ADAHRS....

[Bender]

Please tell me what you can about the system you've developed for your "guidance". My experience with reliability regarding  these products ( the EFIS market in general) has been generally poor.
I also hope that that the ADAHRS is more robust than how you tackle your current product. Is the ADAHRS ( your development , third party etc) new or an outgrowth of the current product ( still airspeed aided?). All of the screens are very pretty  but its the "heart" I am concerned with.
I'd be happy with grey scale displays if the sys doesn't saturate and tumble. I'd also be interested in the type of components used such as gyros (or the sensors uses as gyros), accelerometers. Are these robust ? or made in Singapore junk or what exactly. I don't mean to be abrupt but I've been burned (some of your competitors) and can't afford to plunk down many thousands of $$$$ for equipment that needs constant updates and doesn't work reliably. Your illumination is greatly appreciated!

 

[Bender]

Dynon Support - please- tell me to go to hell, but please tell me something.
Larry

 

[dynonsupport]

Sorry for the delay Bender. Your normal forum tender has been a little bit behind.

Anyway, I guess we don't tend to categorize ourselves as a normal citizen of the "EFIS market in general". While were weren't the first out of the gate with an experimental EFIS, we were the first to make one affordable that actually does what it says it does, is reliable, has sold well. I think that for the large part, our reputation reflects this too. Our sales certainly do - there is no way that we'd have sold as many units as we have (without getting into exact numbers, it's a good fraction of 10,000 screens between EFIS, EMS, and FlightDEK-D180 screens) if our products didn't live up to their claims.

I'm not sure I follow your question about saturation and tumbling. Our rate sensors, in particular, do saturate at 150 degrees per second, after which the EFIS annunciates that the horizon is recovering. Though some competitors like to make hay of roll rate capabilities, the practical reality is the 150 degrees per second is beyond most airplanes nominal capabilities. One thing that stands out about our products is their ability to self-recover from such an excursion (such as an intentional snap roll in a capable airplane) automatically, without pilot intervention, button pushing, "erecting", caging, or anything other than a few seconds of straight and level.

We don't publish the exact make/models of the accelerometers and rate sensors we use in our products, but they are of the inexpensive MEMS type, not piezo. All products modern motion sensing devices, from Wii remotes, to iphones, to Garmin G1000 ADAHRS, basically use the same types of components. There are a few companies that make good stuff, and one of the things we're particular good at is sussing out the ones that work well in this application, and, more importantly, discovering what kind of calibrations will help them perform the best over time and in different environments.

Anyway, I hope that helps. Thanks for thinking of using us!

 

[PhantomPholly]

Ring Laser Gyros are capable of being a lot more accurate - but last time I checked they were north of $100,000 each. Dynon and the other competitors all use software to smooth out the measured accelerations, and then correlate with inputs such as GPS, pitot, and static to determine if "drift" has occurred.

I wouldn't go doing loops in a thunderstorm, but it does seem to be quite reliable in normal flight.

 

[hankster]

I generally agree with everyone's post previous. 150 degrees/sec yaw rate is achieved in most small aircraft (say, C172 or smaller) in spins. If you happened to spin through a cloud, you would be very disappointed to note that your horizon on the EFIS had tumbled. That scenario is admittedly rare, but it still would be nice to have instrumentation working far beyond what the aircraft is capable of ever doing in flight.

The good news is that MEMs devices are getting better in all respects constantly.

Hankster

 

[dynonsupport]

Everything has a tradeoff. They sell (and have sold for years) MEMS gyros that go much faster than 150 degrees a second. Of course, they have less accuracy and don't behave as well as lower rate gyros. We chose 150 degree rate sensors because they are the correct tradeoff for performance in the aircraft in our market.

You'd be surprised at how fast 150 deg/second is. I doubt any Cessna can hit it, even in a spin. Most RV's won't hit that rate even in a spin. On top of that, the whole point of a well behaving attitude is that you don't need to spin through the clouds since you have a working attitude reference.

And to reiterate: One of the unique advantages of the Dynon solution is rapid, in-flight recovery, so when you break out of the spin, even if it was too fast, you will still have a working EFIS a few seconds later.

 

[hankster]

http://www.youtube.com/watch?v=Fv9Z-MJq3KU

I don't doubt that you did a reasonable trade study to arrive at your 150 degree/second number. Your absolutely right that most folks will never see that number.

However, small aircraft of the C182/C172 sizes or similar can and do easily exceed that in spins. The video link at the top shows a C172 approaching 1 complete revolution per second.

As a general rule, I would like to see the aircraft instruments exceed the capabilities of the aircraft. That's not always possible (many mechanical gyros tumble in spins), and if that's the case here, so be it. Regardless, it's a good goal to shoot for.

Hankster

 

[PhantomPholly]

How many mechanical artificial horizons under $10,000 do not tumble in spins?

The good news is that electronics are advancing (and dropping in price) far faster than ever happened with "your daddy's airplane stuff."

Give it time...

 

[skysailor]

While it would be nice to have attitude sensors which do not tumble even in a spin, I thing Dynon has made the correct choice. Very few non military pilots have been trained in spin recovery while IMC. It is obviously an instruments only operation. I used to train students to these standards as part of the US Navy Advanced Strike syllabus. It will take considerable effort to train for this scenario.

On the other hand, given that an aircraft will not spin absent a stalled angle of attack with the addition of yaw, the Dynon helps by providing so many tools. You have airspeed with colored warning markings, angle of attack, aural stall warning, turn rate and delta heading trend displays. Utilizing these existing tools will prevent the spin in the first place.

 

[hankster]

My intent was to present a philosophy here: Have the instrumentation better than the aircraft. That's a goal, not a hard specification, and not easily achieved. And I don't really see any disagreement with that here. What I see is that practical limits on available sensors make that goal not achievable now. OK, I accept that.

Secondarily, it was stated that the 150 degree per second number is beyond most aircraft's capabilities. I disagree with that. Actually, coming from the manufacturer of an EFIS, it's a bit scary. So, I presented the spin as an example. All smaller aircraft will spin faster than that, some much faster. However, the unintentional spin is, with one exception, a rare event and probably is a red herring as far as the EFIS is concerned.

Skysailor, you comment that utilizing Dynon's excellent tools will prevent a spin in the first place. That's true as far as it goes, but people have brain fades and don't always utilize the available information. The spin exception that I mentioned above is the stall-spin in the base to final turn, which continues to claim a few lives every year. That happens in spite of the green and white arcs on the airspeed indicator, the slip-skid indicator (the ball), and lots of physical cues that go along with a stall. So, lots of tools are no guarantee.

Hankster

 

[PhantomPholly]

Good points. Please don't think I was busting your chops, it's a great goal. The fact is that it is entirely possible to reach your goal; just not at Dynon prices - YET.

That day will come, and I think Skysailor and I were just expressing that we feel Dynon has made good business choices on performance-vs.-price, or "bang for the buck" if you prefer.

Skysailors vehicle-under-construction probably will exceed the limit in roll as well as in a spin. Maybe he will report back to us if the EFIS "kinda" keeps up - it may actually exceed Dynon's specs in such situations.

 

[vlittle]

A question about the ADAHRS.
Typically, one would mount this in a magnetically quiet environment, such as the wingtip or aft fuselage.

However, Dynon wants pitot/static/aoa connections to the ADAHRS, so that requires routing these lines to the unit.  This limits the flexibility of installation.

I like the seperate magnetometer currently used for this reason.

Do I have this right, must I put provisions in place for routing the pitot/static/aoa lines to the ADAHRS?  This is a bit of a pain if they also need to go to the panel, but with a bit of planning it's ok.

Vern

 

[dynonsupport]

The next generation ADAHRS will have the magnetometer in inside of it. So while pitot/static will need to be brought to it, you will not need to bring pitot/static to the back of the screen like you do today.

 

[rckol]

Will AOA and OAT also be connected to the ADAHRS?

 

[dynonsupport]

Yes, OAT and AOA go to the ADAHRS in the new system

 

[rckol]

Thanks, so going into the ADAHRS we have:

Pitot
Static
AOA
OAT

what else? power? DSAB?

 

[dynonsupport]

Power and DSAB are all on one D9 cable that runs to the back of the unit.

 

[woxofswa]

First post. Sorry if this has been addressed previously.

I am building an RV10 and am at the fuselage wiring stage. Is the area under the front seats usable/desirable for ADHARS placement? Would it be a problem if the comm antennae were there too?

 

[dynonsupport]

Under the seat is not a good location since the magnetic sensors are in the box. If you sit down with a pocket full of keys, your compass will be off.

 

[woxofswa]

Thanks for the response.

I guess that leaves the tailcone or the wing. Is there a preference between the two? Also, what runs should someone prewire for the tailcone? Also, would having airconditioning components in tailcone be a problem?

Thanks in advance.