Key Features
| Feature | Specification |
|---|---|
| Dimensions | 36cm height × 10.2cm diameter |
| Weight (Empty) | 250g |
| Water Capacity | 2 liters |
| Max Pressure | 5 bar |
| Flight Time | 15-20 seconds |
| Max Height | 200+ feet |
| Construction | PET |
Component Measurements
Note: Fin measurements are for a single fin. The rocket uses 4 identical fins.
| Component | Volume | Mass | Weight | Dimensions | Surface Area |
|---|---|---|---|---|---|
| Bottle | 2000 cm³ | 0.05 kg | 0.49 N | 36cm × 10.2cm | N/A |
| Cone | 313303.718 mm³ | 0.313 kg | 3.07 N | 15.5cm × 16.8cm | 0.00174 m² |
| Fin Sleeve | 184705.679 mm³ | 0.231 kg | 2.27 N | 11.7cm × 11cm | 0.00351383 m² |
| Fin (Single) | 19241.25 mm³ | 0.02 kg | 0.196 N | 10cm-3cm × 7.5cm | N/A |
Rocket Variants Comparison
| Variant | Volume | Mass | Weight | Surface Area |
|---|---|---|---|---|
| Cone 1 Hemisphere | 0.0076223 m³ | 9.0272 kg | 88.557 N | 0.586 m² |
| Cone 2 Arrowhead A (Short) | 0.0078924 m³ | 9.3612 kg | 91.833 N | 0.612 m² |
| Cone 2 Arrowhead B (Long) | 0.0096573 m³ | 11.5712 kg | 113.513 N | 0.751 m² |
| Cone 3 Blunt Arrowhead A (Short) | 0.0082257 m³ | 9.7822 kg | 95.962 N | 0.638 m² |
| Cone 3 Blunt Arrowhead B (Long) | 0.010260 m³ | 12.3252 kg | 120.910 N | 0.799 m² |
| Cone 4 FMJ A (Short) | 0.0097912 m³ | 11.7392 kg | 115.162 N | 0.759 m² |
| Cone 4 FMJ B (Long) | 0.012454 m³ | 15.0672 kg | 147.809 N | 0.973 m² |
Performance Specifications
- Compressed Air Pressure: 8 bar (800,000 Pascals)
- Thrust Generated: Approximately 1700N
- Air Resistance: Varies by cone cross-section
Safety Features
- Pressure release valve for safety
- Reinforced nozzle construction
- Impact-resistant materials
Materials Research
We had to identify a material that provides high stiffness, low density, excellent dimensional accuracy, and reliable 3D printability. The following table presents five candidate materials and their key properties. These values have been gathered from aerospace materials databases and published literature.
| Material | Density (kg/m³) | Young's Modulus (GPa) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Cost (USD/kg) | Printability |
|---|---|---|---|---|---|---|---|
| PET | 1350 | 9 | 150 | 40 | 32 | 1.52 | Very good |
| HDPE | 950 | 0.8 | 28 | 33 | 367 | 0.93 | Good |
| LDPE | 920 | 0.3 | 20 | 10 | 200 | 1.19 | Do-able |
| LDF | 350 | 0 | 1.94 | 0 | 0 | 1.94 | No (machinable) |
| MDF | 700 | 4 | 18 | 0 | 0 | N/A | No (machinable) |
| HDF | 900 | 10.5 | 35 | 25 | 0 | N/A | No (machinable) |
Material Selection Rationale
After extensive evaluation of various materials, PET (Polyethylene terephthalate) was selected as the optimal choice for our water rocket. Key factors in this decision include:
- Superior tensile strength (150 MPa) compared to alternatives
- Excellent 3D printability for easy manufacturing
- Cost-effective at $1.52/kg
- High density (1350 kg/m³) providing structural integrity
- Good balance of strength and flexibility (32% elongation)
While other materials like HDPE and LDPE offer good printability, their lower tensile strength makes them less suitable for high-pressure applications. Wood-based materials (LDF, MDF, HDF) were excluded due to their lower tensile strength and higher manufacturing complexity.