Hi, from a newbie in duct fan.
With standard prop planes, i usually power/prop them to have more thrust visit weight.
Exemple: 5lbs racer plane, with ±7lbs thrust and prop pitch of 8 or 9 = ±140 mph and more.

With ducted fan Im lost?

Here my setup:

Neu motor 1521 (780kv)
Castle creation HV 110A
2x 35C 6S 4000mAh (45volts)
4” (101mm) modified Haoye fan (intake lip, balance rotor, motor mount reinforcement)
I push this setup easily over 3000 watts, and with fresh lipo it stand between at 3600, 4000 watts. No overheating at all (ok, zippy lipo start to puff a little! need to change them for 35 or 40C)

I put an intake lip and a 85% fsa thrust tube (6" long), it give me 9lbs of thrust full throttle.
Without the thrust tube, I get 11.5lbs of thrust.

The airframe is big and massive but clean (I will post pictures soon), its a 70 inch upper wing configuration , no retracts.

9lbs of thrust visit 9lbs ready to fly weight, what should I expect from?