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The Mosquito used a lot of casin glue, based on milk. It did OKay in Northern Europe but not in tropical climates such as India, Burma, and the Pacific. One engineer from the UK went to India, looked at their Mossies and told them they were unserviceable because of the way the local bugs were eating the glue. When no one paid attention to his concerns, he took a saw and cut the wings off them.
The other glue in use at that time was Resorcinal. It is a thin very volitile glue that required absolutely flat and smooth mating surfaces, followed by careful clamping that had to make the joints tight but not starved of glue. .
Today, when we think of gluing wood we imagine using two part epoxies, polyurehtanes, and so forth. One of the problems of restoring older aircraft is that while the modern glues are definitely superior, the FAA says that was not the glue the airplane was certified with, so you can't use it.
Does anyone know the number of fuselages that were produced every day for each individual mold?
I imagine that at least two or three hours of curing were necessary to allow the glue to be catalyzed and, considering at least another two or three hours to place plywood and balsa on the mold, I do not think that with single mold they could build more than four raw fuselages per day.
But these are only assumptions, some additional information would be very welcome.
The Mosquito used a lot of casin glue, based on milk. It did OKay in Northern Europe but not in tropical climates such as India, Burma, and the Pacific. One engineer from the UK went to India, looked at their Mossies and told them they were unserviceable because of the way the local bugs were eating the glue. When no one paid attention to his concerns, he took a saw and cut the wings off them.
The other glue in use at that time was Resorcinal. It is a thin very volitile glue that required absolutely flat and smooth mating surfaces, followed by careful clamping that had to make the joints tight but not starved of glue. .
Today, when we think of gluing wood we imagine using two part epoxies, polyurehtanes, and so forth. One of the problems of restoring older aircraft is that while the modern glues are definitely superior, the FAA says that was not the glue the airplane was certified with, so you can't use it.
I wonder if the glue varied from plant to plant. Were Canadian mosquitos glued with the same stuff as British ones?I thought he glue used for the Mosquito was a resorcinol based resin.
Don't know how long it took for the fuselage half to set hard but some factories used concrete moulds with hot water pipes in them to heat the mould.
I hadn't heard that but heat lamps were also used.
The time taken to produce one half was not only affected by glue setting time but also by the fact that the skins were produced in stages, each of which required clamping. The inner skins were first glued and screwed to the bulkheads and other protruding internal stiffening members and then clamped to the mould using steel straps. After a sufficient cure, the straps were removed and inter-skin components, primarily spruce stiffening members and balsa filler strips, were glued in place. The balsa strips had to be dry-fitted and custom cut/adjusted before gluing to the inner skin. The inter-skin layer was then strapped again and allowed to cure. Once cured, the straps were again removed and the balsa strips were shaped to a smooth contour to receive the outer plywood skin. The outer skin was then glued to the balsa and the spruce structural members and strapped again for curing.
I have yet to come across the time taken between the start of this sequence and the point at which the final straps were removed. In our restoration work using modern epoxies, the recommended setting time under clamps is 8 to 10 hours at room temperature and we followed those recommendations with successful results. In wartime aircraft, the casein glues initially used are known today to cure in about 4 hours. The glue used later (not sure when the switch was made) was a urea-formaldehyde glue and modern versions recommend a clamp time of 6 hours. That said, I still don't know what actual clamp times were used in production with added heat sources.
A very successful, but quite not a straightforward method of construction, considering also that probably a major repair on the field of such a structure (say, changing a wing...) would have been difficult, I dare say.
I doubt there was very much wooden furniture being made during the war and I assume that meant they had some excellent craftsmen available. And besides, it greatly annoyed the Germans, who did have a serious shortage of aircraft materials. Goring raged about the British being able to build a very fast aircraft out of wood when it was the Germans that were short of aluminum.
Interestingly enough, in WWI the Germans introduced the steel tube fuselage because they were out of suitable wood.
View attachment 590566View attachment 590567
Let's also not forget that Hugo Junkers was developing all-metal aircraft in 1915, with the original J I, but with wooden forming elements. His choice of metal construction came from his realisation of the inadequacies of wood as a structural material, being subject to greater change in rigidity owing to fluctuations in temperature and humidity. The J IV, militarily known as the J I, which confuses things since Junkers' first all-metal aircraft was called the J I, was an all metal armoured ground attack biplane that did incorporate wooden formers in the fuselage.
Junkers J IV (J I) fuselage.
View attachment 590949Junkers J I
The Junkers J I was not a 'ground-attack' aeroplane it was an 'Infantry' aeroplane to conduct 'Contact Patrols' to locate 'friendly infantry' and get that information back to commanders.
I thought he glue used for the Mosquito was a resorcinol based resin.