http://www.androidzoom.com/android_applications/productivity/aircraft-horizon_zcuz.html

    Robin Bergland.

    That would be worth buying a small Android tab just for that.

    http://www.everbuying.com/smlclass854.html?gclid=CJr9qfbE7awCFUWMtgodigzI9A

    Paul Lamar

    I know many phones and tablets can sense which way is down to
    determine portrait or landscape orientation of the display but that
    is a single axis sensor.  How does he get roll AND pitch?  i am
   suspicious!

    SD

    I suspect the sensors are 3 axis.

    There is an ap out there where you can look at the night sky and
identify    star names by merely tilting the tab back and fourth
pointing it in    the direction of interest. It also uses the GPS to
locate one on the    planet.

    Paul Lamar

   It can do all of that stuff with just 3-axis accel, compass, and
GPS. To   get "real" horizon info and not just a toy that works
while you're standing   on earth, you need a gyro. I believe some
phones may have a MEMS gyro, but   that software only claims to use
the accelerometer, which is a flawed   method.

   -Chris W

   It sure keeps my toy helicopter flying straight.
   A lot depends on the A to D used. A 16 bit A to D is one part in
   65,000 more or less. In terms of percentage that is .0000153% I think.

   Having said that I don't know what the A to D is but 12 bits are very
   common and cheap. One part in 4096 or .000244%.  Modern CPU chips
found in   desk tops and tabs have enormous computing power.

   Paul Lamar

Your toy helicopter uses a gyro and not an accelerometer, as far as
I know. At least my toy helicopter does. :)

-Chris Wood

What is the difference?

Paul Lamar

A gyroscope  provides a reference from which you can directly measure
angular displacement and rate.  Note that you need at least 2 gyros
for full spatial measurement, that is why airplanes have an
artificial horizon AND a gyro compass.

An accelerometer measures single axis, linear acceleration.  Even
with 3 orthogonal accelerometers you still can only measure
acceleration.  With an array of 6 suitably oriented and displaced
accelerometers and appropriate integrators for each you could
theoretically calculate angular displacement but the drift might be
far worse than gyroscopic precession.

Like someone said earlier, if it was easy, your inner ear would be
sufficient for IFR!

As for inertial navigation systems that the airlines and the
military used before GPS, note that they were based on ring laser
GYROS, not just accelerometers.

SD

IMHO:

An accelerometer coupled with a computer equals an attitude gyro.

This law of physics (see the jpg) for constant acceleration gives a
distance or angle. If the acceleration varies in a known
mathematical curve it can be integrated using calculus. If the
acceleration varies in a non mathematical way a $30 computer can
accumulate all the little bits of acceleration to determine a total distance
or angle. It is called integration in calculus speak.

For that reason cheap computers have replace calculus :)
Mathematicians that teach calculus have been replaced by
teachers teaching programming :)

I think a ring laser gyro is a rate gyro or angular accelerometer
and not an attitude gyro. Four simple accelerometers (mass between
two springs or a mass at the end of beam) equally displaced from a
central point can replace a ring laser gyro with the help of a computer.
Perhaps not as accurate.

Here is a blown up picture of a MEMS. IMHO they are tiny masses on
the ends of tiny beams. The beams are instrumented to measure
bending stress due to acceleration of the tiny mass. My guess.

Paul Lamar

Computers are not smart. They can only process input information according to
the  programming somebody has put in. Calculus can only be accomplished with
one when it has the program information. Miss one key and it does not know
what to do or takes you down the wrong path. Try searching for Scat
crankshafts. That was a learning experience on what not to key in! :-)))  They
are marvelous tools when all goes well.

Regarding my Bluetooth; the lady at the comm store even had fun with it. The
delete for the "pairing" was kind of hiding and did not want to co-operate at
first. The the boss wanted me to change the out going message to one for me
instead of the previous user. I had tried and could not find the change
message tree. It took her three tries to find it. Technology is great when the
stars are lined up; but God help us when a glitch happens. So of the wireless
stuff is negatively affected by solar events. The sun has been on an extended
calm period of solar activity, but is coming back to life. We have not had
much for Northern Lights for a few years but have had some beauties lately and
it will get more so over the next couple of years. All wireless devices may
not function at times. I would not want to be in a position that I had to rely
on the wireless connection. As an extra bit of information to help make
quality decisions with may be good.

Dale Davies