Flywoo FlyLens85, the test of a nano racer 2S equipped with a lightweight DJI O3

The FlyLens85 is the nano racer 2S model from Flywoo, which competes with the Pavo Pico from BetaFPV, Happymodel Mobula8 HD, and theAcrobee75 from NewBeeDrone... Although it is labeled 85, it is a slightly more imposing device since its diagonal from motor to motor is 9,3 cm. But its main characteristic is that it is equipped with a DJI O3 Lite.

What is a DJI O3 Lite?

It's a DJI O3 box and its camera that have been stripped of the superfluous by Flywoo to save a few grams. The promise is a more responsive nano racer with better autonomy…

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Slimming diet?

The FlyLens85 is sold in several versions. The one I bought is ready to fly, pre-equipped with a DJI O3 box in Lite version. The O3 Lite is a kit offered by Flywoo to tinker with a DJI O3 and reassemble it with a minimalist support. It is also sold already disassembled and reassembled with the kit, for those who do not want to take the risk of tinkering with their O3. It is this version which is integrated into the copy that I tested.

O3 Lite?

The case is more compact (28,5 x 28,5 x 12,5 cm instead of 30,5 x 32,4 x 13,8) and lighter (18,2 grams instead of 27,8). The camera also undergoes a slimming regime (5 grams instead of 9) (1,65 x 1,8 x 1,4 cm instead of 2,12 x 2 x 1,79). That's a total of 10,6 grams gained. On a device that weighs around a hundred grams, that represents around 10% and that's a lot! The polarized antenna with double connector and thick cap is replaced by two flexible dipole antennas, for a few grams less. 

The compromises?

To install the O3 Lite on board, Flywoo made choices. The first is to place the box under the device, protected by an open plastic cage. It therefore acts as landing gear and is exposed to shocks. Suffice to say that the system surprised me, knowing that the O3 is the most expensive component of the configuration.

Accessing the memory card is not easy, but it is possible. It is better to be equipped with tweezers to facilitate insertion and extraction. The USB-C connector is a little more difficult to access with a commercial cable. Flywoo provides a USB cable with an angled USB-C plug for easy connection.

The camera is also without its case. It is installed on a special support mounted on 3 rubber shock absorbers. It is quite exposed to shocks, but the lens is protected by a UV filter provided by Flywoo. What there is to know ? Filters for DJI O3 (see here for a comparison) are not compatible with the Flywoo O3 Lite camera. If you want an ND filter, and it is very likely that you will need one, we will see, you have to order special O3 Lite ones from Flywoo…

The carbon structure?

It is made of a single piece, very openwork, on which the motors are directly installed. A propeller protection, also in one piece, is fixed to the structure at 4 points. There are no hoops to the motors – so it is recommended not to put your fingers under the unit when the propellers are spinning. However, as I have experienced, there is not much risk other than a scratch.

Inside this protection is a thin blue LED, attached to a translucent sheath. Everything is connected with a 2-wire connector to the on-board electronics. To gain access to the interior of the device, simply remove the 4 screws that hold the O3 Lite support. We note the presence of a BEC which powers the O3 and the LED strip. 

The layout?

The two dipole antennas for the O3 case are guided by a TPU part, just like the ExpressLRS T-shaped antenna. The assembly is clean! The motor wires are attached to the frame with plastic clips. Clean too! There are no protruding wires, nothing that could get caught in the propellers or be torn off during a crash. The motor wires, however, are soldered: changing them requires drawing out the soldering iron. The flight controller's microUSB connector is easily accessible from the top, even when the battery is in place.

The battery holder?

The battery is to be installed in a fairly thin TPU piece, on the top and across the width. By default, the one for the Flywoo 2S 750 mAh LiHV battery is installed. Inserting this battery seems impossible at first: it doesn't fit! But we eventually understand how to force the passage and put it in place. The advantage? It holds up very well! On the other hand, a 450 mAh battery is too small for this part, it does not hold in place. The trick is to slide a piece of foam to hold the battery. Or a piece of wood, as I have done several times in the field, in the absence of moss.

Other battery holders?

In the box, Flywoo provides another support intended to accommodate a 1000 mAh battery. The online accessories listing indicates that a holder for 550 mAh batteries is also available. To remove the support and replace it, turn it 90° and pull it towards the front of the device. Here again, it's a little complex the first few times, but you can get there quite easily with practice. 

The flight controller?

It's Goku Versatile F405 AIO based on an F4 processor, with 6 UARTs, an 8 MB Blackbox, an altimeter barometer, an integrated 2,4 GHz ExpressLRS module (on UART 1), a connector for an O3 Air Unit from DJI, and a 4-in-1 12A ESC for 1S and 2S batteries. The motors are brushless 1003 to 14800KV for 2-inch Gemfan 2015 two-blade propellers. These motors are positioned in push mode, oriented downwards. The propellers turn in the opposite direction to Betaflight's usual direction. In case, here is a dump of the factory settings.

Start-up

The Flywoo video manual prompts you to pair the ExpressLRS module with the battery connection technique 3 times. I prefer the firmware flashing method, made easier by the fact that the ExpressLRS module occupies a UART (rather than present in SPI). The ExpressLRS Configurator tool allows you to create firmware based on the “ Flywoo 2.4GHz » and the device “ Flywoo EL24P 2.4GHz RX ”, with the Binding Phrase that you use with all your ExpressLRS hardware – which eliminates the need for a pairing procedure. 

To carry out the flashing?

Simply turn on the drone, ventilate it so as not to risk overheating and wait a little over a minute for an ExpressLRS wifi access point to be created. You must then connect to it, if necessary with the expresslrs password, then access the url 10.0.0.1, and flash the firmware. Simple and very effective! 

Other settings?

In theory, you have to connect the O3 box with the software on Windows PC and Mac OS X to activate it. But on the device I purchased, the activation had already been carried out (I don't know with which account!), probably to carry out tests of the correct functioning of the O3 Lite.

The configuration of the radio control is very classic, with the usual switches for arming, flight modes, Flip Over After Crash, failsafe verification. Plus an switch to associate with USER1: it will control the switching on and off of the LED strip. Remember to make a dump of the settings before starting to make changes, especially because the USER1 settings are not common (here mine).

Dimensions and weight?

The FlyLens85 measures 12,8 x 12,8 x 4,5 cm, weighing 79,7 grams without the battery. Allow 35,5 grams for a LiHV 2S 750 mAh from Flywoo, 26,1 grams for a LiHV 2S 450 mAh from Gaoneng, and 28,4 grams for a LiPo 2S 450 mAh from BetaFPV. The device in flight order is therefore approximately 115 grams. Not bad ! I didn't have a Flywoo 2S 1000 mAh LiHV battery to try.

First takeoff?

The FlyLens85 climbs very quickly, showing power when pushing the throttle. This is good news, compared to the other much more sluggish 2S O3 nano racers. Its featherweight allows for committed flights and a bit of freestyle. But that being said, that's not what it's intended for. Moreover, flying with too much throttle is the guarantee of a pitiful flight time, less than 2 minutes! The behavior of the FlyLens85 is healthy: it responds well to commands, so much so that you can forget that it is a nano racer.

Flexible and responsive

The good performance of the FlyLens85 allows you to perform fast flights, climb quickly, turn sharply, and throttle back at the end of a dive without risking propwash. You can even encounter dives on walls – but be careful, the device is sensitive to wind! It is not a 4 or 5 inch, it is generally away from the wall or on the contrary pushed towards it if there is wind. No problem in any case for flying outdoors, this nano racer is clearly designed for that.

And indoors?

The FlyLens85 is a little too nervous for indoor flights without changing the settings, particularly throttle management. Consider creating a Rateprofil for the exterior and another for the interior if you want to avoid hitting any obstacles and if you plan to return from the flight with flexible images. I reduced the throttle impact in Betaflight to avoid the yo-yo effect when I wanted to maintain a constant height.

Yes, but…

I happened to take off in Acro with intense vibrations, to the point of having to land. More annoying, when taking off in Angle mode, I also experienced these vibrations which disturb the flight controller to the point that it climbs quickly and without the possibility of descending: I had to disarm urgently. 

These issues occurred only once in Angle mode but several times in Acro mode – probably because I rarely fly in Angle. I suspected for a while that the battery was fixed, then the propellers, but the strong vibrations appeared with a perfectly seated battery and a set of new propellers. Strange, especially since I still don't know the reason for the problem.

Images ?

The O3 box allows superb video feedback, with Betalight OSD (already configured by Flywoo at the factory), with battery status indication (cell average and total voltage), as well as flight height relative to the take-off point.

But the most interesting thing is of course the recording of videos on the O3 box on board. Indeed, we can obtain 4K up to 120 images per second, with the possibility of natural colors (meaning pushed to be vibrant) or D-Log M (for management of colorimetry in post-production), with stabilization in real time or in post-production with Gyroflow.

Image stabilization?

When flying indoors or outdoors without wind, the camera vibrates little or not at all. But we see a Jello appear, discreet but present, when there is wind. The Rocksteady stabilization of the O3 case allows you to partially erase this Jello. But to get rid of it completely, like on other 2S nano racers, you have to install an ND filter.

I didn't have any on hand, and the ones designed for O3 are not compatible. If you decide to invest in the FlyLens85, don't miss out on Flywoo's O3 Lite ND filter kit...

When vibrations are compensated by stabilization, blurring is observed in the images. As usual, the automatic settings accentuate the blur when the light is low, in this case you have to take the time to make manual settings for the ISO and shutter speed.

Add an HD camera?

Flywoo has provided 3 mounting holes for mini camera supports, with the help of accessories (additional charge). These supports are intended for the GO1, GO2 and GO2 from Insta360, the Thumb and Thumb Pro from RunCam or the 4K Thumb from Hawkeye. There's no point trying to install a GoPro on board, even the naked type, it's too heavy for the FlyLens85.

Not really enough to surpass the O3 which is capable of producing cool images as long as you spend time with a post-production tool like Premiere Pro from Adobe or Da Vinci Resolve from BlackMagic…

Autonomy?

If you fly very aggressively, regardless of the battery, you will hardly exceed 2 minutes of flight time. On the other hand, if you fly without strong and sustained throttle inputs, even if you fly fast, you can count on 3 minutes with a 2S 450 mAh LiPo, 3 minutes 30 with a 2S 450 mAh LiHV, and a little less than 4 minutes Around 30 with a LiHV 2S 750 mAh – and up to 5 minutes 30 by pushing it to its limits and flying very smoothly./ Be careful, if you go too low, below 2,90 V per cell, the video feedback of the DJI O3 will be discontinued. Suffice to say that it is recommended to buy a few 750 mAh LiHVs if you plan to enjoy great flight sessions.

Solidity ?

The O3 Lite under the device which serves as landing gear, its boned camera, the thin propeller protections without hoops: this is not very reassuring as to the solidity of the FlyLens85. However, unlike other 2S nano racers that I have used in the same environments, with the same risks, this device is the one that came out with the least damage. The propeller protections withstood head-on impacts against trees, neither the camera nor its UV filter moved. 

The support of the O3 Lite, under the device, did not inspire confidence in me. However, he withstood violent landings without flinching and especially rapid flights that were a little too low, scraping tarmac! Not bad, and I'm the first to be surprised. On the other hand, the propellers are poorly protected, and quite naturally are damaged during shocks and crashes, especially in trees and in the presence of twigs or stones. In 2 weeks of flying, I used 8 spare propellers, which is a lot more than on other nano racers.

The heating of the O3 Lite?

Besides the solidity, my other fear regarding the O3 Lite was the inevitable heating in the absence of the case acting as a heat diffuser. What you must remember ? In flight, I never experienced overheating despite fairly high ambient temperatures, up to 30° (there are more seasons, you know). On the ground, plugged in and waiting, the O3 Lite, on the other hand, heats up much faster. 

With an ambient temperature of 25°, the original O3 mounted on a BetaFPV Pavo Pico indicates overheating after 2 minutes 02, and turns off for protection after 2 minutes 15. Under the same conditions, the O3 Lite on the FlyLens85 warns at 1 minute 12 and turns off at 1 minute 18. Is it serious, doctor? In flight, no, since the O3 Lite does not overheat. But if you crash the FlyLens85 and it takes you a little time to get your hands back on the device, be aware that the video cuts out in about 1 minute.

The little extras

The LED strip is perfect for quickly finding the device if you plant it in the forest: the light is strong enough to see it perfectly and from a distance. The accessory is ideal for revisiting the Airgonay races in the NoComp Stadium, especially since Flywoo offers versions in red, pink, green and white. I'm not usually keen on Christmas tree-style drones. But in the case of the FlyLens85 and for use in the forest, it's perfect!

Note that the Flip Over After Crash function works well, and allows you to flip the device so that it can take off again. Please note, the arming angle is fixed at 25° in the factory settings – remember to increase it to 180° to take off even if the aircraft is leaning (especially perched in a tree).

Should I buy it?

The FlyLens85 is the most “sporty” of the 2S O3 nano racers. It is therefore suitable for fairly rapid, precision flights, rather outdoors. He is not afraid of obstacles or shocks – up to a certain point, of course. He can return from flight with beautiful images with the help of the O3 Air Unit and post-production work. It is recommended to purchase 750 mAh LiHV batteries for good battery life and ND filters to remove any Jello. If you want a softer device, or one intended exclusively for indoor flights, this is not the right choice. For my part, it is the device, in the nano racer 2S series, which brought me the most pleasure!

The price ?

The FlyLens85 O3 (with an integrated O3 Lite) starts at €384 directly on the Flywoo website (excluding shipping, excluding taxes). The version I bought and tested, with an ExpressLRS 2,4 GHz radio module, starts at €397. There is also a TBS Crossfire Nano RX version and a FrSky XM+. A GPS can be installed as an option, but it is not really of interest on this type of device.

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