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Jerry324

Long EZ elevator weight/balance discussion

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I am installing an autopilot trim servo to my Long EZ. I mounted the control servo to the bottom of the canard. I have mounted a 0.50" dia. X 1.00" lg. aluminum tube spacer and an AN3 bolt and nut to the left CS12 bracket. The spacer, bolt and nut connects to the elevator trim servo control rod.

 

I believe these items need to be included in the weight and balance of the elevator. I have weighed the elevator with the spacer, bolt, and nut. The weight is 3 lb. 10 oz. which is under the 3 lb. 14 oz. max weight but the balance is 9 degrees which is outside the 12-22 degree balance limit.

 

I can move the balance to 15 degrees by adding 1.8 oz. of lead weight to the outboard CS10 weight OR remove around 3 oz. of weight from the inboard CS11 weight.

 

I am not sure what the corrective solution should be. Has anyone addressed this issue on your plane?  I Would appreciate  your input.

 

Jerry324

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... I can move the balance to 15 degrees by adding 1.8 oz. of lead weight to the outboard CS10 weight OR remove around 3 oz. of weight from the inboard CS11 weight.

If adding 1.8 oz. to the outboard mass balance weight will bring the elevator into spec (more than 12 degrees TE up, and less than 22 degrees TE up), then that's the right answer. The CP's are clear that if weight is to be added, it's to be added to the outboard mass balance (although I've seen numerous folks do the wrong thing, and have fixed a few planes that were set up that way).

 

I don't understand why you believe that removing weight from the inboard mass balance, which is also ahead of the hinge line, could possibly make the elevator balance more TE up. If you need to add weight to the outboard mass balance, then you'd also have to add weight to the inboard mass balance (_IF_ that were an acceptable method of balancing the elevator, which it isn't).

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Marc Thanks for your reply.

 

I tend to over think a problem. I had also read that I should add weight to the outboard mass balance weight but I had also read that keeping the elevator as light as possible helps reduce the distructive low frequency isolations so I was not sure what direction to go. 

 

I will add the weight to the outboard mass balance weight as you have suggested. 

 

My background is in mechanical engineering and product design but I am not an aeronautical engineer so I am trying to be extremely causes when I make changes on my plane. 

 

Thanks again Jerry

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I tend to over think a problem.

You and 90% of other builders :-).

 

I had also read that I should add weight to the outboard mass balance weight but I had also read that keeping the elevator as light as possible helps reduce the distructive low frequency isolations so I was not sure what direction to go.

Balance is critical - weight is desirable. If you can meet (or be very close to) the weight requirement while maintaining the balance, that's the path to take. Do NOT reduce weight unless you can stay in balance (after paint).

 

... so I am trying to be extremely causes when I make changes on my plane.

A prudent path. Edited by Marc Zeitlin

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