In this review I set out to build an ultralight micro brushless quadcopter based on the 16mm FULL SPEED Baby 2S F3 Flight Tower. The goal was to get less than 40g with a full featured brushless micro. Previously I'd achieved 41g using a smilar setup with a 2 and 3s capable 20mm flytower but found that the weight penalty of the 3s battery did not give back in performance on the little 1103 motors. More details on that quad on my rotorbuilds page. Please bear in mind this is not a simple build - motor wires are extremely fragile, solder pads are small and space is super tight, even with micro components. The outcome however is might impressive but I'll get to that more later.
I won't go into detail about why I chose the other parts but will list them here:
For the build itself I shelved the stock standoffs for the fc/esc since I wanted it super low profile. Instead I used 20mm nylon m2 screws with nylon m2 nuts and m2 orings to get the height I wanted. See my article making a low profile micro stack. I had to mount the ESC upside down and the flight controller rotated 180° about yaw in order to stop esc connectors touching and limiting height reduction. I also went through the painful task of cutting, tinning, soldering and heatshrinking the ESC signal cable to get it as short as possible - not just to reduce weight but because I have so little room to work on this build. I stuck with a JST connector and a short run of 20AWG cable since the connector is much lighter than an XT30 and it won't be passing a lot of current anyway.
I'll make a quick note that I used a AIO camera VTX since for this build I decided a superior micro CCD camera like the micro swift adds too much weight for me. The CM275T is the best of the bunch for me at the moment - it is very light at 3.3g and it has standard wiring that allows for betaflight OSD. UPDATE: I never was able to get this to focus correctly so reverted back to an old Eachine TX01 modded for video in and out. I also used the ghetto antenna mod I wrote about here.
So what was the final weight? 36g! better that I was hoping especially since I know I can get another 0.5g off from a receiver swap and another 1-2g from a different camera mount. That can wait though as I want to focus on flying this now rather than building. Click on the pics below to embiggen.
Once I finished the tricky stage of completed the build, ensuring all wiring was routed to avoid possible prop strike, the flight controller was set up. This is a full omnibus f3 FC and BLHELI_S esc setup which means I get all of the best betaflight features - Betaflight OSD, Dynamic filtering, Anti-turtle, ESC beeps vis dshot command. The only issue I had here was finding the camera was NTSC rather than my preferred PAL meaning I had to move my OSD elements a little close to the centre of the screen.
Since this was one of the two quads I took with me on my Summer beach holiday I got a good amount of flying in with a chance to try some different propellers. I settled on the Gemfan Hulkie 2040 (reviewed here) but think the 1940 version of the same prop would be slightly better as the offer a little more clearance and the 2040 is slightly over-propped - a little too floaty with a big disc/weight ratio. I actually think a 2 bladed prop would be best here but cutting down a larger prop like the gemfan 3020 will mess up the geometry too much with that much trimming. I plan to try the gemfan 2035 quad blades with 2 blades removed at a later time. Just a quick note here that although in the past I found the Hulkie 2040 propellers to be brittle. Not an issue on this quad as the low weight means crashes have very little force. UPDATE: Have now tried the 2040, 2-blade 2035 and 1940. 1940 is the best prop for durability and performance. The 2 blade 2035 was ok but didn't give me the efficiency gains I was hoping for.
So how does it fly? I'm impressed. On a 2s 300mah weighing just 17g I get 3 minutes of hard flying time coming down at 3.8v per cell - would be easy to go to 4 minutes but I have plenty of these $4 batteries so it's not an issue to change regularly.
In terms of what can be done with the quad it just makes this little guy so much fun. You can fit in tiny gaps with good fine control like a whoop but the top end speed and power for acro make it something else altogether. It doesn't have the speed of a 5" obviously, nor the momentum for tricks but you can still put it where you want, when you want. What separates this from bigger, heavier 1104 and 1105 based 2" micros and more traditional 3" micros is the lack of weight makes it feel so much smoother and easy to recover rather than feeling like a flying brick - something I've felt in all BNF 2" quads 55g and up and in traditional 3" quads like the Furibee X140 (review here) and the GEP RC Sparrow MX3. So far as bro-science is concerned this is not to do with power to weight (for example the GEP sparrow has wicked power/weight with those big 1408 motors) but more to do with disc loading - the area of a 2" is very small and can only support a small amount of weight. Even stepping up to 2.5" allows a lot more weight to be carried for a simlar feel (e.g. the Leader 120). In his own rambling way Bob Roogi does a good job of explaining this further here.
After flying exclusively with ccd cameras now I forgot how AIO cameras struggle with light handling. It's not a fault of the VM275t in particular which does seem to be one of the better of the bunch, just the particular CMOS technology used in these cameras. On a good sunny day it is not an issue though and on the cloudy days it is something you can get used to. If you did want to go CCD though I'd recommend swithcing to a micro CCD, FSD TX200 vtx and the FlexRC Ascent frame for an all up weight penalty of about 8g - not my objective for this build but may suit you better depending on your application. Albert Kim actually did a build similar to this in his video here.
Coming back to this review being one of the flytower though I can thoroughly recommend it for a lightweight 2s only micro build. The only equivalent that really comes close is the HGLRC Zeus which is 2-3 times the cost and won't fit in small frames like my Eyas build, although it is capable of 3s @ 16A. I'd also like to suggest that the 1103 motors seem to be a good match - they are as light as 3g each and will not stress the little 6a ESC. I'd very much like to try this combination for a cruising micro with a 2.5 or 3 inch superlight frame to see what kind of flight times I can get but for now, this small and ultrlight quad comes with me practically everywere.
UPDATE November 2018: It's hard to imagine I've now had this almost a year now and it is still going strong many crashes later. I've settled on the Gemfan 1940 props as the best in this configuration and the Fullspeed FRSKY nano receiver with weight down to a hair over 35g. Current hype is all around the 2s whoops and (Mobula 7 in particular which I'm in the process of reviewing) but objectively speaking this build is superior outdoors because:
Here is the latest image: