So I am building a electric combat plane to fly in the Air to Air combat (http://streamershuttle.blogspot.com)
So I have a Russian combat plane (very light) and I installed a Hacker A30-18M with a KV of 2900 or maybe 2850 50amp draw. I had this motor laying aroung.
It is recommender running a 3S battery but that puts me in the RPM range of 30K,
If i run a 2S I am in the 21K.
The contest is for 5 minutes and a max speed of 75mph.
Bob Mears is winning the series at this point (there are gas and electric, check out the rules) because Bob get max points for flying an electric profile plane.  Anyway he make a pit stop can changes batteries.  He says he usually get more points than is gas counter points because of the engine runs.  OBW Bobs a great flyer. 
So what do you think will work the best with my Hacker?
11.1 or 7.4
What prop would you start with?

I had some success with a Russian wing using 1350 to 1400 Kv motors turning a 7 x 6 APC E prop at around 14 500 rpm. I used a 4S 1300 lipo although it was actually 2 x 2 cell packs because I could not find a 4S pack here. I put one pack inside each leading edge to get the CG a bit forward. It gave me 3.5 second lap times on standard FAI line length of 52' 3", and 3.8 secs/lap with a streamer. I tried a 8 x 6 prop as well and it goes much faster, down to 3.2 secs/lap but it turns slower and flies for a shorter time. I get our required 4 mins on the 1300 4S pack but then there is only 12% left in the battery, so I guess that a 4S 11500 pack would be better. For a solid 5 minutes, maybe you'll need a 1800 mAh pack.

My esc was a 30 Amp type and I used one of my Compact timers. For my WW2 profile combat planes, I use the same 1400 Kv motors but turning an 8 x 6 prop on 3 cells. That's fast enough for WW2 combat.

Keith R