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Title: Building tip: Balancing propellers Post by: anwar on July 05, 2009, 05:08:45 PM Some people I fly with say that it is not really needed to balance props (they usually come balanced from the factory, but after getting any cuts or nicks, they lose the balance).
1) Do most people here worry about balancing their props ? 2) How do you balance it ? Title: Re: Building tip: Balancing propellers Post by: anwar on July 06, 2009, 03:26:17 PM Ismail - Do you balance your props occassionally ?
As a heli flyer, I just get factory balanced main rotor blades. We do apply weight stickers to further balance, if we feel significant stability/vibration issues. But for helis, 99% of the time the issue is the non-symmetrical setup of linkage rods on the head, causing one blade to rotate in a different plane than the other. Title: Re: Building tip: Balancing propellers Post by: izmile on July 06, 2009, 04:31:31 PM Normally, I do not. However, if I find excessive vibration then I check it. But it mostly gets resolved by giving a shave on the other end of the prop with a file. I just go with trial n error method.
Title: Re: Building tip: Balancing propellers Post by: saikat on July 11, 2009, 07:35:20 AM This is just another myth evolved to sell stuff to modellers -
viz - prop balancers . If fact I would'nt be surprised if the people who make prop balancers - have an understanding with the prop manufacturers - to make deliberately unbalanced props. Facts: 1. you can never achieve perfect prop balance with an IC engine at all RPM ranges 2. electric motors run so smoothly that the negligible imbalance due to manufacturing will not make a difference. Title: Re: Building tip: Balancing propellers Post by: saikat on July 11, 2009, 11:16:54 AM And another thing - just to muddy the waters further
all this talk is just about static balance - ie both blades weigh the same. what about dynamic balance ? say pitch of one blade is greater than the other ? Title: Prop question Post by: PankajC on August 13, 2009, 10:41:10 AM Guys,
Do the props need balancing? i mean since they rotate at such high speeds, a slight difference in weight distribution could create a whole lot of vibration isn't is? How does one deal with this situation? Pankaj Title: Re: Prop question Post by: Pikle6 on August 13, 2009, 10:44:53 AM this one is a good thread on prop balancing
http://www.rcindia.org/tools-materials-and-building-techniques/building-tip-balancing-propellors/ (http://www.rcindia.org/tools-materials-and-building-techniques/building-tip-balancing-propellors/) Title: Re: Prop question Post by: atul_pg on August 13, 2009, 10:57:36 AM I was just browsing around some days back and got a prop. chart , this might help anyone decide a prop to buy according to the engine size..
hope this helps ? cheers atul g. Title: Re: Prop question Post by: rcforall on August 13, 2009, 12:22:28 PM Most props come fairly well balance now a days.
I have never felt the need to do any special balancing for electrics. Sai Title: Re: Building tip: Balancing propellers Post by: mpsaju on August 13, 2009, 12:29:21 PM Saikat
Is it not a fact that one gets better performance of the plane (better thrust and better control) when the prop is balanced, be it an IC engine or an electric motor ? We have seen it a number of times at Kovalam. I think Sai can bear witness to this fact as he has changed props to get better performance in actual flight... So, prop balancers are not I think running in cahoots with prop manufacturers. Another fact is that any imbalance in pitch (dynamic imbalance) will also be seen with the wobbling of the aircraft and excessive vibrations. An imbalance on the shaft of the motor or IC engine can spell disaster for its life as the rpm will be high. Also the vibrations when transferred to the model will spell disaster for its structure Saju Title: Re: Building tip: Balancing propellers Post by: anwar on November 11, 2009, 10:35:54 AM Isn't balancing props critical for larger engines (like, say a 50cc gasser) ?
And how does one balance the spinner ? |