I recently bought an Erle copter and managed to put the pieces together. But I'm having an issue getting it off the ground. I'm not sure what the problem is since everything seems to be in place and the propellers seem to be rotating correctly, the only thing I can think of is that the add-on parts are too heavy for the the drone to fly, even though they were all optional parts from the Erle Robotics website. The following video will show you the problem better.
Thanks for your help in advance.