Radial prop plane sound

Four and a half firings per revolution is the giveaway. A nine-cylinder radial is a four-stroke, so it fires nine times every two revolutions, which is 4.5 per revolution. An odd cylinder count on a four-stroke produces half-orders, and that is why a warbird radial has its distinctive uneven bark rather than the clean note of an even-cylinder engine.

Ten seconds from a standing start. The launch, the gearbox working up through the ratios, then the overrun as the throttle closes. Driven by the same gearbox model the simulator runs, so the shift points are the ones you would hear in the car.

The ceiling is 2,800 rpm. Aircraft piston engines turn slowly because the propeller tip cannot go supersonic, and the whole character follows from that constraint: big, slow, and heavy on the low orders. Bass at 125 and the sub at 80 carry that mass.

Noise sits at 130 and pipe length at 165, a long exhaust with a slow decay, standing in for open stacks. Unevenness of 15 and jitter of 12 keep the firings from landing on a grid, which matters more at low rpm where the ear can count them.

Brightness is held at 80, on the low side. A radial is not a bright sound. It is felt more than heard, and pushing the upper orders would make it thin.

Like the steam locomotive and the jet, it runs a single ratio, here 42 km/h per 1000 rpm. There is no gearbox on an aeroplane, and adding one would have been the easy wrong answer.

One ratio at 42 km/h per 1000 rpm puts 100 km/h near 2,400 rpm, just under the ceiling. Like the locomotive it has no gearbox to hide behind, so the only thing that changes as you drive is how hard the engine is working.

Specification

Every figure above is read from the preset the app actually runs, not retyped.

Drive it

Open the simulator with this engine selected, allow location, and press ignition. See how it works for what happens between GPS and sound.

Related

• Steam locomotive sound
• Jet turbine sound
• Single-cylinder thumper sound

Every other engine

• RECORDED CARS
  • BAC Mono
  • Ferrari 458
  • BMW M1 Procar
• SUPERCARS
  • Muscle V8
  • Modern V8
  • V10
  • V12
  • Anti-lag rally car
  • Air-cooled flat-six
• NORMAL CARS
  • Three-cylinder
  • Four-cylinder
  • Turbo hot hatch
  • Inline-six
  • Diesel
  • Flat-four boxer
• FUN SOUNDS
  • Steam locomotive
  • Jet turbine
  • Alien craft
  • Single-cylinder thumper

All twenty on one page, with redline and gear count for each.