3 ms·

Thanks. The explanation there makes sense. Still, this must be a secondary effect since there are plenty of examples of even-bladed and non-prime bladed propell

• lazide 4y ago
  Sometimes, the constraints make the extra work worthwhile. It’s an engineering problem. Typically, you’ll see more blades when you have a limited area you can cover with the blades (aka, low wings or stubby wings, or lots of engines relative to the wing size) and need more power/thrust. Adding more engine power is easy enough, if the decrease in overall efficiency and stronger airframe required are ok. It’s not a super common trade off, but it’s not that uncommon. If the ‘more blades’ math means it’s an even number, then so be it. Balancing them more carefully, strengthening the airframe in problems areas more, etc. is all part of the equation. It is more work though. You’ll see similar tradeoffs between something like a jet ski water impeller and a cargo ship prop. Jet engines have similar type of trade offs - max power vs overall efficiency, or efficiency at cruise vs efficiency during variable condition use. Or noise vs power. The type of engine used in a fighter jet makes very different tradeoffs than in an airliner. Adding ducting around a prop or fan also allows much higher total thrust for the given real estate, at the cost of weight and a bit of efficiency. 3 is usually the cheap and easy answer. Sometimes it’s even the exhaustive and time consuming answer too!