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Thread: AOA

  1. #1

    Join Date
    Aug 2011
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    Fort Vermilion Alberta
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    196

    AOA

    I have been popooing angle of attack instruments as being unnecessary, until I used one in a friends airplane.
    Now I'm a convert. I just installed the one AS sells, pressure type, no electronics.
    Apparently it is not an AOA but a lift reserve indicator. Whatever, it works.
    Really it is just a hyper sensitive airspeed for low speed.
    Mount it up on the dash and keep an eye on it over the nose and I can see where it is a life saver and a short field enhancer.

    IMHO

    Ray

  2. #2
    FlyingRon's Avatar
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    NC26 (Catawba, NC)
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    The LRI is NOT an angle of attack indicator, although just like your wing it is affected by it.
    I find the documentation on the popular one somewhat misleading.
    Stall does not result in all lift going away. It's just where increasing further AOA causes a decrease in lift. The AOA vs. lift slopes are pretty symmetrical around the stall point.

    That's not to say the LRI doesn't give a useful reading. It tells you a number most people (incorrectly) equate to stall which is insufficient lift to maintain flight.

  3. #3

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    Aug 2011
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    Rolls Eyes

    Quote Originally Posted by FlyingRon View Post
    The LRI is NOT an angle of attack indicator, ...
    There's a good Oshkosh forum on this topic on Tuesday, 8:30AM, Forum stage 2. Please grill the presenter.

    Ron "still not quite Wright" Blum

  4. #4

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    Quote Originally Posted by Ron Blum View Post
    Please grill the presenter.

  5. #5
    Sam Buchanan's Avatar
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    Quote Originally Posted by FlyingRon View Post
    The LRI is NOT an angle of attack indicator, although just like your wing it is affected by it.
    I find the documentation on the popular one somewhat misleading.
    Stall does not result in all lift going away. It's just where increasing further AOA causes a decrease in lift. The AOA vs. lift slopes are pretty symmetrical around the stall point.

    That's not to say the LRI doesn't give a useful reading. It tells you a number most people (incorrectly) equate to stall which is insufficient lift to maintain flight.
    The LRI "controversy" has been ongoing for many years. But regardless of what you want to call it, the thing works very nicely and indicates the point when the the aircraft will begin approaching the ground at a (very) high rate of descent. I've been flying an LRI in my RV-6 since 2000 and it is the primary instrument I use for takeoffs and landings, especially when a max performance op is needed.

    Ray, you will enjoy flying your LRI!

    By the way, the LRI is not a hyper-sensitive airspeed indicator. Do some test flying at different flying weights and you will see how the LRI indicates loss of lift regardless of the airspeed. Landing or taking off hot, high and/or heavy is where this type of instrument pays for itself.
    Last edited by Sam Buchanan; 07-20-2018 at 02:42 PM.
    Sam Buchanan
    The RV Journal RV-6 build log
    Fokker D.VII semi-replica build log

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