LO,
Sorry, I think I could helpfully respond here:
The empty weights I quoted were actual 'as weighed' from the 2016 OT&E report. Once again, for clarity, all three variants (that's A, B and C) have 'aggressively lightened airframes'.
Yes, the B and C don't have an internal gun, but the point I was trying to get over (and clearly not doing very well ) is that the B and C both have substantial 'penalty weights' for ship operation. (I suppose I could make the argument that the A model carries a penalty weight for having to have a gun - I believe that it was the only variant for which an internal gun was specified in the System Requirement Document). The B and C also lack the heavy boom refuelling receptacle that the USAF demanded for the A. Apples and oranges and all that....
LO is correct that the C was the last variant to be designed, but I'm not sure that this is relevant to the weight issues. For clarity, the original 'batting order' for the programme was A, then B, then C. Once the weight problem was realised around 2004, the weight reduction effort was focussed first on the B, as that was the variant most severely affected. From then on, the batting order ran B, A, then C. Almost all of the weight saving measures developed for the B were moved over to both the A and the C. What is true is that the C was able to exploit most of the B's weight saving changes earlier in its design cycle than the A, so there was less rework than on the A. One big measure it couldn't adopt, though, were the reduced size tail fins - the C had to keep its big fins for the low speed approach.
Yes, the F-35C does lack the F/A-18's slotted flaps, but that was driven by LO issues and known at the outset when the wing was sized. I have to gently disagree and say that, for my money at least, the F-35C's design is a perfectly valid example of a 'CV penalty'. I had some involvement in some of the CV specific design work and I can confirm that deck ops exacted a significant penalty in weight. The main thing I took away was that the DOD's selection of carrier approach speed (Vpa) as a Key Performance Parameter (KPP) was absolutely on the nail - it was the parameter that drove much of the C's design.
LM used CATIA, not always as well as other companies I worked with, but they got better as time went on. Yes, they wanted to limit the number of differences between variants, but during the weight reduction effort they had to make more compromises than they originally wanted. In some cases, it was found that 'commonality' was imposing severe weight penalties, and variant specific changes were essential. As to 'cousin parts', LM used the idea frequently, and had been for some time - McDonnell Douglas were certainly using them in the 1970s and 80s. As I've posted a number of times, LM made a poor job of the airframe design and, unforgivably for any combat aircraft but especially for a power lift aircraft, failed to keep control of airframe weight. In my view (and just opinion) it cost the programme at least two years and a ton of money.
I hope these posts help people understand that getting the F-35 programme across the line has been a massively difficult undertaking. Yes, one can pillory LM for not doing better. One can also recognise that they (and NG and BAES) have made some towering technical achievements along the way to get the programme to where it is now. And those achievements rest on sheer hard work and brilliance from thousands of dedicated people.
Best regards as ever to my friends at LM and BAES,
Engines
PS: and now I really will go quiet for a bit.