03 / Propulsion analysis
Two Stage
Launch Vehicle.
A conceptual vehicle study exploring how motor selection and sizing affect the mass allocation, geometry, and stage assumptions used by the broader team.
Project outcome
A two-stage concept.
Six recorded sizing trials.
The study produced a conceptual vehicle design, component CAD work, a motor-sizing comparison, and a documented optimizer iteration record. The numerical results below come from the course models and final report.
concept
What I contributed.
I led the team and the motor-sizing work, using Castor-120 and M-34 solid motors as reference designs.
I applied the course scaling relations to estimate motor dimensions and masses and modeled components in CATIA. I also used an existing MATLAB Stage Optimizer GUI to compare structural coefficients, propellant mass, and stage delta-V, documenting the assumptions and calculations in our report.
Connecting the analysis.
Thrust and burn time informed the motor scaling. The resulting motor dimensions and mass estimates then had to be considered alongside the vehicle layout and stage assumptions.
Reference motors
Use Castor-120 and M-34 as the reference designs for the motor-sizing study.
Apply course scaling
Estimate motor dimensions and masses from the required propulsion characteristics.
Model components
Use CATIA to represent components and relate the sizing work to geometry.
Compare stage assumptions
Use the existing MATLAB Stage Optimizer GUI to examine structural coefficients, propellant mass, and stage delta-V.
The six-trial design record.
The iteration history shows which assumptions moved with each output.
The report records six optimizer trials. Total mass and the two structural coefficients were varied, while the optimizer table held specific impulse at 365 s for Stage 1 and 449 s for Stage 2. Most adjacent trials changed more than one input.
| Trial | Total mass (lbm) | SC1 | SC2 | Total ΔV (ft/s) |
|---|---|---|---|---|
| 1 | 500,000 | 0.20 | 0.15 | 36,204 |
| 2 | 400,000 | 0.24 | 0.18 | 32,348 |
| 3 | 360,000 | 0.26 | 0.20 | 30,382 |
| 4 | 345,000 | 0.26 | 0.20 | 30,223 |
| 5 | 335,000 | 0.27 | 0.21 | 29,383 |
| 6 | 335,000 | 0.41 | 0.25 | 25,048 |
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Between Trials 5 and 6, total mass stayed at 335,000 lbm while SC1 changed from 0.27 to 0.41 and SC2 from 0.21 to 0.25. The recorded total ΔV changed from 29,383 to 25,048 ft/s.
Source: final report, p. 7, Table 2. These values belong to that optimizer study; the later motor-sizing section used a different specific-impulse basis.
From targets to a motor envelope.
The later motor-sizing section used Castor-120 and M-34 as reference designs. Its thrust and burn-time targets came from the selected course trajectory spreadsheet; the reported diameter and height estimates were then used to consider vehicle packaging.
| Quantity | Stage 1 | Stage 2 |
|---|---|---|
| Reference motor | Castor-120 | M-34 |
| Target thrust | 359,022 lbf | 87,427 lbf |
| Target burn time | 131.6 s | 177.4 s |
| Assumed specific impulse | 280 s | 301 s |
| Reported scaled diameter | 9.05 ft | 9.46 ft |
| Reported scaled height | 34.6 ft | 15.5 ft |
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The comparison connected propulsion inputs to physical dimensions: the first-stage concept had the greater thrust target, while the second-stage concept used a longer burn. The geometry estimates provided a starting point for component modeling and integration discussions.
Source: final report, pp. 10–13. These are course-model targets and historical sizing estimates, not measured motor performance.
Checking the structural allocation.
The course criterion compared each motor’s structural weight with the structural weight allocated to its stage. It was a 40–60% budget check, rather than the motor’s structure as a percentage of total motor mass.
| Quantity | Stage 1 | Stage 2 |
|---|---|---|
| Allocated stage structure | 22,900 lb | 10,000 lb |
| Motor structure used in that comparison | 13,740 lb | 5,000 lb |
| Motor / allocated stage structure | 60.0% | 50.0% |
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The arithmetic gives 13,740 / 22,900 = 60.0% and 5,000 / 10,000 = 50.0%. Both sit within the stated course comparison range on that table’s inputs.
Source: final report, pp. 14–15. These are the report’s comparison values; they do not resolve the different mass estimates elsewhere in the document.
What the models reported.
The team produced a conceptual vehicle design, CAD representations, and a final technical report. The selected trajectory summary recorded a final model velocity of 25,048 ft/s and a final-burnout altitude of 133.1 nmi.
The final-velocity comparison in that section used 25,455 ft/s as its reference, giving a reported difference of about −1.6%. The 5,000 lb payload and 100–200 nmi altitude remained the concept’s design targets.
Source: final report, p. 9. These are reported academic model outputs, rather than measured flight results or a validated orbit-insertion claim.
One shared input set.
A stronger next iteration starts with consistent inputs.
I would maintain one controlled set of mass and performance inputs across motor sizing, the trajectory model, and CAD geometry, then rerun the comparisons. That would make each result traceable to the same vehicle configuration before making a performance claim.
Assumptions to reconcile in a next iteration
The optimizer table used 365 / 449 s for specific impulse; the later motor section used 280 / 301 s. Motor mass entries also differ between the worked scaling text and the summary table, and the report’s earlier required-ΔV calculation uses a different reference from the final-velocity comparison.
These historical values are kept with their originating calculation here. Reconciling those assumptions, recomputing the mass budget, and checking the motor envelope against the vehicle geometry would be the next engineering step.
Project record: Team Aurora Launch Vehicle Project final report, pp. 7 and 9–15, plus the team assembly figure on p. 32. The team assembly figure is attributed separately from my CATIA component work.