Polished aluminium aircraft surfaces
 

Anyone know if the AA 767s are simply polished aluminium or have a protective coating applied after polishing? I'm assuming this is done to reduce profile drag and not just for aesthetic reasons.

it has nothing to do with drag, it has to do company image. there in no protective coating, what makes the shine last is the quality of the wax they use, and the buffer they use, it usually last about a week before starts to get dull again. Aeromexico and Mexicana used to do the same thing with their DC-9/MD-80 and 737. hopes this helps.....

we stripped some 744 freighters, to save money in fuel burn (less weight to carry around) trouble was it costs more to maintain than the savings made on fuel.:ugh:

At least you can see the cracks:)

Interesting question which surfaces every now and then .. personally, I reckon a silver bird looks absolutely ripper.

Main Advantages

(a) significant weight and associated painting cost savings

(b) looks great - possible marketing tool.

Main Disadvantages

(a) aluminium is quite reactive and forms a surface oxide any time the metal is exposed to air - this is the basis for anodizing - colour the oxide and you get a nice coloured finish. Longer term polishing progressively has the associated risk of sheet damage. (We can exclude the idiots who feature in the tale about the car dealer who wanted his nice new aircraft polished up - just a little problem with all those tiny bumpy bits over the skin - never mind, grind off the rivet heads and the problem went away ..... thank heavens for the Darwin Awards to give us a vehicle to put such stupidity on a pinnacle when it is fatal).

(b) lots of lap and other joints just asking for corrosion problems to be accelerated compared to a nicely painted surface.

Which wins ? .. the numbers give the clue.

So the low cost airline should be flying around with an anodized surface, ugly as all get out but would make a statement, call it "Go Green".

John I believe someone mentioned above that the cost of polishing is near equal to that of paint, low overhead high maintenance.

So the low cost airline should be flying around with an anodized surface, ugly as all get out but would make a statement, call it "Go Green".

doesn't bear thinking about ... but, then again, perhaps Hein's delightful grook is appropriate .. "my face I don't mind it .. because I'm behind it .. it's the people in front who object"

cost of polishing is near equal to that of paint, low overhead high maintenance.

possibly outweighed by the spectre of corrosion. If your thesis were valid, surely we would have far more aircraft in shiny tin rather than paint ?

Good luck buffing that 787 :}

http://www.jetphotos.net/news/media/...7838952821.jpg

cost savings?
 

I really would like to see some hard numbers on this- AA has had the same livery for 40 years now, vs. UA has had what, 4 different corporate liveries in the same time, not counting Shuttle and Ted? I have heard that Boeing has to take extra precautions with AA skins for color matching, and have seen that some airplanes, when stripped of paint, have some ugly surprises like greenish panels.

It seems to me that AA has a huge cost advantage when you look at the amount of paint they haven't bought, versus UA having to repaint their fleet constantly. Not to mention the 600 pounds or so of paint that a wide-body carries around on every flight. And I don't remember seeing an AA airplane that looked bad, but I can find a UA airplane looking ratty any time I want.

With 2024 clad sheet having a thin outside surface of relatively pure aluminum, I don't think corrosion is a huge problem, and it sure seems like skin inspections would be easier w/o paint.

I wonder what AA's gonna do when they get their 787s? Gotta have paint on those...:=

American had to paint their A300s as well which was part of an anti-corrosion requirement of the manufacturer. They used a grey aluminium-lookalike (almost) colour.

American are unique in having changed their livery just once in the near-80 years since metal aircraft came along in the 1930s, and in fact the only change was from the old orange-flash cheatline to the red/white/blue line around 1970.

In the 1930s all modern aircraft were unpainted, it wasn't until after WW2 that paint first appeared, first as a white top to reflect radiant heat from sunlight, which experiments proved was worthwhile in notable reduction of load on the cabin air con equipment (another positive for paint), and then integrating this with cheatline colours. BOAC were a pioneer of the white-top approach in the late 1940s, to deal with excessive heat on tropical sectors (flight deck crews had been seen operating in their swimwear), firstly just over the flight deck, moving on to the whole upper fuselage,

Only in much more recent times have liveries come along with dark-coloured upper fuselage, a double negative of adding weight by paint without the benefit to the cabin air con of the solar heat reflection. You will invariably find such colour schemes are devised by design houses who have no aviation experience.

when stripped of paint, have some ugly surprises like greenish panels.

primer .. more a surprise and worry if it's not there ..

With 2024 clad sheet having a thin outside surface of relatively pure aluminum, I don't think corrosion is a huge problem,

gives some cathodic protection but only if you don't scratch the surface .. so, what do we do ? .. we drill lots and lots of holes in the sheet ... the reality out in the dirty world is that corrosion of skins and such is a MAJOR problem, takes a lot of resources to be thrown at it, and is a right pain.

For interest the link is to a general Data Sheet from Alcoa.

The clad surfaces themselves are oxidised .. aluminium oxidises (corrodes) fairly readily. However, like any cathodic protection system, if you can keep the mechanicals OK, and the clad layer intact, you can do a good job of thwarting Mother Nature's endeavours to bring you unstuck with corrosion ...

and it sure seems like skin inspections would be easier w/o paint.

that's true enough .. but I suggest the main interest is weight saving and, for AA, brand differentiation.

Actually AA initially painted the A300s in the beginning but then reverted to the polished aluminum on the fuselage. Same as the rest of the fleet.

The only disadvantage to AA's paint schemes is all of the hydraulic/oil stains are very visible on the painted gray tails.

No clue as to what they will do with the 787. I suspect they will finally revise the livery.

Or buy some "Aluminised" sticky tape?

I keep hearing the term (skin inspection), the only skin inspections are the obvious smoking rivit and phase inspections done for corrosion from the inside (usually bildge and lav/galley areas that are prone).

The only exterior surface inspection i know of was the lap seam (i said was) as they have been done away with, with exception of a few classic aircraft. The ironic part is that lap seam inspections are suspect to at least one catastrophic failure, lap seams have to be aerodynamically filled with a compound usually the same that seals in fuel tanks, this is some tough stuff. it is supposed to be removed with a non-metallic tool. Years of suspect usage of metallic tools to cut this junk out cut the seam and eventually created a explosive seperation (aloha 737).

Back on point, paint does not make inspecting aircraft skin much harder than it is W/O it.

With insulating blankets along the whole aircraft would it really make a difference today?

In fact, I believe that polished alloy aircraft require especially prepared skins, handled very carefully during the component and final assembly stages. If I am not mistaken, I believe AA needed their first A-300's quickly, before Airbus could make the required skin spec changes, and the first ten aircraft were delivered with semi polished Alclad, not quite to the fine polished skin standard of Boeing, or of Fokker on the F-100.

'aa73' and 'twochai': I remember, from Flight International I believe, a slightly different slant on this topic. When AA first ordered Airbuses, they wanted to maintain their tradition of bare metal fuselages but Airbus refused to give them a warranty on the skin unless it had some form of coating. So an agreement was reached whereby a coating was applied. Perhaps when the warranty expired AA reverted to bare metal.

We did polish our Lightnings (RAF) in the 60's to make them "nice and shiny" for displays etc (large amounts of Wadpol") until it was suggested that we were removing the anti-corrosive treatment from the wings and fuselage. As the ratio of 100 hours maintenance to 1 hour flying, I guess that it did not really make any difference !!! Not so happy days!