777ord
Topic Author
Posts: 675
Joined: Sat May 15, 2010 12:04 pm

Paint Job And Weight/balanace Issue

Wed Sep 21, 2011 6:44 pm

I was reading the recently posted topic about Finnair's "Angry Birds" paint job and it made me wonder what sort of challenges/ changes are made to an aircrafts W&B to compensate for the new paint job, as well as what sort of drag changes/ challenges are made to compensate for the newly done paint job when it comes to flight planning.

When looking at such fascinating paint jobs as Peter Max on the CO 777, or Wanulu dreaming for QF etc... vice the AA 'bare bone' style paint job really come to mind on the topic, too.

Thank you all for your input.
 
Fabo
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RE: Paint Job And Weight/balanace Issue

Wed Sep 21, 2011 7:06 pm

I guess the airplane is weighed after paint job, as it is periodically weighed anyway, so you have that covered for a while.

I believe that weight of a typical livery on a typical 737ish size jet is about 200kgs, IIRC.
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KPWMSpotter
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Joined: Tue Dec 26, 2006 1:01 am

RE: Paint Job And Weight/balanace Issue

Wed Sep 21, 2011 7:46 pm

For aircraft as a whole, the weight change will be considered, but the paint doesn't contribute enough to the aircraft's CG to be considered. The paint scheme can be assumed to be an evenly distributed loading, especially when compared to the total weights in play across a whole aircraft. Weight will need to be factored into the aircraft's total weight, but not so much balance.

On the other hand, balanced components like rudders, tabs, and other flight controls must be considered for balance after paint work, as any change in the part's weight/balance can have significant impacts on the part's flutter properties. Other components (winglets, for example) are also weight and CG controlled - Boeing's APB winglets for example are typically allowed a +0.5lb variance in weight after repair/refinishing, anything larger than that will prompt an in-depth flutter analysis.

Most of the time flight controls aren't repainted with the aircraft (ailerons and elevators usually don't make up any important part of a livery), but rudders (and especially McDonnell Douglas rudder control tabs) must be removed and balanced after any work is accomplished.
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tdscanuck
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RE: Paint Job And Weight/balanace Issue

Thu Sep 22, 2011 2:10 am

Quoting 777ord (Thread starter):
as well as what sort of drag changes/ challenges are made to compensate for the newly done paint job when it comes to flight planning.

A paint job makes no meaningful change in drag (unless it's done really badly) except via its weight...knowing the weight is sufficient to get accurate results for flight planning.

The exception is natural laminar flow designs where smoothness really matters...but those will have special painting instructions anyway and are fairly rare on large airliners.

Tom.
 
777ord
Topic Author
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Joined: Sat May 15, 2010 12:04 pm

RE: Paint Job And Weight/balanace Issue

Thu Sep 22, 2011 3:39 pm

Awesome! Thanks guys!! makes perfect sense.

I appreciate the input.

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