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  #1  
Old 08-04-2013, 09:14 PM
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LAMPSguy LAMPSguy is offline
 
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Default Mass balancing engineering question

The ailerons use a steel tube for a mass to balance them. I am directed to cut it to a specific length. But what if someone does not prime inside? What if I heavily prime? Obviously the weight is small, but is must be significant enough to measure I would imagine.

Any active aero engineers that can answer this? I can't find my old text books and those classes...well...they are a bit fuzzy!

I imagine the tiny weight differential would/could be offset by trailing edge geometry. Just curious, not worried!
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  #2  
Old 08-04-2013, 09:18 PM
johnny stick johnny stick is offline
 
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Default My take

Although I am by no means an expert compared to others on this site, I believe more mass actually helps with flutter control. The farther in front the aileron's CG is from the center of pressure (of the aileron) the more flutter resistance the surface has. But I will let others correct me.
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  #3  
Old 08-04-2013, 09:22 PM
rgmwa rgmwa is offline
 
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Default

Isn't the tube stainless steel?
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  #4  
Old 08-04-2013, 10:11 PM
eddieseve eddieseve is offline
 
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Default

The tube is galvanized iron and does need to be primed internally.

I agree with Johnny's comment about the extra weight in front of the CofG being OK.

Not enough weight where the wright is behind the CofG and the aileron is unbalanced if I recall is very bad.

Cheers
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  #5  
Old 08-04-2013, 11:41 PM
chrish chrish is offline
 
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Default

The amount of paint on the aileron will probably have more effect on total mass balance than the amount of primer on the inside of the galvanised tube.
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  #6  
Old 08-05-2013, 12:18 AM
Andy_RR Andy_RR is offline
 
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The idea behind balancing is that any vertical motions/accelerations/forces are applied directly to the centre-of-mass of the control surface so as not to cause any unwanted control deflection

If they balance on their hinges, all is well.
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  #7  
Old 08-05-2013, 06:35 AM
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M McGraw M McGraw is offline
 
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Default Mass balance

If your building the RV14 the tube is stainless and the instructions say there is no need to prime. With that said, should you choose the prime the extra weight would not hurt in any way.
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  #8  
Old 08-05-2013, 08:48 AM
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airguy airguy is offline
 
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Default

My aileron tubes (9A kit) were 304 stainless, no priming needed.
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