Case study 02 · Launch vehicle · Structures & design

Team URSA G-class launch vehicle

Airframe and fin development for the UKSEDS National Rocketry Championship, translating stability, load, manufacturing and integration constraints into a reviewable launch-vehicle design.

My role: Airframe · Structures & design
Scope: Fin trade-off, CAD, stability and verification
Review point: PDR · CDR · Manufacturing review

SolidWorks external and sectional views of the Team URSA launch vehicle — Airframe configuration showing the nose, payload volume and swept-fin arrangement.

2,200 ft: Mission target
G74: Selected motor
3: Swept fins
1.75-2.5 cal: Updated stability band
1,971 ft: Updated predicted apogee

The engineering problem

Constraint before configuration.

Challenge

Team URSA had to approach a 2,200 ft target apogee while carrying customer and rideshare payloads, preserving a safe stability margin and supporting reliable recovery. Changes made for manufacture and integration affected mass, drag, stability and altitude together.

My responsibility

Within the airframe team, I contributed to fin planform and material trades, airframe geometry, stability modelling and manufacturing/test planning. The work linked SolidWorks geometry and OpenRocket results to decisions that could be reviewed, built and verified.

Engineering approach

From requirement to evidence.

Trade the fin configuration

Compared rectangular, tapered and swept planforms, then evaluated three versus four fins around stability, drag, mass and manufacturability.

Connect CAD and trajectory

Used SolidWorks geometry with OpenRocket flight and stability modelling to expose the consequences of each configuration update.

Design for manufacture

Planned a repeatable fin-can integration route using controlled slots, dry fitting, alignment checks and resin reinforcement.

Define verification

Mapped axial and transverse fin-load tests, airframe stiffness checks and recovery tests to competition requirements and safety factors.

Decision record

Why the configuration changed.

Design decision	Evidence used	Trade-off accepted
Three swept fins	Rectangular, tapered and swept planforms—and three- versus four-fin layouts—were compared through stability, drag, mass and manufacturing criteria.	Lower drag and mass placed more importance on accurate fin alignment and repeatable manufacture.
50 mm × 590 mm airframe update	The revised model brought stability into the 1.75–2.5-calibre band while reducing predicted apogee from about 2,171 ft to 1,971 ft.	Improved stability and integration were prioritised despite an approximately 200 ft performance penalty.
Slotted, reinforced fin-can assembly	Controlled slots, dry fitting, alignment checks and resin reinforcement formed a repeatable manufacturing route.	The stronger, more controllable joint added process steps and resin mass that needed to be managed.
Physical verification before flight	Axial and transverse fin-load tests, airframe stiffness checks and recovery tests were mapped to the review requirements.	Additional schedule and test effort was required to close uncertainty left by trajectory and CAD models.

Technical evidence

Analysis that changed the design.

Updated OpenRocket apogee plot for Team URSA showing the prediction changing from 662 metres to 601 metres — 02
Updated modelling exposed the apogee cost of manufacturing-stage geometry changes.

Team URSA swept-fin dimensions and manufacturing plan — 03
Fin geometry and integration planning built around repeatable alignment and dry fitting.

Source documentation

Open the review record.

These collaborative project documents substantiate the design-review trail. The case study above identifies my individual responsibility within the wider team effort.

Preliminary design review

Team URSA Preliminary Design Review

Collaborative team presentation · 17 pages

Critical design review

Team URSA Critical Design Review

Collaborative team report · 25 pages

Manufacturing review

Team URSA Manufacturing Review

Collaborative team presentation · 21 pages

Limitations

What the model did not prove.

At the documented review stage, physical structural and recovery tests had not yet been completed. OpenRocket could expose trajectory and stability trends, but final mass properties, surface finish and as-built alignment still carried uncertainty.

Next engineering step

What I would validate next.

I would close the apogee gap through measured as-built mass properties, surface-finish and fin-geometry refinement, then rerun the wind envelope before completing fin-load, motor-mount and recovery deployment tests.

Methods & tools

SolidWorksOpenRocketLoad analysisManufacturing planningRequirements verification

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