On Feb 16, 1:04*pm, "S. Murry" wrote:
I have several hundred hours of actual instrument time in single engine
airplanes. *I've had vacuum failures in solid IMC (i.e real-world
partial-panel flying), and lots of instrument training on instrument
flying with all sorts of limited instrument situations (as have all rated
instruments pilots). *I also have a Garmin GPS 496, that features a
GPS-derived AH display. *I have taken up a safety pilot in a fairly stable
(compared to most sailplanes) airplane and attempted to see if I could fly
IMC using my Garmin 496 (which I note is a dedicated aviation instrument,
thus I believe a step or two ahead of smartphones in terms of refresh
rate, etc.). *My conclusion is that it is NOT possible to use this
instrument to "cloud fly." *It MIGHT be possible in a very stable plane if
already configured in wings-level attitude to stay that way using a GPS
derived AH, but probably even this would not be possible for a very long
time. *To me, the ability to maintain wings level for a short period falls
short of "permit[ting] flight without reference to the ground".

Thank you for this informative post. The above paragraph,
unfortunately, contains an incorrect assumption. The new
"smartphones" being discussed are capable of more than just a GPS-
derived AH display. They contain full 3-axis solid state gyroscope,
accelerometer, and magnetometer (3D compass) sensors. Given the huge
size of the phone market, a single integrated circuit containing all
of these sensors now costs under $10. They are there primarily for
game playing and "augmented reality" applications, allowing the
orientation of the phone in 3D space to be determined in a stable,
repeatable, and accurate fashion, to within fractions of degrees, with
update rates upwards of 100 Hz. Software already exists (typically $5
in the appropriate app store) for some of these phones to implement a
full inertially-based (not GPS-derived) artificial horizon. With
properly implemented software, the performance can easily exceed that
of the spinning mechanical device in your IFR panel. Competition has
resulted in all new high end phones (like iPhone 4S) and tablets (like
iPad 2) being produced with this full sensor suite. This will filter
down to lower end smart phones and smaller tablets over the next few
years.

Converging from another direction are devices built, using the same
low cost sensor chips, for use in hobbyist autonomous UAVs. There are
huge online communities of people developing open source software and
hardware to allow these things to fly in a stable and controlled
fashion. Given that there is no pilot directly controlling what are
in some cases highly unstable aircraft (helicopters, quad rotors, high
speed ducted fans, even jets), accurate high rate attitude
determination is a must. This is why we're suddenly seeing phones,
tablets, varios, flight computers, etc., with usable artificial
horizons. This capability will only become more ubiquitous as time
goes on...


Marc