As wildfires grow more intense, aerial firefighting capabilities must evolve. At Qomalra, we redesigned a helicopter water bucket. We increased its capacity from 900L to 4000L. We also ensured its structural integrity under extreme operational loads. Here’s how we achieved it.
The Challenge
Existing 900L buckets lack the capacity needed for modern mega-fires. Our goal was clear. We aimed to redesign the mechanism to safely carry 4,000 liters, which is equivalent to 3,920 kg of water. The new design must withstand turbulence, rapid deployment stresses, and aerial maneuvers.
Original Design Limitations
The baseline 900L bucket weighed 67.5 kg (including doors) and measured:
- Upper radius: 0.54 m
- Lower radius: 0.46 m
- Height: 1.16 m
It used lightweight 19×19×1.5 mm square pipes and 6.35 mm steel plates—inadequate for scaling.
Methodology
We ran ANSYS Static Structural simulations with a 1.6 safety factor, evaluating designs against Von Mises stress criteria (yield strength of stainless steel 316: 205 MPa). Critical failure points were identified through deformation analysis.
Key formula:
Design Load = Water Weight × Safety Factor
Water force: 4,000L × 9.8 m/s² = 39,200 N
Design load: 62,720 N (applied to the bucket’s base plate)
The Design Evolution
Simulation 1: Scaled Baseline
- Original structure enlarged to 4,000L dimensions.
- Result: Catastrophic 752 mm deformation. Weaknesses: upper/lower frames and legs.
Simulation 2: Initial Reinforcements
- Upgraded pipes to 25.4×25.4×3 mm + cross-bracing.
- Result: Deformation dropped to 359 mm, but legs remained failure points.
Simulation 3: Leg Reinforcement
- Enhanced legs to 50.8×50.8×3 mm pipes; base plate thickened to 12.7 mm.
- Result: Deformation controlled—but base plate became too heavy (180 kg).
Simulation 4: Weight Optimization
- Base plate reduced to original 6.35 mm; lower pipes upgraded to 31.75×31.75×3 mm.
- Result: 13 mm max deformation with 22.9 MPa average stress (well below 205 MPa yield limit).
Final Optimized Design
- Capacity: 4,000 liters
- Weight: 197.1 kg (doors excluded)
- Dimensions:
- Upper radius: 1.879 m
- Lower radius: 1.52 m
- Height: 1.76 m
- Reinforcements:
- Legs: 50.8×50.8×3 mm pipes
- Lower frame: 31.75×31.75×3 mm pipes
- Base plate: 6.35 mm thickness
Why This Works
- Safety: Stress levels at 11% of the material yield strength.
- Efficiency: 197 kg frame supports 3,920 kg water payload.
- Stability: 13 mm deformation ensures in-flight stability.
Conclusion
This validated design achieves a 344% capacity increase with minimal weight penalty. Ready for manufacturing, it empowers firefighting teams to combat mega-fires effectively. At Qomaira, we merge precision engineering with real-world impact—one lifesaving innovation at a time.
Images referenced: Include Figures 1–13 from the report to visualize design iterations and simulation results.