Hello, Daggets!
I do not think that you want to turn an 11-7 at 15,000 RPM, unless you are looking to waste energy and make a lot of noise.
Seriously, the propellor tip howl and the energy wasted at such tip velocities is contradictory to good performance.

I think you will be best withthe following:
A 5S 4000 mAH ~ 5000 mAH battery (1/2 of a modern F3A pack)
An outrunner of Kv = 650 (like an Electrifly Rimfire 60 or Eflite Power 46)
A prop ranging from an 11-10 to a 12-12. Currents will range from 55A with the smaller prop to near 70 with the largest. Expect about 10,000 RPM.
The motors specified will weigh ~ 300 grams. The overall weight of the system will be between 950 and 1000 grams: compare this to a 60 / pipe / tank / fuel!

Regards,
Dean Pappas