Re: Hey Dynon - Failure Modes - What should we exp
No, our products do not cross-reference GPS or other data against the airspeed requirement for the attitude indication. One major issue here is that there is no way for the system to know the pitot is blocked. 0, 180, and 262 are all valid airspeeds, so there's nothing that says your pitot is blocked. The difference between pitot and GPS is wind, so even that is not super reliable.
At the end of this post is the statement from our latest manual regarding airspeed. The exact effects are not easy to quantify since attitude performance without airspeed depends on the airplane, the speeds involved, the flight conditions, and the way the airplane is being maneuvered, and the way in which the pitot has failed. If you have a backup airspeed indicator, we suggest disconnecting the pitot from your Dynon it and see how it performs, but even this is not a test for all pitot failure modes. We do consider airspeed as a required element of our attitude algorithm, and we do not make specific claims on performance without it. Attitude performance will be reduced.
Some other thoughts:
All modern, non-multihundred thousand dollar ADAHRS systems use sensor platforms that marry different sensor inputs to arrive at the indications you see. Even at the certified level, if you take a look at the G1000 manual (the G900X manual is a bit more accessible), you'll find that attitude requires a GPS lock, or in the absence of that, both IAS and magnetometer data. They document this fully, and we try to be similarly upfront about how each element of our display is derived (see the tables in our latest manual).
While our products do require airspeed, we think that on balance, our overall attitude algorithmic approach offers the blend of performance, affordability, and reliability that our customers are looking for. We invite you to test our attitude in slips, stalls, mushing descents, continuous and prolonged turns, and other scenarios you can think of. Not every system out there can cope with the stranger flight regimes (and these are the ones that you need help getting out of when you encounter them).
Our particular algorithm has some other unique strengths as well. For example, our products are ready to display attitude within a few seconds of powering up, even when started up in flight. Other manufacturers' solutions may require minutes to capably give you attitude, and some can't come back online period if they (or their aircraft power) glitch in flight. And remember, while we do require airspeed, other products may require a GPS lock, or a magnetometer that is working and calibrated (it, like any electronic component, could fail individually).
Finally, we always encourage our customers to consider their aircraft's mission when they're planning their panel. We've found that many IFR-equipped homebuilts are not used in prolonged flight conditions that could conceivably result in an iced up pitot. Instead, they are more typically used to get through the occasional cloud layer. If you're equipping for "hard" IFR, you should already be doing some deep thinking about how you can cope with any single system or instrument failure, especially the failure of your "gyro" sources such as your EFIS. If you're considering an all-Dynon panel (multiple EFISs or an EFIS/FlightDEK combination) to accomplish that redundancy, it's not insane to think about multiple pitot tubes if you expect to be in conditions where you'll be relying on pitot heat all the time. Consider your mission, your risk tolerance, your budget, and your backups. And if you're equipping for IFR at all, you REALLY should have a heated pitot, period. That alone really cuts down on the already small risk of ever losing airspeed information. Finally, keep in mind that other forms of backup, like autopilots, may rely on airspeed in non-obvious ways. For example, if your autopilot has a minimum airspeed setting, and your pitot ices up and airspeed goes to zero, you'll be left with an autopilot that pushes the nose continuously to try to compensate.
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AN IMPORTANT NOTE ABOUT AIRSPEED
As depicted above, your FlightDEK-D180 depends on airspeed (pitot and static) for many of the primary flight instruments. If a problem develops with your airspeed reading, treat all of the instruments on your EFIS with skepticism – especially attitude. Also, know that without airspeed, the EFIS instruments that depend on it are most prone to error when the aircraft is accelerated. Hence, the less the aircraft is maneuvered (power application/reductions, and changes in direction), the better the EFIS performs.
