For some reason I enjoy results that contradict expectations. You'd think being 75lbs lighter would be better but their conclusion of the paint making it more aerodynamic makes sense.
I was fortunate enough to hear Chuck Yeager speak at the EAA. He related the story of how when unpainted aircraft began showing up at his base in WW2 he commented to his crew chief that they looked good. His crew chef and his team, without telling Chuck, stayed up all night removing all of the paint from his P51 Mustang. Chuck was certainly surprised the next morning.
@@PoochAndBoo I just listened to Bud's audiobook, and it's in there. Funny thing is that the crew all had German last names, yet they bent over backwards and Bud never aborted due to mechanical reasons - a very rare achievement.
My father served in a B-24 outfit flying out of England. I recall him telling me that many aircrews preferred painted bombers as they considered the camouflage lucky.
Our dad was a B-24 nose gunner. Over Ploesti etc. flying out of Africa, Italy, and England. Passing in 2002, I could only get him to discuss it a few times. Flak through the plexiglass necessitating sideway facing turret the rest of the mission, was about all he could come up with as a close call. Two kills, no details. I wonder what he would have thought of these productions?
I attended an airshow where a C5 Galaxy did a low pass escorted by a P-51D. The (famous) announcer noted that the P-51 weighed less than the paint on the C5... I was impressed!
You are right if the aircraft, like the B29 mentioned at the end, has flush rivets. The B17 did not, but the paint smoothed it out, and the joints in plates, making the painted plane more aerodynamically efficient.
The Streak Eagle was an example of an unpainted aircraft which was faster. It was used to set airspeed and time to climb records in the '70s. Aside from all non-essential components, McDonnell Douglas also removed the paint to save weight.
My dad flew B-17's during the war and firmly believed that the unpainted birds would have greater range because it was lighter. He loved the Flying Fort and was transitioning to the B-29 when the war ended. He would have been startled had he seen the data you presented.
@@SP-sy5nq My dad was fortunate in that he served in a training command from 1942 on. He was a flight engineer and they put in a lot hours in the birds getting plots, co-pilots and navigators snapped in on these complicated machines. If I recall when he was transferred to a tactical command it was in early August 1945 and the war ended before they deployed. After the war he worked at Republic Aviation as a final inspection crew chief for the F-105. When Republic folded he went to work for Grumman on the L.E.M. and the F-14.
I absolutely love you keep his memory alive, thank you for sharing. And i would absolutely recommend writing down what he did And experienced, Even though its second hand account its still The closest The future generations Have of him. Largely unrelated, forgive me: my fathers gave My grandfathers war diary, from 1939 to 1940. He served in Finnish army as a jaeger battalions signal trooper And partook in large battles on karelian isthmus against red army. His diary goes through The Time when tensions were rising And first half of winter war. His diary ends abruptly after The major battles, My father thought It was because after seeing enough he didn't feel like writing about it anymore. Whatever The case, that tarnished And spotty old diary is full of amazing memories And, as a good writer, very lifely commentaries about everything front related. I want to save his memories And so im making an audiovideo of The diary for RU-vid. I think thats The most important thing, to keep them remembered And their accounts saved
My Dad was in B-24s, flying out of England. I remember him telling me about this. I no longer remember the actual figure but I know he had a much higher value for the weight savings, along the line of hundreds of pounds.. His aircraft were all painted. Based on this video and associated comments, either I remember wrong or Dad had the wrong numbers.
@@anttitheinternetguy3213 The courage and resourcefulness of the Finns in the Winter War is one of the most inspiring epics to come out of the war. Hopelessly outnumbered and outgunned the Finns fought Stalin's army to a standstill, but of course you already know this. Diary 's are some of the most important documents to historians because they recount the events as they happened, before aging memory and myth have their way with the human mind. I'm a big history buff and simple things like what the weather was like on a certain day can shed light on the events that happened on that day. That diary is a gold mine to truly understanding the events of that era, what happened at the tip of the spear, and what it felt like to the men doing the fighting. Your post makes me want to break out the books I have on the Winter War and revisit those momentous events. Thanks, and stay safe.
Painted aircraft flying faster than unpainted ones makes sense to me. I read in a book about the Spitfire that they did all kinds of testing with the prototype to see where they could make paint savings on the production aircraft. Basically the prototype had very smooth paint-job all over to smooth out seams and rivets but it had been very laborious to apply so they stuck split peas all over the plane to simulate rivets and removed them in sections to see the performance change. From memory the all over riveted plane was something like 25-30 MPH slower but if you had rivet heads on the fuselage and upper surface of the wing you only lost 5-10 MPH. The worst place for drag to have rivet heads turned out to be the wing leading edge.
Interesting, but I think there are other aspects to consider here. For example, the effects of non-flush riveting on the wing in relation to stall-speeds, and on which part of the wing stalled first, and finally on how much and when pre-stall buffeting occurred to alert the pilot of the incipient stall. On the Fw190, the stall had very little pre-stall buffeting, and consequently the pre-stall or pre-spin buffeting offered little warning, leading to FW190 pilots being cautious in a turn-fight where there was insufficient height to fly "on the edge". Incidentally, the chevron drag-strips on the inboard upper wing of a Pa28 are there in order to cause a breakdown in laminar flow at the wing-root, before it occurs at the wing-tip, thus giving earlier indications to the pilot of a stall, and to ensure that it stalls at the wing root, not the wing-tip. (Other measures such as reduction of angle of incidence at the tip, also apply to the same end.)
I found this interesting. My father was a B-17 pilot in WW II. He was shot down over Germany on July 26, 1943 by FW-190 pilot Klaus Decker, who was also shot down and killed on July 30, 1943 by an unknown P-47 pilot. Germans kept much better records that the US. Five of my dad's crew were killed and five survived and became POWs. I had always assumed that towards the end of the war when unpainted B-17's became more of the standard was because they were lighter and the US had gained air dominance with flak still being one of the main threats to bombers. I like these technical videos of WW II, especially of the B-17s.
Aluminium self oxidizes on exposure to air if there isn't already an oxide layer or paint present. The oxide layer is thin, slightly opaque, non-porous and prevents further oxidation and corrosion. This is what causes the finish to appear dull over time compared to the polished finish after the panels are first produced.
The part you missed is where he talked about the difference between Alclad and uncladded sheet. Alclad has a pure aluminum skin a few thousandths thick over an aluminum alloy. The aluminum alloy itself is far less corrosion resistant than pure aluminum so it forms that oxide layer faster (it also turns white rather than the darker color of an oxide film on pure aluminum), and the unoxidized alloy has a different color as well since it's partially alloyed with copper and other metals. That's why the two types of panels are able to be visually distinguished on the same aircraft.
@@pan2aja I suspect you're talking about aluminum foil using for cooking? The reason why one side is shiny and the other side is dull is because of how they manufacture it. Because the rolling dies can't form a sheet that thin, they take the foil and fold it over on itself with a thin layer of oil between, then run it through the dies. This allows them to get the desired thickness of the foil. The dull side is the part that got folded in on itself and coated with oil, while the shiny side is the part that was on the outside and came into direct contact with the polished rolling dies.
Everything that I was told about painted and unpainted B17's has just been thrown out the window with this video. Well presented and the results speak for themselves. Keep up the great work.
Reminds me of an email conversation I had with a P-47 pilot years ago. In one he mentioned that he cleaned and waxed his aircraft whenever he could, it made a noticeable improvement in performance. It was a camo razorback P-47D
The RAF had been lightly sanding and polishing their spitfires and they gained some speed from it a noticeable amount although the sheen of the paint tended to be like maybe slightly shinier than an eggshell but not flat like an eggshell but the surface itself was smoother plus when you do that you knock off all the overspray that goes on with the colors meet what color will overspray on to the other and in those areas the surface will be slightly rougher I could see how it could add up
You know you could probably wax and all metal plane and gain something and that would be dirt probably wouldn't stick to the surface as much dirt dust the mineral deposits from rain and washing it keep the surface clean and smooth it'll work better
Toward the tail end of the war they used putty and wax to blend and seal all the panel joints on a P-51H to see what kind of speed they could get it up to. I believe they used 60-something pounds of it in total, and that was in addition to what the factory already added to the aircraft in order to assist the laminar flow airfoil. But yeah, they absolutely used putty to seal panel joints on earlier mustangs during the war, and crews often did the same thing to aircraft that weren't P-51's in the field, such as the P-47, P-38, and so many others. Once they got wind of a speed trick they all incorporated it in their planes, sanctioned or not. Lots of people looked the other way because they knew it worked, but also knew they couldn't officially approve it or say anything to the brass about it.
@@Thenogomogo-zo3un That's actually true, and the same goes for the P-51 as well. I believe the P-47D lost about 16mph when made with a bubble canopy, but the P-51 was half that. Later P-47's had other aerodynamic and power upgrades over the razorback to negate that advantage, but had they kept the razorback it would've given them a slight increase in speed on top of what the later models had. The Reno Air Racers that win the unlimited cup all have custom razorback canopies (albeit, much smaller and more cramped), simply because it's more aerodynamic. In addition to the speed advantage, they also had better yaw stability, which is why you generally only see the dorsal fillet on the vertical stabilizer of bubble cockpit variants. The exception there is that some P-51B's had the fillets installed because it restored the stability lost when the rear fuselage fuel tank was installed. For the most part all of these aircraft were originally designed with razorbacks, and the vertical tail/rudder was sized accordingly to get a good balance between stability and performance. When you change that up by adding a bubble cockpit, it throws the whole thing out of balance and you end up needing aerodynamic "bandaids" like the dorsal fillets.
Absolutely riveting video. (No pun intended). I am just blown away by the amount of data you presented in just 7 1/2 minutes. Utterly astounding, interesting and like all good stories, it has a "twist" ending. I couldn't subscribe fast enough!
I knew a man that was a ball turret gunner on an early “G” model that was bare metal. His aircraft was the only bare metal aircraft in the formation heading to Holland. The German fighters picked them out and they had to bail out because of the damage. He spent 2+years as a POW. After the war he became a noted orchid grower.
This is super interesting. Before I watched I figured 2 contradicting things: 1) the unpainted one would fly faster and farther because they didn't have the extra weight of paint. 2) the painted one would fly faster and farther because the paint added some kind of aerodynamic advantage. I was still somewhat surprised by the result (no spoilers)
The "unpainted" are normally referred to as "natural metal finish" or NMF. The directive ordering the deletion of primer and paint was issued sometime around March or April 1943. It would be interesting to know the official rationale for it. A big consequence of having no primer was that it inherently limited the serviceable life of the airframes. Although the life expectancy of a B-17 in the 8AF in late 1943 was a matter of weeks, that was a temporary situation. Later, many survived long enough that corrosion could have been a significant issue during the War. Certainly more warbirds would have survived in better condition with the proper application of primer even if only on internal surfaces. As for the aerodynamic effects of uncoated exterior surfaces, taping skin gaps and a generous application of carnauba wax in the field would have more than made up for it if getting a little more speed or fuel efficiency was that important.
The reason they quit painting them is because when all the aircraft were painted it was done at the factory, the directive was simply to speed up manufacturing and simplify the delivery process. It was then up to the commander's whether or not they'd be painted according to how urgent a replacement plane was to be pressed into service and whether or not they felt it was necessary due to effectiveness. As far as "more warbirds surviving" it wouldn't have mattered, all the aircraft overseas were scrapped because of the cost of bringing them back, any aircraft not wanted by a foreign power or that wasn't going to be used by a unit staying overseas was scrapped due to the cost of returning them, the downsizing of the military and all the planes midway through the manufacturing process and in depot awaiting shipment was enough at time, coupled with new designs ready to be produced meant they just didn't need to return aircraft that were busted up and stressed from combat.
Actually, orders to stop painting these airplanes went out to all aircraft factories in October of 1943. Thousands of painted airplanes were still on the assembly line, and thousands more were lined up waiting to be delivered. That's why these new, natural metal, airplanes weren't seen in combat until February of '44.
The directive from HQ AAF was dated 3 Nov 1943. Units in the field were given the option to remove the camo paint from existing a/c or add it to NMF a/c at their descretion. Recently saw a video of late B-17G production and they were zinc chromating all interior surfaces and the anti-glare panels on the nose and insides of the nacelles. I have a sequence of photos of the crew of a brand new B-24J prepping the a/c for a mission and the interior of the fuselage structure is not only completely NMF but the inside surface of the skin appears to have been polished. It looks like a tunnel of mirrors.
My question would be production time and delivery turn around. It seems that later in the war, there was more of a concern for replenishing lost aircraft in a timely manner. I'm not wondering if the time in the factory to paint offset the loss on performance.
@@BonnKialStevens The consensus seems to be it was to expedite production and that the OG camo scheme was no longer needed. While the NMF aeroplanes are beautiful, they should have used a color scheme similar to modern combat a/c in the European environment. Also see "PRU Blue" and "haze" color schemes.
To be honest, I was under the impression that it was the opposite and that was the reason they were unpainted. Your video was the first that explained it fully....I expect the tests were performed because flight engineers and navigators were seeing a noticeable performance differences in their ships during debriefings.
Random thing come up in my RU-vid feed. This little gem was the most interesting 7 minutes of data and graphs that I’ve watched in a long time. The results of testing provided an unexpected result and a somewhat counterintuitive solution (at least at the surface, ahem). Even though the paint made the b17 75lbs heavier, the painted b17 was actually more fuel efficient and faster than an unpainted b17. Just goes to show that testing and gathering data is a huge part of a better outcome.
Thank you for the amount of research you put into these videos. Even including the flush rivets and panel fit of the B-29 in comparison. Like everybody else, I've always admired these warbirds from afar, and thought I pretty much knew all about them-- until I started watching your posts. These are must-watch...
Very interesting who would have thought. When I worked for Cessna (Mil-Twin Division) the company charged extra for unpainted twins. I was told that was because sometimes the assemblers had to use rubber mallets and the "damaged" unpainted shin had then needed to be buffeted out.
thank you for sharing your sources and images you have helped me to uncover a gold mine of information I've been trying to find for years. most people are not willing to help others find information, not willing to help people find and access the resources they are struggling to find/obtain. can't express how appreciative I am of that subtle bit of this video.
I'm so glad I found your channel! Really enjoy your coverage of technical details like the explanation of the properties of the alloys used in the B-17's skin. Great work man!
Even after watching one of your videos, I get the impression you're very well accustomed to delivering the maximum amount of CLEAR verbal information in the shortest time. EXCEEDINGLY well done yet again, and a tremendously difficult skill to master.
Fascinating - I'd spent my life believing exactly the opposite. I was lucky enough to have gotten around 10 minutes of left seat time in an unpainted B-17 some 25 years ago. I couldn't get over the force required to move the control surfaces, even at a relatively modest airspeed. Your videos are a fascinating deep dive into these aircraft. Thank you!
Thank you very much for a fascinating , in-depth , and reasonable explanation for the 2 finishes . For nearly 70 years , all 'in the know' , RAF , USAAF and others I spoke with explained it was a 'simple' matter of 'air superiority' . Opposing side overhead , you camouflage . No threat , no need to bother about camouflage . IE , why pay the time and expense for something not required ? Simple . Or not , as it transpires ! I am truly amazed . I am now truly intrigued as to what you have next lined up for us . Full marks . Pete UK 8-)
What a great, in-depth analysis. I have always wondered, 1) what the weight of the paint was, 2) how the drag coefficient affected flight speeds. Now that you pointed out the butt & lap joint effect plus the rivet type used, that totally upended what I had thought. What an excellent video! Thx!😁👍🏼
In this same line of thought I've often wondered: 1) what is the airspeed velocity of an unladen swallow, and 2) what the drag coefficient of a laden swallow is.
Excellent video, thank you. When I was a teenager I was a volunteer at Duxford, UK. and every weekend I was there polishing Sally B’s aluminium body and wings. It concerned me then that the polish and wire wool was pretty abrasive let alone hanging on to her when I was 20 feet above the ground. Happy days. Anyway in later years she got painted and I have wondered from time to time what the difference might be.
Great video! Thanks for providing such an interesting, test-data driven analytical glimpse into one of the decisions made about the great workhorse of the USAAF, the B-17. Well-done … as usual!
The respective weight trade-offs is exactly what I was thinking about during the video. I am glad to see that you addressed that. The filling in/covering rivets hypothesis may also be at the root of the old ground crew advice during W.W. II to get more speed by covering a plane's surface with avgas.
Back a few decades ago when I was a young helo crew chief in the army nat. guard, there were still some Viet Nam vets serving. I remember a couple of them used to rub down the fuselages of their assigned Hueys with gearbox/engine oil or sometimes floor wax, and it made the bird a little faster and the exterior corrosion resistant.
So if you get a B-17 going in a glide path that is slowly coming down the thing will come most of the way back home on one engine at least get you out of dangerous territory there are many stories of things getting shot up on the way back and making it back to England so they could land on the ground crash land or bail out and let it crash to the ground by getting the right glide path in the engine setting and going with the one engine that's working
Neato! I wonder if dimpling the fuselage, as they do to golf balls, and on that Mythbusters episode would result in greater efficiency, savings? I love this kind of experiment.
Nope. Dimpling energises the boundary layer to delay separation due to the balls shape, a streamline aircraft shouldn’t have any areas of separation that would be improved by energising the boundary layer so you would be increasing drag for no benefit. On high laminar flow wings like gliders they will sometimes have an energising strip on the wing but a riveted skin is nothing like a smooth carbon fibre skin. Some STOL aircraft will have tiny fins to energise the boundary layer at high angle of attack, delaying stall onset but with a drag penalty at cruise, not what you want on a bomber.
I recall an exchange with an actual bomber pilot, me being an armchair simulator player wondering whether a 2 mph increase makes any difference. His answer shifted my perspective wonderfully, and, no I don't recall the exact words, but: if 2mph in an 8 hour mission means you go 16 miles further, it could be a big difference whether you're making it home or not.
A fascinating bit of research you have done there. I was aware of the later ones not being painted but had always accepted the view that the paint was just added weight that achived nothing once in the air. Very interesting to see how much more complicated the truth was.
Amazing video, thanks for your research, in-depth knowledge on the topic. This is incredible history, it's fantastic that someone is putting this into easy (well somewhat easy) to understand content.
Very interesting indeed, clearly demonstrates the importance of data over "gut feeling", something I've experienced a number of times during a career in industry.
A fascinating reveal that certainly went against my initial expectations, so well researched and presented thank you. It is amazing the precision and presentation of such detailed engineering drawings and test data etc - all done by hand (good old Engineering and Drawing Offices) no computers (neglecting Colossus at Bletchley Park or similar etc) or printers that we would use today. Seventeen bombers produced per day, wow that is some war effort.
As Spock would say...Fascinating! For some reason I get giddy when I learn new things like this! I've been a WWII buff and model builder for many years and I still did not know this! Thank you!
It has been an interesting day as the B-17 Sentimental Journey, also a Mitchell B-25 are doing passenger flights, out of Glacier Park international airport, Kalispell, MT. Those big old radial engines just thrill me.
This is very interesting... my take has always been that on a sunny day all metal finish aircraft are highly reflective and thus more difficult to engage correctly at certain angles . I wonder if any glare tests or fighter pilot records on same were conducted... I am impressed with the 3 percent reduction however.. quite a marked difference..
Thanks for the fascinating overview of the advantages/disadvantages... 👍 (I've forgotten all my aerospace formulas, but I wonder if the coefficient of drag C_D difference could be calculated from the data in the plot.)
Very interesting . The British Lancaster bomber weighed 56 lbs more painted . I often wondered why they continued to paint them all through the war . Side note. The black underside paint , was a special paint that stopped German search light reflection .
@@harryspeakup8452 that makes sense- a sparkly silver thing in the sky would be far easier to see at night. I've always wondered if ditching all the guns would have been a good idea. A lot less weight and a faster aircraft might have saved more lives. Then there is the 3 or 4 less gunners that would have died. It all depends on how many night fighters Lancs shot down ( not many I imagine ) and the psychological aspect.
@@olivercromwell3575 The logical conclusion of the speed as rescue/defense solution would have been to use Mosquitoes instead of heavy bombers . If I recall correctly, the Mossie could carry quite a bomb load.
