Pioneer I

The centerpiece of this style of dual-stage design is the coupler that attaches the two stages together. In a typical dual stage design, this would simply be a section of coupler tube that would slide into the bottom of the sustainer airframe, but with a minimum diameter upper stage, that's not possible. The solution to this is to have a section for the sustainer to slide into, and a lip for the bottom of the airframe to rest against, which transfers the thrust from the booster motor directly into the airframe, rather than indirectly via the fins, which runs the risk of sheering off the fins if the epoxy isn't bonded well enough to the airframe. In theory, this would be a low risk, but with all the other unknowns at play, I made the decision to add the lip to make the design less dependent on the layup. The ISC is made of 6061-T6 Aluminum, and is bolted to the top of the booster upper airframe, and has a slip fit with the sustainer lower airframe. Upon stage separation, a pyrotechnic charge pressurizes the internal volume of the ISC, and forces the two apart.

Pioneer-1 Lifted off the pad on June 7th, 2025. It left the rail traveling at approximately 230ft/s, and ultimately reached a speed of 391ft/s. Around 3 seconds into flight, the rocket experienced a anomalous decrease in acceleration before the rated burn time of the M2245 that propelled the booster, causing the rocket to destabilize and flip over, ultimately breaking up. Some small pieces were recovered so far, including the sustainer AV bay, which allowed us to look at the flight data that was recorded.