So a while ago my dad went to a maker's fair and saw a panel about DIY Drones. He then got the idea that he could use one to survey the small orchard that we have(it's about 19 acres). It was his understanding that with this software it would be completely antonymous and he would only need to watch it fly.
So i have a few questions:
1. Given that the trees are 18 feet apart would a plane be able to make the turn to go down each row?
2. Is there a better platform for this purpose? I.E. quad-copter
3. What size plane will we need?
4. Where would I need to start?
Sorry if this seam like stuff I should know from the forums but I have looked a bit and there is just so much information it is making my head spin.
There are systems you can buy that are completely hands off but they're probably above your budget if you're just doing it for fun. The best way to accomplish what you're looking for is to use something based on Ardupilot which at this point still does require some ability to fly manually for takeoff and landing of a fixed wing plane and for the whole flight realistically for a quadcopter.
For that small orchard you could accomplish the task with a quadcopter or small fixed wing like a Bixler. A Skywalker is a little easier to work with because of the size of the internal compartment but both could work. My mapping platform, the E382 at Event38.com, is based on the Skywalker and can map over 200 acres in an hour at 5cm resolution. You don't need to go down each row individually unless you specifically want to see the ground between each row. If you want to build the platform yourself, start with a Skywalker or Arducopter 3DR-B and an APM and work from there. Sounds like a great project, you're sure to have fun doing it!