Weight and Balance - a micro-rant

On Thursday, August 29, 2013 11:38:23 AM UTC-7, Eric Greenwell wrote:[color=blue]
Brad Alston wrote, On 8/28/2013 9:36 PM:

'Uncle Fuzzy[_2_ Wrote:

;844103']On Wednesday, August 28, 2013 2:30:05 AM UTC-7, Uncle Fuzzy

wrote:-



No, different 'previous owners. The measurements that they 'inked'

into the log books were accurate - with both wheels on the hangar

floor. Unfortunately, that's not what the POH calls for. Both manuals

specify 'level' and the Janus, (if I remember) actually gives a

distance. from the floor to the tailwheel. (which, conveniently

corresponds to the height of the box the scale comes in.



Is he difference significant? I doubt it. But I'm kinda' OCD about

specifications (also why I won't use RG-58 for L band (yet another

rant.

LOL-[/blue]



What?...you mean we should read AND understand the POH!? Hmmmm...when

you are throwing your person into the air and trusting in laws of

physics and someone else's engineering, I would think accuracy counts!

But then again, that's just me thinkin' again!



The difference in the two measurements is small (1% or so) and therefore

irrelevant. The critical measurement that will be strongly affected by

measuring in the wrong attitude is the distance of the main wheel axle

from a datum point; in the case of my ASH 26 E, that datum point is the

leading edge of the wing at the root. A 1" error in this measurement

means a 1" error in the location of the CG - a substantial error on wing

chord of only 33".



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm

http://tinyurl.com/yb3xywl

The weight distribution between the main wheel and the tail wheel/skid changes with the aircraft attitude because the vertical CG is above the tire contact patch. Like the others have said. Follow the manual.

Craig