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2 Stage blow-by

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Jacques

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I just flew my two stage Estes Renegade. The first stage liftoff was fine and stable. At the second stage ignition, a split secong after the booster tumbled away, I heard a pop and the nose cone came off while under power. It did a few loops and finally the parachute popped out. It landed and seemed unharmed, until I looked at the secong stage motor. The centering ring holding the motor tube was blackened and pushed in forward fro about one third of the circumference. My guess is that the combined effect of the tube coupler and the two side pods being so snug to the second stage kept it attached long enough for the compartment to overpressurize and push in the centering ring. The gases prssurised enough the forward end of the rocket to push out the only the nose cone.
Maybe this is why they don't put a stage coupler on the CC Express. Would it be advisable after repairs to punch two vent holes in that coupler compartment?
 

phaar

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Well if it does not say so in the directions, then I would not. Try maybe sanding the "pods" so they arent so snug. Punching vent holes may be too much for the small engines (actually not sure of renegade engine size). Just do some trial and error.
 

shreadvector

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If it's snug, then adding vent holes will allow the gasses out without ever allowing pressurization to pop the stages apart. In other words, the lower stage will stay attached and be roasted.

Sand it so that the stages come apart easily.

Add tape to the nose so it does not fall off during the "staging event" (called the "train wreck" by the Apollo astronauts).

Use better glue for the motor mount? (Did you use yellow wood glue?)

Build a new one with thin spacers under the side pod tubes so they don't interfere with the main body.
 

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