What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

AOA

olyolson

Well Known Member
Friend
Thinking about adding AOA in my RV-8. I have an AFS 5500 touchscreen with the Skyview network and looks like the Dynon heated AOA pItot tube would work with a fairly easy install. I have the SV 201 Adhars so it would be easy running an extra pitot line from the tube to the adhars.

BUT- the Dynon heated AOA probe is $435 plus connectors etc. then add on whatever the tone generators would cost. Rob from AFS says Vac?s tone generator won?t work with AFS, however, AFS is working on a tone generator but in any case it will require a flap position sensor or flap switch neither of which I have. My flaps are activated by the small toggle switch on the Infinity stick grip.

So if I don?t want to wait, my question to the brain trust is what system would work if all I want is the aural tone like Vac?s tone generator provides for AOA. I don?t really need the visual AOA indicator on the EFIS since I envision only using it in the pattern or while maneuvering while looking outside. I liked the AOA audio in the A-10 I used to fly in the 80s and it sounded just like Vac?s system.

Any suggestions?
 
I have been following Vac's website and his YouTube videos.

Saw you join his forum a few days ago.

I would like to suggest that you ask if you can get a 2nd generation beta unit to help the organization collect test data. I know you have the flying skills necessary.

My RV-8 left wing has a Garmin AOA probe and tubing to add the FlyOnSpeed.org unit when the airplane is done.

Since we have know each other for several years, I would be willing to do the solder and electronic assembly for you if you want to go the OnSpeed.org route.
 
Thinking about adding AOA in my RV-8. I have an AFS 5500 touchscreen with the Skyview network and looks like the Dynon heated AOA pItot tube would work with a fairly easy install. I have the SV 201 Adhars so it would be easy running an extra pitot line from the tube to the adhars.

BUT- the Dynon heated AOA probe is $435 plus connectors etc. then add on whatever the tone generators would cost. Rob from AFS says Vac’s tone generator won’t work with AFS, however, AFS is working on a tone generator but in any case it will require a flap position sensor or flap switch neither of which I have. My flaps are activated by the small toggle switch on the Infinity stick grip.

So if I don’t want to wait, my question to the brain trust is what system would work if all I want is the aural tone like Vac’s tone generator provides for AOA. I don’t really need the visual AOA indicator on the EFIS since I envision only using it in the pattern or while maneuvering while looking outside. I liked the AOA audio in the A-10 I used to fly in the 80s and it sounded just like Vac’s system.

Any suggestions?

I'm kind of in the same boat as you are regarding the AOA, I was just about to place the order. I emailed Vac for advice, waiting on a reply.

I have a Dynon FlightDek180 so installing the Dynon heated tube and adding the GEN1 would seem to work but I'm not sure. I also saw the GEN2 installed on an inspection plate and thought that will save the hassle of feeding another 1/4" tube from the wing to the panel for the AOA, but it's not heated.

Have you thought about how you're going to get that extra tube over there?
 
The AFS EFIS and our stand alone AOA Pro and AOA Sport are designed to have two separate AOA databases. When you put the flaps down you change the airfoil shape and that will change the stalling, approach and L/D max AOA values.

If you don't install a flap sensor it will just use the same database for flaps and and down.

Rob Hickman
Advanced Flight Systems
 
Timeline?

Rob,
Any idea of a timeline for when Ken will be getting an audible tone output similar to ON SPEED enabled on the 5600T units. Since there is an "Angle-Angle-Push" alert already in existence, moving from that to a tone would be very nice.

Thanks for your great products and fantastic customer support!
 
It is near the top of the software list, before Sun-n-Fun

Rob Hickman
Advanced Flight Systems / Dynon Avionics
 
Outstanding!

Looking forward to that update! That will be a really nice "addition" to the system and safety.
Having everything internal (software wise) using already existing wiring to the comm panel keeps it simple and clean.
 
Rob,

An experimental test pilot buddy of mine has an RV-4 with a sport system. We are going to strap a Gen 2 V3 box in the airplane and test the feasibility of using AFS-style wing ports as the coefficient of pressure source for V3 as part of beta test. We'll instrument the airplane with a calibrated test boom; so we'd be happy to test new software/tone logic in the sport simultaneously. I've been running the Dynon-based Gen 1 system (tone generator only) in my test airplane simultaneously with Gen 2 (full up AOA computer with IMU); so we should be able to do the same thing with an AFS system and a V3 box (i.e., allow the pilot to listen to simultaneous audio signals for test and evaluation). We record all data (pressure sensors, IMU, boom and EFIS) simultaneously to the V3 SD card for analysis--we could probably figure out a way to shoehorn sport data in there as well. We use GPS time to synchronize data. Data is downloaded from V3 wirelessly post-flight.

We've found one aircraft curve is sufficient for the RV-4 equipped with a Dynon sensor for all flap positions, but the software is capable of accommodating multiple curves. We normally run three (one for flaps zero, flaps 20 and flaps 40) for test purposes to stress the software. We are using GPS speed runs to derive curves and initial set points based on physics/aero using Dr. Rogers technique spelled out in DOT/FAA/TC-18/7. We can determine the optimum number of curves required analyzing the GPS speed runs in different flap configurations. Lenny is working on a wifi interface to allow real-time adjustment of settings in flight via iPhone. This will help with fine tuning set points as well as allowing the pilot to adjust damping for test purposes.

We'd be happy to collaborate or assist. We are a non-profit, open source group of volunteers trying to bring some stuff that worked well in the military into the EAB/GA world...If we can help one pilot avoid an unintentional loss-of-control situation, it'll have been a good effort.

Hardware schematics and software are available on our website (flyonspeed.org) and GitHub. Obviously, we are biased towards accurate, performance based AOA/energy cues that can be used as a primary eyes out reference for maneuvering and approach and landing. We just started experimenting with 3D (stereo) audio to use the tone to also provide a yaw cue (using data from the on-board accelerometers), which is kind of nifty. Uses either a stereo input in the ICS or bluetooths to a stereo headset in airplanes without stereo ICS capability. One of the primary objectives of beta test will be to determine the feasibility of fully automating the calibration process.

Oly,

If you have a wingman with a soldering iron, we have a couple of extra boards laying around. Parts list is on the website and we'll help with tech support. Drop another line if you gents want to give it a go. Gen 2 V3 works well with the Dynon probe. The number of curves you need depends on airfoil, flap configuration and probe location. Since the -8 has essentially the same wing as the -4, likely it will look very similar. Regardless, you still need a flap position sensor for the various tone set-points--very easy to add one to the RV-8. Without one, it's sort of practical to optimize ONSPEED cuing for Flaps 40 and start of the flaps tone with L/Dmax; but I don't recommend that. I've got a blog post up that explains these plots if you're interested in the aero or how the software uses the math. We'll be starting Garmin probe testing next week. Rob is spot on with L/Dmax shifting as you deploy flaps; but effectively it just slides into the ONSPEED band (which is the way it worked in the jet BTW--we just added the feature for straight wing props to the Flaps 0 logic so you can hear Vy, max range glide and max endure). That's why the caveman simple "turn now/set lift flaps/maintain ONSPEED" plan works when the engine quits and you have to BFM the runway: https://youtu.be/trnwzBYvBQg

Here's what the three curves look like when they are plotted together. The fact that they largely overlay each other means the airplane is a candidate for a single curve calibration:

3c039a_19e6821f451f4818882dfdaecbf498f1~mv2.jpg


You can collapse these curves into a single one that's still very accurate (that's indicated by the high R2 value under the equation):

3c039a_df4b93f664d842ad8e972266960f1cca~mv2.jpg


For the RV-10, however, you can clearly see that a single curve isn't gonna' cut it:

3c039a_7dee30ac2a69430aa771bb000d2daf66~mv2.png


If you do decide to build a system, once it's in, it would be fun to see how it works in a one-circle fight :D

Alternatively, we are finishing up production of 25 shipsets of Gen 2 V3 (box + harness) for beta test. After we finish designing the beta experiments, we may have a few left over for distribution--I'll go giant voice on the safety page like we did for Gen 1 if/when that happens to coordinate with folks in the VAF family that want to help out. Also, the basic USAF tone logic is available in the Alpha Systems systems.

v/r,

Vac
 
Last edited:
Mike, spent many hours last night reading and studying every post here, every blog post on ON SPEED, every forum post, every YouTube video :) .....I think I'm good now and see where the communication breakdown was.

Anyway I left a comment on your blog and I think I emailed you also about it. I'm ready to help build those boxes for your BETA testers if you need that assistance and also eager to build one for myself too.

I'll call you before noon today.

Carlos
 
Rob,

An experimental test pilot buddy of mine has an RV-4 with a sport system. We are going to strap a Gen 2 V3 box in the airplane and test the feasibility of using AFS-style wing ports as the coefficient of pressure source for V3 as part of beta test. We'll instrument the airplane with a calibrated test boom; so we'd be happy to test new software/tone logic in the sport simultaneously. I've been running the Dynon-based Gen 1 system (tone generator only) in my test airplane simultaneously with Gen 2 (full up AOA computer with IMU); so we should be able to do the same thing with an AFS system and a V3 box (i.e., allow the pilot to listen to simultaneous audio signals for test and evaluation). We record all data (pressure sensors, IMU, boom and EFIS) simultaneously to the V3 SD card for analysis--we could probably figure out a way to shoehorn sport data in there as well. We use GPS time to synchronize data. Data is downloaded from V3 wirelessly post-flight.

We've found one aircraft curve is sufficient for the RV-4 equipped with a Dynon sensor for all flap positions, but the software is capable of accommodating multiple curves. We normally run three (one for flaps zero, flaps 20 and flaps 40) for test purposes to stress the software. We are using GPS speed runs to derive curves and initial set points based on physics/aero using Dr. Rogers technique spelled out in DOT/FAA/TC-18/7. We can determine the optimum number of curves required analyzing the GPS speed runs in different flap configurations. Lenny is working on a wifi interface to allow real-time adjustment of settings in flight via iPhone. This will help with fine tuning set points as well as allowing the pilot to adjust damping for test purposes.

We'd be happy to collaborate or assist. We are a non-profit, open source group of volunteers trying to bring some stuff that worked well in the military into the EAB/GA world...If we can help one pilot avoid an unintentional loss-of-control situation, it'll have been a good effort.

Hardware schematics and software are available on our website (flyonspeed.org) and GitHub. Obviously, we are biased towards accurate, performance based AOA/energy cues that can be used as a primary eyes out reference for maneuvering and approach and landing. We just started experimenting with 3D (stereo) audio to use the tone to also provide a yaw cue (using data from the on-board accelerometers), which is kind of nifty. Uses either a stereo input in the ICS or bluetooths to a stereo headset in airplanes without stereo ICS capability. One of the primary objectives of beta test will be to determine the feasibility of fully automating the calibration process.

Oly,

If you have a wingman with a soldering iron, we have a couple of extra boards laying around. Parts list is on the website and we'll help with tech support. Drop another line if you gents want to give it a go. Gen 2 V3 works well with the Dynon probe. The number of curves you need depends on airfoil, flap configuration and probe location. Since the -8 has essentially the same wing as the -4, likely it will look very similar. Regardless, you still need a flap position sensor for the various tone set-points--very easy to add one to the RV-8. Without one, it's sort of practical to optimize ONSPEED cuing for Flaps 40 and start of the flaps tone with L/Dmax; but I don't recommend that. I've got a blog post up that explains these plots if you're interested in the aero or how the software uses the math. We'll be starting Garmin probe testing next week. Rob is spot on with L/Dmax shifting as you deploy flaps; but effectively it just slides into the ONSPEED band (which is the way it worked in the jet BTW--we just added the feature for straight wing props to the Flaps 0 logic so you can hear Vy, max range glide and max endure). That's why the caveman simple "turn now/set lift flaps/maintain ONSPEED" plan works when the engine quits and you have to BFM the runway: https://youtu.be/trnwzBYvBQg

Here's what the three curves look like when they are plotted together. The fact that they largely overlay each other means the airplane is a candidate for a single curve calibration:

3c039a_19e6821f451f4818882dfdaecbf498f1~mv2.jpg


You can collapse these curves into a single one that's still very accurate (that's indicated by the high R2 value under the equation):

3c039a_df4b93f664d842ad8e972266960f1cca~mv2.jpg


For the RV-10, however, you can clearly see that a single curve isn't gonna' cut it:

3c039a_7dee30ac2a69430aa771bb000d2daf66~mv2.png


If you do decide to build a system, once it's in, it would be fun to see how it works in a one-circle fight :D

Alternatively, we are finishing up production of 25 shipsets of Gen 2 V3 (box + harness) for beta test. After we finish designing the beta experiments, we may have a few left over for distribution--I'll go giant voice on the safety page like we did for Gen 1 if/when that happens to coordinate with folks in the VAF family that want to help out. Also, the basic USAF tone logic is available in the Alpha Systems systems.

v/r,

Vac

For the life of me I don't know why Dynon hasn't implemented flap position inputs into its AOA on Skyview. As this post shows, it *may* be okay to use a single curve for some planes, but not others. Several of us have been asking for this for years now, to no avail. I don't get it.
 
After research and discussing a solution with AFS and Mike Vaccaro it looks like the easiest solution to work with my touchscreen AFS 5500 & the Skyview network is below:

- Replace my heated pitot tube with the Dynon Pitot/AOA probe and install the heater/controller. Use existing wiring for the new pitot tube heater.

- Run an additional pitot line from the AOA port on the new probe all the way back to the Adhars. No additional wiring needed because the Adhars is already wired to the EFIS and working. When the EFIS senses the AOA it will display the AOA bracket in the upper left.

- Install a flap position sensor and wire into the EFIS to display flap position and allow AOA calibration points with the normal flaps down landing position and flaps up.

- AFS is working on a tone generator similar to Vac’s that will allow selection of this or the current “Angle-Angle-Push” audio tone.

- Complete the recommended AFS AOA calibration procedure

I think that covers the installation I’ve discussed with Rob at AFS. I could install Vac’s system but the AFS solution seems easier to implement without having to build the AOA computer box and I would still need the AOA probe anyway.

So if anyone has the new Dynon Pitot/AOA probe or the Ray Allen POS-12 flap position sensor not being used let me know. I am debating whether to start purchasing components or just leave everything as is. I would like to have AOA but don’t relish the cost or extra work & down time to do it.
 
Last edited:
So if anyone has the new Dynon Pitot/AOA probe or the Ray Allen POS-12 flap position sensor not being used let me know.

The Ray Allen POS-12 is the flap sensor needed for the RV-8? I have an order pending with Aircraft Spruce so I'd like to add it if that's the size I'll need too.
 
After research and discussing a solution with AFS and Mike Vaccaro it looks like the easiest solution to work with my touchscreen AFS 5500 & the Skyview network is below:

- Replace my heated pitot tube with the Dynon Pitot/AOA probe and install the heater/controller. Use existing wiring for the new pitot tube heater.

- Run an additional pitot line from the AOA port on the new probe all the way back to the Adhars. No additional wiring needed because the Adhars is already wired to the EFIS and working. When the EFIS senses the AOA it will display the AOA bracket in the upper left.

- Install a flap position sensor and wire into the EFIS to display flap position and allow AOA calibration points with the normal flaps down landing position and flaps up.

- AFS is working on a tone generator similar to Vac?s that will allow selection of this or the current ?Angle-Angle-Push? audio tone.

- Complete the recommended AFS AOA calibration procedure

I think that covers the installation I?ve discussed with Rob at AFS. I could install Vac?s system but the AFS solution seems easier to implement without having to build the AOA computer box and I would still need the AOA probe anyway.

So if anyone has the new Dynon Pitot/AOA probe or the Ray Allen POS-12 flap position sensor not being used let me know. I am debating whether to start purchasing components or just leave everything as is. I would like to have AOA but don?t relish the cost or extra work & down time to do it.

Have you attacked these installations yet? I'm going to install the Dynon heated AOA pitot this weekend and have to fish the extra 1/4" tube through the wing too. Also going to install the flap position sensor. Looking for suggestions from anyone who's done it recently.
 
Carlos,

There is actually a Van's drawing for the Ray Allen flap position sensor in the RV-8. I used the same sensor in the -4 (which might be the only airplane with Armstrong flaps and a flap position sensor!). I used an adel clamp and digital welding rod ;):

3c039a_2a9b697830ec449fb3e4c62c801e5c5e~mv2.png


3c039a_a330a1af2d094f14b23214c374acdc46~mv2.png


Oly,

The AFS tone will be similar, but will be based on a .wav file which is not the same technology that we are using in the ONSPEED experiment. Our system works like the USAF systems: it actually computes AOA using pressure and IMU inputs, and then generates a tone based on actual AOA and rate of change. We've designed it for high G onset rates (which equates to good damping in turbulent conditions as well as good performance during BFM) and recently cracked the nut on high-alpha performance post-stall (which can be used to generate a recovery display). We are also incorporating OWS (overload warning logic) and airspeed warning as well so we can essentially "paint" the entire envelope using aural logic (while accommodating symmetric and asymmetric G loading). I'm not sure how well a .wav "look up table" AOA logic will work in a maneuvering environment. It may work great, but we won't know until it's tested. AFS has boatloads of experience with AOA, so we are looking forward to seeing what they come up with!

v/r,

Vac
 
Last edited:
Carlos,

There is actually a Van's drawing for the Ray Allen flap position sensor in the RV-8. I used the same sensor in the -4 (which might be the only airplane with Armstrong flaps and a flap position sensor!):

Oly,

The AFS tone will be similar, but will be based on a .wav file which is not the same technology that we are using in the ONSPEED experiment. Our system works like the USAF systems: it actually computes AOA using pressure and IMU inputs, and then generates a tone based on actual AOA and rate of change. We've designed it for high G onset rates (which equates to good damping in turbulent conditions as well as during BFM) and recently cracked the nut on high-alpha performance post-stall (which can be used to generate a recovery display). We are also incorporating OWS (overload warning logic) and airspeed warning as well so we can essentially "paint" the entire envelope using aural logic and accommodate symmetric and asymmetric G loading. I'm not sure how well a .wav "look up table" AOA logic will work in a maneuvering environment. It may work great, but we won't know until it's tested. AFS has boatloads of experience with AOA, so we are looking forward to seeing what they come up with!

v/r,

Vac

Plus the yaw angle where the pitot info ends and the internal gyros take over, that's impressive GOT magic dragon stuff there !

Thanks Vac, those pictures are exactly what I needed to get an idea. I'll also go search for the Van's drawings.
 
AOA Display

-8A. I'm a biased former Navy carrier guy so I installed an AFS AOA system on my initial 3500, upgraded to 4500. No issues with the operation. However, one big issue with my thought/decision process.

I elected to have the display only on the AFS EFIS screen. Should have installed an AOA indicator on the glareshield to be visible throughout the landing/maneuvering envelope - just like the Navy proved eons ago. Have to refocus from the runway/outside to inside the cockpit to see the display. Not difficult or dangerous - just somewhat disruptive.
 
For those who have installed the Flap Position Sensor already, did you verify if you get the full 5 ohm difference during operation or even if it needs it? After 3 days breaking my back installing it I finally have it to where I get a full extension of the sensor with flaps extended but when they're fully retracted I still have a little play left.

I'm getting the following readings on the green and blue wires :

Fully extended flaps 4.97 ohms
20 degree flaps 2.7ohms
Fully retracted flaps 1.25 ohms

Since I don't know how this is measured in the system or when calibrating, would these values seem correct?


Carlos,
There is actually a Van's drawing for the Ray Allen flap position sensor in the RV-8. I used the same sensor in the -4 (which might be the only airplane with Armstrong flaps and a flap position sensor!). I used an adel clamp and digital welding rod ;):
Vac

Never found the drawings on the Van's plans but your pictures were helpful. Based on the above resistance values, will it work with the ON SPEED box?
 
Carlos,

You don't need to have full travel of the flap position sensor (potentiometer). It's actually better to leave a little play on both ends.

The values you mentioned will work with the OnSpeed Gen 2 box. You can calibrate each flap position to any potentiometer value, and use up to 5 positions.

Lenny


Based on the above resistance values, will it work with the ON SPEED box?
 
Last edited:
Carlos,

You don't need to have full travel of the flap position sensor (potentiometer). It's actually better leave a little play on both ends.

The values you mentioned will work with the OnSpeed Gen 2 box. You can calibrate each flap position to any potentiometer value, and use up to 5 positions.

Lenny

Perfect. Thanks Lenny !
 
Hi,
Sent a lot of what I considered relevant and technical queries which included many of these items to Dynon/AFS.
Haven't heard a dickie bird since so they obviously aren't actively promoting the Sport or Pro very disappointing.
I am an amateur in this field so I asked probably what are silly questions to an expert, but still expected a reply in a reasonable timescale.
It has also cost me money as I was waiting for a reply prior to buying one on forum and opportunity lost.
 
Six Months On. Status Update?

Rob,
Checking in to see if there's any noteworthy update on Ken getting the software modified to give out the AOA tones?
I, and I'm sure many more, hope you and yours are fairing well during the current "incarceration" situation.
Thanks for a great product and superb support.
 
AOA on Glareshiel

Just to highlight what was mentioned at least once before - There is a distinct advantage to having an AOA indicator on the glareshield vs on the glass panel or audio tones. It is more visable at critical times when you are heads up.
I have the Garmin set up with G3X but never look at the option on the glass panel. Thought it was just an extra bell or whistle but it is GREAT.
 
...There is a distinct advantage to having an AOA indicator on the glareshield vs on the glass panel or audio tones. It is more visable at critical times when you are heads up.

What can be better at "critical times" when you're looking outside than audio? The OnSpeed system not only gives you AOA audio but it also gives you "yaw audio" so you know when you need to "step on the ball", or in the OnSpeed system "step on the tone". You get all this without having to look at the panel, or the dash, or even look toward the front, so you get all tones even looking to the side in a turn.
 
Does anyone know if something like ONSPEED is coming to Dynon as well? I?d love to hear it on my Skyview.

The Skyview has the AOA built in. It requires displaying it on the screen. Then just follow the calibration as outlined in the manual and turn on the audible in the sound setup. Gives a beep over the headset increasing in frequency the closer you get to stall. The icon is in a poor location for viewing on the display but having the audible is great. Used it on my old Classic and now on my new HDX.
 
The Skyview has the AOA built in. It requires displaying it on the screen. Then just follow the calibration as outlined in the manual and turn on the audible in the sound setup. Gives a beep over the headset increasing in frequency the closer you get to stall. The icon is in a poor location for viewing on the display but having the audible is great. Used it on my old Classic and now on my new HDX.

The Dynon AOA doesn't come close to the OnSpeed system. Do a search and read where Vac explains the difference, it might even be on this thread somewhere on a previous post.
 
The Dynon AOA doesn't come close to the OnSpeed system. Do a search and read where Vac explains the difference, it might even be on this thread somewhere on a previous post.

I was not making a comparison...just letting the poster know that audible AOA annunciation was already on the Skyview. The Skyview signal can also be input to the Gen1 OnSpeed system if someone wanted to use that.

I have seen the videos and posts. I know OnSpeed is a great system with much more functionality. Last time I checked it was something you need to build and program yourself which is not for someone as computer/programming illiterate as myself.:confused:
 
AFS is not the same as Dynon

I know AFS is a sub-company of Dynon. However, they are not the same systems. What Skyview has is not necessarily in the AFS EFIS units.
Ken - software engineer at AFS - has been working on software specific to the AFS units. Earlier, Rob indicated they were hoping to get the audible outputs developed for Sun & Fun. Since that show didn't happen but I'm wondering if AFS has made any progress on the audible AOA programming.
 
FWIW; I absolutely LOVE the SkyView AOA audio tones. Having some kind of display is great, but not optimum for me. The last thing I want to do when approaching critical AOA is look at some "indicator" and not keep my eyes outside the cockpit. That is where audible tones are so handy.

As an example, I don't even have AOA displayed on my SkyView system, I just use the tones. To give you an idea, I have no clue at what IAS my wheels touch the runway. They touch when the tone goes from beeping to solid. Has worked superbly for the last 600+ hrs. YMMV

:cool:
 
Last edited:
Audio and Video

Foremost, anyone that is using any AOA system (Dynon, etc.) and has developed a good feel for audio cues--that's a GREAT technique for flying AOA. Cues will vary by system and calibration. Many EFIS have the capability to display AOA or generate some sort of AOA/progressive stall warning tone, and we (the ONSPEED team) would highly encourage folks to install the appropriate sensor and try to utilize that capability in accordance with the manufacturer's instructions.

It's important to understand that even with the same system, specific cues don't translate from one airplane to another. Cues depend on calibration (just like an EAB pitot/static system, i.e., the IAS in my RV-4 don't apply in another RV-4). Even the commercially available AOA systems depend on calibration. Now, if someone was to certify an AOA installation (much like a certified pitot/static system), then specific cues would be the same from airplane to airplane, just like they were in the military. I only point this out for folks that have transitioned to EAB from the certified world where stuff just works, because it has to (to be certified, that is...at least that's the hypothesis).

In the military, we developed JHMICS (joint helmet mounted cuing system) to put the HUD and 3d audio wherever the pilot was looking and listening. While it would be excellent to have that in the mighty RV-4, we realized that was probably gonna' be cost prohibitive ;). So, in our AOA project we started out with the audio component. Recently, I caved to visual display pressure; and with Vern Little's help, we developed an inexpensive "energy" display that combines AOA with airspeed and G (the three things you need to know to understand energy state, provided the ground isn't in the way). While I think a simple tone pattern that tells you if energy is positive, neutral (ONSPEED) or negative is just about the simplest way to tell the pilot how much to "pull on the pole," I also get that some folks may prefer a visual display; so now we've got both in the ONSPEED system.

We've also learned that properly calibrating an AOA system that uses differential pressure isn't easy; and we want to accommodate all the different commercially available sensor configurations to generate AOA accurate to less than 1/2 degree that works well at high G onset rates (4G's/sec) and performs well under sustained G. I haven't seen any published accuracy numbers for commercially available systems, but the FAA did look at ten systems: http://www.tc.faa.gov/its/worldpac/techrpt/tc18-19.pdf

Since calibration isn't easy, we are currently working to develop a software "wizard" that takes care of that. Our other science project is to integrate the IMU in the system to provide sideslip correction for the AOA cue. Remains to be seen what we'll be able to accomplish...the reason we want all of this performance is so that pilots have the confidence to use AOA as a primary indication in the traffic pattern and, when appropriate, during maneuvering flight. We think that if pilots have a handle on AOA, side slip and energy, the odds of losing control unintentionally go way down.

Cheers,

Vac
 
Last edited:
VAC Your last post is EXCELLENT, especially the "Cues will vary by system and calibration". IMHO everyone contemplating an AOA system should read this post.

:cool:
 
B6476D99-459A-4232-884E-46561902A2CC.jpeg

With a glareshield display at eye level, you can combine other information. For example, this is a display I put together for aerobatic use. This one uses a conventional AOA indicator, but I will merge the OnSpeed energy display soon.

The combination of audio and visual feedback provides choice/redundancy. In this case, I can clip the display on my seat back for the GIB as well.

V
 
AFS Update in Testing

Spoke with AFS yesterday. Their software update containing the AOA audio tones is in the testing phase now. Not known when it will be rolled out, but they're aggressively testing to get it out soon.
Though not specified in our conversation, there are a lot of other software tweaks involved in this update too.
 
View attachment 209

With a glareshield display at eye level, you can combine other information. For example, this is a display I put together for aerobatic use. This one uses a conventional AOA indicator, but I will merge the OnSpeed energy display soon.

The combination of audio and visual feedback provides choice/redundancy. In this case, I can clip the display on my seat back for the GIB as well.

V

This display can also be used as a backup if you lose your glass panel.
 
VAC Your last post is EXCELLENT, especially the "Cues will vary by system and calibration". IMHO everyone contemplating an AOA system should read this post.

:cool:

+1. My concern about AOA in the past has always been about trust. If you are going to depend on it to perform a short field landing on a sandbar with a circling full slip max AOA approach, (aka carrier landing) we need to embrace standards of repeatability, accuracy and precision.

The certified world has figured this out, but what can we do for experimentals? I think that the OnSpeed approach (no pun intended) gives us all the tools to develop rigorous and transparent calibration procedures that we can trust. This is unique for every amateur-built airframe (and configuration).

Flying behind the proprietary and opaque OEM systems, calibrated by an inexperienced pilot flying a few stock manoeuvres always gives me the willies. I am not saying they don't provide the accuracy and precision we need, it is just that we have no way of knowing. Because of this uncertainty, we will always be inclined to 'add a few knots' just in case, and performance will suffer.

Oddly, we have panels full of indicators that we do not trust... that's why we do instrument scans. Want to slip? The ASI may read high or low by several knots. The heading indicator drifts, the altimeter setting may be wrong. The attitude indicator tumbles. The compass lies. We should have at least one critical instrument (AoA/energy) that speaks true. That is our mission!

If we prove the model, and the big avionics manufacturers embrace it, OnSpeed will go quietly in the night, having accomplished the goal of helping to make flying safer, more efficient, and more enjoyable.
 
We've also learned that properly calibrating an AOA system that uses differential pressure isn't easy; and we want to accommodate all the different commercially available sensor configurations to generate AOA accurate to less than 1/2 degree that works well at high G onset rates (4G's/sec) and performs well under sustained G.

Vac - is this mostly due to latency of the pressure changes in the line between the pitot tube and the pressure transducers? I suppose a sure-fire fix for this would require a transducer (or pair of them) built into the pitot tube mast mount for nearly instantaneous response - though this would need filtering for signal/noise ratio since you lose the volume-bottle effect of the long line. The trick then becomes balancing the filtering to accommodate rapid-onset without jumpy/jittery data.
 
Last edited:
We currently have a number of people flying our latest beta version of AF-5000 V16 software that has the AOA tones. You have the option to select: Tones, Tones + Voice, or Voice only.



Rob Hickman
Advanced Flight Systems
 
Hi Greg,

Ringing in the lines is certainly a factor as is dealing with a noisy signal; but it's more complicated than that. We are trying to accommodate multiple sensor configurations, and each one has different pressure characteristics. We are also using a multi-point calibration curve (which is required for accuracy) and can accommodate multiple calibration curves (up to five for various flap settings). And, we learned in our first generation experiment that just calibrating and understanding a commercial system can be difficult for the average pilot. Our current challenge is developing a wifi based calibration "wizard" that steps the pilot through calibration using basic maneuvers that are in any pilot's tool kit.

As Vern said, we also want our system to meet stringent performance criteria: accurate AOA computation (1/4 to 1/2 degree throughout the flight envelope); work at G onset rates up to 4G's per second, work under sustained G, work at high AOA (up to 45 degrees post stall) and, lastly, to correct for side slip. We think these capabilities are required to provide accurate and dependable performance cues to the pilot throughout the flight envelope and when the aerodynamic limit is exceeded (intentionally or otherwise). Those capabilities combined with a simple "fast, ONSPEED, slow" tone logic really simplify energy management. So far we're 4 for 5; and we are currently testing to see how well we are doing with meeting our objectives. Correcting for side slip (and automatic calibration) require integrating the on-board IMU, which we are currently working on. This requires lots of flight test, lots of data reduction and lots of engineering. Fortunately, we've got a great team of talented volunteers from the VAF family that give up a lot of free time to make this work; but since we've all got day jobs, we don't work uber fast :D

There is nothing cosmic about our hardware (details are on our website and GitHub site) other than the fact we are using accurate pressure sensors. Our hardware design objective is buildable with basic electronic skills and total cost of less than 300 bucks with an optional visual display. We hypothesize that our software could be adapted to any EFIS system with appropriate sensors. Our code is also available on GitHub. And, even though we're having this discussion in a "glass cockpit" area, the system is designed to work in any airplane--even one equipped with steam gauges.

Ultimately, we'd like to perhaps produce a kit or even a box already built at minimal cost (we're a non-profit group), but our priority right now is engineering and flight test. And, like Vern said, we're happy to collaborate with anyone that wants to adapt it. Sounds like AFS may be :). It will be cool to read flight test results!

Cheers,

Vac

Oh, the reason for all of the high G (and post stall) performance capability is not because we expect everyone to fly to envelope limits all of the time, but because all that capability means rock-solid performance during normal flight at 1 to 1.4 G's even under challenging conditions (turbulence, gusty winds, etc.)...
 
Last edited:
Spoke with AFS yesterday. Their software update containing the AOA audio tones is in the testing phase now. Not known when it will be rolled out, but they're aggressively testing to get it out soon.
Though not specified in our conversation, there are a lot of other software tweaks involved in this update too.
Thanks, that's good to hear. Did they happen to mention if they're doing an update for the standalone AoA Sport/Pro systems as well? Would probably mean a box or ROM swap, but I'd be interested.

Dave
 
Standalone AFS

Sorry, no there was no discussion about those systems. I have the Dynon AOA Pitot, feeding into my 5600T EFIS.
If the standalone units feed into your EFIS, where I imagine some processing is performed, the update may well support you in that the AOA data is resident in the EFIS and "should" be able to be used to generate the tones.
BUT, I am only theorizing. Rob Hickman is the definitive source for a 100% answer.
 
Back
Top