I am starting to test a RQ-11 from Nitroplanes with a E=-Flight 15 outrunner, 50A ESC, APC 9x7.5 composite propeller and a 3300mAh 30C lipo battery.
I found the flight duration very short and I am asking someone who already have made some experiences, looking for the longest possible range.
I am running e-flight park 480 1020kva, parkzone 3 blade 9x7.5 prop, castle 56 esc, turnigy 2200mah 3s 20c batt
I had a 25 min flight at about 1/2 throttel carrying a second battery and fpv gear. not shure what auw is
MY opinion is this plane is not a very good fpv platform. no glide, very twitchey not stable and smooth, have had to reglass the bottom from landing the fiberglass is very thin just one layer, ripped the horizontal stab. off, landing in grass, now its sold sheet balsa. I do not think the plane will last many flights. my friend skidded his wing tip on landing and ripped the wing off at screws and cracked the fiberglass around them on his first flight.
It seems as though your model is slightly overpowered. I looked at the specs for the RQ-11, and if its this one it only calls for a 20 to 30 amp esc which means that a outrunner 400 to a 480 would probably do just fine. the 400 consumes about a third of the amps of your 15, which would definitely increase your flight time if used. You might consider getting a larger capacity battery, but for airfoils there is a maximum amount lift they can provide so your plane might not even be able to carry a larger capacity battery.
now that Ive talked your ear off here's my diagnosis =)
Your 15 may make the plane go faster, but it sacrifices power and lots of it, so i would try something smaller like a 400 or a 480. It may fly a little slower, but it would definitely have a longer flying time.
If you have extra money to throw away, i would even try a larger capacity battery and see how it handles the extra payload