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weight and balance

edward7048

Well Known Member
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?
 
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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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.
 
balance

I believe 2 " blocks under the mains brings it up to level if using 3 scales blocks still needed
 
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.
 
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.
 
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).
 
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?
 
They do have an influence.
The wheel pant kit is supplied with info regarding the typical weight and C.G. influence when installing the wheel pants (Close enough for amending the weight and balance if added after the aircraft was weighed).
 
Would anyone have a weight and balance for a Dual G3X-equipped RV12 they'd care to share? Mine has come out a bit heavier than expected but more importantly seems rather nose heavy so I'd like to compare results. I do have the ADS-B IN and OUT options, Garmin autopilot, full Vans interior, parking brake valve and wheel pants. I have also fully primed the interior in 2-pack, but the outside isn't painted yet.

My weighing figures are as follows:
Nose 164.6 lbs @ 29.5" aft of datum
Left main 304 lbs @ 92.875"
Right main 315.9 lbs @ 92.875".
Total weight 784.5 lbs with C of G at 79.58"

Thanks in advance

Harry
 
Download THIS spreadsheet. Change numbers in yellow cells only. It looks like you will be OK with balance unless the pilot and passenger are heavy and fuel is low and there is no baggage.
 
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