Paint and Performance?

[Ginger.]

Further down the page someone made the point about dollops of paint effecting performance.The Germans got round it by printing the colours on the fabric.Most of our aircraft were one dull shade,did it not occur to the British to do the same?

Ginger
Apparently not. The fabric had to be doped anyway for tautness and protection from the elements. I expect it was a case of if it works, don't fix it.
Theres my two cents worth,
Terry

Did they not make colored dope in those days or ever? this would reduce the layers of paint and or dope over the fabric.

Also, remember that these aircraft already had been painted. These decorative schemes were painted over the original paint schemes thus adding weight. Also, these aircraft had been in use for some time, most of them. Some of the 'dazzle' painted aircraft served with more than one squadron. There were a couple of articles in Over The Front 1999/2000 that had additional photos of some of these aircraft. Several, still in their dazzle schemes were crated up and shipped to Poland for their fledgling air service. Other US squadrons did this as well. The more recent article is about Elmer D. Cook who served in the 638th Aero Squadron postwar. They decorated their SPADs for an Air Carnival that was held at Coblenz April 21, 1919. Cook complains in the account about the performance being degraded after the paint was applied.

[Ginger.]

The lozenge printed fabric would have to be doped after fitting too.I wonder if this was a good idea we never had!

[Dan_San_Abbott]

Ginger:
The printed fabric was developed in 1916 by the Germans in order to conserve dope. and dyes used in coloring paint. Cellulose dode is made from cotton as is gun powder. In Germany there was a shortage of cotton and as a result cellulose dope was critical, therefore oil paints had been used in painted camouflage. In order to reduce the dyes, and oils in paints and dope Idflieg came up with the printed fabric. The fabric was given 3 coats of dope and one coat of copal varnish to waterproof the surface. The varnish created a problem when the fabric had to be patched. Before the linen patch could be doped on the mechanic had to remove the varnish.
I know the French experimented with printed fabrics, I don't if the Royal Aircraft Factory did, I would be surprised if they did not.
Blue skies,
Dan-San Abbott

[Volker_Nemsch]

Hello Ginger!

Maybe this website will be helpful for you:

http://www.wwiaviation.com/lozenge.shtml

Best regards
Volker Nemsch

After airsuperiority was acheaved in WWII the allies stopped painting their aircraft and started to use the natural metal finish. This increased the aircrafts performance and gave them longer range because they weighed less than a painted aircraft. Even today unpainted aircraft for airlines have better performance/efficiency than painted aircraft. I can't remember where I read it but it, is amazing how much a coat of paint on an airplane weighs.

At this time period Germany was at the fore front pertaining to dyed fabric. No other country had the expertise to print fabric as the Germans did.

>After airsuperiority was achieved in WWII the
>allies stopped painting their aircraft and
>started to use the natural metal finish. This
>increased the aircrafts performance and gave
>them longer range because they weighed less than
>a painted aircraft.

Matt paint adds parasitic drag as a result of skin friction against the opposing air flow. Having a highly waxed or a waxed aluminium surface helps reduce that component of surface drag. In the pacific, the matt Olive Drab and Foilage Green schemes were drag producers but also the highly corrosive environment wasnt much good for the paint either and its drag reducing properties.

Probably is one of the reasons the US 5th AF and RAAF werent too worried about the changeover to unpainted skins. The RAAF didnt appear to care too much about chipping paint lol. There was a Spitfire in 452 Sqn RAAF that was waxed and polished to extremes, in formation it was so slippery in comparison to the other Spits that it had to be continually throttled back.

Parasitic Drag increases with airspeed and lessens with altitude. Maybe at the speeds and altitudes and the designs that were being flown in WWI, the parasitic drag from skin surface effects were minimal in comparison to profile drag (the aircrafts profile to the oncoming air)and interference drag ( dirtying the air with things like undercarriage and flying wires ). Also at those speeds (and those airfoils) the induced drag from creating lift would have been greater, maybe induced drag was the major drag component. An aeronautical engineer will be better able to explain all that than I can. (KillRatio? Ron?)

The WWI aircraft were shined up pretty well with the cellulose doping which would have helped reduce drag. New aircraft out of the factory are very shiny, dont know how long that lasted. The field aircraft dont appear so shiny, so they may have worn hard. The PC10 doping was the best compromise between camouflage colour and wearability, IIRC the PC12 was better wearing but more conspicuous.


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