I bought an Estes "Shattered" E2X kit today. I just finished putting it tog ether and realized that it didn't come with the metal clip that would usually be present to hold the engine. Does this model not need the clip? I woul d think that without it, the plastic on the bottom of the rocket would melt . There is, however, a cap that screws on over the exposed end of the engin e. Perhaps this model doesn't use a clip? Please help as I am joining my mo ther-in-law's 5th grade class tomorrow to shoot some rockets.