Long-Nose Shot Getter
This is my first scratch-built plane. It was designed by a fellow RCAP (radio-controlled aerial photography) enthusiast and posted in this thread on RCGroups. He calls it the "Shot Getter." The design is still changing as he learns more, incorporates feedback and pushes the design further.
My Getter is basically the second iteration of the design, but I've made several modifications, not all of which had the intended consequences. In particular, I shortened the fuselage and made some modifications to the tail fethers, which shifted the CG (centre of gravity) rearward by rather more than I was expecting. As a result, I had to extend the nose (which supports the flight battery) forward, hense my new name for this plane, the "Long-Nose Getter."
The plane is 42" long, with a wingspan of 60". Wing chord is 10½" for a total wing area of 630in². All-up weight with camera is 49.5 oz (1400g).
Power is provided by an AXI 2808/24 turning a 9x4.5 APC "thin electric" prop. The battery is a Flight Power 2500 mAH LiPo (Lithium Polymer) battery in 3s configuration (three cells in series). The motor draws just over 20 amps at WOT (wide open throttle) on a fully charged battery, and provides about 40oz (1135g) of thrust.
The camera I'm using now (the one in the photo) is a Nikon Coolpix 7600. This is a 7-megapixel camera with fairly good optics for its price range.
This platform is almost ideal as an aerial photography platform. It flies very slowly, is extremely stable and has no bad habits. It is not the sort of plane you can do aerobatics with!
I have started documenting the build on this RCGroups thread, although it hasn't been updated in quite a while. If you are interested in further information on this plane, your best bet is to read the RCGroups thread by the guy who designed it. If you are interested in my modifications (those that worked, those that didn't...), email me and I will see about updating this page with further information.
Here is an in-flight video taken September 1, 2007.
This video is slightly disappointing for several reasons. First, it appears the camera sets the focus when the video is first started and does not re-focus after throughout the flight. Since the camera was pointing at the grass several feet away when the video was first started, it remained focused there throughout the flight and the video is not well focused.
Second, the Getter was tossed around be gusty conditions rather more than I anticipated, making the video rather jumpy. When the motor is off, you can hear the servos when control inputs are made, and it is surprising how continuously one makes these adjustments. If I had known in advance this was going to be a problem, I would have tried to fly more smoothly and limit my control input to what was absolutely necessary.
You will notice also some dropouts in the motor power during the flight. This problem turned out to be some current-hungry servos (GWS micros) that were drawing enough current to briefly shut down the BEC. Peak currents for these servos was about 1.2 amps (for very short times, visible only on an oscilloscope). Since I was using two, that meant that the BEC would sometimes have to supply up to 2.4 amps! I have since replaced these servos with Hitec HS-81MG's and have had no trouble since.
Anyway, enjoy the video for what it's worth. I will undoubtedly try it again some time and know how to solve at least some of the problems.