The Cessna 150 would not make a good trainer - its designed for more experienced pilots and aerobatics. Also wingspan doesn't make a plane a park flyer. If that's the case, then my F-27Q Stryker would be 98 mph park flyer. If you go by the AMA definition, park flyers are electric powered, have a max level speed of 60 mph, and weigh 2lbs or less. Due to its flight characteristics I consider my 54" Hobby Shack School Boy a park flyer since its performance is slower and more docile than other park flyers I've seen. Its more about weight and speed than size. Powered gliders make good park flyers due their slower flight speed, and some older 1/2A planes (converted to electric power) such as the Airtronics/RCM Q-Tee are also good planes for the park setting.

The thing to look for in a plane that will be used as a trainer, especially in a more restrictive environment such as a park, is slower speed, gentle flight characteristics, and electric power (sound issue). You have to match the plane to the environment. And it doesn't necessarily have to be 4-channel - many of us learned to fly on 3-channels. Small trainers do great on rudder/elevator/throttle.

I've watched an Alpha 450 fly and it appears that it can be kept in a small area. Based on the specs, the Mini-Mag should also (probably most speed-400 class trainers). A lot comes down to the capability of the instructor to help keep it in a more confined area.

Hogflyer