An aircraft that ascends into the air using some form of reaction motor, without the use of aerodynamic lifting surfaces. Model rockets have the following characteristics: Gross launch weight, including the motor(s), does not exceed 1500 grams. Motor power does not exceed 160 newton seconds of impulse and/or contain more than 62.5 grams of propellant each, and no more than 125 grams of propellant in multiple motor configurations. All components of model rockets must be of wood, paper, rubber, breakable plastic or similar material and without substantial metal content.