ORIGINAL: Flypaper 2
Aerodynamically, the rounded trailing edge causes much more turbulence than the squared off TE. tapered TE, is aerodynamically cleaner than both. I remember one of the X rocket planes had a very thick squared off rudder TE, but I imagine it was for supersonic reasons.
The X-15 has very thick and squared off control surfaces... I know that squared off provide less turbulence and I like the look better so I leave mine squared off... They're also easier to cover!
