Aircraft Wing construction

[earl1937]

  There are about as many different wing designs as there are aircraft flying today, but one thing is constant: The wing is either monocot or semi-monocot constructed! All aircraft which flew in WW2 were semi-monocot constructed wings. The following is a semi-monocot constructed wing and gives you some idea of the bracing which is enternal and covered by the aircraft "skin" on the outside of the wing structure;


The method of fasting used during that time frame is as follows:


This is a cut-a-way of a P-38, showing the internal bracing and reinforcement spars and many other fittings, gussets and fillets:


Following is a picture of the simplest of Monocot constructed items, which is where the skin of the object is the strength of the item, wing or what have you:

As you can see, it is a common egg!

Lets just see if anyone can list a aircraft which is being used to day, which has monocot constructed wings?

[GScholz]

Monocoque

[earl1937]

Monocoque

  An aircraft by that name?

[GScholz]

And not all WWII aircraft were of monocoque or semi-monocoque design. The Hurricane for example was a steel-tube structure with aluminum cross-bracing, with wood and fabric covering.




Another famous internally braced WWII aircraft was the Wellington bomber with its geodesic construction. It was very strong and resistant to damage.

[GScholz]

  An aircraft by that name?

Monocoque, not "monocot". From the Greek for single "mono" and French for shell "coque".

[earl1937]

Monocoque, not "monocot". From the Greek for single "mono" and French for shell "coque".

Spelling has never been my strong point! Point of info: Any aircraft wing which has enternal bracing such as cross arms, ribs and other devices to strengthen the wing is consistered a semi-monocoque constructed wing. Even the tube type wings such as the one you show were also consistered this method!

[GScholz]

Semi-monocoque construction is also known as stressed skin construction, where the skin carries some of the load. In the Hurricane and Wellington the skin was mostly doped fabric and carried no load. Wellingtons in particular were known for their ruggedness and regularly returned with large parts of the skin burned or blown away.

[pembquist]

Looking at the props on the Wellington makes me wince.

[Cthulhu]

Another Barnes Wallis creation.

[earl1937]

Looking at the props on the Wellington makes me wince.

Not sure the reference to the props, but what scares me is looking at that small "rudder". No wonder that they had so many accidents after losing one engine. I have often wondered at what time during the development of twin engine and or multi-engine aircraft, did someone say, "We have to been concerned with the minimum control airspeed when designing these aircraft"!
Generally speaking the larger the rudder and vertical stab, the lower the VMC of that aircraft. A good example of that is the B-24J, which had 2 rudders and 2 stabs, they were still relatively small for that size aircraft. The U.S. Navy had the "privateer", I think which was designated PBY4-1 and -2.





I am unable to find the info needed to compare the VMC speeds with 2 engines out on one side, but I think it was a pretty good difference, which, as these aircraft were used as anti-submarine patrol aircraft and carried large loads of fuel, the margin of safety was wider with the single rudder as opposed to the twin rudder set up of the 24.
Don't ask me why Consoladated did not choose the single rudder and stab as opposed to the twin setup, because I have no idea! Again, this aircraft was designed during the development of aircraft and not sure if any wind tunnel tests of any kind were conducted.

[Cthulhu]

Semi-monocoque construction is also known as stressed skin construction, where the skin carries some of the load. In the Hurricane and Wellington the skin was mostly doped fabric and carried no load. Wellingtons in particular were known for their ruggedness and regularly returned with large parts of the skin burned or blown away.

(Image removed from quote.)

What made the Wellington so survivable was the inherent redundancy of the geodesic structure, with many alternative load paths.  It wasn't a terribly lightweight structure though.

[Cthulhu]

Don't ask me why Consoladated did not choose the single rudder and stab as opposed to the twin setup, because I have no idea!

In all likelihood Consolidated went with twin rudders on the B-24 to minimize hanger door height requirements and possibly to avoid the need for high torsional stiffness in the rear fuselage. The downside is that the twin rudder configuration can be more susceptible to the effects of prop wash and wingtip vortices, making for some weird stability issues.

[GScholz]

What made the Wellington so survivable was the inherent redundancy of the geodesic structure, with many alternative load paths.  It wasn't a terribly lightweight structure though.

No, "redundancy" and "ruggedness" is usually the enemy of "lightweight". It was also really complicated to manufacture and assemble.

[Cthulhu]

No, "redundancy" and "ruggedness" is usually the enemy of "lightweight". It was also really complicated to manufacture and assemble.

Do you have any info on the manufacturing process? I'm curious what the tooling looked like, and if the parts count was really high.

[GScholz]

The unique part count for the fuselage alone was over 1500 if I remember correctly. All those little struts and braces...