Here’s the presentation of my first 2" 2S, based on the famous DRAKNIGHT HGLRC, in O4!

The original DRAKNIGHT HGLRC in its analog version weighs about 45g without the RX. Thanks to an AIO ELRS board, optimized wiring by reducing wire length and eliminating motor plugs, the weight has been minimized.

The DRAKNIGHT O4 weighs about 47-48g without the battery and reaches 76g in flight with a 2S 550mAh Li-HV battery. It is equipped with Happymodel EX1102 10000KV motors, offering an excellent power-to-weight ratio. This configuration allows for lightning-fast acceleration while maintaining great maneuverability.
No frame/ props in view with this quad but the aluminium cage protect the camera very well.

Thanks to FUNKOLIUS' PID settings and filters, the DRAKNIGHT O4 offers a smooth and responsive flight. The factory Betaflight 4.5 settings with the RPM filter and Master Multiplier Slider set to 1.35 also work well.

The low-pitch propellers optimize freestyle flying while maintaining very good acceleration. With this combination, the DRAKNIGHT remains agile and dynamic in all situations.

The 2S 550mAh Li-HV batteries allow for extended flights between 4 and 9 minutes, depending on the flying style. The response to controls is instantaneous, and the flight stability allows for remarkable fluidity when performing maneuvers.

To maximize battery life, flying at 10 MHz 25 mW reduces the power consumption of the DJI O4 Air Unit, which is known for its high energy usage. This setting helps conserve battery while maintaining good video transmission quality.

The DRAKNIGHT O4 provides video feedback without jello, ensuring a clear and stable image. Vibrations only appear at very high speeds, but they remain negligible for freestyle use.

The small TPU horn proves indispensable and very effective for flipping the drone when it falls on its back.

Possible Optimizations: The 8 M2x3mm screws on the chassis and the 4 M2x18mm screws are made of steel; aluminum screws could be used to save about 1.5 grams.
Using TPU-LW is an option, although the DRAKNIGHT O4 needs very little of it.
Using the BT 3.0 battery and connector system seems to reduce mass, though I don’t have exact figures (it definitely looks cleaner aesthetically!).

A huge thank you to FUNKOLIUS for his invaluable help in optimizing the DRAKNIGHT. His advice, along with the 3D TPU files he sent, helped further improve the drone's performance and durability.

Check out FUNKOLIUS' channel! He has plenty of original videos on various drones, and of course on the DRAKNIGHT O4: https://www.youtube.com/@funkolius/featured