AOA

[lpaaruule]

I agree with the plan to keep the nose below the horizon. In an emergency hopefully a pilot would be intensely focused, maybe so much that an audible alarm would go unnoticed (I think that it where a stick shaker helps)

I wonder if distractions such as shown in this AvWeb video are more applicable to the use of an AoA indicator.

https://youtu.be/-2mzsjXn88Y

[jerryhain]

[quote="Scott Todd" 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.
[/quote]
I agree, with the sole exception being you have the altitude to do a 180 back to the runway, bank angle should be 45° plus or -5. Less than that you fly too far away and you may not get back to the runway, more than that you’re just giving up altitude.

[Scott Todd]

If you're turning back, you've decided you have the altitude and/or speed to make it. If you have the altitude, it will be a descending turn. If you have the speed, it should still be a descending turn. Either way, the nose shouldn't come above the horizon. If it does, you're too slow. I teach it all the time and the critical teaching point is to keep the nose below the horizon. As a teaching point, its about avoiding stall/spin. Some people, usually the STOL crowd learning back country and short unimproved strips, really master the turnback and we start to push the limits. This is where AOA helps. But the average reader here is a long way from this. Especially in a Sonex!

[rick9mjn]

to add my 2 cents...... about the using a AOA and doing the impossible turn. everyone should go for 2 glider flights and one of them being a rope break, and it being winter time in the US. another idea, is to a GOOGLE search on u tube for "glider rope break"
....good day.../ rick

[markschaible]

Hello All,

Great discussion on AOA and flying technique! I'm breaking from my norm in replying directly to this thread vs. to the Sonex posts section where I want to begin creating a permanent archive in the Sonex posts section on these topics so that folks can quickly see "what the factory says" beyond what's on our web site. We will write-up something on the topic of AOA to post to the Sonex section for that purpose. I do want to reply directly to this thread today in a more casual manner on a number of areas to keep the momentum of positive dialogue going!

Regarding AOA and stall warning devices, at the EAA Safety Committee we are at the very beginning stages of organizing a new outreach and education campaign to promote the wider use of AOA devices in EAB aircraft, and as I mentioned, we are advocating for devices with audible warnings because you *should* be looking out the window, especially in some of the most vulnerable scenarios in the traffic pattern. I also recall a conversation a few years ago about there being a number of loss of control accidents involving pilots practicing turns around a point.

There are a lot of great native solutions in most modern avionics packages nowadays, including our in-house favorite MGL Avionics, to add AOA capability to your aircraft, in many cases with the option for audible warnings. Admittedly, we haven't done much of anything with AOA at the Sonex factory because AOA pitot probes are really expensive, and we like the simple and inexpensive pitot-static probes that you can get from Aircraft Spruce. We do have a unique one-off pitot-static-AOA probe on "Sharky," our gray-colored SubSonex prototype with the shark mouth nose art. The probe is retractable to help avoid people spearing themselves on the nose cone mounted proboscis, and has ports for pitot and AOA with static holes on each side of the probe. We haven't even really done much with that, however, as it would be an expensive little bugger to produce and sell with the retractable feature. Hmm, maybe we should do a simpler non-retractable version suited for under-wing mounting as a new, inexpensive AeroConversions product -- literally just had that thought today, so don't start pressuring us for it yet -- there's never enough hours in the day!

As Kerry mentioned in his earlier post, we dabbled in stall warning/AOA warning devices probably about 10-15 years ago when AOA wasn't such a standard feature in avionics. We had a concept for a simple and tiny single port probe to put on the wing, connected to a little plastic box about the size of pack of cigarettes that took a 9 volt battery. It had a calibration button, and the concept was that it would give an LED light stall warning, and I think we were also thinking about an audible warning at that time as-well. That project hit a stop when we had trouble with the performance of the probe design and other, more pressing R&D and customer support priorities got in the way. I still think that concept is a great one, especially with the modern advances in bluetooth technology, and if produced inexpensively with a probe design that actually works, would be a fantastic low-cost retrofit for all kinds of homebuilt and ultralight aircraft, especially those that do not have avionics outfitted with native AOA capability. With the nightmare that is the electronics supply chain right now, don't hold your breath for anything along those lines to come from Sonex or AeroConversions any time soon, although it would be cool if we could eventually pick that project back-up. If someone wants to beat us to it, I won't be upset as I think it would be a great safety-enhancing product for sport aviation if done right.

I'm not sure if it was specifically mentioned in this thread, but I believe it was the general focus of the tech support conversations with Kai: the Van's Aircraft AOA port installation. This involves popping the mandrel out of a rivet in the top of the wing forward of the main wing spar and connecting your AOA air data port to the back side of that blind rivet. According to Van and his customers, it works great. The drawback in our assessment is that it requires cutting an inspection plate hole in the bottom of your leading edge skin, and for structural reasons we never recommend cutting holes in the D-tube section of the leading edge unless it's done in the outboard-most rib bays of the wing. I'm also not sure how they avoid creating a water trap in that installation with a downhill section of air data tubing -- I'll have to ask Van the next time I talk to him, or maybe some of you are familiar with the installation and can enlighten me and the group.

Of course, being homebuilt aircraft, any AOA or stall warning device, even those that include factory instructions or are otherwise "factory blessed" must be calibrated by the builder during the Phase I test flight -- there's pretty-much no getting around that, so don't expect your stall warning or AOA to be accurate on the first flights of your aircraft until you calibrate the system. That's an important point that it seems people don't always think of, and it's a great point to argue with those foreign agencies wanting "factory" AOA systems: These are not factory-built production aircraft, so no AOA system installation is going to come without customer flight testing & calibration, therefore ANY reputable AOA product on the market should be considered acceptable to foreign CAA's regardless of whether the aircraft designer has experience with them. Of course, that doesn't mean that foreign CAA's are going to accept the logic of that argument.

Also a great discussion in this thread about flying technique, although I wouldn't take the leap in logic to say that we shouldn't also be looking to develop, improve and install AOA devices as another tool to help improve safety. As always, Paul Bertorelli is spot-on with his video about flying and avoiding distractions in the pattern. Incidentally, we had the unique opportunity at Sonex to name one of the roads in our neighborhood, and we named it Red Tail Way because of the family of red tail hawks that live just on the other side of our airport gate on Hughes Road. One of them has even soared with the factory Xenos motorglider a few times.

If you subscribe to Kitplanes Magazine's Homebuilders Portal newsletter, you may have seen that they reposted this great article about forced landings during traffic pattern operations yesterday: https://www.kitplanes.com/the-dawn-patrol-26/
Although a Sonex doesn't have the challenging aerodynamics of these WWI replica homebuilts, there are some really great lessons to be learned in this article. I have to admit to becoming a member of the "Combine Service" myself, as I had a forced landing into a cornfield in the Rotax 447 powered ultralight that I own last year. I had a partial (almost total) loss of power on initial climb-out and it was an immediate pitch-down input and literally talking to myself out-loud to resist the temptation to attempt a turn-back that allowed me to walk away without a scratch. I was also fortunate to have landed in a bare-spot in the late-summer tall corn and although I wiped-out my landing gear and spent all of last Fall repairing the aircraft, at least I didn't do more damage by getting into the tall stuff which I really feared would have flipped me over.

Speaking of turn-backs, many of you are aware that there is a Turn-Back Project in-process right now, in-which a couple members of the EAA Safety Committee and members of other groups are taking a scientific approach to "The Impossible Turn." I personally have mixed feelings about this project because I believe most pilots won't get away with it in a true emergency situation even if they had spent time practicing it at-altitude under a controlled and non-emergent setting, but I do have to admit that the work they are doing is extremely interesting and will ultimately prove valuable in some ways. For those of you who have done some of this practice in their Sonex, it can be a great and very informative exercise. I just wouldn't be too quick to try to duplicate the maneuver in an emergency.

One very interesting tool that a member of the Turn-Back Project group is working to develop is an app called "Takeoff Advisor." Takeoff Advisor is intended to be a preflight tool for your phone or tablet that will take information about whatever airfield you're about to depart from, combine it with current weather information and some test flight data that you will enter for your specific aircraft, resulting in a graphical display of various options that you will likely have in the event of a loss of power on initial climb-out, including predicted results of all possible pilot actions to cope with the emergency in order to help determine your best chances of success. I've seen an online demo of this tool in one of our meetings and I love it. Although it does include possible turn-back scenarios which again, I'm not a big fan of predicting success there, I love it because it shows when turn-back is REALLY a bad idea, and it also shows your predicted chances of executing a forced landing in all other possible locations and which would most-likely be the best choice, whether it be an adjacent runway on the same airport, a taxiway, a field, road, etc. Using this tool during your preflight gives you a plan of action to prioritize your options of where to go should you find yourself in a takeoff/climb-out emergency.

I understand from recent updates from Turn-Back Project members that there are currently some tech challenges associated with correcting flight test data taken at-altitude and under different weather conditions to predict performance at pattern altitude and current weather. I do hope they persevere and can successfully overcome this challenge to bring the Takeoff Advisor to fruition. Aside from the whiz-bank technology itself, I really love it because it makes you THINK about this scenario during your preflight, before you even leave the ground.

Whether we have a tool like this or not, we should always be thinking about where to go and what to do in that situation on that specific day from that specific runway with the current weather conditions, and the current conditions of the crops on nearby fields! Whenever I'm driving my car in the areas that I typically fly (and subconsciously when driving anywhere at all it seems), I constantly find myself looking at fields and roads and stands of trees thinking about what crop is currently in a given field (it's not always easy to tell from the air), how muddy a field is and how rough the furrows are, how much room there is between ditches and tree lines, etc. for a forced landing site. This is on my mind maybe because of my experience last year, or because I'm just far more-likely to find myself in that place in my ultralight, or maybe because I'm also constantly but not seriously looking for a good piece of property to put a house and a grass strip. Regardless, it's kinda fun, and probably good practice. If you decide to make that part of your driving habits as well, just remember to always Drive the Car, Drive the Car, Drive the Car!