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  #1  
Old 06-30-2012, 05:02 PM
edward7048 edward7048 is offline
 
Join Date: May 2010
Location: Kokomo, In.
Posts: 95
Default weight and balance

the manual said to put 2 inch blocks under the main wheels to level
the aircraft. My aircraft is level when on the main gear. I wonder if this
is normal?
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  #2  
Old 06-30-2012, 06:31 PM
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MartySantic MartySantic is offline
 
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Location: Davenport, IA
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Default

Why do you believe it is level without the 2" blocks. What is your reference?
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  #3  
Old 06-30-2012, 07:56 PM
edward7048 edward7048 is offline
 
Join Date: May 2010
Location: Kokomo, In.
Posts: 95
Default weight and balance

with the canopy open I amchecking for level at the longeron as in the
manual.
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  #4  
Old 06-30-2012, 08:58 PM
sf3543 sf3543 is offline
 
Join Date: Jan 2005
Location: San Antonio, TX
Posts: 926
Default If its level, then its level!

You could also let air out of the nose wheel to get the nose down.
Don't forget to close the canopy to get the correct weight on the scales.
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Last edited by sf3543 : 06-30-2012 at 09:00 PM. Reason: Added comments.
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  #5  
Old 06-30-2012, 08:59 PM
morsesc morsesc is offline
 
Join Date: Sep 2007
Location: Columbia SC
Posts: 62
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This was confusing. We assumed that you put 2" blocks under the mains when you place the nose wheel on the scale to make level. If using 3 scales, no need.
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  #6  
Old 07-01-2012, 02:26 AM
crashley crashley is offline
 
Join Date: Jun 2009
Location: hazelwood north vic
Posts: 165
Default balance

I believe 2 " blocks under the mains brings it up to level if using 3 scales blocks still needed
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  #7  
Old 07-01-2012, 09:59 AM
morsesc morsesc is offline
 
Join Date: Sep 2007
Location: Columbia SC
Posts: 62
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A fellow builder said he called Van's about this and was told that 2" blocks were used to raise the mains only if using a single scale for the nose wheel. After wheel pants, paint and carpet, my 12 is due for another wt and bal. Need to find out for sure.
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  #8  
Old 07-01-2012, 10:26 AM
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Walt Walt is offline
 
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Location: Dallas/Ft Worth, TX
Posts: 4,871
Default

Every aircraft must have a leveling means to determine CG, if it's not in the manual somewhere than Van's needs to supply that info.
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  #9  
Old 07-01-2012, 03:06 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,854
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Quote:
Originally Posted by morsesc View Post
A fellow builder said he called Van's about this and was told that 2" blocks were used to raise the mains only if using a single scale for the nose wheel. After wheel pants, paint and carpet, my 12 is due for another wt and bal. Need to find out for sure.
Lines of communication must have gotten crossed somewhere, because the above is totally wrong. How would someone at Van's now how thick the scale being used was?

When computing the weight and balance of an aircraft based on weights obtained at the locations of each of the wheels, the airplane must be positioned at the same pitch attitude that was used by the manufacturer when they derived the C.G. range limits.
The RV-12 PAP specifies that the airplane be weighed in a level attitude when measured at the canopy side rails.
This can be done one wheel at a time, but it is usually not as accurate.
Regardless of how you choose to do it, the pitch attitude needs to be adjusted because the normal static pitch attitude with the airplane sitting on all 3 wheels is tail low. To get it level it requires the main wheels to be shimmed up about 2" (the reason it calls for the 2" blocks).
If you are weighing one wheel at a time, it would require 2" blocks under each main wheel, plus blocks equal to the scale height, under each wheel not on the scale.
Another method for leveling the airplane can be to remove air from the nose tire, but the reason the blocks are specified is that you need to make the nose tire almost completely flat to get the fuselage leveled at the cockpit side rails.

Which weighing method used does not matter, but the pitch attitude the airplane is in while doing so is critical if the final results are going to mean anything.
As already mentioned, remember to close the canopy after getting it leveled on the scales (it does make a difference).
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  #10  
Old 06-04-2018, 11:36 AM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 243
Default Factor Wheel Pants on and off for W&B Calculations?

Unable to find VAF discussion on RV-12 Wheel Pants regarding W&B. Is the weight significant to recalculate whether they are on or off?
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