Hey Frank Stewart,
re
Given the defects inherent in "Elliptical" wings, why would you ever consider them for high volume manufacture?
Part of the reason Mitchell selected the elliptical wing was due to the nature of the aircraft they were designing, along with the level of aeronautical engineering knowledge and technology at the time.
The theory Mitchell operated under at the time of his participation in the design said that an elliptical (or semi-elliptical) wing had a lower overall drag factor and wing structure weight in the airframe performance range he was designing for - while still providing enough lift and wing area vs the aspect ratio(s) needed for said overall lift and wing area - without the need for heavy and/or sophisticated/and or complex additional high lift devices such as slats or various types of slotted or Fowler flaps. Simple split flaps were all that was needed for TO and landing.
The other reason for Mitchell's selection of the semi-elliptical wing (from what I have seen over the years) is the inherent need of many engineers-inventors to try out new methods, to push the envelope/limits of current technology, and generally attempt to 'improve the breed'.
It is easy now - with hindsight - to look at the problems Mitchell and Supermarine had with the manufacture of the wing and say it was a bad decision, but at the time the design was committed to it was not obvious. And I think it is correct to say that despite the popular hindsight view of it being a problem not worth pursuing, the fact that other aircraft designs were not and are not also criticized in the same way tends to invalidate the criticism. As far as I know there has been no long term popular contemporary or hindsight based criticism of the He112's elliptical wing, or the A5M's elliptical wing, or the P-47's elliptical wing, or the Tempest's elliptical wing, etc. The simple fact is that the theory of the elliptical wing was not the problem - it was the manufacturing and materials technology, along with the size and condition of the British aerospace industry, that were the limiting factors.
In reality of course, Supermarine ran into 2 major problems (not necessarily in order of importance) which were:
1. The time required to manufacture the wing which resulted in higher costs than a more conventional wing.
2. The wing twist that occurred when high aileron forces were encountered - rendering the effectiveness of the ailerons marginal in certain flight regimes.
And in reality, the 5 advantages (not necessarily in order of importance) were:
1. Reduced drag for a given wing area/wing loading vs wing span/aspect ratio.
2. Reduced drag for a given wing area/wing loading due to the thinner wing section.
3. Reduced weight of the wing for a given wing area/aspect ratio.
4. Good stall characteristics.
5. Very high dive speeds for such a large wing area/aspect ratio.
There are other criticisms laid at the feet of the elliptical wing on the Spitfire, but as far as I can tell they are not the fault of the elliptical planform chosen - rather they are the result of the overall size and weight of the airframe along with the performance parameters required by the Air Ministry in their F.5/35 and F.10/35 Specifications. Having only about 1000 BHP to work with during the design stages precluded an airframe the size of the Tempest or Thunderbolt - both of which had no particular problem with the elliptical planform of their wings due to the greater depth of the wing girder - despite having a similar wing thickness to chord ratios. The larger airframe/deeper wing girder also allowed heavier armament to be put in the wings, along with a landing gear arrangement that gave a wider track and closed inward (rather than outward as in the Spitfire and Bf109). In the case of the Tempest Mk I and Fury Mk I it also allowed the radiators to be placed in the wing leading edge.
Even on the smaller Spitfire airframe/wing planform, if the later laminar flow wing section of the Tempest had been available to Mitchell we would not be having this discussion.
Spitfire______ NACA 2213.2-2209.4 (13.2% - 9.4%)
P-47________ Republic S-3 (15% - 9%)
Tempest_____Hawker H/1414/37.5 - H/1410/37.5 (14.5% - 10%)
PS We are reading your posts. We just disagree with your conclusions sometimes.