How do you take your Propeller? One blade or two?

[facthunter]

In a 4  the pistons come to rest all at the same time twice per revolution. The flywheel effect from them varies from a maximum to ZERO twice per revolution causing undesirable pulses of torque. Having no flywheel except the prop generally, FOURS are usually noticeably rougher than  others unless an effective harmonic balancer is part of the deal . Torsional harmonics are not anything to do with centrifugal or centripetal forces. The pistons and a % of the conrods may be considered to be masses accelerating and stopping constantly in a straight line at each limit of the stroke taking and giving back torque from the rotating parts.. 

  A three cylinder and even a VEE are better configured in this respect. A four stroke radial has uneven cylinders as it's designed for even firing and there is always a gap of one  to the next one which is fired. A  nine cylinder firing order goes 135792468. A two stroke radial can have an  even number OR an odd number for even firing. Nev

[danny_galaga]

Sorry for not reading the whole thread through in case someone already mentioned it. Single bladed props have been used for decades in model aircraft. Particularly control line speed models, which are high powered, revving at say 30,000 rpm. And also some rubber powered free flight models, where the revs are quite low. So at least at small scale, quite versatile.

 

Check out this short clip, the sound of that engine when it comes on song is unreal!

 

http://airpigz.squarespace.com/blog/2010/3/16/36000-rpm-1-blade-prop-and-208mph-control-line-model-airplan.html

 

Edited February 15, 2021 by danny_galaga