Weight and balance cautionary note

[Greg Arehart]

After flying for a year now and making a few modifications plus painting, I decided it was time to do a reweigh on my 9A. Some interesting observations I made: as expected, the overall weight increased by 31 lbs (mostly paint) and CG moved aft (I lost 15 lbs from the nose). However, the most interesting observation I made was the weighing process itself. I used good quality aircraft scales and carefully zeroed them. My initial weights for the L and R mains were 447 and 425 lbs, nose at 275. The 20-pound difference puzzled me (I could rationalize a few pounds, but not 20!). In looking at the nosewheel, it was about 15-20 degrees off of being straight, so I straightened the wheel and reweighed things. Voila! the two mains ended up at 436 and 437! So, my cautionary tale is to make sure that your nose (or tail) wheel is straight when weighing your airplane. I would not have thought that this would make so much difference. Didn't really matter to the overall W&B of the airplane since both mains are at the same distance from the datum, but interesting nonetheless.

As they say, part of this is "for education" and I certainly learned something today.

Cheers,
greg

[David-aviator]

Greg,

Thirty-one pounds of paint? That seems like a lot of paint.

[Greg Arehart]

David,

Certainly mostly paint, but it was originally weighed with the fairings piled in the approximate position plus I have made a few additions (like brackets for oxygen bottle etc.). I might go back through the archives and see if that is an exorbitant amount of paint (it is yellow and red, which have heavy pigment).

greg