At present, two-stroke reciprocating internal combustion engines with a small total cylinder displacement are used to power ultralight aircraft. Their principal drawback is loud operation, particularly for operating and maximum values of the crankshaft rotational speed (RPM). The primary load on the powerplant is the propeller directly coupled to the engine crankshaft. This propeller to a large extent determines the characteristics of the sound level (acoustic signature) generated by the entire aircraft propulsion system. Additionally, the propeller blade airfoil itself generates additional aeroacoustic noise. Currently, engine designers pay a lot of attention to the sound level especially for civil aircraft, working near residential facilities or recreational areas. Tests were performed on a dedicated stand at a fixed distance. A simultaneous, dual-station setup was used—microphones in the propeller disk plane (L) and in the wake (T) - with thrust recording and five repeats per setpoint (A-weighted, FAST; energy-averaged means) for three 3-bladed CFRP propellers (Biela 32×12, Biela 32×14, Falcon 32×13) at 3000/4000/5000 RPM. Results show a monotonic rise in SPL with RPM and clear downstream directivity. At 5000 RPM, mean L(MAX) lies in 102.5–104.2 dB, while T(MAX) lies in 102.9–109.3 dB; mean thrust increases from ~111–147 N (3000 RPM) to ~323–405 N (5000 RPM). Biela 32×14 offers the most favorable thrust-to-noise trade-off (≈4.6 dB per 100 N). Practically, operating at ≤4000 RPM keeps mean maxima near ~102 dB at both positions for noise-sensitive missions. The innovativeness of the study consists in the simultaneous, dual-station noise measurement (in the propeller disk plane and in the downstream/wake direction) coupled with thrust recording and a full uncertainty budget, carried out on a dedicated test stand enabling stabilization of the shaft rotational speed and comparison of three propeller geometries.