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Retrofitting the AFS Pro AoA - cheap insurance!

Ironflight

VAF Moderator / Line Boy
Mentor
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?.

P1010856.JPG



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!


P1010858.JPG


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
 
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.
 
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. :eek:

In either case, it's reassuring hearing Jennifer Hickman giving me aural warnings without having to look at the EFIS.
 
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
 
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.
 
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
 
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
 
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.

img1449g.jpg
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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!
 
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
 
AOA probe

Paul and others: wondering what type of AOA probe you are utilizing? I intend to use AFS but looks like their probe is a little more difficult to install.

Bob
 
rwelsh

I am not familiar with the other systems, but the AFS is pretty simple. No problem putting it in a completed & painted wing.

Jim Berry
 
Paul and others: wondering what type of AOA probe you are utilizing? I intend to use AFS but looks like their probe is a little more difficult to install.

Bob

It probably took me an hour to do the wing portion of the install after I had removed the wingtip - no problem at all on an RV!
 
Paul and others: wondering what type of AOA probe you are utilizing? I intend to use AFS but looks like their probe is a little more difficult to install.

Bob

AFS doesn't have a probe. You drill a couple small holes in your wing. If you are already flying, it's pretty easy to install with the wing tip off. Paul's pictures at the beginning of this thread are pretty illustrative of the process. You just have to run a couple small lines to the cabin.

Like Jim stated, it's pretty easy.
 
Paul and others: wondering what type of AOA probe you are utilizing? I intend to use AFS but looks like their probe is a little more difficult to install.

Bob

I'm using the Dynon heated AOA/pitot probe on a Gretz mast.
 
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Which second AOA

My GRT Sport EFIS has the AOA feature.

I would also like to have a second AOA, preferably with audio.

I bought the Pro system years ago before it was owned by Advanced and have it in a box ready to install. I also have a Dynon D6 that I use as a backup EFIS, which has its own AOA with audio.....I just need to switch out my current Gretz heated pitot tube for the Dynon pitot tube. The wings are not installed on my airframe yet.

My delimma is whether to go with the Dynon D6 AOA or the Pro. It seems that the pro would be more work.

On the cost side, I would have to sell my gretz heated pitot, unused....and buy a dynon pitot.

On the time and effort side, it would seem that the Dynon route would be easier, I have already wired the audio out into my audio panel and I would avoid the installation issues that Paul is not going through.

I think using all 3 would be a bit much.

Input would be appreciated.

Thanks Paul for starting this thread. A very safety related issue.
 
My opinion, if it were my decision to make, would be to go with the AFS Pro. My reasoning that you already have the derived AOA on the Sport. I would think that the AOA on the D6 would be difficult to read based upon screen size and most likely not in your line of sight when landing. You could get one of the glare shield mounts for the AFS Pro, where it would be more visible and useful.

As fas as effort goes, I think it's a flip of the coin. You still have to run extra tubing for both solutions. I think they both would take about the same time to implement.

My GRT Sport EFIS has the AOA feature.

I would also like to have a second AOA, preferably with audio.

I bought the Pro system years ago before it was owned by Advanced and have it in a box ready to install. I also have a Dynon D6 that I use as a backup EFIS, which has its own AOA with audio.....I just need to switch out my current Gretz heated pitot tube for the Dynon pitot tube. The wings are not installed on my airframe yet.

My delimma is whether to go with the Dynon D6 AOA or the Pro. It seems that the pro would be more work.

On the cost side, I would have to sell my gretz heated pitot, unused....and buy a dynon pitot.

On the time and effort side, it would seem that the Dynon route would be easier, I have already wired the audio out into my audio panel and I would avoid the installation issues that Paul is not going through.

I think using all 3 would be a bit much.

Input would be appreciated.

Thanks Paul for starting this thread. A very safety related issue.
 
Buttoning Things Up

Well, the Val isn?t quite back together (finishing up the airframe part of the annual and have to re-install the panel tomorrow), but the AoA installation is pretty much finished. Overall, very straightforward ? a few notes?

1) I made sure to leave enough slack in the cable between the brain box and indicator head so that I can pull the head back off the glare shield to work on it if required ? the extra slack is a service loop behind the panel.
2) The pins you have to put on the end of the indicator head cable are VERY TINY ? take the time to find the right crimper, it is graduate-level work!
3) Turn down the heat on the soldering iron when putting leads onto the push-button switches ? you can ask me how I figured that out, but I won?t answer on the grounds that it might incriminate me?. (just a TOUCH of heat will do it).
4) I simply velcroed the AoA brain box on top of my AHRS ? it?s very light, and I saw no need to make it complicated.
5) I tied the ?Audio Out? line from the AoA into the (unused) Marker Beacon In position on my PSE audio panel ? that has a latching switch to enable the audio, so if I for some reason want to silence the AoA audio, I can just deselect it. I?ll nominally leave it selected.

I?m looking forward to getting her buttoned up ? maybe tomorrow (have an airpark fly-out to another airpark for lunch ? all this flying gets in the way of building!) ? and then giving it an airborne try-out.

Paul
 
My opinion, if it were my decision to make, would be to go with the AFS Pro. My reasoning that you already have the derived AOA on the Sport. I would think that the AOA on the D6 would be difficult to read based upon screen size and most likely not in your line of sight when landing. You could get one of the glare shield mounts for the AFS Pro, where it would be more visible and useful.

As fas as effort goes, I think it's a flip of the coin. You still have to run extra tubing for both solutions. I think they both would take about the same time to implement.

I put the D6 in mine as a backup EFIS to the G3X and since it does AoA I decided to go ahead and wire it up. The D6 isn't derived AoA though, it uses two pressure ports on the Dynon heated pitot tube and calculates the AoA based on the pressure difference between the two ports.

One of then nice things about the Dynon is that the audible alarms can be configured to be be progressive; meaning that the closer you get to a stall, the more intense the audible warning is. So you can keep your eyes out of the cockpit and let your ears do the work.

It's pretty nice to have the D6 actually contributing positively to the overall functionality of the panel instead of just having it along for the ride and taking up space.

Phil

From the D6 installation manual

ALARM SETUP

Enter the EFIS > SETUP > AOAALM menu and press any of the buttons beneath the AUDIO label to select the point on the AOA bar at which you wish the alarm to sound:

AUDIO: ALWAYS OFF
AUDIO: ON IN RED
AUDIO: START YLW TOP
AUDIO: START YLW MID
AUDIO: START YLW BTM

The latter three alarms (the ones that begin with START) are progressive, meaning the audio alert gets more intense as your angle of attack increases. You may set these progressive alarms to start at the top, middle, or bottom of the yellow section of the AOA bar. Setting AUDIO to ON IN RED configures an intense alarm to occur only when the AOA indicator is in the red.

To reduce nuisance audible AOA alarms ? such as when taxiing, taking off and landing ? the alarm can be inhibited below a selected airspeed. While in the EFIS > SETUP > AOAALM menu, press MINSPD to configure the minimum airspeed at which an AOA alarm can occur. Anytime airspeed is below the MINSPD value, AOA alarms will not occur; anytime it is above the MINSPD value, alarms can occur. If the AOA alarm is already sounding as airspeed falls below this threshold, it will continue to sound until the high AOA condition is resolved.
 
I should catch this thread up! I finished the installation last weekend, and have done a couple of flights with the AoA now - and I love it! The calibration was perfect right out of the box (they can send it to you pre-programmed for the RV-4,6,7,8) and so long as you put the sense ports where they tell you to, it should be pretty close on the first flight.

AFS really does think of everything - from including a #60 drill bit to make the sense holes (face it, all of our drill bit sets are missing that one because we broke it the first time...right?) to a pair of heavy-stock printed flight test cards to walk you through calibration and testing. I flew with he "Testing" card and did all the checks to prove that the system was right on.

I haven't flown an exhaustive test program yet, but my initial results show that I have a comfortable margin above the stall buffet when I get the "Angle, Angle, Push!" audio, no matter the attitude or G-loading. Straight and level, in a steep turn, or at the top of a loop, the display and warnings confirm what I feel in the seat of the pants regarding the wings relationship to the free stream.

On future flights, I want to do some direct comparisons to eh computed AoA that I have on the GRT EFIS, and see how the two correlate (a quick look shows that they do a good job matching each other on final approach, but the AFS AoA is far superior in unusual attitudes), and I want to play with the the AFS AoA more in aerobatics, to see if I can find a way to fool it.

So far, however, it is easy to see why Jerry VanGrunsven is such an evangelist for this device - with the display in the center of the windshield, as far forward as I could get it, the color bars are there almost like a HUD on final - my eyes see around it, so it isn't an obstruction, but it is right there in the subconscious, doing it's job. I look forward to trying it at altitude, in the mountains, with a loaded airplane....we all know how to fly our airplanes the way we normally load - it is at the edges of the envelope that I expect these things can really save our bacon!

Paul
 
AOA Pro

Over 500 hours on my AOA pro in the 7A. I haven't even really started using it for visual on landing as it is on my panel but the audio warning is really, really helpful in cases where you are near the edge an have a high workload. When she starts talking you really pay attention.

As a side benefit, if you happen to start generating lift on the wing as in a takeoff roll but have left a pitot cover on, the AOA pro will start talking to you. Don't ask how I know.

Andy
 
I was similarly sold on the idea of AOA from two pilots before I'd hammered the first rivet. I really like the AFS Pro and would like to use it.

One issue that I have is I am also a big fan of the AFS-5000 series and am leaning that way for my EFIS. The AFS 5000 has AOA built in as a feature. Unless this has been changed recently, there is no way to have that nice AFS Pro annunciator and the AFS series of EFIS w/built in AOA. Having this option would allow me to put the annunciator anywhere on the panel I like. With the AOA integrated into the EFIS the annunciator seems relatively small and your eye needs to be down on the screen to see it rather than looking into your turn. Aural warnings are nice, but I'd really like to be able to see the annunciator so I might arrest an issue before it becomes a problem.

I'm glad you got it installed and working. Did you run the tubes through a conduit to get them to the tip of the wing?
 
This post is to describe a thought I had some time back about the visual annunciator portion of an AOA installation. I did enough work with this to implement it on the work bench but it is not yet installed in the airplane.

The thought was pretty much the same as everyone else, that is the AOA is a valuable tool in landing; but also that are certain other visual annunciators that you would want very close to your line of sight, to indicate various alarm conditions. People currently build these as annunciator lights and put them high up on the panel.

The thought was to combine these two in a single glare shield mounted, high intensity LED display. There would be 8 LEDs in the display, 3 red, 3 amber, and 2 green. They would be driven by a small module that would control their function and intensity. There would be basically 2 input sources to this module, the output of the Advanced AOA 'brain' and up to 8 chosen engine/airframe inputs. For AOA, the functioning is the same as normal AOA, only brightness controlled. For the engine/airframe annunciators, the alert would be blinked at a programmed rate depending on alert.

The glareshield module mount would be hinged so that the display could be horizontal or moved to vertical position. The controller would also be used for brightness control on other devices.

Here are some drawings:

annunciator_257.png


annunciator0001_288.jpg


Just a thought,
GH
 
I'm glad you got it installed and working. Did you run the tubes through a conduit to get them to the tip of the wing?

Yup - I just used some corrugated conduit to protect the tubing and ran them through lightening holes Securing them at sopts I could reach through inspection covers).
 
Quote One issue that I have is I am also a big fan of the AFS-5000 series and am leaning that way for my EFIS. The AFS 5000 has AOA built in as a feature. Unless this has been changed recently, there is no way to have that nice AFS Pro annunciator and the AFS series of EFIS w/built in AOA. Having this option would allow me to put the annunciator anywhere on the panel I like. With the AOA integrated into the EFIS the annunciator seems relatively small and your eye needs to be down on the screen to see it rather than looking into your turn.

Not sure I am interpreting your comment correctly, but it is possible to drive more than one AFS AOA display from one set of ports and tubing. As mentioned in a previous post, I have the Pro display in my AFS efis, but prefer the glare shield display. AFS confirmed that I can tee into the existing tubes to drive a second display.

Jim Berry
RV-10
 
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