Blockchain offers a secure, automated, and highly traceable foundation for UAV swarms, supporting optimized flight management, enhanced efficiency, and increased system trustworthiness. However, applying blockchain to the unique context of UAV swarms introduces adaptability challenges that must be carefully addressed. To overcome issues such as limited decision-making capabilities and insufficient security in asynchronous UAV networks, we propose a blockchain-based framework specifically designed for such environments. It features a trust-based asynchronous consensus mechanism, where UAVs within a ground control station (GCS) elect a primary node, and inter-GCS coordination achieves global consensus. To support resource-constrained UAV nodes, the framework also incorporates a hierarchical identity authentication mechanism using OpenSSL certificates to ensure secure node participation.