Wilcharl From United States of America, joined Jun 2000, 1158 posts, RR: 3 Posted (11 years 6 months 4 weeks 1 day 3 hours ago) and read 908 times:
okay guys.. here is a quesiton that has intriged me for years..
when you see aircraft being manufactured and they have they are unpainted/puke green primerd the veritcle stabalizer is always paitned... i never understood why... is this because of the high use of composisits and requries the paint to be cured in a special manner or something... i really cant figure out a logical reason short of aircraft identification... but who cares while they are rolling down teh line... i have seen airbus and boeing do this... i would think that during the instalation the paint would get damaged and then it would have to be masked and overspray problems etc.etc..etc..
PW4084 From United States of America, joined Mar 2001, 291 posts, RR: 0 Reply 1, posted (11 years 6 months 4 weeks 1 day 3 hours ago) and read 898 times:
I've been told that manufacturers do this so they can balance and fine-tune the plane's aerodynamic characteristics earlier in the manufacturing process. If I recall, it has something to do with the weight of the paint and getting a baseline reading of the vertical stabilizer's effect on the airplane...from a flying and a CG standpoint. I learned that during a tour of the Everett Assembly Plant. I know I'm forgetting a bunch of details and there should be more people that can provide better info. But that is what I remember.
PW4084 From United States of America, joined Mar 2001, 291 posts, RR: 0 Reply 4, posted (11 years 6 months 4 weeks 1 day 2 hours ago) and read 885 times:
Thanks for confirmation Jetdoctor, I took that tour about two years ago and that question came up. It probably does often because the newly painted tails do stand out, as Wilcharl can probably attest. It's not just airline vanity
Peterba69 From United States of America, joined Mar 2002, 70 posts, RR: 0 Reply 8, posted (11 years 6 months 4 weeks 7 hours ago) and read 802 times:
It may have been hard to notice, but they have to be aerodynamically balanced before installation. Therefore painted completely. Rudders aren't that big anyway compared to the V/fin. Ailerons and elevators have to be balanced as well.
Duncan From United States of America, joined Apr 2002, 131 posts, RR: 0 Reply 9, posted (11 years 6 months 4 weeks 7 hours ago) and read 803 times:
It's not the full vertical stabilizer that is painted as the Aircraft rolls down the line, it's just the rudder. If an airline has a fairly simple paint scheme and the rudder is all one colour, it may not be noticeable that it is even painted.
As mentioned by Jetdoctor, the rudder is a flight control surface and has to be perfectly balanced for it to operate correctly. The hinge line of the rudder is held horizontally in a tool (after painting) and if it doesn't lay level, then counter weights located forward of the hinge line are either added or subtracted until it does lay level. It's a very precise procedure, so much so that placing a penny on the surface of the rudder while it is in the tool and moving it an inch forward or aft can change the balance of the rudder.
I used to do this procedure on the BAe Hawk military trainer in production, the same principle applies to large commercial aircraft. Since the counterweights are close to the hinge line they are made from very dense material (I forget the name of the exact alloy, but it's something that when you pick one of these up, you think "Wow, heavier than I thought"). One of the few applications when heavy material is prefered in aircraft manufacture. The same kind of counterbalances can also be found in other locations on various flight controls systems depending on the a/c type and system involved.
Ailerons also require the same kind of balancing procedure before installation.
Also after repairs to the structure in service, these flight control surfaces should be re-balanced.