Position of propeller

[John Carrodus]

I have a few questions lately. Another one that bugs me.........
Is there an optimal position to locate a two bladed propeller on the shaft in relation to the piston?

[Craig Beswick]

Interesting question. I have read there is an optimum position  so the blades are parallel when the engine stops, but I don't know what it is.

Craig

[Tom Luciano]

I was taught at a very young age between 1-2 o'clock. Been doing it that way for 50 years.

It works for me!
Tom

[Dan McEntee]

   On I/C powered airplanes, it is desirable to have the prop positioned so that after the engine stops, the blades are parallel to the ground as the piston hit compression on the way back up the cylinder. This helps protect the prop against striking the ground on landing, especially on grass. Three bladed props can get close to this by stopping with one blade vertical to create as much clearance as possible between the ground and the other two tips. On electric models, I don't know if there is any option for the prop to be stopped in any position. In my R/C electric days, I used a servo to trigger an on/off switch, and the other control arm moved a length of plastic push rod to stop the prop level with the ground.
   Type at you later,
   Dan McEntee

[M Spencer]

I put the prop so its flat , agaisnt compression , almost . Itll go a bit more with airload against comp . Depending on how clapped out . for a TIMBER PROP .
this way if the earth is on top off the aeroplane , when it lands , if its fairly smooth , it should be o.k.

TWO Props , a TWIN . ! Inner Flat - Outer vertical . If you put BOTH at Full Compession T.D.C. its opposite ? So you flick UP on the inner so you dont get blood on the aeroplane
flicking ACROSS into the Outer . Tho theres sometimes a fuselage in the way . that can hurt too .
BUT , if the two props are at 90 degress , the V I B R A T I O N seems somehow to Not Get Cumulative , as it offten does with BOTH indexed the same ! 

Most people ' reverse ' bump start these days . Though. Prop Fwd. against compression, after checking for ' bump ' ( ign ) the belt backward across the slack , so it hits Rev. Comp. and BACKFIRES FORWARD ,
and shees running .

For a unbalanced prop ( blade ) and a vibratory engine , put it at T D C . the counterweights then opposite the cylinder . put the HEAVY Blade opposite the cylinder too ( in synch with the crank counter weight .
THIS gets lesss ' rock ' as its less angular unbalance , and theres not twelve cylinders to even it out .

[John Carrodus]

Ok - Ill clarify- with the horizontal thing I knew that and got it when I was a kid with $2 week pocket money- ouch ? Broken props hurt! I mean wot is best for the motor? Thanks for the harmonics twin thingy input expatKiwi - hadn't a clue till you told me!

[Brett Buck]

Ok - Ill clarify- with the horizontal thing I knew that and got it when I was a kid with $2 week pocket money- ouch ? Broken props hurt! I mean wot is best for the motor? Thanks for the harmonics twin thingy input expatKiwi - hadn't a clue till you told me!

    I don't think it makes much difference to the engine.  I always set mine so the prop is horizontal as it comes up onto compression. My only real consideration is that I can safely start it without cutting my fingers off. I have done it the same way for however many (10-15000) flights, if I changed it now, I would probably end up at the emergency room.

    And, with the 3-blades the RO-Jett usual stops with one blade straight down, because it runs up into the taper quite a way, well onto compression. Rarely an issue.

    Brett