So you want a cheaper motor than Hacker, you want to use 5S LiPo, and you want to use a 16x8 prop. And you want the same power and thrust, using 4000mAh LiPo packs, as you have with the Hacker A50-14 S motor.</p>

-Just to understand the situation a little better, and to look at what might be the best Kv for a motor, I did some simulations using DriveCalc.
a: The first shows your present situation -using Hacker A50-14 S motor (Kv 424), with 16x8 prop, and 5S LiPo.
As you can see from pic 1 below, this produces:
50.6A; 935.8W (input power, not power produced by motor ..); prop RPM 6850; thrust 4.97kg;</p>

b: So what happens if we use a motor with a higher Kv -like Hacker A50-12 S (Kv 492), with same 16x8 prop and same 5S LiPo ? This is shown in pic 2. This produces:
78.3A; 1449W; prop RPM 7865; Thrust 6.8kg;
-Prop RPM is higher, because motor has a higher Kv; This higher RPM produces an extra 1.83 kg of thrust. Pitch speed is higher (96km/h) so the plane will have a higher top speed.
BUT: current draw is much higher, at 78.3A; The max current for this 12S motor is 70A -so this large current of 78A may damage the motor, especially if flowing through the motor for long periods.</p>

c: And what happens if we go to a motor with a lower Kv -like Hacker A50-16 S (Kv 378) -same prop, same 5S LiPo ? This is shown in pic 3. This produces:
37.9A; 700W; prop RPM 6257; Thrust 4.04kg
Prop RPM is lower, because Kv of this motor is lower. And this gives less thrust, by almost 1kg, compared to the 14S motor.
Current is also lower (and input power is lower at 700W) -so flights will be longer with this set-up (for a given capacity LiPo pack) because the rate at which the LiPo pack is discharged is lower.
-This lower Kv setup is probably best with 6S LiPo.</p>

d: And this is what is shown in pic 4; This Hacker A50-16 S setup with 6S LiPo produces:
51.4A; 1141W; prop RPM 7249; 5.65kg thrust;
With 6S LiPo, current is now back up around 51A; prop RPM is increased with the higher voltage of 6S LiPo, and we have a higher thrust of 5.65kg.
Compared with situation a, with the 14S motor and 5S LiPo, the current draw is about the same. So the LiPo pack will be discharged at the same rate. However, the LiPo is now a 6S pack, and will be heavier than 5S. Thrust for this set-up is higher than for the 14S motor with 5S LiPo.</p>


<span style="font-size: small">SO: What does all this tell us?</span> Apart from a lot of navel-gazing ?
I guess it tells us that if you want to continue using 5S LiPo, with a 16x8 prop, and if youwant to have the same power and thrust as the Hacker, then you will need a motor with a Kv around 420.
The maximum current for the Hacker A50-14 S motor is 70A and max power is 1700W; its so-called "operating current" is 45A - https://www.aero-model.com/8_69_901/...-14S%20V2.html
-So current for any motor needs to be kept below 70A, and probably around an "operating current" of 40 to 50A.
The simulations show it is clearly best NOT to use a motor with a Kv as high as ~490, 500 with 5S LiPo and a 16x8 prop -because this will draw too much current.

It is also worth noting from these simulations, that the thrust values are quite impressive. The Hacker A50-14 S motor with 16x8 prop and 5S LiPo is calculated to produce 4.97 kg of thrust, and for an aeroplane with 2.7kg flying weight, this is close to a 2:1 power to weight ratio. A set-up using a motor with a Kv around 420, and this prop and 5S LiPo, is bound to give sparkling performance to a plane like the Angel 50.</p>