The Flying Gator

The goodies

The red Sparkfun box we had been waiting for arrived early last week.  Everything that was ordered came in… Here is a look at what we bought.

1) ArduPilot Mega

This board is the bigger brother to the very popular Arduino Based ArduPilot.  The ArduPilot Mega was designed by Chris Anderson and Jordi Munoz at DiyDrones.  The Mega utilizes the Atmega 1280 microprocessor which has 16 MHz of processing power, as well as the Atmega 328 as a hardware failsafe in the case of a program crash.  The pilot has the ability to reroute servo control back to the Radio control transmitter and turn the autopilot off through the 328 processor in the case of a software problem on the main processor.  The ArduPilot Mega has can be used with up to 8 channels from the Radio Control system.

ArduPilot Mega control board

2) Venus GPS Receiver and external antenna

The Venus GPS receiver boasts better than 2.5 meter accuracy which gave this chip the heads up over the other GPS chips available.  It allows tracking of 14 seperate satellites (even though its only possible to see a maximum of 12 at once!), as well as a refresh rate that can be increased up to 10Hz! The Venus ouputs standard NMEA data and has both a UART serial interface as well as SPI connectivity.  At just under $50 for the Chip and another $12 for the antenna, it is a very attractive choice for this level GPS.

Venus GPS Receiver and External Antenna

3) Razor 6 Degree of Freedom Inertial Measurment Unit

The Razor IMU contains one LPR530AL two axis gyro (pitch and roll), one LY530ALH single axis gyro (yaw) , and a ADXL335 three axis accelerometer. This is a very compact chipset that should give us a good idea of what attitude we are at in 3D space.  The chip we received initially from Sparkfun had a few surface mount components that were missing or not where they were supposed to be, but Sparkfun quickly remedied the situation and dispatched a new board right away.  Thanks to the folks at Sparkfun for great customer service!

Razor 6DOF IMU

Coming Soon: Building the Flying Gator!

Thats all for now!

A very stable aircraft is important in UAV design and construction.  Originally we had proposed purchasing and building the very popular GWS Slow Stick that has helped many beginners start their journey into the world of Radio Control airplanes.  Being basically a stick this airplane would lend itself well to attaching sensors and other cool “stuff”. But…

After researching, it seems as though the Slow Stick is not the greatest platform since it only utilizes a three channel control system.  Each radio control channel gives you proportional control over one aspect of the aircraft while in flight; in the case of the slow stick throttle, rudder, and elevator are the three controls available.  Throttle controls the speed of the airplane, elevator controls the pitch of the nose, and the rudder on the Slow Stick (due to the large amount of dihedral) has both an effect on the roll and yaw of the airplane.  We decided that we would like to have individual and finer control over the roll and yaw axes of the airplane in flight.  This would require at least a custom wing, or a different platform…

The Flying Gator

Wingspan: 62″

Wing Chord (front to back): 12″

Sneak Peek of the Flying Gator

Here is a quick look at a picture of the wing seated on the fuselage.  The wing is all foam construction with a full length wood spar, and carbon fiber/ wood leading edge.  More construction details will follow with pictures!