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Thread: A Basic Pilot Skill

  1. #1

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    A Basic Pilot Skill

    When you are starting as a brand new student pilot, what is vital to learn? It may seem that there is so much and it can be overwhelming or confusing.
    There are some things like your planning and preflight, checking the weather, making sure you have full fuel or at least plenty of it, that are primo.
    But how about the actual flying skills?

    A wing needs a certain amount of airflow over it to develop lift, that is you need a certain amount of airspeed to fly. any less than that minimum amount of air and you stall, you lose lift. So this is critical. But is it not quite that simple. The angle of attack, in other words the angle that the wing is hitting the wind at is the critical item, it deterimines when the stall occurs. For many wings this critical angle of attack is about 14 degrees. But it is the angle against the wind, not against the horizon that matters. So while a simple learning stall might be done in a 172, wings level, in straight flight, power off and occur just like the book says when you raise the nose somewhat above the horizon.
    But how about a acro plane that might stall at the bottom of a loop, even with the nose pointed down or inverted? Or a fighter doing a low pass and pulling 3 gs in a steep bank turn to downwind?

    So a plane in a a bank will stall at a higher than normal speed, and when pullling more that I g load the stall speed goes up again.

    And it the stall is uncoordinated (with the nose yawing to the side), the plane will or may roll even tend to spin, rather than just falling straight ahead.

    IF THE STUDENT CAN LEARN AND INGRAIN THIS, SORT OF HAVE A 2ND SENSE OF HOW CLOSE TO STALL YOU ARE, I E HOW MUCH EXCESS LIFT (AIRSPEED ) YOU HAVE IN THE BANK, IT WILL SERVE YOU WELL.

    There are still many accidents, usually fatal from stalls and/or spins. Can be in a simple trainer, even a glider or in an airliner.

    The student needs to know how much margin of lift above stall he has and what he can do, and it is very good when it becomes like an ingrained 2nd sense. Learn it from reading the books, and looking at the cd rom, but also go out and try it, with a good CFI in the airplane.

    If you go do one power on , uncoordinated, steep bank, pulling g stall in a T-6, it ought to get your full attention and you ought never to do anything remotely like that when down low turning base to final, in any plane, and damn sure not in a T-6. And I know most of you don't fly a T-6, but learn it in whatever you do fly; and even better once you get to be a pilot go down to Florida, or wherever and get the T-6 training. That is why the Texan (the real one, not that air conditioned modern imitation one) is called an ADVANCED trainer.
    Last edited by Bill Greenwood; 03-17-2012 at 10:46 AM.

  2. #2
    John McGinnis's Avatar
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    I'll gladly add my voice to the (growing) call for Angle of Attack awareness! Unlike airspeed indicators, AoA indicators do not require pilots to calculate or remember how much faster they need to be flying to avoid stalling at '2.7 Gs' when '123 lbs under gross' at 8700 ft on a blistering day. They just tell you what you need to know, regardless of temperature etc: your wing's angle of attack... and therefore your reserve lift capacity.

    Skilled and experienced pilots can develop a sense for this using a number of cues, such as stick position and feel, sound, and of course our backsides. Like Bill says, we must!

    But these are not as good as an AoA because they'll lie to us when something isn't right. Unexpected CG, a funky trim change, a little ice or any number of other factors might 'feel' fine but still let you buy it when the angle of attack suddenly turns out to be higher than you thought it was.

    This is not news!!! A lifetime ago, our forebears simply made the wrong call about which primary instrument to use for flight envelope safety. The only mistake is to repeat it, indefinitely, without cause. The Navy, for one, has taken the lead in correcting matters for the next generations.

    EVERYONE should have an AoA. Front and center. Then go crank that T-6 like it was supposed to be flown!

  3. #3

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    John, angle of attack would be a good thing to know, but I think I have acually seen such an indicator in only one gen aviation airplane, not on any T-6s. Don't know about the new so called T-6s, they probalby have lots of gadgets and may have one. So almost all pilots have to rely on the traditional if secondary method of being aware of where the nose is pointed, which gives an appoximation of angle of attack, as well as the info from the airspeed indicator, and what power and g's you are using for what stage of flight or what manuever. In other words, an awareness of how much lift you have in reserve and if you are getting close to using it all up.

    You may have heard the strory that about 1950 Wilbur Wright was invited up to the cockpit in flight of a big piston airliner, and told them they ought to have an indicator and be flying by angle of atttack.
    Last edited by Bill Greenwood; 03-22-2012 at 04:02 PM.

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    MEdwards's Avatar
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    Quote Originally Posted by John McGinnis View Post
    EVERYONE should have an AoA. Front and center.
    John, you'd be a good source of info that I've wondered about for a long time. How does an AOA indicator work? In qualitative terms without equations if possible, but if it's really complicated, have at it! Thanks.

  5. #5

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    There are two companies that I know of that make aftermarket angle of attack indicators; not counting some multibucks type to go in new jets.
    They have a small sensor that you cut at small slot to fit in the leading edge of the wing, then a wire that runs into the cockpit to the instrument.
    The display on the instrument can be two types, one is a dial where one side is green and as you get less lift, the indicator needle goes to yellow then at the stall it is in the red.
    The other one uses a series of lights, again green is good, then moving to red as the stall is met.

    It seems to be to be somewhat like a current stall indicator, but more sensitive and detailed.
    Last edited by Bill Greenwood; 03-22-2012 at 08:40 PM.

  6. #6
    The first thing one should do is to understand the real way airplanes fly and react. That will lead to proper pilot input to the controls. The best book I've ever seen on the subject is "STICK AND RUDDER, an explanation of the art of flying", written in 1944 by Wolfgang Langeweische. It is a priceless education. You will discover that you don't need a fancy AOA indicator, there's already one in every cockpit. Learn what it is, by reading this book.

  7. #7
    John McGinnis's Avatar
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    Guys, Angle of Attack indicators are "stupid simple" devices that can be made cheaply, using several different principles. There are lots of them available commercially as well. My point is the same as Wilbur's and for the same reason; every cockpit needs an AoA, just the same as it needs an airspeed indicator. In fact, far more than it needs an airspeed indicator.

    Wright was trying to help correct this same mistake of history, that's all. It was probably way too late by then.

    AirSpeed Indicators have killed and continue to kill people by the thousands, because airspeed does not by itself reflect whether a wing is at or near stall. That number changes with all kinds of influences that we do not always account for or calculate correctly. Can you name them all? Would you get a headache if I quizzed you on the new "stall speed" of a plane affected by half of them at a time? Did you know that it doesn't even matter, because your ASI is able to read the same speed at totally different angles of attack, one flyable, one not?? It ought to be a crime that we continue to teach misleading falsehoods like "stall speed" to new pilots. Wings stall at an angle, not at a speed.

    AoA indicators (usually) use the same exact principle of an ASI, namely pressure differential, but they use it differently: to determine changes in angle of attack. One pressure port is basically aiming downward and one upward in most designs (but are of course slightly more refined than a simple statement of the principle implies), and the pressure differential is calibrated to display 'the angle of the instrument to the oncoming air' on a guage. An airspeed indicator could certainly be converted to an AoA by a clever student of the matter. Another style simply uses a vane that responds to incoming wind direction like an arrow or weathervane.

    Do we complain about needing an airspeed indicator or suggest that adequate stick and rudder skills take away the need for them? To me, the more hotshot you actually are, the more likely an AoA is to save your bacon someday.

    I'm not selling guages, people. Count me among those who actually feel like Bill and blueskies: "Instruments? We don't need no stinking instruments!"

    But the truth is that we often DO like (or need) to know things that we cannot determine adequately without them, and the angle of attack instrument is the one and only instrument that tells the truth about reserve lift. Stick forces and location varies with CG, changes, and problems... and your butt is NOT properly calibrated at every density altitude, CG, or weight.

    Your AoA is.

  8. #8
    steveinindy's Avatar
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    Guys, Angle of Attack indicators are "stupid simple" devices that can be made cheaply, using several different principles. There are lots of them available commercially as well. My point is the same as Wilbur's and for the same reason; every cockpit needs an AoA, just the same as it needs an airspeed indicator. In fact, far more than it needs an airspeed indicator.
    My last instructor used to say "The purpose of an airspeed indicator is so you know when you'll arrive and so that, if you have the necessary thrust, you don't rip the wings off the plane. The purpose of an angle of attack indicator is to keep the ground or trees from doing that for you."
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  9. #9
    steveinindy's Avatar
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    You will discover that you don't need a fancy AOA indicator, there's already one in every cockpit.
    As John pointed out, your butt isn't that reliable of an AOA indicator or else we wouldn't have had the problems with spatial disorientation/stall/spin that we have had. That goes back to even the days when the lessons of "Stick and Rudder" were standard knowledge because of the lack of instruments. The macho "you don't need an AOA indicator" BS is exactly what has gotten lots of pilots killed, probably far more than have died as a result of the use of such tools.
    Unfortunately in science what you believe is irrelevant.

    "I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.



  10. #10

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    Improved "Stick and Rudder" and AoA Instrumentation

    Quote Originally Posted by blueskies747 View Post
    The best book I've ever seen on the subject is "STICK AND RUDDER, an explanation of the art of flying", written in 1944 by Wolfgang Langeweische.
    "See How It Flies" is available online for free and is, in my opinion, a more complete and modern equivalent of "Stick and Rudder". In particular the explination of how lift is generated is good, not the old bernoulli principle explanation that frequently assumes for no apparent reason that the air flowing over the top of the wing must travel to the training edge of the wing in the same time interval as that of the air flowing under the wing.

    I have flown with angle of attack indicators and find that for typical light aircraft they are of little use and are not sufficiently stable and accurate. I will conceed that AoA instrumentation is of great value for some aircraft, specifically aircraft with poor stall characteristics and some high speed aircraft particuarly those with swept or low aspect ratio wings and high wing loading.
    Last edited by jedi; 03-24-2012 at 11:59 AM.

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