However if you allow for most of the journey to be done by sea and assuming your destination is relatively close to the coast and you do not care if it takes ages, then you could transport a small aircraft in one of those passive sea drones that navigate using variable buoyancy by gliding underwater to a set depth, before going back to the surface again for a recharge and gps check.
Flying over terrain is hard. Wind shear is a huge issue (I've seen situations where there was a 20 knot wind at ground level and still air at 100 m) as is turbulence and stuff in the way (trees, rocks, mountains...)
I've often wondered if a combination of storage batteries and solar panels could give you unlimited range (for some part of the Earth, at least, during some times of the year: high latitudes in the summer, say.) A high altitude design would also facilitate that, as power consumption could be minimized during the dark hours at the cost of losing some altitude (simply gliding through the night is not possible with any reasonable design parameters.)
The total cost of such a project would be low enough that I'm a bit surprised no one has done it yet.
See http://www.solarimpulse.com/en/our-adventure/solar-impulse-2
For non metric people, your proposition is calling for something to be able to transport a package around 2lbs approximately 9,000 miles.
Flying below radar has its own challenges, as described here: http://aviation.stackexchange.com/questions/2952/can-you-act...
Your real issue would be finding an efficient enough engine to fly that far with a few refueling points along the way, thus making the trip longer than what you're probably envisioning. This is why I'm assuming jeffasinger has proposed a blimp or some form of a blimp to get this accomplished.
Yes, it can be done, but with several caveats.
A couple of things:
- is it a mission that requires 1 continuous flight? That would be very difficult to accomplish. You need a lot of fuel to go that far, which in turn increases your mass, which increases your fuel requirements, etc. - speed requirements? How long do you want it to take? It may be possible to use a balloon and take advantage of wind + solar power. - size? route? service ceiling? None of these are defined very well so it's hard to say.
My guess would be it'll probably be very difficult to accomplish without being detected by someone.
http://www.popularmechanics.com/technology/engineering/robot...