building a long range kwad – iFlight XL7 Lowrider frame – 2021 update

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  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  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 😉

 

 

around 10-11mins of flight time with 2700mah 4S

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.

2020 Version with Racestar 2507S Motors

2021 UPDATE

Problems encountered with 2020 Version

  • some electrical Noise in video transmission
  • hard to find a good tune – probably because of the noise
  • 4K recordings were not perfect due to microvibrations/noise
  • not as powerfull and efficient in 80-100km/h cruising as expected

Watching KababFPV’s Review of the Racestar/T-Motor AirA 2508 Motors i came to the conclusion that nearly 900g all-up-weight is too much for the cheap 2507 motors and i have ordered a set of 2508 AirA Motos together with a new 4-in-1 ESC by T-Motor, the Velox 45A.

 

 

 

parts used in this build

2021 version new parts