Stick and Rudder". You can read it free on line at Google Books. Read these books - please! There is simply no subject in aviation that is more fundamental or important to your survival. Bill Daniels |
#10
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Angle of attack
On Dec 13, 7:10 am, Scott wrote:
This is an interesting topic. How exactly does the horizon give you angle of attack reference? It does NOT give an angle of attack reference. The pitch attitude (horizon) differs from AOA by the climb angle. See http://www.av8n.com/how/htm/aoa.html for a good explanation. While I agree that understanding of AOA is crucial for a pilot. I don't think that a AOA indicator would be very useful in gliders. (except for flight testing of a new design) I think that stall accidents are caused by lack of awareness and lack of attention. Letting the airspeed "creep away" and incorrectly responding to the loss of airspeed. Substituting an AOA dial for the airspeed dial, won't change that. AOA gauges seem best suited for heavy aircraft flown by reference to instruments. Where you might have to wait a couple of minutes after setting the AOA and power lever to get the airspeed to respond. Gliders will change their airspeed much quicker than a 747 or F-14. We also only really fly at 2 or 3 different weights. No ballast, half or full. So we only really have to remember the best L/D speed for these conditions. Todd Smith 3S |
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