Balancing a prop
09-19-2003 | 08:17 AM
#2
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From: Somewhere in,
IN
RE: Balancing a prop
Good question. I would like the answer too. I am flying the alpha with the 3 bladed prop and have never balanced it. I was talking to a friend who suggested I balance it. I hope someone who has the answer shares with us.
09-19-2003 | 08:35 AM
#3
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From: kaisersluatern
RE: Balancing a prop
i'm not too sure on this, but i imagine it's similar to balancing a two bladed prop. If you have a prop balancer, put the prop on it and take note of wich blade falls. Then take some finger nail polish and put a dab on the light blade. Repeat this untill the prop stays in whatever position you put it. I.E. prop doesn't fall to one side. For a three blade, I would apply polish to one blade at a time. Maybe someone with some 3 blade experience can chime in here.
09-19-2003 | 08:39 AM
#4
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From: Toronto, ON, CANADA
RE: Balancing a prop
First, you put it on the plane.
Then you nose-over on take-off, break the prop.
Buy a new one.
Repeat until you happen to buy a prop that is balanced ....
Joking. Have a look at:
http://www.bollyprops.com/propbal.html
Also there are some informative threads on the Questions and answers....
do a search for [link=http://www.rcuniverse.com/forum/searchpro.asp?phrase=prop+balancing&forumid=ALL&pr oduct=&topicreply=both&message=both&author=&timefr ame=%3E&timefilter=0&language=single&top=300&crite ria=AND&minRank=10&submitbutton=+OK+]Prop Balancing[/link]
gus
P.S. Everything I have read indicates that you should NEVER alter the width or length of a prop. Also, you should never add or remove weight from the "flat" side of the propellor (the side closest to the engine). To change the balance, either sand the airfoil side, or add weight (using CA, epoxy, paint, dope, nail-polish, etc) to the airfoil side.
Apparently, changing the pitch, chord, and length of the prop all have a more significant effect on the "dynamic balance" of the prop than changing the airfoil.
Then you nose-over on take-off, break the prop.
Buy a new one.
Repeat until you happen to buy a prop that is balanced ....
Joking. Have a look at:
http://www.bollyprops.com/propbal.html
Also there are some informative threads on the Questions and answers....
do a search for [link=http://www.rcuniverse.com/forum/searchpro.asp?phrase=prop+balancing&forumid=ALL&pr oduct=&topicreply=both&message=both&author=&timefr ame=%3E&timefilter=0&language=single&top=300&crite ria=AND&minRank=10&submitbutton=+OK+]Prop Balancing[/link]
gus
P.S. Everything I have read indicates that you should NEVER alter the width or length of a prop. Also, you should never add or remove weight from the "flat" side of the propellor (the side closest to the engine). To change the balance, either sand the airfoil side, or add weight (using CA, epoxy, paint, dope, nail-polish, etc) to the airfoil side.
Apparently, changing the pitch, chord, and length of the prop all have a more significant effect on the "dynamic balance" of the prop than changing the airfoil.
09-19-2003 | 08:53 AM
#5
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My Feedback: (4)
RE: Balancing a prop
Like this:
But seriously folks...
A good prop balancer like the one put out by Great Planes can be very handy. The one made by Dubro works well with larger props. With a 3 bladed prop, you know that it's perfectly balanced wheh it comes to rest in a different position each time it stops. In other words, if you give the prop a slight spin, and each time you do it, it stops in the same position, the bottom side is heavy (This is reguardless of how many blades it has). And it should not start to spin in the opposite direction after it stops)
But don't get too crazy. Unless you are doing VERY presision stuff, like extreme speed, there is rarely a case where a prop under 14" ever really NEEDS to be balanced.
And when they do, "Close" is close enough.
But seriously folks...
A good prop balancer like the one put out by Great Planes can be very handy. The one made by Dubro works well with larger props. With a 3 bladed prop, you know that it's perfectly balanced wheh it comes to rest in a different position each time it stops. In other words, if you give the prop a slight spin, and each time you do it, it stops in the same position, the bottom side is heavy (This is reguardless of how many blades it has). And it should not start to spin in the opposite direction after it stops)
But don't get too crazy. Unless you are doing VERY presision stuff, like extreme speed, there is rarely a case where a prop under 14" ever really NEEDS to be balanced.
And when they do, "Close" is close enough.
