iFlight 7" 4S F40pro II 1600kv Crossfire Long range

By HalfFPV on Mar 28, 2018

48  6,660  19

I want to build a 7", I did alot of research about what motor to use, its very hard to find thrust tests for this kind of motors. In the end I choosed t motor f40 pro II 1600 kv, I will see if they are efficient.
Kiss24A ESC I thing I will bypass the current limiter, I have a friend that flies like that for a long time.
I will use a 2400 mah 250g battery and a 3700 mah 340g battery

I just ordered the parts, Now I am waiting.

Update 28.03.2018
Arrived most of the parts and I started building. I am still waiting for a cable for the FPV system and the gemfan 7042 props and hq 7x3.5x3.

Update 09.04.2018
I finished the build and used the HQ 7x3.5x3 props. I had a tone of problems with some weird twiches when punching the throtle, the quad will dip a corner or dip the front.
The flight time with a 1300 mah 4s is 6 minutes (average of the many flights I did tunning), at full acro, no throtle management at all.

This video is in day time, best tune yet.

The video may look super smooth, but this is because its night and the shutterspeed is low. I have a lot of oscilations, that I can't get tunned. At mid throtle moustly.
With throtle management and slow fly, I can get 10 minutes with 1300 mah 4s.

After a lot of tunning and changing FC's and ESC's, I could get a decent tune, but still had oscilations. Then I wanted to see what the motors are doing, and run them in the motors tab on the bench with props off, they were all vibrating like crazy past 50% throtle. I did not crash, the motor just went bad very quickly, one week fo use. I contacted T motor, but they said that this is my problem. :|

I think I will buy some TBS endurance motors, and try with that. And some hq 7x45x2 props, maybe some 6" props for testing.

Please note: I tried gemfan 7042, and they do not fit on this frame, unless you take the front standoffs off, and still then it will hit the top plate a little and dent the prop.

Update 12.04.2018
So t-motor support just ignored me, I send them an email with the details of my problems, they responded with "Can you check with your PID", reply to them with that I did and the motors are the problem, never heard anything back from them.
So I proceeded on balancing the motors myself, and had some good results.

I ordered some hq 7x4.5x2 props to try out, they should be here by friday.

Update 18.04.2018
Tested the hq 7x4.5, but I still have some oscilations, I ordered a prop balancer
to balance the props, we'll see if that solves all the oscilations.

Update 11.05.2018
I did some more tests after my go pro replacement arrived. I was thinking what else to change for this build towork, and then it hit me, I was running reversed props, because the hype was that its better, the hype was wrong. After changing the props to some new hq 7x3.5x3 props and changing the FC and motors back to normal rotation and put an ND8 filter to the go pro, It flew amazing. Check the video: https://youtu.be/Gv9YLYMxZzY?t=36s

I am pleased enough with the result, and I will leave it here. Because I am going crazy. :)

Update 22.05.2018
After flying with multiple batteries, i can say the sweet spot is 2200-2400mah 4S.
Tattu r-line 1300 95C 4S - 6 minutes
2x Tattu r-line 1300 4S - 8 minutes
Zippy 3700 mah 35C 4S - 11 minutes
bolt 2400 mah HV 4S - 10-11 minutes

Update 06.05.2019
So, long time no see. I switched the frame to Reverb 7", the shakes were still there, but eventually I got rid of them somehow...
I balanced the motors + props and I'm using an ND filter, the footage is much better.
Also changed the ESC to an 4in1 35A so I can use 6S battery.
I am using a Li-ion 6s 3000 mah VTC6, I get like 15-25 min flight time. Depends on the weather conditions and weight of the quad.

Update 06.08.2019
I changed to HQ 7x4x3 props, feels much better. Added some 3d prints and hero 7. With hypersmooth the video is so nice, no more shakes or headaches.
I added some new pictures.
How it looks now:

Update 12.09.2019
The HQ 7x4x3 props i chanbged the other month, I have more control, so better for freestyle, but they are not as efficient as the HQ 7x3.5x3.
I tried 4s 3000 Li-ion with the hero 7 on bord.
HQ 7x4x3 = 15 min flight time (also the cells got really hot, dangerously hot) and with 4s2p li-ion = 24 min, cells at 2.5v
HQ 7x3.5x3 = 20 min flight time (the temperature was way way cooler than with 7x4x3, safe temperature)

With 7x3.5x3 I was using like 35% throttle and ended up at 50% by the end of the flight, because of the battery sag.
Battery was down to 2.8v/cell. I did not look check the throttle for 7x4x3, but it was aprox the same, like enought to cruise slowly, no crazy speeds. I will post the raw HD videos from both flights as soon as they render.
Flight with 7x4x3:

Flight with 7x3.5x3:

With 6s li-ion 3000 mah and HQ 7x3.5x3 I managed to get 19 min flight time.
I think the sweet spot for this setup is 5s, because back when I started I used a 5s li-ion, and manage to fly 26 min with a go pro session 5.
I will be building a 5s pack soon and test again.

If you have any good info, please comment below.


Part List


Impulse RC Reverb Frame 7" (3 builds)


XL7 V2 Long Range FPV Freestyle Frame (9 builds)

Flight Controller

KISS FC V2 - 32bit Flight Controller (62 builds)

Flight Controller

KISS FC - 32bit Flight Controller V1.03 (6 builds)


Aikon AK32 V2 32Bit 35A 2-6S 30x30 4in1 ESC w/ BEC (37 builds)


KISS ESC 2-5S 24A Race Edition - 32bit brushless Motor Ctrl (10 builds)


TMotor F40 PRO II - 1600KV (35 builds)


HQProp DP 7X3.5X3 V1S PC Propeller (Set of 4 - Black) (17 builds)
See Site

FPV Camera

RunCam Micro Swift 2 2.3mm Lens FPV Camera - $36.69 |GearBest.com (282 builds)

FPV Transmitter

TBS Unify Pro 5G8 HV (SMA) (596 builds)


Team BlackSheep TBS Triumph Antenna: SMA (7 builds)


TBS Crossfire Nano RX (SE) (412 builds)
See Site


12 x 18650 Murata (Sony) VTC6 li-ion akkukenno - Ei suojapiiriä - Flat-top (10 builds)

Power Distribution

Lumenier 4Power Mini PDB (21 builds)


FrSky TARANIS X-Lite (Black) (65 builds)
See Site


Fatshark Dominator HDO OLED FPV Goggles (137 builds)
See Site

HD Camera

GoPro HERO5 Session (303 builds)

Radio Module

TBS Crossfire TX (16 builds)
Show stores (13)


Sign in to comment

vbp6us   Oct 05, 2019  

Such an amazing build! Great job and thanks for sharing.

HalfFPV   Oct 24, 2019 

Thanks for the support!

Alpha   Apr 25, 2019  

do the 7 inch props always get in view of gopro ? (like this in your video https://www.youtube.com/watch?v=V-jl9A6FoEI&feature=youtu.be&t=50s ) ?

HalfFPV   Apr 27, 2019 

Hello, no, in that video the gopro mount angle was too low. Check out the latest video:

Here I have 30 degree mount.

elexFPV   Feb 12, 2019  

Very nice and clean build! And also very inspiring, cause I also want to build a 7" LongRange. Thanks for sharing!
By the way... I love that motorpigtails. Flying viking ship! ,)

HalfFPV   Apr 06, 2019 

Thanks! Today I tried to beat the old record, I did 7.5 km out. I will be posting the video soon on youtube. www.youtube.com/halffpv
Edit: check the updated description, I added the video link.

HalfFPV   Jul 06, 2018  

I can't edit this, idk why.
Do not buy this frame (iflight v2 xl7) because you can't fit most 7" props on it. Like dal 7056x3, gemfan 7042x2.

freerider101   Jan 24, 2019 

How about the v3s?

HalfFPV   Apr 06, 2019 

they fit :) sorry for replaying so late

Skygarage.de   Aug 08, 2018  

Did you try 5s at all?

HalfFPV   Nov 26, 2018 

Sorry for the late reply. Yes, 5s li-ion 3000 mah 25 min flight time, very slow. And with 6s li-ion 3000mah for some reason, only 20 mins.

warpout   Jul 03, 2018  

Hello, what is your dry weight with gopro?

HalfFPV   Jul 06, 2018 

Dry weight is 411g. AUW is 750g, with 2400 mah and go pro session 5.
The battery is 248g.

so dry weight with go pro is 502.

ICEMAN   Apr 19, 2018  

Any vibrations with the 7" props?

HalfFPV   May 07, 2018 

Yes, but i'm not sure if the motor or the props are the problem

leigerreign   Mar 31, 2018  

Looking forward to your results! Is this a 4S build?

HalfFPV   Apr 09, 2018 

yes, 4s

Currently   Mar 28, 2018  

Nice and tidy :)

HalfFPV   Mar 29, 2018 

Thanks, I hope its going to fulfill my expectations :D

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