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Oct 21 2010

EasyStar Modifications

Ever since our first flight with the EasyStar it was clear that a few modifications were necessary  for the plane to become a usable alternative to the SlowStick. Over the past summer Evan had spent a significant amount of time improving the EasyStar by making it easier and more convenient to use as an image acquisition platform. The following serves as an explanation of the most successful modifications that were made to the plane, many of which will be incorporated into the autonomous EasyStar project.

To provide the EasyStar with more power the stock 400 speed brushed motor was replaced with a 400 speed Turnigy brushless motor running a 6x4 APC propeller. A Turnigy 30A brushless ESC was also used along with a 11.1V 2200 mAh battery. This power system gives the EasyStar enough thrust to carry a standard digital camera, external GPS unit and FPV equipment with ease. Because of the EasyStar’s large wings it was extremely unresponsive to rudder inputs, making it difficult to maneuver.  To fix this the rudder was extended by approximately 1.5 cm to give the plane more agility when turning.

The inside of the EasyStar was carved out to make room for the battery pack and camera. Access to the planes internal components was provided by small plastic hinges mounted along the bottom of the fuselage which enabled it to be opened and closed easily. In order to protect the camera lens when landing plastic skids were created and mounted to the underside of the fuselage with hot glue. Magnets were also added to the front cover, allowing for easy access to the electronics near the nose of the plane while also providing a break-away point in a crash.

Initially, Evan and I had trouble with the elevator becoming jammed so it’s important to make sure that it can move freely in either direction before each flight. The EasyStar’s center of gravity was also found to be abnormally far forward for a high wing plane, making it difficult for us to pinpoint. After a series of test flights we had found that the EasyStar performed best when the center of gravity was located approximately 1/5 of the wing past the leading edge.

In my past experience with the EasyStar, landing has been somewhat difficult due to its natural tendency to fly fast and glide for long distances without throttle. The following are some modifications that I believe would enhance the EasyStar’s ability to land in small fields like HR. Remotely activated Air breaks could be mounted on the body to help slow the plane down when landing. This would consist of a piece of foam connected to a micro-servo which would be activated by a toggle switch on the transmitter, extending the foam and inducing drag. Another solution consists of attaching  flaperons to the trailing edges of each wing. This would act as an extended airfoil to help slow the plane down without compromising its lift. Furthermore, the addition of Landing gear would allow for rise-off-ground (rog) takeoffs and landings while also serving as a replacement for the plastic landing skids used previously.

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