The Cannabalizer is a device that changes the trim of the model at various attitudes. When yaw command is applied, the device will tend to add or subtract (depending on its trim set up) some pitch trim and hence fix the model's attitude under the circumstance. An example is the general trend of certain designs to pitch to belly in knife edge. The Canna will take care of most if not all of the unwanted pitch without having to make an electronic trim condition in the radio. In other words, the Canna fixes a fundamental aerodynamic issue.

On the other hand, such "external" strakes or extended surfaces can be used to enhance certain flight characteristics or control response. For example, consider the role of the dorsal fin of a shark. The fish uses the fin as a pivot to turn on a dime on its prey as it propels itself with the tail. Without the dorsal fin, a shark wouldn't be able to turn as quickly. Such a device on an aircraft has similar effectiveness when rudder is applied....it essentially improves yaw response compared to the same exact design without such a device installed.

The grandfather of the use of such a device on models is Nat Penton. He pioneered such devices about 25 years ago in his VooDooXpress design, a model way ahead of the schedules flown at that time. Fast forward 25 years and here we are.

These devices are not necessary for some designs due to the designer having taken the necessary time and effort to perfect his design before offering it to the public. Bryan Hebert's design are most noted for their neutral flight envelope regarding this feature. Chip's also

MattK