how alt-hold work?
the altitud is specified in the firmware or ArduPilot will try to hold in the altitud plane is, when fail safe turns on ?

Out of the box, altitude hold maintains the altitude the aircraft is at when the autopilot is turned on. But you can modify the code to include different altitudes with each waypoint. The code is open source, so ArduPilot can have any functionality you want to add. It's also set up to take external pressure sensors if GPS altitude is not enough for you.

what you think about add a second gps connector in the board in order to connect also an osd using same gps?

finaly will be possible to buy just the cpd4 head and connect it to ArduPilot? or its necessary the use the cpd4 block ?

will it be compatible with that micro gps ? http://www.nghobbies.com/cart/index.php?main_page=product_info&products_id=162

im very happy to see that project progressing,

We have no plans to connect a second GPS connector for an OSD, but you're welcome to modify the board to do that yourself if you'd like

For ArduPilot, you need the CPD4 head and block; for ArduPilot Pro, which is not available yet, you'll just need the head.

We are planning to make ArduPilot compatible with 5HZ GPS modules, including micro gps and Ublox5. Stay tuned.

I know rear read read. I figured it out from the sch.

any idea when the big day will be?

We're working as fast as we can, but I still don't have a date for you. Making a few boards is easy. Making hundreds, reliably, is hard.

does it work with V-Tail planes like EPP Eagle ?

Hi everyone, I am a aerospace engineering college student who stumbled upon this website and I am very excited.

Is there a way that I could use something like a XBee and make real time changes to the GPS way points? I'm not sure if there is a ground station in the works, but I think it is something that is definitely worth it.