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  #1  
Old 10-17-2012, 12:41 PM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
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Default Retrofitting the AFS Pro AoA - cheap insurance!

One of the outcomes of our trip to Van?s back in September was a religious conversion (courtesy of the evangelical Jerry VanGrunsven) to a belief in the effectiveness in AoA systems in reducing a measurable percentage of EAB accidents. I?ll be doing some writing on this in the near future, but in order to come up with meaningful comments, I figured it was time to install a real, sensed system in the Valkyrie (and compare it with the derived system I have on the GRT EFIS), so last week I received a nice box of parts from Advanced Flight Systems, and the Val went down for minor surgery.

Of course, minor surgery is a matter of perspective. The Advanced Pro system is very well packaged, with good instructions, but it is a bit invasive ? I needed to run sense lines from the wingtip and an additional micro-switch to pick up a ?flaps deployed? indication ? which meant pulling up floors, removing a wingtip, and pulling the intersection fairing. Then, of course, there is the brain box, switches, and indicator, which means that the panel had to come out?.




By the time I got very far into it, I figured ?what the heck??.might as well just sign off the Condition Inspection when I get done!




One of the lessons I?d share from an installation like this is the careful planning of wiring interfaces. Since my panel is removable, anything that crosses the interface between panel and airframe has to have a disconnect. The AoA system has a harness which is centralized on the brain box and needs power, ground, inputs from the switches, and outputs to the indicator and audio system. Good planning puts the brain box on the airframe side of the panel interface, and minimizing the number of disconnects meant putting the witches on the fixed portion of the panel (the airframe side). This means that only ONE line has to cross the disconnects, and that is the audio output from the AoA to the audio panel (mounted in the removable panel). It took some doodling at the design desk to come up with this realization ? well worth it before diving into the project!

I figure that a few day?s work will see the system back ready for flight.

Paul
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Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
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Dayton Valley Airpark (A34)
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  #2  
Old 10-17-2012, 12:56 PM
BobTurner BobTurner is offline
 
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Location: Livermore, CA
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Default

I have the derived GRT AOA and the Dynon D6 AOA from their pitot tube. As far as I can tell they both work. But the D6 is very superior when in the pattern because of its audio warning. Who's looking at their attitude indicator when in the pattern? OTOH I think the GRT is better in warning of departure stalls when IFR, since then you are looking at it and the big red bars cannot be missed.
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  #3  
Old 10-17-2012, 03:10 PM
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rleffler rleffler is offline
 
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Location: Delaware, OH (KDLZ)
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Default

Quote:
Originally Posted by BobTurner View Post
I have the derived GRT AOA and the Dynon D6 AOA from their pitot tube. As far as I can tell they both work. But the D6 is very superior when in the pattern because of its audio warning. Who's looking at their attitude indicator when in the pattern? OTOH I think the GRT is better in warning of departure stalls when IFR, since then you are looking at it and the big red bars cannot be missed.

Good point. I have the AFS AOA, but the display is on my EFIS. They also have an external display, like the one that Paul has. One clearly is better for IFR and I suspect the other is better for VFR (if you mount it on top of the glare shield) since we are supposed to be looking out the window.

In either case, it's reassuring hearing Jennifer Hickman giving me aural warnings without having to look at the EFIS.
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  #4  
Old 10-17-2012, 03:41 PM
N15JB N15JB is offline
 
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Location: Denver
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Love my AFS AOA. I have the pro display that is part of my efis, but actually prefer the glare shield display that I flew with Mike Seagar. Confirmed with AFS that I can use the same aoa ports and plumbing if I decide to add the other display. Doesn't every RV need 2 aoa systems?

Jim Berry
RV-10
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  #5  
Old 10-17-2012, 06:02 PM
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Ironflight Ironflight is offline
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Default

I think one of the most telling things about a good AoA indicator - one that is accurate and in the line of sight on a visual approach - is that in a day at Van's, I flew five different airplanes, all with AoA, and I never had to ask anything about stall speeds - I just went out and flew to the (known calibrated) AoA instrument on approach. I have flown experimentals (non-RV) with very little aerodynamic stall warning, and it is hard to get yourslef to fly them slow for short landings, because you're not sure when they are going to give up. AoA makes that a whole lot less scarry.
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RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
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  #6  
Old 10-17-2012, 06:26 PM
Vac Vac is offline
 
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Location: Niceville, Florida
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Default Eyes Out

There's a lot to be said for an aural AOA system. The benefit of hearing your AOA allows "eyes out" maneuvering and greatly simplifies instrument cross-check. The F-4 had a great system that was invaluable in the landing pattern. The F-15 displayed AOA in the HUD and has a pilot programmable tone.

It also helps to have the tone and display mech'd to stall AND L/D max since there is generally no reason to fly an AOA in excess of L/D max unless the pilot's intension is to bleed energy or drag in an approach/landing. Thus, L/D max becomes "on speed" for approach and maneuvering purposes and stall becomes "slow warning." It actually sounds more complicated than it is in practical application.

From a safety standpoint, any AOA system is a great addition to any airplane! Well done, Paul.

Cheers,

Vac
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  #7  
Old 10-17-2012, 07:29 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Vac View Post
There's a lot to be said for an aural AOA system. The benefit of hearing your AOA allows "eyes out" maneuvering and greatly simplifies instrument cross-check. The F-4 had a great system that was invaluable in the landing pattern. The F-15 displayed AOA in the HUD and has a pilot programmable tone.
Vac
I am also a strong proponent of the aural cues for AOA, since hearing is really an unused sense that you can "parallel in" during approach phase. I like a continuously-varying tone, or a varying frequency tone that works like an analog gauge for your ears, rather than simply a voice warning when you get too high - I would like to see this in every AOA system, with the option to turn off the audio for pilots whose brains don't work that way. I've flown aural and visual systems, and find that for my brain, the tone cues are excellent.

Paul
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Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
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Dayton Valley Airpark (A34)
http://Ironflight.com
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  #8  
Old 10-17-2012, 08:05 PM
Tom Martin Tom Martin is offline
 
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Location: Ontario, Canada
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The key to an effective aoa is to have it in your line of sight, mine is on top of the glare shield. I have been using this AFS sport aoa for seven years and have found it to be reliable and predictable. The only problem is that rain can cause an error in the system if the ports get covered. It does let you know that it is not in service at those times with an aural warning.
I plan on two or three yellow lights on final and it is accurate regardless of load.
I added a little cover over the display that always keeps the lights in the shadow and thus they are clearly visible in all light conditions.

[/url]
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  #9  
Old 10-17-2012, 08:10 PM
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LAMPSguy LAMPSguy is offline
 
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Default A little off topic, but vary similar

to paul's last comment. I prefer the varying frequency as well, much easier for my brain, and can be adapted to many things. I am quite sure arduino-smart people could come up with them...a tone for fuel when you have a very small amount that can be used in sustained inverted flight, or same for oil pressure, or I have even "seen" one for us in helicopters that used a variable frequency force generator to make the collective "buzz" the closer you got to torque limits.

There was a company a few years back working on a vest that pulsed with drift in a hover...they put you in the vest, gave you a quick 30 second explanation, and EVERYONE was able to hover the helicopter (simulator) in a brownout!! It didn't get the DoD funding as I remember. It also had a GREAT upside, the vibrations were pneumatic, from the ECS system...cooling vest...flying in the desert!
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  #10  
Old 10-18-2012, 03:08 PM
Jim F Jim F is offline
 
Join Date: Dec 2008
Location: Canby OR
Posts: 119
Default AOA

Paul
I got the same "sermon" from Jerry when I was building my 9A and incorporated the AFS AOA in from the start. I have almost 300 hrs on it and love what it does for stablizing my approach.
It also gives me the opportunity to bug Jenny when I see her at a Ch 105 meeting....
I have also pushed the people I have met from AOPA and FAA about easing the cert. of AOA for all basic GA. It is the one thing we could do to make a serious dent in the accident rate.
Jim Frisbie
RV-9A
N571 DF
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