I'm designing an electric rocket, for the lack of a better word. I'm posting it here so that you can catch all the rookie mistakes I probably made

This is a rough diagram of how it would look:
i.ibb.co/fY1P8gfq/image.png

The vehicle is designed to lift off, hover and land vertically. It's powered by a brushless motor and a propeller, and it uses thrust vector control.

The main structure is a cardboard tube which acts as a duct for the propeller. At the bottom of the tube, a 3D print is inserted and bolted into it and extends the tube (propulsion assembly). This print holds the 4 landing legs through a rail system that allows for height adjusting of each leg, for keeping the vehicle perfectly level when standing. The print also holds the motor through structs, and the 4 MG966R servos with surfaces for TVC. I've seen these servos are cheap and precise, but I'd love to hear your recommendations
The print holds a LiDAR sensor pointing downwards as well (not shown in the diagram) to determine the height from the ground.

At the top of the tube, another 3D print is inserted (component assembly). This print holds the components and includes a Venturi effect ring for extra thrust. Some components are attached to the outside of the print, whereas batteries are housed inside a center pod, as shown in the diagram. This way, most components are easily accessible while keeping the center of mass not too far to the side, in case of attaching the batteries to the outside as well.

The components include:
- A Lipo battery and ESC to power the motor
- A Li-ion 2S battery to power the Arduino
- An Arduino UNO
- 2 battery management systems with cell balancing
- An HM-10 Bluetooth module. This allows me to use a launch countdown software in my computer to send the signal to the vehicle
- An SD card module for data logging
- An intertial measurement unit, probably a BNO055
- A buzzer for state indication

Some components like the Arduino and the batteries will be in 3D printed boxes for easily taking them in and out. Most components will have connectors for easily taking them or the whole assembly out for testing.

One thing I wanted to ask: I've seen similar projects use counter rotating propellers in the same duct to cancel their torque. However, as far as I know, the second propeller wouldn't provide any thrust, as the two propellers and motors are identical and should accelerate the air to the same speed, am I correct? If they did provide extra thrust it might be better to buy 2 less powerful motors and propellers, but if not this setup is fine and the roll caused by a single propeller should be ok for the TVC to correct.

Thanks in advance

interesting engineering solution...