I was a little hard on my initial QX90 review, REVIEW: Eachine QX90 Mini-Drone. Before I dive into the details the QX90 will fly out of the box but it flies even better with a few enhancements. If you fly racing quads like me you have a good understanding of electronics and how to use a soldering iron. These improvements will be easy for you. This post covers the parts I choose, where to purchase them, and my impressions of the flight characteristics.
After the review I began to think about what it would take to get the Eachine QX90 micro quad to fly better. Here are some parts I purchased frm RC-Drones.com. These guys ship really fast and even put a personalized, "Thank You!", note in the box. Who does that? Nice touch. The following are the parts I purchased.
CL-0820-17-11T Gear CL-0820-17-11T Dark Edition Coreless Micro Motor Set(4)8.5x20mm $34x1 = $34
PROP-HUB3BLADE Hubsan Style Black/White 3-Blade Micro Props For The DP03 Brushless Motors (8 Props Total) $6.00 x 4 = $24
3.7v 750mAh 25C Eachine LiPo (purchased separately from Bangood)
I wanted to get new flight camera but I noticed after I ordered the micro camera was made for 5v systems, not 4.2v-3.3v (or 1S). The camera specs are definitely close and if I try it I will post the results. Taking off the old motors and soldering on the new motors was a snap. I didn't want to take the drone apart and solder the new motors to the board. Instead, I went for the easy approach, on the stock motors I cut the leads about 1cm from the base of the motor and tinned the wires. Next, I cut the long wires on the dark edition motors about 2cm from the base. I wanted to give myself some extra room if I happen to cut through the leads when I trim the insulation off. The new dark edition motors are the same size as the stock with the exception that the shafts are shorter. Still plenty of room to the 3-bladed props on.
When I was flying stock motors I switched over to 380mAh cells. These are the same size cells flown on the similarly sized Hubsan X4. After you mount the new motors and props the first thing you will notice is that the aircraft is sluggish and does not perform. The 380mAh cell does not have enough power. I switched over to 750mAh cell. The video Pimped QX90 is a video I made flying the dark edition motors, 750mAh cell, and 3-bladed props.
I don't recommend flying this aircraft in too much wind but it's loads of fun. Mine still needs some tuning but it's definitely running well enough to fly and have some fun. I don't believe this receiver has telemetry. I can set a timer on my transmitter but I would feel better with a proper low-battery sensor. The crash at the end of the video was due to a blade breaking off on one of my 3-bladed props which was weakened from a previous crash.
Crazy cool! Amazing aircraft and loads of fun.
October 7, 2016, quick update. I'm noticing the new motors get fairly hot between batteries. I tried going back to 2-bladed props. Seems to fly well on the 750mAh battery. A made another video of some flights on the QX90. Flies much better. This aircraft is not like flying your 180mm/250mm quad racing drone but it's still great nevertheless. Still it takes a few modifications and a far amount of tuning. Spoiler alert, I almost got my QX90 run over by a car, lol.
October 16, 2016, I have stabilized on the stock 2-bladed props with the dark edition upgraded motors and upgraded 750mAh battery. This provides a flight time of around 3 minutes. There is no telemetry with this flight controller so I set a timer to count down from 2.5 minutes when the throttle is engaged. This gives me audible warnings so I don't damage the batteries or loose the aircraft.
Photo: Betaflight 3.0.0 PIDS and gains(click to enlarge)
Following is a video I made with the new pids. It feels very locked in to me. Almost like flying a 250mm quad but not quite as much power.
A big benefit of these micro-quads is that they can be flown almost anywhere. The modified aircraft comes in just under 40g without the battery. So although the aircraft flies fast (40-50mph) danger to people and property is very low.