Update 3/26/2017 – Gearbest is finally stocking parts! See below.
The KingKong 90GT is the best micro FPV quadcopter I have ever flown. That’s a strong way to start this article, but it’s the best way to convey how impressed I am with this tiny quadcopter.
Over this winter, we’ve had the chance to test and review several FPV microquads, including the Eachine QX90 and QX70, the Blade Inductrix FPV edition and, of course, the Tiny Whoop. We’ve had a blast with all these little toys. They are a fantastic way to keep your flying chops up to date over a cold or stormy winter such as the one we had in California this year.
Thing is, after flying “whoop”-style quadcopters for a few months, I was ready to hang them up so that I could get back out to do some “real” flying. These little guys are fun for indoor obstacle courses, but their tiny brushed motors and 1S batteries lack the power needed to do anything but forward flight. Even indoors, where power isn’t a huge deal, I get annoyed by the fact that they need 2-3ft to recover from a power drop.
Enter the KingKong 90GT
KingKong 90GT Review
As luck would have it, the first whoop-sized microquads to have brushless power systems hit the market just as the temperatures are starting to warm up this year. The KingKong 90GT is the first one I have been able to get my hands on – and what a blast it is! This is the first microquad I feel equally comfortable flying indoor and out. I can shoot small obstacle courses a la the “tiny whoop” videos, and then fly out an open door and do gravity flips down trees in my yard.
As a Spektrum guy, I received the DSMX-enabled variant of the 90GT. It came in a nice plastic carrying box with a variety of accessories. Included with the quadcopter is:
- The RTF quadcopter, including motors, ESCs, flight controller, frame, FPV camera, VTX and DSMX receiver.
- 8 Props (4 of each direction)
- A battery
- Plastic prop guards
- USB micro cable for programming flight controller
- Prop removal tool (which I found unnecessary for this quadcopter)
- Flight controller connector which could be use to connect FC UART ports to accessories
- Extra screws
- Extra rubber band to hold battery
This quadcopter was provided to us, on our request, from Gearbest. We want to sincerely thank them for giving us the opportunity to try this copter out. You can purchase the from them here. We have always had a fantastic experience working with Gearbest, especially their lightning fast shipping. We don’t think you’ll be disappointed by giving them your business.
The number one feature of the 90GT is its brushless power system. This quadcopter is roughly the same size and weight as the Eachine QX90 but is capable of putting out more than three times the thrust on the stock power system. Not to mention the fact that brushless motors have virtually no wear factors – which means you will practically never have to replace them.
The flight controller on the 90GT comes from the factory preloaded with Betaflight 3.0. Frequent readers of this site know this is our flight control software of choice for it’s smooth flight characteristics and configurability. The ESCs also come loaded with BLHeli_S – another cutting edge technology which really leaves the options open for this quadcopter. I was pleasantly surprised by both of these facts. It means that the quadcopter flies great right out of the box with minimal software set-up. For those who like tinkering, it is also Betaflight 3.1 and DSHOT ready as we’ll explore later in this article.
The last feature this quadcopter has over the whoop crowd is that it runs on 2S batteries. That’s twice the voltage and twice the power available to a quadcopter that is otherwise the same size and weight as its competitors. You do need to own a real LiPo charger to charge the batteries though – no USB charging with this aircraft.
How does it fly?
The 90GT has about the same power to weight ratio as a 5 inch quad on 3S batteries. That is to say – it doesn’t perform as hot as a cutting edge 4S racing quad, but it has more than enough power to do some serious acro. Indoors, the extra power can be challenging to control, but not overly so. Besides, having a deft right thumb is really the key to becoming a fantastic drone racer pilot. Installing the optional prop guards really helps to tone the aircraft down, and makes it safer to boot.
Flying outdoors is where the 90GT really shines. It is at home doing loops over trees and laughs at most breezes, just like its larger brethren. That being said, my biggest problem with this microquad is that the designers didn’t build in the voltage margins to be able to fly with small 3S batteries. It can’t have been difficult or expensive to do and really would have offered some really insane outdoor performance that would have turned this drone into the ultimate trainer quadcopter.
Once I upped the rates from their stock settings, I found that flips, rolls, spins and inverted flight are very easy to perform on the 90GT. It has more than enough power to pull itself out of any dive – something that cannot be said for the Whoop or its clones. One thing I did note was that the copter retains the telltale “floaty” feel that all microquads seem to have. When you do hard banks, for example, the quadcopter has a tendency to pull up too fast and gain altitude. I believe the reason for this is that these microquads are so light that they don’t have the momentum going in to turns that a larger 5″ quadcopter has. Because I’m used to the big boys, I pull up more than I should, resulting in the “float”. So, in the end, this might just be a piloting problem, but I’m sure other miniquad pilots will notice it.
An extremely wide angle lens is used on the FPV camera. This is similar to many other “whoop”-style quadcopters. It is a bit disorienting to fly with this lens outdoors while doing acro. The bent angles make it hard to time your maneuvers if you are used to the narrower field of view of a bigger racing quadcopter.
Here is some acro footage taken from the DVR recorder on my FatShark goggles:
The KingKong 90GT is constructed in a fairly basic manner. The frame of the quadcopter is made of 2mm carbon fiber. The electronics stack is mounted directly to the frame with a set of plastic standoffs and screws.
The 4-in-1 3A BLHeli_S ESC sits on the bottom of this stack. It is directly soldered to the flight controller sitting on top of it with a set of pin headers. I was a bit disappointed by this because it means replacing either the flight controller or the ESC will mean doing some tough soldering work. I’ve ruined my fair share of electronics trying to desolder pins from holes. The 4-in-1 ESC provides contains a voltage regulator which provides power to the FC, video transmitter, and FPV camera.
The flight controller sits directly above the ESC. It appears to be an SPRacingF3 clone that has had it’s footprint significantly reduced. It has a set of pin headers for hooking in the ESC signal inputs and a cluster of micro JST connectors which contains the inputs for the rest of the features on the board. (UARTS/buzzers/VBAT/etc) You can access these inputs using a cable that is provided with the quadcopter. I don’t know how you would expand this micro quad being that it is so compact – but the option is there if you want to try! The board also has a bootloader button. Yep – the feature that even many “big”, “expensive” flight controllers can’t fit on their board for some reason. This nano FC has it and it works great. Thanks KingKong for not making me do a voodoo dance with a pair of tweezers!
A second 2mm carbon fiber plate is secured to the top of the flight controller with 4 screws. The FPV camera is super glued to this plate in a fixed, “straight forward” orientation. The lens extends out from the frame by quite a bit, leaving it pretty vulnerable to getting scratched or damaged in a hard crash.
The video transmitter is stuck to the top of this plate with double sided tape. I wasn’t able to figure out what kind of video transmitter this was – it’s a really odd looking one. It is extremely small, about half the size of an LED strip. It is protected with heat shrink and gets pretty hot while the quadcopter is turned on. A zip tie on the back of the frame top plate supports a linear dipole antenna, which is attached to the video transmitter. It has been shown that for close range flying, this type of antenna more than suffices and saves a lot of weight to boot. A good call, if you ask me.
In the RTF variants of the quadcopter, the receiver is stuck to the bottom of the main frame with double sided tape. The receiver antennas splay out along the legs of the quadcopter. This is not a great location for long range radio reception but should work fine when flying within a quarter of a mile or so. I would expect the video reception to go out before the radio control link. The RX itself was unlabeled – some sort of Spektrum clone. The box the 90GT came in said that the RX was “DSM2”, but when I bound the receiver to my TX it showed up as a DSMX receiver. Same went for programming it into the FC.
The battery is held against the RX on the bottom side of the frame with a large elastic band. A spare band is provided with the kit, though I can’t see the one that comes with the quad ever breaking. The battery is a 2S 350mAh battery that hooks into the quadcopter using the balance port. A charger is not included with the kit so you’ll need to have your own LiPo charger. With the stock battery I’m seeing 5 minute flight times indoors and 2-3 minute flight times outdoors. This quadcopter can easily support a heavier battery. I would feel comfortable moving up to a 500mAh battery to get more power and flight time.
The props that come with the quadcopter work great. Unlike the QX90, they have some semblance of balance to them from the factory and I didn’t have any vibration issues out of the box. They are made of very brittle plastic, though. If you crash onto a hard surface, you are sure to break the blades. I recommend you purchase some spares when you buy the quadcopter. They can be purchased from Gearbest here.
All said, I found the build quality very nice. None of the components are flopping about and everything seems tight and well built. I have no doubt this thing will survive some crashes. My bet is that the FPV camera lens is the first casualty, though.
There are a few options for replacement props and batteries you may want to consider, please find links below:
Any 2S battery between 250mAh-500mAh will work. This quadcopter can carry some extra weight if you want to get a bigger battery. This quadcopter uses the battery balance lead to get power, so make sure the battery you buy has one. When searching for batteries, it was helpful to search for “E-flite UMX 2S battery”. The batteries the UMX planes use are compatible with this quadcopter, and there is a good selection on the market. Here are a few:
$21.41 – Venom Fly 30C 430mAh 2 Pack (Amazon)
$13.27 – E-flite 430mAh 20C (Amazon)
$4.63 – Turnigy Nano-tech 300mAh 35-70C (HobbyKing)
The stock props that come with the 90GT are pretty good, but you can eek more performance out of the quadcopter by buying some upgrades once you’ve broken them. We’ve had the best luck searching for “1935 props”. That’s 1.9″ diameter, 3.5″ pitch props. There are a lot of vendors out there offering these types of props. Here are a few notable options:
$5.75 – 20x stock props (Gearbest)
$20.00 – FuriousFPV transparent 4-bladed 1935 props x 16 (Amazon)
$8.99 – RJX 3-bladed 1935 props x 10 (Amazon)
KingKong 90GT Setup Guide
Assembly and set-up
There are only two things you absolutely have to do after unboxing the 90GT before you can fly:
- Bind your FrSky or Spektrum transmitter to the quadcopter. For the Spektrum models, you can put the RX into bind mode by simply holding down the button on the RX while you power the quadcopter on (or plug it into a USB port). Then bind like normal. I imagine the procedure for the FrSky models is “as normal” too.
- Insert the props and screw them down. Unlike other microquads, the 90GT has props that actually screw into the motors. I really like this design – it feels a lot less hokey than the Inductrix clones.
Those are the things you have to do. In reality, I would have crashed my quadcopter badly if I hadn’t first run through the Betaflight set-up process before attempting to fly. Our extensive quadcopter software set-up guide works perfectly on the 90GT. If you don’t want to read through that guide, here are the items I found that needed correcting (in Betaflight Configurator):
- Configuration tab. Set “minimum throttle” to 1150. This is the most important thing you need to do. Without doing this the motors can stop during flight causing a crash!
- Configuration tab. Disable motor stop. You want your motors spinning when your quadcopter is armed so that you know it is armed! Even though the 90GT won’t likely hurt anyone with it’s small props, we still recommend turning this feature off.
- Receiver tab. Check that the correct radio transmitter sticks are moving the correct values, in the correct directions. (e.g. left is left, up raises values, etc) Several of my channels were reversed from the factory, which would have caused an immediate crash. If this confuses you, please read our guide..
- Modes tab. Check that your arm switch and mode switch are configured to working channels on your transmitter. My mode switch was reversed from what it should have been. If you need level mode on your quadcopter, make sure you know what switch activates it. The default settings use AUX1/CH5 for arming and AUX2/CH6 for mode switching.
- Modes tab. Enable airmode if you want to fly outside. It really improves performance.
- PID tab. Check to make sure your stick rates are to your liking. For beginners, the stock settings are just fine. For anyone with flight experience, you should probably at least turn the RC Rate up.
- Blackbox tab. Turn logging rate down to 500Hz or less. 4kHz wastes CPU and memory.
- Failsafe tab. Test your failsafe! Arm your 90GT, and turn of your transmitter. Your quadcopter should disarm within 10 seconds. Save yourself the heartbreak of a fly off!
Two other things I did before I flew my 90GT for the first time:
- I applied some hot glue to the motor wires to hold them against the arms. Some of the wires were long enough that they could get sucked into the props. I definitely did not want to do any repairs on these tiny wires!
- I found that the double sided tape on the Spektrum RX hadn’t had the “sticky” part uncovered on one side. This meant nothing was holding the RX down except the rubber band and flight battery. Easy fix, but worth a check if you buy an RTF variant.
KingKong 90GT Mods
As of now, I’ve made two mods to my 90GT: upgraded to Betaflight 3.1 so that I can use DSHOT, and adding tilt to the FPV camera. I will keep this section updated as I perform other mods in the future.
Flashing Betaflight 3.1
Why do you want to flash Betaflight 3.1? Well, for a few reasons – but mostly because of DSHOT. DSHOT greatly eases the set-up process of your quadcopter and improves the accuracy of the ESCs it uses. DSHOT requires an F3 flight controller and BLHeli_S ESCs – both of which the KingKong 90GT has. So, I figure – why not!
The first step of upgrading is to save your stock Betaflight configuration. If you lose your settings and for some reason can’t get your quadcopter to fly, you’ll want to be able to go back!
Next up, download the latest Betaflight firmware from the Betaflight releases page. You want the hex file for the SPRACINGF3 board. Open up Betaflight Configurator, go to the firmware flashing tab, and configure the checkboxes as follows:
Disconnect your 90GT from your computer. Now, while pressing the boot button on the flight controller (this is the only button on the flight controller), plug it back into your computer. Flashing should begin automatically. For some reason my quadcopter failed the “verification” step of the flashing procedure, but the flash had otherwise succeeded. I don’t know if this is a limitation of the flight controller or just a problem with my particular quad. Either way, it doesn’t matter – flashing worked.
Next up, flash your ESCs with the latest BLHeli software. This will ensure you have software that supports DSHOT. From here, simply walk yourself through our Betaflight configuration guide to get the quadcopter ready to fly again. Here are a few tips:
- The stock Betaflight PIDs are too high. Use the PID values that came with the quadcopter. If you didn’t save those, use half of the stock Betaflight pitch/roll P values and 75% of the stock yaw P value.
- The serial receiver used on the quadcopter is on UART1.
FPV Camera Tilt
The stock FPV camera has no tilt whatsoever. This is great for indoor flying, but quickly gets old when trying to any sort of acro flying or racing outdoors. Fortunately, it is an easy fix.
The FPV camera is glued to the top carbon fiber plate of the quadcopter with superglue. You can separate it by carefully bending the frame and camera apart. Once I did this, I used hot glue to re-seat the camera to the top plate. Since superglue bends easily, I could then bend the camera to the angle I wanted to fly at. Once I re-assembled the quadcopter, I used a dab of hot glue to adhere the camera to the bottom plate as well as the top so I was sure it wasn’t going anywhere. This has served me fine with a 20 degree angle – much better for acro flying!
I want to thank Gearbest for providing us with a sample KingKong 90GT for review. This proved to be a fantastic little aircraft that would serve as a great platform for both getting into the hobby or staying current without leaving your home.
If this review / guide helped at all, we humbly urge you to support Gearbest. You can purchase the quadcopter from them by following this link. From March 14th – March 18th they are having a sale which knocks 18% off of RC gear, which should apply to the 90GT. Use the coupon code RC18OFF to get this discount.