Hi folks, wonderful resource. I'm a total new comer to RC flying, but a seasoned amphib ultralight pilot. I started to ponder AP platforms for shoreline surveys on long remote lakes a while back, as part of my hydrographic survey work. I stumbled into DIY Drones from Sparkfun, looking at arduino stuff. My jaw dropped at the possibilities as I spent a few days combing SPAD and RC based AP. I've been lurking awhile here now, and finally decided to pop a few questions.
My target concept is to fly a good digital SLR plus a precision survey GPS + antenna (2cm accuracy), plus telemetry and control / autopilot / live video hardware. Maybe 3 to 4kg total. I am thinking about flying off the water, because we work from boats anyways, and would be line of sight at all times that way. With the precision GPS, I hope to be able to switch from RC control for takeoff & landing, to fly autopilot for reasonably accurate survey flight paths, given good weather of course.
1. For lift capacity, I can't help wonder about wing design trade offs. Are sailplane / glider wings a good choice for their high efficiency? Multiplex Cularis has huge wonderful looking wings at 852 sq.in., and I can't help wonder why they wouldn't be perfect for any DIY drone build. At $115 a set, they seem like a nice off the shelf solution to a common need (good wings).
2. Then again, there is the wonderful world of SPAD. I wonder if great wings couldn't be built using carbon fiber spars, foam ribs (to enforce profile), and thin (2mm) coroplast for lightness. Is there a weight issue with SPAD construction in general? Am I missing some major drawback that everyone else just knows about already?
3. Aspect ratio? High or low, and why? I note that high aspect can give more efficient wings, and would think that high lift with low drag would be a common target.
4. I am interested in very slow flight: is there a particular relationship between aspect ratio and stall speed here? Or is it just wing loading by area? What are the main parameters that make for very low stall speed?
5. The weird question: How about multiple wings? My initial idea is to use two wings, one at the front and one at the back of the aircraft, maybe 4 to 6 feet apart. Would the rear wing be too impacted by turbulence from the front wing, or could it just be mounted higher? CG variation due to fuel consumption and equipment changes might be less troublesome, with greater trim-ability. The front wing could be a little smaller to give sensible nose first stall behavior. My initial airframe idea is a long pair of light aluminum angles spaced maybe a foot apart (kinda like SPAD on rails), which would allow for easy attachment of instrument packages / modules between the rails.
Well, am I crazy? Any links, appropriate search terms, thoughts and insights will be most greatly appreciated.