AOA

[Kai]

Mark’s latest safety posting:

Now I am confused (nothing to worry about- it happens every now and then).

A while back we had a few isolated cases in this country with people falling out of the sky, alas some fatal, although none Sonex. Since those dangerous LSA’s and the maniacs flying them are always in our authorities’ focus, the discussion about an approved mandatory audio stall warning device installation at least à la the ‘Cessna Switch’, in all LSA’s came up. It went so far that I had to get in touch with Sonex Tech with an inquiry about the installation of such a device in the Sonex/Waiex range.

Let it be said that I persoally hated the idea. Having all and sundry throttle jockeys hacking away at their wing leading edges for openings to fit the contraption, not to mention suddenly having som 400 aspiring test pilots falling out of the sky, was certainly less of a temptation.

To nobody’s particular surprise and my intense relief the answer came back that sorry, we can’t help, no research data available, no test installation completed, do not open up/puncture the wing structure- especially not the wing leading edge, etc, etc. Which all was what I wanted to hear.

BUT
Now Mark writes something along the lines of:……. This reinforces the need for all builders of homebuilt aircraft to install an AOA device, preferably with an acoustic signal…….

That’s news! Is this the new Sonex policy?

If so- is there anything available from Sonex, i.e. tests, recommendations, installation, equipment??

Thanks
Kai

[GraemeSmith]

I don't think I was around to hear that.

Things change. The FAA started actively promoting AOA installations for GA in 2015:

https://www.faa.gov/newsroom/faa-and-ga ... e-campaign.

And the planes are EXPERIMENTAL - meaning you can buy any of the products now on the market and try them yourself (or choose not to). Many of the EFIS vendors are now including AOA sensing built into their pitots. You can make your own to either work with your EFIS or even use a simple pressure gauge and a couple of tubes and calibrate it to create a "Lift Reserve Indicator" which is a form of AoA.

Heck even the quite old MGL ENIGMA will generate a "virtual" AoA without a probe after you fly it through a calibration routine.

Have at it and find out what the many vendors are offering. But don't beat on Mark and Sonex - IMHO that's not fair.

[Sonex1517]

The Sonex Builders and Pilots Foundation has an article on building your own LRI. I have one in my Sonex and it is a great tool for reference.

https://img1.wsimg.com/blobby/go/e83c7c ... 4222140376

[karmarepair]

Mark’s latest safety posting:
<snipped - RRY>
BUT
Now Mark writes something along the lines of:……. This reinforces the need for all builders of homebuilt aircraft to install an AOA device, preferably with an acoustic signal…….

That’s news! Is this the new Sonex policy?

I didn't read Mark's message that way.

It felt like a bit of reaction to Graeme's work on accidents and incidents, which I at least found a little dis-heartening. I saw Mark opening up a dialog, and engaging with one of the Homebuilt world's most studious and careful compiler of accident statistics. My take aways:

1. Sonex accident rates are roughly in line with other experimentals.
2. Experimental hours flown are going up, and the accident rate is going down.
3. We as a community can still do better, and AOA indication is one of the things EAA is looking at, in an industry working group, which Sonex is a part of.

AOA indication has been a feature of general aviation for a LONG time. The vane type sensors were invented in the 1940s. Reed type stall horns have been installed on every Cessna 100 series since, what, the 1970's? But even these simple AOA indicators ("Idiot Lights" rather than gauges) are rare in homebuilts, including Sonex, even though Tony Bingelis described how to do it back in the 1980's (https://www.eaa.org/eaa/aircraft-buildi ... ng-devices?), and there have been several articles in Sport Aviation and Kitplanes since then. I, for one, think we can do better, and it sounds like Sonex feels that way too.

That alone is not going to make Experimental aviation as safe as walking to the corner mailbox (I wish we had a better system for transition training, but I know that various people are working on that issue), but it's a step.

As to myself, the next time I fly the aero club's Cherokee, we are going to practice engine out during climb scenarios, by establishing VsubY climb, and then pulling power, and pitching down to establish VsubG. I'm also going to see if I can arrange some instruction in a local low wing LSA, and practice the same maneuvers.

[Kai]

No,

No beating on Graeme or Sonex intended!

Our predicament was indeed before 2015. The issue was that should one decide to install a stall warnng or AOA device, it should be something that Sonex had tried out and tested. Our national CAA was horrified at the thought of self proclaimed test pilots scooting around and testing either something they had dreamed up themselves, or storebought something that they thought looked good. Since this was going to be mandatory safety equipment, what they wanted was something that was developed and tested by a reputable manufacturer for the specific aircraft.

The idea of a RLI of course came up- however: it is not acoustic, which was an absolute requirement. ASAS had a spoon operated switch in their program intended for Vans aircraft, which looked promising. However, Sonex had (at least back then) no experience with it and could consequently offer no installation advice.

I would be very interested if something was coming along in the Sonex pipeline.

Thx
Kai

[SonexFactoryTech]

To nobody’s particular surprise the answer came back that sorry, we can’t help, no research data available, no test installation completed, do not open up/puncture the wing structure- especially not the wing leading edge, etc, etc. Which all was what we wanted to hear.

The specific question Kai asked of us on October 23, 2015 and our specific answer is here:

Kai:
"The AD will require at least the installation of an inexpensive audio stall warning system (not necessarily an AOA). The question is if Sonex has any experience with such systems- any recommendations, operational and installation?"

Sonex Aircraft Tech Support:
"We do not have any direct experience here at Sonex with any sort of stall warning system. However there may be some experience within the Sonex builder community. You may want to post the question on the builder forums at www.sonexbuilders.net and see what kind of response you get there."

I feel the actual exchange is somewhat different than what is portrayed in Kai's post.

We had tested an audible stall warning system that never came to fruition. My personal airplane was fitted with an LRI AOA (non-audible) from its very first flight in 2004. I spoke of it positively at every builder workshop. I spoke of it positively at every AirVenture forum I delivered. I spoke of it positively in every one-on-one conversation I've had with builders when the topic came up. We have NEVER discouraged the use of AOA instruments but we will NEVER offer specific advice on third-party products for which we have no experience. We will offer specific advice against doing things that may compromise the structure and safety of the airframe. For instance, cutting out the leading edge anywhere but between the most outboard ribs is ALWAYS discouraged for any reason, even the installation of an AOA/Stall warning system.

Use the information provided on this forum with caution, particularly when it invokes an indirect quote of what "Sonex" said.

Sonex Aircraft Tech Support

[DCASonex]

Since most all of us wear some form of headset when flying, any auditory alert need to be made through the audio panel and to override any other input. personally I would prefer an nice bright light to any audio alert, but currently only have the gauge on my LRI.

David A.

[Scott Todd]

Lets stir the pot a bit. There is nothing wrong with using AOA. Many people like them and think they help in some way. But lets face it, most of the airplanes out there don't have one. There is a simple alternative already built into the Sonex family of airplanes. LOOK OUT THE WINDOW. Try practicing engine outs and don't let the nose go above the horizon. I've been teaching this for nearly 30 years. Feel the stick force. Practice, practice, practice. If it ever quits, LOOK OUT THE WINDOW. If the nose doesn't go above the horizon, it won't stall. I know, what about turning? Well in those shallow turns, which you should be shallow in an emergency, the nose STILL shouldn't go above the horizon.

Now that I've calmed down...In a well maintained airplane with simple systems, like a Sonex, if it quits, its something bad. They never quit at several thousand feet, and if it does, run the checklist. They mostly quit when you are low. Don't they Lou? Most likely you won't have time to run the emergency checklist, put the map away, or even tighten the seat belt. You shouldn't be distracted by ANYTHING in the cockpit. You need to immediately focus on flying the airplane to that clearing or road. It may not be the best glide speed but with a little practice, it will be close and you won't stall it. I like to teach the nose NEVER goes above the horizon unless in the final flare. Aerobatics or playing is different.

There will be haters but don't hate until you go out and try it. Just don't let the nose go above the horizon. It works.

[pappas]

I agree with Scott. My trouble started at 3500 MSL, which is about 2400 AGL in that area of the desert. Still, my final touchdown was between 6 and 7 miles away from the point I turned towards my intended landing area and I was trying to burn off altitude by slipping pretty hard at the end.

I reviewed the flight data from the Dynon and I did not maintain a constant max glide speed. (I wonder if I was more nervous than I remember?) Nah!... Probably could have made over 7 miles altogether if I needed to and was more attentive to my airspeed.

Keeping the nose below the horizon is really good advice. I also like to look at the wingtips. As long as they are flat with the horizon, I am at pretty close to best glide.

[Kai]

Regarding the Sonex Factory Tech posting above- right on the button and I can offer no argument! I have neither any wish nor intent to enter any sort of discussion with either them or the rest of the staff. They have always provided the help and assistance I sought to my full satisfaction, which I hope will remain so.

However, our predicament back in ‘14/‘15 was, that the Dept of Transportation controlled CAA, more or less demanded an immediate mandatory installation of a ‘fit and forget’ acoustic AOA (or, more precisely, at least an acoustic stall warning device) in all operational LSA’s. Something the airplane manufacturer had tested, knew would work, and could recommend. And, mind you, absolutely not anything found on builder’s networks.

Now, there are seven flying Sonexes in this country (not a lot). All 7 owners, who had flown their aircraft successfully and without the slightest difficulty for years by looking out of the window every now and then, heaved a sigh of relief when it became clear that Sonex as a manufacturer did not have anything finished, tested, and recommended to offer- which meant that we 7 were let off the hook as the airplanes were all built according to a loophole (oversight?) in our national LSA regulations- the 51% rule, and were consequently excempt from anything mandatory. None of us had the slightest interest in starting private development work- which by the way and as mentioned previously, the CAA would not allow.

So, our Sonex SW/AOA problem went away, at least for those already on the register- sort of. For what then happened was that the CAA (always heavily influenced by what happens in the US) rewrote the regulations which they dumped on our heads: all LSA’s, either assembled by manufacturer or homebuilder, to be granted a permit to fly after May 1, 2016, now must have this confounded device. If the finished factory built airplane, or the construction drawings for that matter, do not include this SW/AOA thing: sorry- no permit! To put it carefully, the admission of new LSA’s has dropped significantly since then.

Hence my interest in anything Sonex has, or is planning to develop. The ways of official bodies are indeed not always the easiest to comprehend.

Thx
Kai