 The 3E model utilized a new technique of rocket grain construction  that consisted of laminating sheet double-base propellant grain under hydraulic pressure.
<clarity>  The 3E model utilized a new technique of rocket grain construction  that consisted of laminating sheet double-base propellant grain under hydraulic pressure.
 The 3E model utilized a new rocket grain construction that consisted of laminating sheet double-base propellant grain under hydraulic pressure.