ESRA IREC Launch Vehicle Airframe

Overview

I led the design and manufacturing of our rocketry club's first in-house composite nose cone for the 2025-2026 ESRA International Rocketry Engineering Competition. This is a Von Kármán nose cone built to fly at Mach 0.8 speeds and reach a 10,000 ft apogee.

I used a dissolvable 3D-printed mandrel, Ansys CFD/FEA structural mapping, and precision tolerance stackups to integrate seamlessly with existing flight hardware and COTS components.

• Primary Software: OnShape, Ansys Mechanical (FEA), Ansys Composite PrepPost (ACP), Ansys Fluent (CFD), Bambu Lab, OpenRocket

• Materials & Manufacturing: Biaxial Fiberglass Sleeves, High-Strength Aeropoxy Epoxy Resin & Hardener, PVA/PLA 3D Printing, Vacuum Bagging, CNC Lathe

• Key Focus Areas: Transonic Aerodynamics, Composite Layups, Tolerance Stackup Analysis, Rapid Prototyping

Modeling & Simulation

• Goal: Validate structural integrity and aerodynamic heating for a Mach 0.8 flight profile facing 530 lbf of peak motor thrust.

• CFD Analysis: Simulated the transonic flight in Ansys Fluent using a k-omega SST turbulence model. Mapped pressure distributions across the geometry, calculating a maximum stagnation pressure of 20 kPa at the tip.

• Thermal Validation: Verified the adiabatic wall temperature peaked at 328 K (130°F), well below the 194°F glass transition temperature of the selected Aeropoxy.

• Composite FEA (ACP): Imported the Fluent CFD pressure map directly onto the shell surfaces in Ansys Mechanical. Modeled a 4-layer E-Glass wet composite stackup, validating a hoop stress of just 0.72 MPa at the nose cone base. This provided a massive safety factor against the material yield limits.

Composite Layup & Vacuum Bagging

• Goal: Achieve the desired Von Karman nose cone shape with a 0.079" fiberglass wall thickness.

• Execution:

  • Fiberglass Sleeves: Utilized two different tows of Soller Composites biaxial fiberglass sleeves in a 4-layer stack: Light, Heavy, Heavy, Light (inner to outer). The Light tow yielded a smooth surface finish, while the Heavy tow provided much of the thickness and stiffness.

  • Wet Layup & Vacuum Bagging: Applied AeroPoxy PR2032 epoxy resin and PH3360 epoxy hardener, followed by fabric peel ply and two layers of breather cloth to absorb excess epoxy. Sealed this configuration in vacuum bagging material.

  • Curing & Demolding: Pulled a 6-8 inHg vacuum for 24 hours, followed by a 12-hour ambient cure (all at room temperature). For the post-cure, I made an initial cut at the tail end of the layup to dump out the sand. I had designed the mandrels with excess length at the tip and tail sections to account for this. After the breather cloth and peel ply were removed, the layup was run under hot water for 10 minutes before the PVA mandrel softened to be pulled out.

Post-Processing & Tolerance Stackup

• Goal: Cut and sand the cured layup to integrate with a machined aluminum tip and COTS body tube.

• Execution:

  • Nose Cone Tip: Nose cone tip was machined into Von Kármán profile from 3-inch diameter Aluminum 6061 stock on a programmed CNC lathe. It was hollowed out with a tapped standoff inside the base to allow for a threaded rod integration into the airframe.

  • Cutting Jig: Designed and 3D-printed a custom holding jig to stabilize the cured, curved composite shell. This allowed for perfectly square, repeatable base cuts using a chop saw.

  • Tolerance Fit: Sanded the interior and exterior of the nose cone to precision-fit the aluminum tip from the tip end and the 5" COTS Wildman fiberglass body tube and couplers. This yielded a flush aerodynamic profile with no in-flight rattle or instability.