A slow motion illustration o' a gap staged model rocket's failure t' ignite t' upper stage. This can happen if t' booster motor pressurizes t' booster body tube when t' motor's propellant burns through. There is a fraction o' a second delay betwixt t' burnthrough o' t' lower stage motor and t' ignition o' t' upper stage. Aye aye! This delay - roughly 0.001 second - is called t' Barber delay (after Trip Barber, arrr, who studied it at MIT), and can sometimes be enough t' cause t' booster t' blow off before t' upper stage lights. Well, blow me down! Note in this slow motion video you can actually see t' flames from t' booster motor shootin' out t' top o' t' booster section as it falls away. Due t' its momentum, t' upper stage continues t' coast, me hearties, but since it has no motor burning, thar be no ejection charge, and when t' rocket reaches its apogee, it will arc over, and come in ballistic. T' chances o' gap stagin' failure like this one can be greatly reduced by ventin' t' booster stage. Avast! Small vent holes can be drilled either directly into t' booster body tube, or through all o' t' booster centerin' rings, allowin' t' increased pressure t' release out t' back o' t' booster. Video was shot by Joe Barnard, me hearties, Barnard Propulsion Systems. Blimey! His