Angle of Attack Indicators

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  • #84471

    We’re looking at installing an AoA indicator in the 310 this year. Has anyone on here done this? I’d appreciate pictures of the installation if you do. I’m trying to think about how I’d like to mount it and which one to go for. The round style appeals to me the most, but I’m not sure how I could mount it in the panel while still having it in view on final. The current panel looks like this:

    What’s cropped on the left is the clock and the Bonzer Mini-Mark radalt (which is inop… if anyone knows where to get parts for them or an expert on them I’d appreciate it). There would be room to put the round gauge on that side, but it would require cutting a hole and still not be in good view. The horizontal/vertical rectangular ones I don’t think could fit between the Aspen and the top of the instrument panel, but maybe… haven’t measured.

    For those who aren’t familiar, Alpha AoA is here:

    http://www.alphasystemsaoa.com/electronic-kits.html

    #100915
    quote TDUPUIS:

    We’re looking at installing an AoA indicator in the 310 this year. Has anyone on here done this? I’d appreciate pictures of the installation if you do. I’m trying to think about how I’d like to mount it and which one to go for. The round style appeals to me the most, but I’m not sure how I could mount it in the panel while still having it in view on final. The current panel looks like this:

    What’s cropped on the left is the clock and the Bonzer Mini-Mark radalt (which is inop… if anyone knows where to get parts for them or an expert on them I’d appreciate it). There would be room to put the round gauge on that side, but it would require cutting a hole and still not be in good view. The horizontal/vertical rectangular ones I don’t think could fit between the Aspen and the top of the instrument panel, but maybe… haven’t measured.

    For those who aren’t familiar, Alpha AoA is here:

    http://www.alphasystemsaoa.com/electronic-kits.html

    Mine is going on the left side of the panel eyebrow. Prominence is important. Especially when you are cranking it over and an accelerated stall is the risk.

    #100922
    pmcnamee
    Participant

      Guys, JMHO, you are simply wasting your money on AOA indicators for Twin Cessnas. These airplanes essentially have variable critical angles of attack. The amount of prop wash going over the wings and tail surface will make the indications worthless. You will never be able to calibrate the indicator to a true stall indication. Justing adding 10% power on the engines will give you a completely erroneous indication of an approach to stall.

      I have flown these AOA gauges in Riley Turbine Rockets — they were required as part of the FAA STC. Totally worthless. The AOA in the Cheyenne II is used for the Pitch SAS; its indication to the pilots is worthless. The AOA system in the Jets is used for the stick shaker/Pusher systems, and again nobody is going to be looking at that instrument when you’re in that critical condition. All the Boeing airliners have AOA systems and no indicator for the pilot. AOA gauges have no valuable information to the pilot, except for maybe a fighter jet with different stores on board. Today’s fighters have performance computers on board that always know the weight and configuration of the airplane and figures the Vref speed.

      The best Angle of Attack indicator in a twin Cessna is the control yoke vibrating in your hand. The dirty air shaking the hell out of the elevators gives you more than enough indication of approaching the critical AOA. Regardless of weight, CG, and load factor, the shaking elevator is telling the true story. Go out and do full and accelerated stalls in your airplane and turn around and watch what the horizontal stabilizer is doing. Don’t let it scare you, it isn’t going to come off. It takes a hell of a lot of G’s to make it fail. Vg’s will allow the the airplane to climb away from a stall indication.

      Spend your money on air-conditioning, A cool pilot is a safer pilot. Again, JMHO.

      Keep ’em Flying,

      Pat

      #100926

      Pat, I understand your view. I’ll admit to having never flown with an AoA, but those I know who’ve used them typically like them, including a friend of mine who has one on his Baron. Also, the Alpha AoA plugs into the audio panel and provides a verbal indication, which is what I view as the biggest positive. Still, I do understand your point.

      You make a good point on the AC, which is in our list as a high priority. Maybe try to do that first and wait another year.

      #100929

      Ted,
      Have you talked to Alpha lately? When I talked to them at OSH, they were developing a new line. Basically the indicator will receive signals from a remotely mounted device that will have additional capabilities and the new display line will be LCD if memory serves me right.

      I considered adding one to the Aztec, but they convinced me to wait until their new line was fully developed and available.

      #100930

      Jim,

      That’s interesting and good to know. I’ll hold off until that comes out. Did they say when it was expected? Maybe focus on AC this winter.

      The current one has LEDs but has been out for a while.

      #100931

      Ted,
      They complained that they wanted to introduce it at OSH ’13 but have so many irons in the fire that one of their more important projects trumped the AOA. You could give them a call, I had a great phone conversation with one of the owners several months ago about the new unit.

      #100933

      Jim,

      Good info, thanks. I’ll talk to them. Annual isn’t due until January, but as we always have multiple projects we want to do, I’d have no issue with putting off the AoA until another year. I’m not even sure my A&Ps are interested in that since it involves wires.

      #104736

      Garmin just announced an AoA last month, due out later this year.

      https://www.aopa.org/News-and-Video/All-News/2014/March/14/Garmin-AOA-and-radar-altimeter.aspx

      If that link breaks in the future, google “Garmin GI 260.”

      #104753
      rwelsh
      Participant
        quote :

        Guys, JMHO, you are simply wasting your money on AOA indicators for Twin Cessnas. These airplanes essentially have variable critical angles of attack. The amount of prop wash going over the wings and tail surface will make the indications worthless. You will never be able to calibrate the indicator to a true stall indication. Justing adding 10% power on the engines will give you a completely erroneous indication of an approach to stall.

        I have flown these AOA gauges in Riley Turbine Rockets — they were required as part of the FAA STC. Totally worthless. The AOA in the Cheyenne II is used for the Pitch SAS; its indication to the pilots is worthless. The AOA system in the Jets is used for the stick shaker/Pusher systems, and again nobody is going to be looking at that instrument when you’re in that critical condition. All the Boeing airliners have AOA systems and no indicator for the pilot. AOA gauges have no valuable information to the pilot, except for maybe a fighter jet with different stores on board. Today’s fighters have performance computers on board that always know the weight and configuration of the airplane and figures the Vref speed.

        The best Angle of Attack indicator in a twin Cessna is the control yoke vibrating in your hand. The dirty air shaking the hell out of the elevators gives you more than enough indication of approaching the critical AOA. Regardless of weight, CG, and load factor, the shaking elevator is telling the true story. Go out and do full and accelerated stalls in your airplane and turn around and watch what the horizontal stabilizer is doing. Don’t let it scare you, it isn’t going to come off. It takes a hell of a lot of G’s to make it fail. Vg’s will allow the the airplane to climb away from a stall indication.
        Spend your money on air-conditioning, A cool pilot is a safer pilot. Again, JMHO. Keep ’em Flying,
        Pat

        Pat I hate to argue with someone with your background, but the Cessna factory AOA that was an option for the twins after 1975 is a very accurate device and easy to see on the glareshield in front of the pilot. Normally you don’t have to look at it, but when flying out of mountain airports that require steep climb gradients then the AOA real comes in handy. You can climb at max angle of climb which in my 340 at high weights is about 90 knots and I feel comfortable at that speed. Coming out of Aspen, I can get over 1500 feet pre minute climb with my 310 HP engines. It also comes in handy when ATC wants a max climb to a different altitude for crossing traffic. In 1500 hours and 13 years, I have used it maybe 6 times, but it is nice to know it is there. I don’t know how the newer AOAs coming out work or are as sensitive, but they can be of help is installed, calibrated and used correctly.

        #104832

        Bendix-King recently announced their KLR 10 “for certified aircraft…”

        http://www.bendixking.com/Products/Flight-Controls-Indicators/Indicators/KLR-10

        #105103

        I like AOA’s! They are available on Boeings the operator just has to pay for it.

        Upper right of PFD = AOA

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