Im planning to build a long range fpv quadcopter with a GPS system and I need your advice! I want the drone to be capable of flying for approx 15 minutes with approx range of 4km (Maximum speeds of 60mph would be nice, althought Im not too concerned about speed). I want the drone to be able to perform, Return to Home, Hold Position, Hold Attitude and of course Acro Mode. Im still debating as to what FC should I use, Im currently torn between Naza V2, Pixahawk, or F7 Board + M8N with INAV. Any advice regarding the FC's would be greatly appreciated as Im extremely puzzled... I want the drone to be precise and perform its functions, and at the same time I dont want to overkill the build and waste money.
This is the sample setup I have created.
FC: Naza V2? Pixahawk? F7 + M8N?
Frame: Lumenier QAV-R2
Motors: iFlight XING 2207 1700KV
ESC: Aikon AK32 35A 4in1 ESC
Battery: Turnigy Nano-Tech 4000mAh 4S 30C Lipo Pack
FURIOUSFPV TRUE D 2.4GHZ DIVERSITY MODULE
Furious FPV Stealth Long Range 2.4GHz VTX
+ Fatshark's HDO
RC:FrSky R9 868MHz 16CH Long Range Receiver & R9M Module System (EU LBT)
I already own Taranis X9 Lite.
My 2-cents is go with the F7 + M8N or the Beitian GPS module also seems to be working well for me here with a hexacopter. I thought originally bigger would mean more flight time and I do actually get longer flight times out of the hexacopter build but I'm still not sure where the balancing point is really with regard to size (it seems micros will never have the lift to weight they need with the tiny props and needing to still have receiver FC etc. that can only be made so small). Anyways personal opinions and anecdotes aside there is an article here that seems to go pretty in depth on increasing flight times:
While most drones have a flight time of 10 mins, it is possible to achieve much greater duration with good planning and component selection. Here's our layman's guide on how to achieve long multirotor flight times.
Regarding trying to calculate your flight time suggest checking out ecalc.ch, unlocking is worth the price when doing DIY builds:
Regarding things you'd like it to do functionally I think it can all be done with iNav, just about to start digging into that myself though and got my hexacopter (tarot 680 pro based build) flying with a 4k camera on there and GPS hooked up. I activated return to home on betaflight and am getting good GPS connection and compass seems to point home so I think everything is pretty good with the Beitian module (the ublox M8N one I had I decided to ditch after seeing how many clones there were and being very suspect mine was a clone based on the label), anyway the Beitian 880 module gets a lock on satellites pretty fast so I'm happy with it. Lots of gotchas along the way setting up GPS on betaflight but I figured use this first since I sort of understand it at least and then switch to iNav once things are flying.
Also regarding using acro mode on it I would stick with betaflight for that since it's geared towards acrobatic and racing flying then just flash the board with iNav when you want to use GPS/waypoint mode, I think really you want two quads one for acro and one for GPS stuff but you could do both if you get a board compatible with both (I have the Kakute F7 that I think will work with both, but again yet to flash iNav on it)