Hey Terry,
I was commenting on Hairball's remarks -- not criticizing your plane. My point was simply that creating a pretty darn good (edit: I mean realistic! good ≠ realistic) plane behavior (in Unity) is actually pretty easy. (Indeed, creating "cartoony" plane behavior is actually far harder than creating realistic behavior -- which is why flying real planes is harder than flying game planes.)
I completely understand the idea of going for a cartoony style, and I sometimes appreciate your modeling style BUT there's a difference between doing something in a particular way to achieve a specific, deliberate effect and settling for a result because that's what's easy to do.
I think that your plane doesn't look cartoony so much as crudely modeled. A "cartoony" plane would capture the essence of a plane's "plane-ness" in a simplified, stylized form. What you've done instead is to avoid trying to grapple with the fundamental shape of a plane, and instead just "bolted on" detail (like the cockpit and engines) which violate the plane's fundamental form, creating something that looks wrong.
Here's a really well done cartoony plane (the Fisher Price "Little People" plane toy). Note that despite being very simple, it manages to capture the spirit of a plane beautifully. It doesn't have weird details like tipped up wingtips that are an abstruse aerodynamic feature of recent planes that happens to be easy to model, but it captures the subtle shape of the cockpit that happens to be hard to model.
Rather than beat the modeling style you've adopted thus far to death, I think you should challenge yourself more. Decide WHAT you want to do and then strive to achieve it, rather than settling for what you get by doing what you already know how to do.
I hope you take this as constructive and not mean -- I certainly don't mean to be mean.