Most jetliners seen in videos and such have a high-gloss finish. Are there any benefits to this type of finish for working (i.e. in routine, daily use) aircraft, beyond aesthetics?
Note: yes, aesthetics are important when you’re competing for customers. However, I’m just curious about any benefits beyond looking pretty.
I’d think the high gloss would reflect heat better making the aircraft easier to keep cool when boarding, unboarding, taxiing, etc. A benefit at a lot of southern airports where tarmack temps are in the hundreds.
I’ve worked on aircraft that had a matte, camouflage paint jobs and those that had nice, shiny paint jobs. It think that it’s all for looks. I don’t think it was for better speeds or anything as the matte, camouflage painted aircraft could go supersonic while the ‘pretty’ aircraft couldn’t.
It’s easier to maintain a consistent high-gloss finish than any less-shiny one. Any significant degree of matte, and doing touch-ups, polishing etc. leaves visible variations in finish. Gloss is gloss. Most people would not be comfortable riding in an aircraft that doesn’t look factory-new, no matter how many small repairs it might have had.
I know it’s a huge issue in things like Reno air racers, where polishing the skin smooth is taken so seriously that the final polish is done with cornstarch.
This has far more to do with color than glossiness. In sunlight, high-gloss black will be hot; matte white will be much less so.
If the surface feels smooth to the touch, it will generate less air turbulence on the surface than if it feels matte. This skin turbulence can slow a plane down from resistance in high speed flight, but this would be noticeable only at very high speed.
I believe a plane can be painted with a matte outer layer, with only a single layer of highly polished but very transparent gloss. Much of the light will pass through the transparent finish, and be scattered by the matte underneath, so it will have a surface that is not shiny looking (for camo, for example), but at the same have an aerodynamically smooth that will not drag. The more layers of transparent glass on the surface, the more reflective interfaces there will be to mirror the light.
Think of a rough rock and a shiny object under water, the shiny object will still be shinier, even though the surface of the water remains the same texture.
Expounding on something that I know nothing about, but drawing intuitive conclusions.
It is simply drag. A smooth plane has less drag. Less drag mean better fuel economy. Simple as that.
You could also do no paint, which means less weight which also means better fuel economy, but no one wants bare metal jetliners anymore. Aesthetics.
Military planes can go supersonic with matte finishes because they have big engines and don’t care about fuel economy as much.
What about cars? I never understood why cars always have to have these shiny finishes. A plain flat paint job would like a lot nicer. But you never see it except in military vehicles, it seems.
Lots of cars are now available with matte finishes.
The glossy finish probably does help with drag. It also makes the livery more visible as an advertisement for the airline while on the ground or flying low.
Yes, and on that side of the equation, with the rising use of composite materials you no longer have the option of a nose-to-tail gleaming “silver bird” job in many aircraft, and people will feel odd about boarding a “patchy” plane.
Wikipedia sez about night fighters:
Need a citation? I probably read it the same place that guy did, so I’ll be the citation. 
The reason cars don’t generally have flat finishes is they show dirt and especially grease very well. They also aren’t necessarily uniform. Take it from someone who drive a primered Road Runner for years, flat finishes aren’t all that great!
As for composite aircraft, I agree. Here is a classic “no paint for maximum performance” aircraft:
No two panels the same color. But it set 8 time-to-climb world records.
Wouldn’t polished aluminum be the best? Saves on cost of paint and the weight of the paint (which isn’t trivial on a big plane).
Gloss = less drag.
Non-gloss = lower visibility. Preferable for military combat aircraft.
What if there were a magic “golf ball dimple” paint? At what speed would that become a detriment?
Everything is a trade off. New commercial jets, as noted above, use a lot of composite material. Here is a picture of an unpainted Boeing 787:
Don’t forget that drag is so critical on high speed planes that flush rivets are used on all outer surfaces. Even that small rivet head makes that much of a difference.
For military planes, it changes as conditions change. Early B17s in WWII were painted green, to reduce visual detectability. Later, as the Allies gained air superiority, the B17s started to be delivered bare metal. The reduced threat made the weight savings achievable. Which lead to this:
That is a picture of a model, but it was a real plane made from an unpainted G-model front half grafted to a battle damaged but salvageable olive rear half.
After WWII, military jets usually were unpainted aluminum. Later, they were painted to reduce detectability again. Then, low visibility markings were added.
Some paints actually help reduce radar detectability. Early A-12s were bare titanium, with wing edges painted black, but later ones, as well as the SR-71s, were all black, The paint did help with reducing the plane’s radar cross section, but the exhaust was very detectable.
Helicopters have very flat finishes. The Apache paint job almost feels like fine sandpaper. But helicopters don’t need to worry about drag all that much, as they can’t go that fast.
All commercial airplane (except maybe the 787) require a finish of some sort to protect the fuselage from corrosion. On polished skin commercial airplanes, the clad used for the skin also had a layer of pure aluminum instead of the regular clad. This polishes up much nicer than the regular clad. It also requires a clear finish and this finish is thicker than normal paint to provide corrosion resistance. As these plane go through the factory they also require special handling, some of the tooling used during assembly can cause damage to the soft aluminum, this is not a problem on other planes. Here in the 737 factory, the only customer that has a polished skin is American airlines, these planes are covered with notices that it is a polished skin plane and extra careful handling is required. An unfinished plane would begin to show signs of corrosion almost immediately, that is not good.
Sounds like the general consensus is “to reduce drag”.
However, I thought a matte finish was just as smooth as a high-gloss finish (with the gloss being provided, in the case of aircraft, by the nature of the clearcoat). Am I mistaken about that? (On American Restoration they clearcoat stuff all the time (for durability) without giving it a high-gloss finish.
You can’t really have smooth finish without it being gloss. Clear semi gloss or matte are not as smooth microscopically as high gloss. As with all things engineering, there are trade offs. How much money do you want to spend to maintain the ultra smooth finish that nets you X improvement in performance? Can you live with only so-so smooth?
Like early stealth aircraft. To keep the aircraft stealthy required a huge amount of maintenance. Every access panel had to be sealed smooth lest the panel edge reflect radar back. So any time you opened up a panel it was a couple hours getting the finish right again.
The “latest” finish in luxury cars is semi-matte.
I’ve only seen it in two shades - white and black, and both MB and BMW offer it.
