Monday, September 26, 2016

REVIEW: Eachine QX90 Mini-Drone

This is my review of the Eachine QX90 micro-quadcopter.  The point that attracted me to this particular quad initially was that the receiver is directly compatible with the Frsky receivers and 5.8Ghz FPV Goggles like Fatshark.  The idea is that if you have this equipment and race drones already you can purchase one of these QX90's, bind, and your ready to fly.  I will start out by describing features I don't like or where the product falls short of my expectations and I will end on a positive note.

Box Crushed
The drone is shipped in a foam cutout the shape of the aircraft.  The block of foam is pretty tough to withstand bumps during shipment.  The plastic wrapping around the case was not durable at all and falling off by the time I received my drone.  Luckily the drone was fine and protected by the foam.  I'm not really into unboxings.  I don't care about the box something ships in so long as I receive the contents undamaged.

Poor Quality Flight Video
Like many inexpensive cameras the one on the QX90 does not handle significant changes in contrast well.  For example, fly into the sun and all the darker parts of the picture turn black.  As long as light levels within the field of view remain constant, which is almost never the case outdoors, the video is acceptable.

Motors Under-Powered
Hover is at 50% - 75% throttle depending upon how fresh the batteries are.

Batteries Too Heavy
My drone shipped with 680mah batteries which is too big for the aircraft.  The aircraft will fly with them but it's lumbering and not very agile.

Difficult to Tune
I have some difficulty tuning at first.

Now let's switch over the postive.  There's a lot of great things to like about this aircraft.  These are the product features I like the best.

$60 price point
Need I say more?  $60 is a very low price point.  The fact is you can pay more for a single component on a 250mm class racing drone than this entire drone.  If your on a budget, this aircraft is a serious consideration.  However, if your on a budget why would you have an Frsky transmitter and 5.8Ghz goggles?  I like the price point but it's a marketing play to experienced pilots with a fatter checkbook.  While I appreciate the low price point I will gladly pay double or triple the price for a high quality 90mm drone that fulfills all my exceptions.  May I'm too picky.

SP Racing F3 EVO (Brushed) FC
I really like that you get an F3 you can flash with Cleanflight.  In fact, you can also flash this flight controller with Betaflight as well with good results.  Using familiar components and software is helpful for tuning.  Although I noticed that Betaflight was really difficult to tune.  To get the aircraft stable requires far higher Integral and Derivative settings than I usually see on any my 250 quads.  I'm not sure if this is extra error is introduced by the motors, poor quality board, or perhaps it's an artifact of a short 90mm frame size.

Frsky Receiver
Super cool.  The Frsky compatible receiver is also an SBUS version.  SBUS is a little snapper than CPPM.

Voltage Levels Unknown
I really have no idea when I'm flying the QX90 what the voltage levels are and when it's time to land.  There is no buzzer on the aircraft.  I didn't notice a second antenna on the receiver so I don't believe there is any telemetry.  Probably the best to know when it's time to land, once you get your aircraft configured the way you like it, is to set a timer on your transmitter. Set an audible alert after 3-4 minutes of flight time or whatever is appropriate for your aircraft.

Ok, I have covered some of the features I don't like and some I like.  Now I'm going to tell you what I'm doing to improve my QX90.

3-Bladed Props
The aircraft ships with 2-bladed props and it's quite fast but a little difficult to control.  First I'm ditching the 2-bladed props and moving to 3-blades.  I don't care about the top end speed.  This drone has plenty of speed.  I'm looking for more precision flying in tight spaces.  On my 250mm acro drone I fly with 6-blades and it fly's like a Ninja, very locked in feeling and precise.

New Camera
Next, I'm ditching the stock camera and replacing it with a better after market integrated camera and transmitter.

I'm ditching the stock motors and going with a set of 3.3v 17k rpm high output motors.  It could be this is not necessary and upgrading the props will improve flying.

I'm thinking the 680mah batteries are too big.  I had some extra 380mha batteries around that I used for a Hubsan X4.  When I tried these smaller batteries it seemed to fly better.  I'm not firm on this for now.  I still need to do more testing.

Purchasing the extra gear blows the $60 manufacturer price point.  From my perspective I'm more interested in tuning this platform to make it fly more like my larger drones than saving a few dollar.  I like the idea of flying inside the house, super cool.  However, I really want something super precise I can fly easily down a narrow hallway or fly super slow and stable.  After I get my new gear I will post an update to let everyone know if this fly's better.

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