I was just at the local hobby shop and was surprised to see the old Cox X-15 has been released by Estes and was only running about $15. With a minor internal mod, my old Cox X-15 is about the best flying model rocket I've ever flown. And it's nearly indestructible. After the near disaster of having the thing come down without a chute at hypersonic speeds about 4 feet away from me, I found a simple solution. Since the engine ejection charge tends to break the seam where the two plastic halves are attached, I simply installed a small tube inside that fits about halfway down over the engine and runs right up to the nose cone. Took about 30 minutes to open the thing up (it's not glued very well), install the tube and put it back together. I've had about 50 great flights on it now and everyone seems to love watching it fly.
Tony