VTOLs have all the complexity of an airplane and a multicopter combined. So, you may want to start simple. Remember the Bixler we fitted with Pixhawk in the last chapter? This would be an excellent candidate to start with. Why? Because it's already a fully set up airplane. So, the first half is already done. Now we just have to figure out how to hybridize it.
We need to integrate the functionality of a multicopter without adding too much weight to the frame. So, it's not just a matter of gluing on a multicopter airframe. The multicopter needs to lift the weight of the airplane, and the airplane needs to keep the weight of the multicopter aloft during forward flight.
Not only that, but the energy requirements for our airplane are not very high (using just a 3S 1100 mAh LiPo battery). We could easily lift a drone and the airplane's weight with a 6S LiPo battery. But then we have all the extra weight of the battery, and all the extra weight of the motors and propellers...