building a long range kwad – iFlight XL7 Lowrider frame

after some awesome mid range adventures with my Minibigger 7 inch build my thoughts went on how to improve range, efficiency and picture quality. As you can see on the recordings my Minibigger build has some issues with camera jello and vibrations issues starting at 50% and more throttle. I’m not quite sure where they come from but i guess it has to do with the rather small but powerfull AMAX 2306 1800KV motors i am using in the Minibigger 7″ build. Paired together with an rather light 4mm narrow armed frame.

Maybe i should do another try i thought and did use some dark winter nights on making a plan on how to improve. INAV developer Pavel Spychalski confirmed my thoughts in his vlog that a motor with a bigger stator should pump out comparable thrust and probably even more torque with less vibrations on the frame.

Researching for motors bigger then 23xx was a bit disappointing – there are few and most of them are expensive and have less thrust then my 2306 motors. Finally came to the decision that i am going to try out cheap Racestar 2507s motors as they at least in theory meet my criteria – good torque/thrust/efficiency balance for 7 inch props and for about 35€ for a set of 4 even a good balance for my wallet 😉

I went for the IFlight XL7 Lowrider V3 frame with 5mm slim arms and 22mm stand-offs only with the plan B to replace those with 28mm standoffs if things don’t fit inside. Unboxing impressions were really good, no extra sanding needed. Only weak things were the screws – really soft metal and had to replace some with harder screws.

We will see if the narrow 5mm arms will survive any crashes – i’ll keep you updated. At least the slick combination of narrow arms and the new DYS Aria 40A ESC should optimize airflow and therefore efficiency

The heart of my new cruiser is the Matek F722-SE flight controller with dual gyro and dual camera switcher. It hast 5 Uarts an 8 Motor outputs – so you could have an extra 4 softserial ports if you run a quadcopter with it, more than enough for anything i could imagine to attach to it. The power of the F7 processor makes it quite save for future firmwares and features such as rpmfilter, dshot1200 or whatever might come in the next years.

Out of curiosity i did implement the “park assistance” a.k.a “cheater kwad” feature mounting a micro kwad cam in the rear. That lets me actually fly backwards and see where i go – which might be usefull for some 4k shots in low altitude flying through obstacles where people are moving around so i can’t reverse them in post production. The cam is mounted between the GPS module and the long range R9 antennas. Switching is easy as it is on “user2” flight mode in the modes tab in Betaflight. I acutally don’t know if INAV supports it yet – better ask Pavel 😉

I’m running betaflight dev build from 4. march 2019 at the moment and upgraded ESCs to blheli32 32.6
After upgrading ESCs from 32.4 to 32.6 i had some strange issues on bootup that ESCs did not beep synchronous but sometimes, not always in an asynchronous way – which made me a bit nervous for the maiden flight.

So, on 9th of march i did the maiden together with my mentor “Lötmeister B” holding hands. And yeeeehhh it flys! Even smoooth and fast and perfect VTX Signal a good half kilometre away on 200mw. Outside and battery temp were around 5 degrees so i had some voltage sag doings punch outs and felt a bit like the top end of the motor was never reached. Anyway, flight time was around 10 min including some punches and fast flying, even some freestyle.

so whats next? got to do more testing on an open field before going serious – motors and battery came down ice cold on the maiden flight with stock betaflight 4 pids – so i suppose there is some hidden power not yet released in this setup. Also got to check out why i had wrong voltage readouts and tasmanian devil like behaviour when i tried to do a 5S flight – i suspect it has to do with the betaflight 4 dev build or the latest blheli32 update to 32.6 as all components i have used are rated up to 6S.

stay tuned, i will update this page in the next weeks and post some flight footage as soon as winter steps back.

parts used in this build

some test flight footage, still needs clean PID/filter tuning