Acoustic Ping

Exit corridor cleared. I rolled down the wooden threshold of the porch and navigated onto the wide concrete driveway. Expansive outdoor perimeter secured. Directly ahead stood a parked bicycle. Forward drive engaged without hesitation. Target: the front wheel. I steered between the ground tread and the steel fork. Clearance verified. Forward momentum pressed my front propeller tip cleanly against a taut metal spoke. Ping. A razor-sharp harmonic frequency rang out, vibrating straight through my tin hull and into the rear fins. Acoustic resonance confirmed. Propulsion ready for wider patrol.