A good trainer is designed to be slow, predictable, and has some self righting tendencies. These things help beginners by giving them time to react to what's happening in the air. Warbirds are designed to be fast and manueverable, and do not self right. These things make them difficult to learn on. For example, it's common for a beginner to give too much up elevator when the plane nears the ground. A trainer will either climb, if it has enough speed, or perhaps stall. The most likely reaction from a warbird to such an error is often a snap roll, which can be fatal near the ground.

While being able to fly such a plane on a simulator certainly helps, for whatever reason, flying the real thing ends up being more difficult. I sometimes relate what happened when I learned to golf, a very long time ago. I was in a class that began in the winter. We started indoors with wiffle golf balls. No matter how hard we wacked them, the most you could get was 20-30 feet. By the time it was warm enough to go outside, we were all hitting the balls very consistantly. When we got outside, we had more space, and we had REAL (golf) BALLS!!! To make a long story short, the transition from simulator (wiffle balls) to flight (real golf balls) took several weeks. If they had been planes, we would all have been crashing!

Indoor flight actually creates additional challenges that one doesn't face outside. While flying outside, one is only limited by how far they can see to control the plane. If you need a brief timeout, just let the plane fly straight, or climb. When you fly indoors, you have a finite amount of space. You need to be able to control the plane well enough to keep it from hitting the walls or ceiling. When being piloted by someone who is inexperienced, a slow, predictable plane gives more time to make the necessary decisions to keep the plane in the air.