PIONEER I

Pioneer 1 is ITR's first step-down dual-stages rocket with targeted altitude of 80,000ft and Mach 2.5

Design

Interstage Coupler

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.

HEI (Head End Ignition)

Due to the minimum diameter construction of the sustainer, there are 2 options of running the ignition leads from the sustainer AV bay, either running them externally down the side of the airframe, then down into the bottom of the rocket motor, or doing down through the motor retainer and into the forward closure of the motor itself, in a configuration know as Head End Ignition, or HEI for short. We chose the latter following the design philosophy of having the sustainer be as light as possible, and the cable ducting, epoxy, and extra wiring would have added upwards of an extra pound or two, especially if mirrored to ensure even aerodynamic loading at high supersonic speeds.

In an HEI configuration, a small hole is drilled into the forward closure, and two redundant ignitors are inserted, with a pair of red JST connections facing outwards. This way, when the motor is assembled, the ignitors, they are right at the top of the grain, the same place they would be if they were inserted up through the bottom of the motor. Those ignition leads are then attached to a set of wires that run up through the motor retainer, and to another set of JST connectors that connect to the Avionics Bay

Launch Result

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.