Wooden fuselages and the weather

[Akaalias]

There is a photo in "Pfalz Aircraft of World War 1" (Jack Herris, Page 55) depicting Pfalz DIII 4064/17 with its badly wrinkled fuselage, caused by exposure to the weather.

Can we assume that other Pfalz products (eg DVIII and DXII) and even some early Rolands (eg DII) would have reached the same level of damage?

On the other hand, I haven't heard of any such problems with the Albatros plywood or Roland DVI "straked" fuselages. If these aircraft bore the elements better than the shell fuselages of Pfalz, then it looks as if the shell design itself was a problem, or perhaps varnish was a better sealant than silver dope.

Could anybody set me straight on this?

Cheers,
A

[Dan_San_Abbott]

Akaalias:
It was essential that wood interiors be varnished properly, or they would be damaged by the moisture of northern France and Flanders. This got Fokker into trouble on the Fokker E.V wings. They were not properly varnished and caused the plywood covering to delaminate. LFG Roland, to my knowledge did not have any of these problems on any of their aircraft. The Roland airframes were were varnished and the fuselage interiors after varnishing were painted a light greenish grey. Albatros fighter aircraft had problems with the single spar lower wings but not with interior finishes.
In a French report, stated that an aircraft left outside in the elements for 8 days would be destroyed. It was essential that all aircraft be hangared.
If you look at the daily weather listings in Oblt. Karl Bodenschatz's book, "Hunting With Richthofen", you will see that it rains almost every day.
Blue skies,
Dan-San

[Pips]

In the excellent book "In The Teeth Of The Wind" the author (Bartlett) makes constant reference to weather and it's effect on aircraft. Bascially aircraft had to be constantly re-rigged (daily) due to temperature changes and mositure. As Dan mentioned aircraft had to be hangered nightly; if that were not possible then they were draped with huge sheets of canvas erected over them.

Bartlett also makes the point that any aircraft left out in rain for more than a day was viewed with great suspicion by pilots.

[Romani]

One thing I don't understand, if fabric was doped and varnished, and plywood fuselages shellacked and varnished, they should be waterproof, or not? I understand that the varnish on wooden propellers was eroded by rain drops, and i understand same thing would happen to the surfaces of the airplane when flying through rain.

Was dope and varnish not really waterproof after all? I thought sunlight was the main enemy of fabric airplanes, not dampness.

[Dan_San_Abbott]

Romani:
If you will note that most photographs taken in England theskies are grey and overcast. The same applies to Flanders and Northern France. The areas South of the Somme, in Champagne, Vosges and Alsace there is more sun. If the wood surface are not propertly protected, the wood will absorb moisture. The plywood in WW1 was glued together with casein glue. If it is subject to moisture it will delaminate. Most glue joints were with Casein glue, it subectyed to moisture will mildew and destroy the joint. It was absolutely essential that all wood surface were sealed with shellac and varnished to prevent the absorbsion of moisture. With as much rain as it gets in Flanders and Northern France, the air always had a high humidity. Fortunately the humidity was not coupled with heat, with that combination everything rots.
This is what I experienced in India and Burma during WW2.
For example any wood ship or boat would require constance maintaince and varnishing to protect wood surfaces.
All fabrics subjected to sunlight will deteriorate from actinic rays of the sun.The fabric undersurfaces, much less so, because they are not exposed to direct sunlinght. The few occasional times when the machine was up side down, it would then be exposed to direct sunlight. The upper camouflage surface protected the bottom surface from direct sun light.
That was not the problem in Flanders and Northern France, there was insufficient sunlight to be a problem. That is not saying the fabric did not deteriorate for sunlight, in Flander and Northern France it just took longer, the exposure was accumulative.
The damage from the actinic ray of the sun is accumulative, and over time it will require to be recovered.
In 1953, I had designed the Drag Chute for the B-52, the canopy was made of white nylon ribbons 2" wide. After their landing roll, the pilot would release the chute and they generally left to lay along side the runway unti such time some one would go out and pick them up. Over time the nylon deteriorated from the sunlight and at some point the pilot would deploy the Drag Chute and it would fail. From tests that were conducted to determine strength after exposure to sunlight, it was found that after two weeks exposure to the elements, the ribbon would loose 50%of its strengh. These failures were occuring in 50 to 60 deployments. This was occuring in less than the 100 deployments that was determined to be the life of the Drag Chute. when the Drag Chute were subjected to material strength test it was found that the canopies had less than 50 % of the original stength of the materials. As a result of these tests the materials were dyed with a Capracyl dye, it was dark yellow color, this solved the problem along with jacking up the pick-up crews to pick them up with less time in the sun. When you see Drag Chutes that are yellow, that is why! It was found in the testing that black was the best color for protection from the sun. They did not select black because it was too obvious.
Blue skies,
Dan-San

[Sreiko]

One thing is important- they are protected, not sealed and isolated. As I kmow they are only externaly covered, not the inside. Moisture could penetrate everywhere.

[Akaalias]

What was used to protect the fabric fuselages of French and British aircraft?

Cheers,
A

[Sreiko]

British used Cellonit and there was three shades of this coat. Intensity depends of how many coats was applyed and mostly there was two. This goes back in the 1912 when the BASF invented liquid acetate dope. Thomas Tyer licenced this in June 1912, who was member of the Society of British Aircraft Manufacturers. This first dope was alcohol soluble and included 5% of coloring dye. There was several differents type of coats used in UK. After some experimentation was introduced coats made from finely ground pigments into the solid cellulose medium. Miniustry have list of materials where DS was dyed spirit, DV was solid mentioned above and later was introduced sintetic made PC series.

[Akaalias]

Thanks all for your helpful responses.

Cheers,
A