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Cg formula


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Posted

Hello, 

Can anyone provide me the formula for calculating the Cg on the Avid taildragger?

Thanks.

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Posted (edited)

Hello, 

Can anyone provide me the formula for calculating the Cg on the Avid taildragger?

Thanks.

Plane leveled - Leading edge is data point.  Weight on each wheel x axle distance from data point (arm).  Total of all 3 (weights x arms) divided by total weight will give you empty CG.  Recalculate for loaded CG by adding (weights of fuel (6 lb/gal), pilot (FAA=170 lbs), passenger (FAA170 lbs) x arms) added to (weights x arms total above) and divided by new total weight.   The manual gives the arms for fuel and pilot/passenger.  Someone has a computer program to do this with.  Hope I helped - any questions on what I wrote?    EDMO

Edited by EDMO
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Posted

Most likely you will find that the main wheels are in front of the datum point.  In that case, they become a - number.  In other words, in front of the datum point are subtracted.  In the Avid MK IV, pilot moment is 16"  wing tank fuel is 15".  I believe the C model is the same.  JImChuk

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Posted (edited)

Thanks for the correction and added info Jim - I was thinking Kitfox where the mains are usually behind the datum point.  Since he said "taildragger" I didn't add that for a nosedragger the nose wheel arm, or anything forward of the datum point would be a minus number.   That makes a huge difference in CG.   EDMO

Edited by EDMO

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Posted

Or you could just use my excel spreadsheet in the files and forms area and it'll do all the work for you. 

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Posted

I wonder if the 16.5" cg aft limit is set by requirements for the tricycle-gear version, not pitch stability.

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