FRSKY is the most popular quadcopter digital radio protocol because of regular development and the availability of low cost highly effectiver receivers meaning that every quad you own can have it's own receiver without always changing in an out. A benefit to this means is that each quad can have a customised reviever for what that specific quad needs - long range with diversity and redundancy, full telemetry, the new f-port protocol, pwm output for servos or just the smallest and lightest receiver possible.
In terms of the latter, micro quad builders generally need the smallest and lightest receiver possible and up until recently this has been the FRSKY XM. This is a receiver that weights just over 1g and measures 15x10x3.5mm. Silly as it sounds but what if this is too big? In the case of my ultralight X2 Eyas (rotorbuilds build details here) this was exactly the case. The Full Speed FrSky-Nano 2.4GHz 8CH Receiver is the smallest FRSKY receiver you'll find - it is approximately half the size and weight of the XM, coming in at just 0.5g and measuring 12mm x 10mm x 2.5mm. It's worth mentioning that this is the same FullspeedRC that came up with the Leader 120 and the TX200 VTX - strong credentials in the micro quadcopter space. It certainly helps these models are designed and tested by Lewis who is a micro pilot himself rather than just a marketer.
Binding (from FullspeedRC.com)
1. Select D8 mode on Frsky remote control. Hold the bind key on Frsky-Nano receiver and connect the battery, then the receiver's red light will be always on.
2. Select the BIND mode on remote control , the Frsky-Nano receiver's blue light will flash slowly and the red light will be always on which means bind complete.
3.Enter: set sbus_inversion = off (set serialrx_inverted = on if your FC is BF3.3 or newer)on BF CLI and save.
4. Repower the Frsky-Nano receiver . The red light on it will flash very quickly which means it receives the singal from remote control
I did know that this nano receiver sent RSSI over an auxilliary channel but it was a nice surprise to find this set up out of the box unlike every XM, XM plus, XRS, RXSR receiver I've ever come across. Better still was that it was set to Aux 5 (channel 9) meaning all 4 auxilliary channels are available for control. With betaflight set to recognise Aux 5 as RSSI it is easy to add to betafilght OSD and display RSSI which is important as i'll get to shortly.
For a defined digital protocol (in this case SBUS) the only parameter to discuss in receiver performance is range. I'll be the first to admit that my antenna placement is not great but the range was probably a little less that I was expecting. When I ventured more than about 100m away in a residential neighbourhood I started dropping to about 30 RSSI. Given this was an ultralight build with an all in one camera/VTX I was not concerned beacuse this is about the realistic range of my 25mW vtx anyway. The good news is that with RSSI displayed in the OSD you at least have the tool to manage this.
I think the range is a fair limitation for this receiver. I see it being used for ultralight brushless micros or tiny whoops where you mostly fly in close proximity to yourself. It's also worth reiterating that with better pacement of the receiver/antenna I should be able to get much better range if I needed it.
The Emax Baby Hawk R is a micro brushless quadcopter that was launched by Emax in early 2018 as a follow up to the highly successful Emax Babyhawk (not r). It was launched as a 2 inch but 2.5 inch aftermarket arms quickly became available in the aftermarket and hugely improved the power to weight ratio, disc loading and efficiency. Emax themselves have now taken this one step further with the Babyhawk R 136mm (3 inch). Compared to the 2 inch version is has the longer arms with the new Avanflow 3 inch 3-blade propellers and a reduction in motor KV from 6000kv down to 4500kv although motor size is still the same 1106. Weight of the 3 inch is 86g compared to 82g. I will review the Babykawk R 136mm (3 inch) here.
Specs and discussion
On paper none of these components are especially exciting or on the hype-train. A big HOWEVER though - all are very tried and true, solid and well balanced. This means reliability and reduced cost. The each have a job to do and do it without fuss or flair. It's fair to say though that when you bring them together they are greater than the sum of parts.
Quick rambling thoughts how 3 inch quad weights
I think of 3 inch quads in 2 ways - a shrunk down 5" based on large motors and 4s batteries or an embiggened micro based on 11XX series motors and 3s. This clearly fits in the camp of "embiggened micro" since it is based around 1106 motors however it is farily unique in that the ESC, motors as well tough frame and cowling are well and truly engineered for 4s - best of both worlds as it were. By constrast my lightweight FlexRC komori (build blog is here) can take 4s but the frame would not hold up to carrying the extra weight of a 4s. Conversely something like the Furibee X140 (review blog here) is pretty gutless on a 3s where it can't overcome the 120g+ weight of the quad.
I haven't delved into all the betaflight screens this time because for the most part this is down to preference and your gear. What I can say though is that although not installed from the factory, EMAX have provided some VERY good PIDS for both 3s and 4s. Here is the link to their page or for convinience please see below:
Fly the damned thing
At the time of writing I've only run this on 2s and 3s. 2s was using a 46g 950mah turnigy nanotech battery and was very uninspiring but hey, at least it can be done! 3s was much better than I thought it would be. I used the Turnigy Nanotech 3s 460mah battery (about 42g) and got 2.5 - 3 minutes flight depending on how hard i pushed, coming down at about 3.75v per cell at rest.
The first thing I have to say about the flight is that all of these solid if unspectacular components do come together so nicely - they are all well suited which not only make for an enjoyable and reliable fllight experience but means the cost does not blow out. In addition the protection offered by the 3mm carbon-armed and cowled frame means that even after tumbles there is a good chance you can just rearm and get flying again - it is tough! The other benefit of the cowl is that it looks cool, different from the top plate/bottom plate or side cage frames that are out there.
Punch out power is ok on 3s but will hold my judgement till I get some 4s packs. understandably the light 3s packs make for great agility which is why I had a lot of fun with proximity around the small trees in the park that I have close to work.
For FPV camera performance is good - as to be expected from the foxeer arrow micro CCD. VTX is clear in the right conditions and is better than most other micros however I do undersand this can be improved significantly with an AXII ufl antenna (or the cheaper UXII). Channel and power level is easy to change via the small button but as suggested above there is no smart audio or tramp protocol to do this over betaflight OSD.
Obviously I haven't tried on 4s yet (I am just choosing a 500-700mah 4s to order), but based on the performance of 3s I think this quad is a real winner.
Emax have done a fantastic job on not getting carried away on needlessly overspeccing the quad in areas you cannot really taking advantage of. In doing so they have a solid, robust and well priced offering that I can see becoming very popular like the babyhawk before it albeit with less shortcomings. Better still the support that emax appear to be offering beyond regular customer service such as offering tuned PIDs means that community support will mean there are always going to be clever fixes and modifications that will be available, making obsolesence for this model is less likely. Make no mistake obsolesence is a real issue with quads because once the community moves away from a model there is less support in total available.
Although experienced builders and customisers will still likely want to build their own, It is very easy to recommend this as a first 'racing' micro quad becuase of it's inherent features and support. As a micro quad builder myself it's hard for me to say but this is actually more enjoyable to fly than most of my custom builds because it all comes together so nicely. For that reason it is easy to recommend this to the more experienced set that just want to fly and not fiddle with the micro electronics etc - for example if you have come from 5 inch racing or freestyle quads.
The Emax BabyHawk R is currently available from Gearbest with or without receiver. The model without receiver is $166. If I get access to any specials I'll post on my coupons ans discounts page.
I currently run a Floss 2 5" racing rig (see series of articles here) that is powered by 2205 2450kV Returner R2 variants and a HGLRC F428 stack with vtx and camera. The F428 stack has always been fiddly - VBAT pads have broken off easily and I've burnt out 1 ESC when the external cap was knocked off. Although it is still working, I quickly realised I need a very robust (read: crash resistant) system that doesn't leave me wondering if it is going to work or not for each heat I race.
I decided I wanted to replace with an all in one FC/ 4in1 esc to simplify and minimise wiring. I'm confident enough now that 4in1 escs have reached a point in reliability that I'm not worried about a failure obsoleting an entire board. For me the key benefits are:
Because of reliability I decided to go brand name and in doing so skipped the racerstar options from Banggood. I had my eye on the Airbot Asgard and underground FPV kamikaze variant for a while but for around $100 they were fairly pricey. This is when I came across the Cicada AIO F4 30A BLHeli_s for $56 from HobbyCool - about $35 less than the other options. Both the f4 flight controller with mp6000 gyro and BLHeli_S are mature technologies and I know what to expect - solid performance that can handle the latest firmware and options (Betaflight 3.3 / Butterflight 3.4 at time of writing) but will be super reliable - in summary do the basics well day in day out. The BlHeli_32 version of the Cicada AIO had just been released but is about $20 more and at the time didn't see the advantage on what it a straight up racing.
Installation was really straight forward - this AIO board has the standard 30.5mm x 30.5mm mounting pattern and paired it with a new AKK FX2 VTX. I used softmounts out of habit but in reality it's probably not necessary with the MP6000 gyro and 8k/4k gyro/pid frequency. Just a little more insurance if props or motors get donked up.
Wiring is fairly easy after removing the shrinkwrap cover from on the AIO unit. An XMplus FRsky receiver was soldered up to the easily accesible side pads and bound and the AKK FX2 vtx was installed powered by the BEC/filter on board the FC (3A @5v which is plenty). The only thing outof the ordinary for me was wiring the 'smart audio' signal for the VTX to the TX6 on the AIO unit - it is a smaller solder pad closed to the centre of the board on top, clearly labelled. The runcam micro swift 2 camera was powered directly from the VTX as is best practice for a clean video feed.
After making sure the power up was successful I updated to the latest version of BLHeli_S via BLHeli configurator and the latest version of betaflight which was 3.2.5 OMNIBUS F4 target at the time of writing. I've included screens of my specific betaflight setup below but for the most part this will be to your liking and particular motor/prop/frame setup rather than the board in particular. The one exception is the current meter details which should act as a good starting point. This was as accurate as I could get mine using Oscar Liang's method.
3 months on from install the quad is still flying well. I've been through several sets of props, 1 arm and a camera lens but the Cicada FC/ESC nor any of the other electronics have given me no issue whatsoever. Although the HGLRC F428 may have held up similarly at a push, I would not have the confidence to try new tracks with the same gusto as this setup - a concept that is less tangible but is super important to learning and improving. PIDs are stock and since I don't have particularly agressive motors they work well for me using some of the key betaflight 3.2.5 features: dynamic filtering, PT1 filter, notch filters off, airmode etc. Dshot commands are also working well: the beeper has saved my bacon in long grass several times and turtle mode works well with my top mounted battery although I still tend to be scared of it!
So there it is. The CICADA AIO F4 FC W/ 30AX4 BLHELI_S ESC which is availble for $56 with worldwide free shipping from HobbyCool is a stable and reliable solution for simplifying your electronics.