Looks like it is possible,if not perfect.
I have been looking at smartphone gyros for some years now. It all started out very primitive but now I got the Google Nexus 4 (made by LG) and installed a few gyro applications such as ixGyro and Aircraft Horizon.
I have to say I am very impressed. This is very useable and could be a life saver. I would say the reaction to changes in attitude are as good as with the real stuff. Compared to mechanical gyros, the phone's gyro will not start tumbling when exceeding a certain bank angle. The main challenge of course is the erection mechanism (just like in the certified stuff). There are no air vanes in the mobile, no weights and springs etc. The Aspen AI uses GPS and pitot for erection. The Android apps just rely on GPS. You need well thought out algorithms that weigh the GPS and other sensor input and use them to erect the gyro. There is no reason why an Android developer would be less capable of designing such algorithms than Garmin/Aspen/etc.
If you connect the phone firmly to your dashboard and initialize the pitch, I think it is a very good instrument.
If you connect the phone firmly to your dashboard and initialize the pitch, I think it is a very good instrument.
I wouldn't call it a "very good instrument", but it's certainly better than nothing. (Mind you, even the 25.000 Euro certified Meggitt standby horizon in "my" Citation is not a very good instrument, rather a very bad and unreliable instrument to be honest!). I have tried it with the iPad as soon as I got one - it works quite well for maintaining wings level in low turbulence and low vibrations. If you ever have to use it, do so only in combination with other instruments as they taught you in your IR training! If in doubt, rather rely on your turn&bank, VSI and altimeter than on the mobile phone.
If you really want a reliable backup instrument, you absolutely need a proper AHRS. There are battery driven units with wlan (e.g. Levil AHRS G) that will remotely display the attitude on your smartphone or tablet. At 800$, they are a real bargain!
If you really want a reliable backup instrument, you absolutely need a proper AHRS.
What makes the Levil AHRS G proper what makes the Nexus 4 phone improper? I have been observing this for quite some time and I have to say there has been progress. I'm not suggesting to get an Android phone and remove your G1000 but I think the gyros in the cheap phones and the applications using them have come a long way.
Avionics companies tell us their stuff is certified and thus superior. My experience tells me that you find very poor engineering in aviation electronics.
I have been observing this for quite some time and I have to say there has been progress.
Certainly! But have you tried it in the aircraft? As I said, I have experimented with various attitude reference apps on my iPad in different aircraft (single, twin, Citation) and until now, none of them was able to provide reliable pitch and bank after some manoeuvering. One full circle flown at standard rate is usually enough to fool it!
My experience tells me that you find very poor engineering in aviation electronics.
Unfortunately, this is true in some cases. But there are some very reliable pieces of kit out there as well. I have flown with Garmin GNS 430/530 for maybe 2000 hours without a single failure yet (apart from a freshly installed unit where the GPS antenna cable became disconnected in flight, but that was not Garmin's fault! and did not affect the NAV/COM function). Or 1500 hours with Honeywell Primus 1000 (a "bronze age" integrated glass cockpit so to say) without the least bit of malfunction.
I've been looking into getting one of these :
http://www.dynonavionics.com/docs/D1_intro.html
I think the price and what it does is quite interesting as an IFR stand by instrument and definitly better than what I've seen on the smartphones.
Hi everybody, I have an LSA plane that could benefit from a cheap back-up AI to get out of unintentional IMC, and I was thinking of an old Iphone4 I have at home (earlier Iphones - 1, 2 and 3 - don't have internal Gyros, just accelerometers, so no good anyway). There are plenty of free/cheap iphone-apps claiming to simulate an AI: do you have any real life experience with this? A normal GA-certified AI would cost between 1000 and 4000, so I'm really curious to understand if nowadays is possible do get exactly the same function (actually better because solid state gyros don't tumble upon strong upsets) spending a fraction of the money.
The only concern I have is that, reading some other blogs, it seems that you have to "calibrate" the Iphone app while flying straight and level at the beginning of each flight. This would of course make the iphone solution inferior to a normal GA AI... (but then I'm puzzled to understand how is it possible that a normal GA AI doesn't need to be calibrated at the beginning of each flight??)
Thanks, Valerio
I have only used some of the free gimmicky apps on the iPhone / iPad. They are sort of fun to play with, and the best looking one was called "Flight Instruments" by BBFlight LLC - it would show the usual glass cockpit AH with speed and height bars on either side, and a slip ball down at the bottom.
But I wouldn't consider using it in IMC. I just wouldn't have the faith in it. However, in the UK for £695 you can get the item below, which being an add-on will not be certified, but would be more trustworthy than something costing just a few pounds or Euros.
Thanks, but I don't see, a priori, why the solid state gyros and accelerometers of Levil should be better (700 pounds better) than the ones already present inside my Iphone4. I would understand your point if Levil were certified...It's not hard to believe that the business volume of Apple can get Apple better hardware, at better prices, than the Levil niche-volume can get to Levil.
We have had a few threads here previously on this 1 2 3 and a peripherally related one here.
The problem with all the phone gyros is that they are pure accelerometers only i.e. there is none of the slow background erection mechanism which is a necessary component of any workable artificial horizon.
Any gyro will drift, and the solid state ones used in phones, and also in all the GA AHRS systems, drift rapidly. This makes them all useless for navigation (which needs a 100x to 10000x less drift) but it's OK for attitude or heading stabilisation purposes.
I am not a specialist in this but certified instruments need a robust erection mechanism.
In a standard vac AI this is done with the famous "pendulous vanes" which any JAA IR theory connoisseur will be familiar with. In an electric AI it is done with gravity-operated microswitches, or (allegedly) with air-operated pendulous vanes which work off the air kicked about by the motor. Obviously, there is no way for such an instrument to independently determine what constitutes "straight and level" so if you arrange for the gyro to spin up only after you put the plane into a balanced 60 degree bank, it will erect straight and level...
In systems like the G1000 it is done by airdata or GPS trajectory data, which avoids the above issue, but the big names have all struggled with getting this method certified. And anyway you can still fool it if you interrupt the power during flight which is grossly uncoordinated but has a straight and level trajectory.
I can't see why the Iphone can't do the background erection using the "spirit level" which I believe it does contain. My Nokia 808 certainly contains one; not accurate but you can calibrate it. Maybe somebody has thought about it and implemented it?
The method currently used, where you press a button to tell it you are straight and level, is useless because it works only until the thing drifts off.
I don't know what is inside the add-on module in PiperArcher's post but definitely it will be a much better gyro than in a phone and very likely there will be a levelling sensor too - as in my SG102 which obviously has one because it has zero pitch/roll drift even over days.
If you want an artificial horizon, I suggest you pick up an electric overhauled one on US Ebay. Even new ones are about $1500 or so. Or get an OH one from a reputable outlet like this. Used, no paperwork, they go for little money but you take a chance on getting shagged bearings. I am selling a BF Goodrich 28V one, 5 degree panel angle, for £500, with ~100hrs on it and paperwork from Pandect (they had to replace the knob) - was c. £2500 new in 2001.
