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Quick Update


At Oshkosh last summer, I had the pleasure to meet Jeff Brown, creator of an iPhone app called "TLAR," which is USAF slang for "that looks about right." The app is designed to be a performance calculator for GA and EAB types, integrating handbook performance data with real-time METAR conditions. Additionally, Jeff's back country flying experience is reflected in some advanced capabilities, including developing a landing zone ("LZ" in military speak) anywhere. The pilot selects the aircraft type, and airport and either automatically imports METAR data or manually inputs elevation, altimeter setting and OAT. The system outputs takeoff, climb, cruise and landing data. Takeoff roll and distance to clear a 50' obstacle is readily available. The pilot selects climb condition--Vx, Vy, Vz, Economy, calibrated airspeed, true airspeed, or feet per minute. Cruise modes include 65% power, maximum speed/power, maximum endurance and maximum range. For landing, the pilot inputs flap setting and selects a Vref of normal (1.3 Vs) or STOL (1.2 Vs) for short-filed/LZ operations. Landing roll and distance over a 50' obstacle are automatically computed. The app also includes a moving map display and integrates with a world-wide airport data base. This amazing piece of kit is available in the iPhone app store.

After some discussion, Jeff has developed an Emergency Mode which we've been testing for the past 10 months or so. This mode is currently in beta test and isn't yet included in the commercial version. Most folks familiar with our work, know that we've been supporting the EAA power loss on takeoff working group for the past 3 years. This scenario is one of the most challenging in general aviation; and fortunately doesn't occur very often. One of the elements is what is popularly called the "impossible turn," or returning to the runway from which the airplane just departed for an emergency landing. Actually planning and executing this maneuver has so many "it depends" elements, I'm convinced after quite a bit of flight test, that the only real way to sucessfully execute it with a degree of relability is to have the computer helping me out with it's capability to update the physics real-time at 1Hz. Obviously, one of the keys to "max performing" the airplane safely in this scenario is having accurate AOA information available in the cockpit. It's certainly possible to fly the sequence without AOA, and we've done that in testing, but it's not as easy to do.

The other benefit of the emergency mode is the ability to "what if" a power loss on takeoff or during climb when flight planning or briefing. The app computes predicted accelerate/fly stop straight ahead distance as well as a turn back point and altitude based on ambient conditions. The later can be an eye-opener as many aircraft won't have the performance capability to execute a sucessful turn back. The satellite view on the map display is also handy for scoping out potential off-airport landing sites. Once the airplane is on the runway and starts rolling, the phone sensors take over and update the prediction once per second. An intuitive visual display pops up along with two simple voice warnings: "off airport" or "turnback possible." Just as I find the aural AOA cues to be more useful than a visual display, the TLAR "voice commands" don't require any visual scan time. You can see a short video of a recent test here:

For a more in-depth look at a power loss on takeoff scenario, there is a good thread on Van's Air Force on topic here:

Updated AOA "Indexer" Display

The "doughnut/chevron" display dates back to the early 1960's and was the first standard display in the military. It was a no-brainer to adopt it for use with the ONSPEED system. Interestingly, when you stare at something long enough, you don't objectively "see" it anymore. Such was the case with our indexer lighting logic and coloration. Early military AOA systems actually employed a light sequence and combination of lighted segments to provide "fast," "slightly fast," "on speed," "slightly slow," and "slow cues." The lights were also just one color (usually red). This basic logic is shown in this diagram from the F-18 NATOPS.

In addition to the way the lights sequenced depending on AOA, we also changed the colors from the old "yellow, green, red" sequence to "blue, green, yellow, red" as AOA increases, since no gauge progresses in a yellow, green, red sequence! We also improved the readability of the fractional lift display that lives in the upper chevron. As the trend indicator (white bar) moves up, the fractional lift display now remains visible:

The "slightly fast" and "slightly slow" cues are helpful and increase the tactical utility of the indexer, since they effectively translate to Vref and Vapp short field/transition to landing. Big thanks to Bob for his programming to make the new display a reality.


"V4" is the forth iteration of hardware design. We are stepping away from the Teensy 3.6 processor, which is no longer available. The engine in the new design is a sustainable ESP32 chip. Lenny also developed a printed pressure manifold that eleminates the need for the expensive brass plumbing we used in previous versions and simplifies fitting the quick release pressure fittings. Phil is currently assembling 5 prototypes he designed for software development and testing that we hope to have completed by the end of May. We don't know yet whether or not any of the intial hardware will be flown as we move through an iterative design and software development process, but it sure looks good! Thanks, Phil. Our long term objective is to provide built-up systems, ready for installation in the field, sooner rather than later. But based on the amount of work and testing (lots) to be done, I won't hazard a guess as to when "sooner" will be :). Overall, I'm very proud to be able to work with such a great team of skilled volunteers, and see a bright future for the ONSPEED system.

Oshkosh 24

Once again, several of us will be heading to Wisconsin in July. The schedule is still in flux, but when it firms up (likely some time in late June), we'll post a schedule of events. As of this writing, we do know that "AOA Day" at the EAA Pilot Proficiency Center (co-located with the mueseum) will be Wednesday. More to follow.

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May 16

What will the CAN bus connector be used for? When will you have more details on the hardware and software changes? Looking forward to see how this all plays out.



May 15

The new version 4 sounds promising !

Do you have any pics of the inside workings?

Keep up the great work guys!

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