Happymodel Crux 3 Review
• Chris Landa
The Happymodel Crux 3 is a super light weight 3” toothpick based on Happymodels CrazybeeX all in one board. And light weight is not just a buzzword in this case - the model weighs in at just under 42g without a battery (just 70g with a 2S 450mAh GNB battery).
Thanks to banggod at this point for sending me this model for the purpose of review.
Electronics
The flight controller is an AIO board - a real AIO board - it contains flight-controller, receiver and video transmitter all on one single board. It is the CrazyboardX version 2.2. The main difference to version 2.1 is, that the newer version supports video output power of up to 200mW.
As mentioned in previous reviews of copters that used this exact (well, maybe not exact, since thy were version 2.1) board, I really like the efficiency of this board. Everything is plug and play: you plug in the motors and the cam and are basically ready to go.
The Happymodel Crux 3 comes pre-assembled, so you just take it out of the box and you are ready to go.
ESC’s
The ESC’s are capable of continuously pushing 5A and 6A burst. They come flashed with BLHELI_S and you can run BLHELI_M or JESC on them in case you want to run RPM filters. With a dead time of 50, they are on the low side, which is nice - the lower the deadtimes, the greater the potential gains when using higher frequency ESC firmware.
VTX
The video-transmitter is directly integrated on the flight-controller, still it is internally connected to UART 2, which you need to set to TBS SmartAudio in the ports tab of the configurator in order to be able to make adjustments via the OSD. The quality of the VTX is OK - really nothing to write home about. On the DVR you can clearly see flickering stripes/pulsing. You don’t notice them so much during the flight, but a dedicated video-transmitter definitely has better quality.
Receiver
You can get the Crux 3 with different receiver options, I decided to go with the integrated FrSky D8 SPI receiver. I personally like them, since I am from the EU, they are not really the limiting factor for me, since we are only allowed to fly with 25mW.
But you can get it with DSMX, Flysky, FrSky R-XSR or even crossfire receiver - the price will vary accordingly.
Cam
The cam that has been used on this model is the Caddx Ant. A nano sized cam that allows adjustment with the included joystick. Regular readers might know, that I am not the biggest fan of Caddx cams, but with this one I lucked out and (so far) have no dirt on the sensor and also no black corners, which is nice.
The Caddx ant included with the Crux 3 seems to differ slightly from the regular Caddx ant since it comes with an adjustable focus ring. Also the wires are directly soldered to the cam and you only have a plug for the joystick to adjust the settings. I personally did not bother to play around with the settings, but I am sure a lot of you will be happy to do that.
The camera has a resolution of 1200TV lines and an aspect ratio of 4:3. The angle can be slightly adjusted
Frame
The frame is made from 3mm thick carbon. It is a unibody, meaning if you break an arm, you have to swap the whole frame. The frame is quite flexible, especially at the point where the arms meet the body, which is a bit of a shame, since they went with 3mm carbon, they could have taken out less material to give it some more rigidity. The arms are around 4mm wide at their thinnest part.
I don’t really have high hopes for this frame in hard crashes with concrete. I clipped a couple of ghost branches and hit the ground a couple of times without any issues, but I don’t think it would survive a good crash into a wall. So you might want to get a spare frame from the get go, just to be on the safe side.
M2 screws have been used to mount flight controller and canopy. Those are metal screws and go through the whole stack, so no spacers or anything funky like that, which I like quite a lot.
The battery is mounted using rubber bands - this method seems a bit “ghetto”, but does work quite well. To protect the battery from slipping out, some foam pads are included (unfortunately they are not sticky, so the battery might still slip out during a crash).
Motors & Props
The motors are Happymodel EX12025 with 6400KV and a 1.5mm shaft. They have the pretty common 9mm, 4 hole mounting pattern.
The included props are Gemfan Hurricane 3018 bi blade props. They are only press-fitted to the shaft and you cannot screw them down, since the motors are lacking screw holes. That being said, they are on there pretty tight, so I would not worry about loosing them all too much.
You can basically run any other 3” prop too, but I would stay away from tri-blades and props with too much of a pitch, since the ESC’s can only push 5A, you might easily burn out your ESC’s when putting more load onto the motors.
Batteries
This model is designed for 2S. Happymodel also advertises 1S functionality, but the motors being only 6400 KV, does not make it a viable option on 1S - at least in my opinion. Sure, it will fly on 1S, but lacks punch, and you will have a hard time to recover from dives.
The sweet-spot are definelty 2S 450mAh batteries, like my goto’s, the 2S GNB 450mAh batteries. I am pretty sure you could also go with 520mAh batteries, but I don’t have any of those, so I can’t really confirm that.
The GNB 2S, 450mAh batteries yield a flight time of a bit over 6 minutes if I don’t go super aggressive, around 4 minutes if I push them really hard. Which is quite impressive.
Accessories
The Happymodel Crux 3 comes in a nice carrying case. It has a foam inlay into which the quadcopter fits perfectly, even with the props left on.
You will also receive the joystick for camera adjustments. Further you get a good amount of spare screws, a small Philips head screw driver, an allen key, spare rubber bands, a prop removal tool and a complete spare set of props. They also include some rather nice stickers.
Further, included is an Insta360 Go mount which needs to be zip tied to the canopy and does not induce a lot of confidence. I personally did not bother to use it, since I was not willing to search hours for my Insta360 Go in case it got ejected - which seemed like something that would happen with high probability.
Firmware
My Crux 3 came flashed with Betaflight 3.5.7. I am not entirely sure why Happymodel likes to put that version on their CrazybeeX boards, but in my opinion this is a big mistake. Why use a 2 year old version, lacking such great features as RPM filtering?
Apart from that, the stock tune on mine was horrid. I had to switch to PID profile 2 to get a somewhat good flying experience. I asked a couple of other people that also got this model and did not have those problems, so I can only assume that something was off with the tune that came on mine.
Since I wanted to run a more current version with RPM filtering anyways, I did not spend too much time tuning 3.5.7.
And boy, does this thing rip on Betaflight 4.2.x with BLHELI_M and RPM filtering enabled.
If you are interested, you can download my dump for 4.2.4 - keep in mind that you will also have to flash BLHELI_M or JESC in order to run with my settings
Performance
As mentioned in the previous section, I am really digging the performance of the Crux 3. Super punchy on 2S and you can barely hear it. You can fly it in a park without anyone noticing from 20m away.
The flight time is also super impressive. As mentioned before, I get a bit over 6 minutes of flight time on 2S, 450mAh GNB batteries.
Conclusion
If you are looking for a park flyer, the Happymodel Crux 3 is definitely something to consider. Especially at the price tag of around 100$ on banggood, there is not really much risk involved.
If you are mainly flying in bandos, be aware, that this might not be the best choice and you might want to go with something a bit more sturdy, like the Geelang Wasp 85.
Although happymodel also includes a mount for the Insta360 Go, I would definitely not recommend to use it. So if you are looking for something to shoot HD footage, this is probably not it and I would rather go with something like the FullspeedRC Tiny Pusher.
Chris is a Vienna based software developer. In his spare time he enjoys reviewing tech gear, ripping quads of all sizes and making stuff.
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