I'm jumping into this thread *way* late so sorry if any of this was already suggested and I missed it. Here's my advice (I mean this in all positiveness!) Resist the urge to design a plane, resist the urge to design your own flight controller or communication board. Resist the urge to design a boat, or write a computer program, or develop a web site for all of this! Focus on building your first prototype with as much off the shelf stuff as you can cobble together quickly. Be flexible in with your requirements. You want to move forward quickly at the start. Your first prototype might only be 80% of what you want (maybe only 50%) but it gets you in the air doing stuff, gaining valuable experience, learning what works, what doesn't, what needs extra attention, what is easy, what is hard. From there, build your second prototype to improve on a few things that didn't work out as well in the first. Maybe now is the time to design your airplane, or maybe you realize an 8kg beast is a pain to transport and hard to launch and land in areas you would go to actually do work. A lot of people get to this point and decide to focus their energy on shrinking down the gear so they can use a smaller airplane. 6 months or a year from now you might want to design something yourself from scratch, but now you know exactly what you need, you know exactly why the off-the-shelf stuff isn't quite good enough, and now you are going beyond what the average person could just buy somewhere.
So anyway, that's my advice. If you want to develop a complex system to do a SAR task, build your first one as quickly as you can out of commodity parts and ready to go items. If you are lucky, 6 months from now you could be on iteration 2 or 3 and feeling like you are starting to have some things figured out and working. If you want to design a cool plane, design a cool plane. 6 months from now you have a couple iterations of a cool plane.
Oh here's a bonus tip!
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
(From my been there done that file ...) Please steer away from flying wings. Flying wings fly great as hobby planes, I have nothing against flying wings when they are light and fun. The problem is that when you load up your wing with gear and batteries it get heavy and really hard to launch. You'll want to make the wing bigger so you can put more stuff in it and suddenly you realize it's too big to hand launch reliably. So now you are spending the next 6 months designing a cool launcher (which probably doesn't work 100% perfectly every launch ... which means you've had to pause your project a couple times to build another flying wing.) Oh and your heavy flying wing is now fast with a high stall speed and needs a huge area to land (with a really flat long glide slope.) And I'm not saying you can't make a flying wing do all of this if that's what you really want, but your stress levels will always be high.
Oh, so when you do design your airplane anyway (like I would do too)
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
please be really careful designing it for impressive brochure numbers. You might want to fly at 50 kts, for 90 minutes, carry 'n' kg payload, etc. etc. The problem is that you can quickly end up with a plane that has very little margins. You might hit your target specs, cruise at 50 kts, but stall at 35 kts (which would make launch and landing extremely difficult and risky.) Consider a slightly less capable airplane, but one that is pleasant to launch, fly, land. Sometimes you just do what you have to do despite the risk or stress, but for 99% of what I do, I'd take 25% slower cruise speed and less range in return for something that is easy and reliable to operate.
Personally I want to build a fully autonomous foam board plane someday relatively soon. I built the simple storch, but it just felt a little too small and constrained for packing with avionics. Right now I'm flying to full size X-UAV's for work and I *really* like them as a general purpose work horse. I can hand launch them easily. I get > 1 hour flight time without breaking a sweat (longest flight is 77 minutes still with some battery to spare.) The talon isn't perfect for everything, but if you are hunting for a all around work horse as a project starter, you could do a lot worse ...
Here's one of my talons with an 8000mah 4S battery, a Sony A6000 mirrorless camera, with a flying weight of 7 lbs. It launches with not much more than a flick of my wrist:
Sorry for the long message, my fingers are in a typing mood tonight!
Curt.