Jan, this is somewhat inspired by the "quiet props" thread, but also just a pragmatic question.
The HKS 700T engine is an 80 hp turbocharged engine (77 hp continuous) that produces peak power at 5300 rpm (4900 rpm continuous), and has an integrated 2.62:1 redrive, for a prop speed of ~2025 rpm (1870 rpm continuous).
The Sonex Onex is designed around the Aerovee engine, which produces its 80 hp at 3400 rpm, direct drive. It spins a 54" x 44" fixed-pitch propeller, giving a ground clearance of 8" (both taildragger and tricycle).
To stay within the 7" ground clearance requirement for a tricycle gear aircraft prescribed in Part 23, and assuming a similar thrust line between the HKS and Aerovee, the maximum prop diameter for the Onex would be 56". This leads to an HKS tip speed of 150 m/s (~0.44 Mach), which is, as expected, incredibly slow.
So, what does an HKS-driven Onex look like? Lots of blades, I assume. Noise level? Efficiency?
The HKS 700T engine is an 80 hp turbocharged engine (77 hp continuous) that produces peak power at 5300 rpm (4900 rpm continuous), and has an integrated 2.62:1 redrive, for a prop speed of ~2025 rpm (1870 rpm continuous).
The Sonex Onex is designed around the Aerovee engine, which produces its 80 hp at 3400 rpm, direct drive. It spins a 54" x 44" fixed-pitch propeller, giving a ground clearance of 8" (both taildragger and tricycle).
To stay within the 7" ground clearance requirement for a tricycle gear aircraft prescribed in Part 23, and assuming a similar thrust line between the HKS and Aerovee, the maximum prop diameter for the Onex would be 56". This leads to an HKS tip speed of 150 m/s (~0.44 Mach), which is, as expected, incredibly slow.
So, what does an HKS-driven Onex look like? Lots of blades, I assume. Noise level? Efficiency?