Gentlenav altitude speed control

https://groups.google.com/group/uavdevboard/browse_frm/thread/87bc28b1b9ac8f6e#

Uses the kinetic energy of plane for steering and not the throttle or speed of the prop. To gain speed the plane could dive, instead of increasing throttle thus crashing into the ground if options not correctly set

Yaw drift comp. uses air velocit
magnetometer

https://groups.google.com/group/uavdevboard-dev/browse_thread/thread/498179cba65470d9

Regarding strong headwinds with the plane going backwards with respect to the ground, I have tested that, it works just fine, because it is the air velocity vector, not the ground velocity vector, that is used for yaw drift compensation.

Magnetometer mounting
https://groups.google.com/group/uavdevboard-dev/browse_frm/thread/498179cba65470d9?tvc=1

I just want to keep everyone concerned posted on the results of my 3 flight yesterday (in addition to my other 3 flights the day before). All 6 flights indicated perhaps *conclusively, of the magenetometer's * (HMC5883Lfrom sparkfun)
 * accuracy* *when: *
 * 1) it is mounted carefuly aligned to UDB4's IMU and *
 * 2) on a location ISOLATED from any magnetic intereference.*

In my case the magnetormeter worked perfectly well when located under the wing as per attached image, thanks to Pete's recommedation.

http://blogs.freescale.com/2012/10/03/magnetometer-placement-where-and-why/

Here's a discussion of the effects of ferrous materials and current-carrying conductors near magnetometers:

He suggests that 5mA is the max allowable current in a conductor 1cm from the magnetometer. (this is assuming a limit of .1 microTesla for the field strength at the sensor)

73, --Mark