First flight ...

Here is the fists flights of the quad copter:

Note: Very windy conditions and still so stable !!!

At the flight time test ... amazing more than 10 minutes (14 to be more precise) with 4Ah Lipo. This is good time for a quad copter. 

Simple PID adjustment

I was just hit by a idea:
Adjusting PID parameters can be a pain in the ass if the adjuster have no idea what is he doing.
Adjusting as we fly it:
Step 1: have a flyable backup parameters that you can switch with a flip of a finger so you wont crash. This backup can be determined by holding the drone in your hand and see the response but for perfect parameters we need a method to calibrate PID inflight.
Step 2:use one of the AUX channels to activate PID adjustment P parameter (I and D are calculated), than use a VR (futaba like) to adjust the parameter until comfortable fly. I and D parameter can be calculated by the board using Ziegler-Nichols method.
Step3: as soon you have comfortable fly behavior (no woble), land and save the parameters.

The I and D parameters can be determined later by trial and error or/and using http://en.wikipedia.org/wiki/Ziegler%E2%80%93Nichols_method , but the P is important and makes the thing fly. I think we can have the P manual determined by inflight calibration and the I and D calculated by the Ziegler-Nichols method.

Usual the Roll/Pitch PID parameters are the same values for a Quad/Hexa/Octo copters. So why not adjust manually inflight the P parameter same for Pitch and Roll and let the I and D be calculated with the method Ziegler-Nichols. Like this you can achieve the best PID parameters.

Many of the people around here use wifi/bluetooth serial transceivers to do this from GUI. I think it can be implemented (like in flight calibration) to be available from tx also.

It is just a idea, so please do not jump on me. My quad-copter is calibrated by hand with trial and error. Same is my tri-copter.

I got this idea from experimenting with my helicopter the gyro gain in rate and head-hold. I use a VR potentiometer from my futaba to adjust the sensibility of head hold gyro until no wobble than I land my helicopter and check the settings (the value of the channel) and set it as default parameter for that helicopter.

I think this will solve the PID adjustment problem that many have and is not so difficult to be implemented in multiwii software so I will give it a try to code it and keep you informed.