Low-overload internal ballistics in UAV ejection using multiple time-sequenced compressed-air chambers

Area of Science:

• Aerospace Engineering
• Mechanical Engineering
• Applied Physics

Background:

• Compressed-air ejection systems launch unmanned aerial vehicles (UAVs) using high flow rates, causing significant overloads.
• These overloads impose strict structural requirements on UAVs, increasing weight and cost.

Purpose of the Study:

• To propose and analyze a multi-chamber ejection method with time-sequenced actuation for UAVs.
• To reduce launch overload while maintaining high launch velocity.

Main Methods:

• Developed and validated an internal ballistics model incorporating real-gas properties for UAV compressed-air ejection.
• Simulated the performance of multi-chamber (two or three) ejection systems with varied chamber configurations.

Main Results:

• Multi-chamber systems significantly reduced maximum overload compared to single-chamber systems.
• Overload reductions were 20.91% (two identical chambers), 26.08% (two different chambers), and 33.24% (three different chambers).
• The required muzzle velocity was maintained across all tested configurations.

Conclusions:

• The proposed multi-chamber ejection strategy effectively mitigates launch overload for UAVs.
• This approach offers a viable solution for designing lighter and more cost-effective UAVs.
• Time-sequenced actuation in multi-chamber systems is key to balancing launch performance and structural integrity.