Prop Position
Which is the best way to install the prop on the crank to aid balance? Inline with the rod @ TDC or 90 degrees to it. I have known this in the past but have forgotten which way is proper. I am sure this has been asked a zillion times.
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RE: Prop Position
Postion the prop for proper grip when starting
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RE: Prop Position
I use an electric start as this is an older mag engine that is hard if not impossible to hand start. Since prop position for starting is not critical, I would like to place it for best engine balance. I think I remember that the prop lines up with the rod @ TDC, but I am not sure.
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RE: Prop Position
I put them so they are horizontal against compression when the engine stops to protect the prop from damage
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RE: Prop Position
ORIGINAL: planepounder I use an electric start as this is an older mag engine that is hard if not impossible to hand start. Since prop position for starting is not critical, I would like to place it for best engine balance. I think I remember that the prop lines up with the rod @ TDC, but I am not sure. I would make every effort to get your engine properly tuned, cooled, and balance those props/spinners...and fly. |
RE: Prop Position
ORIGINAL: w8ye I put them so they are horizontal against compression when the engine stops to protect the prop from damage Jack |
RE: Prop Position
Yeah you are probably right about the necessity to do this. I just remembered reading about the influence of prop position relative to the dynamic balance of the rotating mass.The prop is the last balancing element. I am sure each engine would be somewhat different, but there was a rule of thumb to follow on positioning it if a starting position was not required. It is on a great running old Homey 30cc. Just balanced a new prop, and was toying with the position issue, I have tried it both ways and it seems a little smoother at 90 degrees. no big thing, just curious.
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RE: Prop Position
ORIGINAL: planepounder I use an electric start as this is an older mag engine that is hard if not impossible to hand start. Since prop position for starting is not critical, I would like to place it for best engine balance. I think I remember that the prop lines up with the rod @ TDC, but I am not sure. With a three blade prop, the effect is quite a bit less pronounced, so much even as to not to bother. |
RE: Prop Position
Thanks for the reply! Any suggestions as to a good starting position?
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RE: Prop Position
If the prop is perfectly balanced, then it shouldnt matter which position its in.
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RE: Prop Position
Not true. The prop (balanced) still has influence on the mass-motion system. Also, precession forces in a two blade prop tend to oscillate, and prop position relative to the engine can dampen or increase these oscillations.
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RE: Prop Position
I put mine on the front. Never had a problem.
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RE: Prop Position
Guess you never has a pusher:D.
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RE: Prop Position
ORIGINAL: lewdfinger I put mine on the front. Never had a problem. Hows Obama working out for you? |
RE: Prop Position
I personally like a little wity funny stuff from time to time. Keeps it interesting and for Pete's sake it's a hobby so I don't take everything so seriously. Also, being from Canada he probably didn't get to vote for Obama.
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RE: Prop Position
ORIGINAL: Jezmo Also, being from Canada he probably didn't get to vote for Obama. |
RE: Prop Position
So the bottom line is that the position for minimum vibration must be found by trial and error?
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RE: Prop Position
"So the bottom line is that the position for minimum vibration must be found by trial and error?" And prop position can make. |
RE: Prop Position
ORIGINAL: w8ye So the bottom line is that the position for minimum vibration must be found by trial and error? For some engines, conversions I believe, the proper position has been posted here on RCU, but I could not find it any more. I would not bet on it that all engines find benefit in prop indexing. That would be some project to find out. |
RE: Prop Position
ORIGINAL: Ralphbf ORIGINAL: Jezmo Also, being from Canada he probably didn't get to vote for Obama. |
RE: Prop Position
Whoa!Hold on fellas...
planepounder - sorry if I sounded flippant about your topic. Vibration affects us all. I do believe I asked a very similar question some years ago on this very forum - that's why I was interested to read your post. Dumb thing for me to say - I must have had a few that night. Ralph - I'd say something witty here but I don't want to start an international incident. Sheesh - take it easy man. Jezmo - Actually I did get to vote for Obama, Several times, while we were vacationing in Florida. Weird eh? ORIGINAL: Ralphbf ORIGINAL: Jezmo Also, being from Canada he probably didn't get to vote for Obama. |
RE: Prop Position
LOL
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RE: Prop Position
Hey, no offense taken, thought it was pretty funny! Guess I can learn about this concept in my leisure now as I lost the old Telemaster in the sun on final Sunday. Guess what the first thing to the crash site was-yep the old Homey! Talk about vibration now! lol.
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RE: Prop Position
Awww man. Sorry to hear that.
(raises glass to Telemaster...) |
RE: Prop Position
Yeah we had a great time together (sniff). I even broke out a new trash bag for her.
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