Flutter is bad, very bad! I lost an Astro Hog last summer from elevator flutter [>:][>:][>:]. I was at 50' on a full power down hill, down wind thrill ride when I heard this buzz. About a second after it began I saw something part company with the plane - by the time I could catch the instant downward rotation, it was too late and I hit one of those spots where gravity instantly increases pulling the plane rapidly to the ground. Most of the plane ended up right in front of me, but it was long walk to get the landing gear that pulled out along with the missing left hand stab and elevator. At least I still have a wing to work with, rest if it is toast.

Hogflyer