Delete comment from: Elements Of Power
Well, I think we're 'good'(?) now, but I think I know why the CAPErs used the 80% factor.
Someone may have mentioned this already over at F-16.net, so you may have heard this speculation already, if you've followed the thread on this (and it sounds like you have been).
I believe the CAPErs used the AV-8B operating mode definitions and the AV-8's nozzles are always swinging around throughout most of the flight regime. But the F-35 uses a completely different approach - one that does not involve 'viffing' for instance and I can't see any reason the F-35 would use any of it's modes (two are really modes IMHO, the rest are states of transition between the two operating modes from what I understand). CAPE and other cost analysts usually (ALMOST always) don't know a thing about whatever hardware or operations they're looking at to estimate the commensurate costs. They rely on 'comparables' more than a new real estate appraiser. When things are 'different' between the apples and oranges, someone usually has to tell them the difference between them and then some fudge factor is pulled out of the nether regions and applied to account for the differences, which may make the estimate even MORE unrealistic.
I've seen the same problem in the industry when companies bring in teams of outside consultants from the really big firms. They are usually led by really ambitious and bright analysts who felt stifled doing gov't work, and as bright as they are, I and others would spend ungodly amounts of time helping them construct a reasonable model of what they are trying to derive a cost estimate for. RAND Corp has a library online with free downloadable 'pdfs' that give insight into the difficulties involved. For instance, when the percentage of composites in airframes started increasing, all the old models for estimating structure costs had to be thrown out. That's when it was discovered that a lot of those models were based on WW2 production data for (relatively) high numbers of aircraft produced/year, though for years before no one could figure out why they were consistently having cost overruns: there weren't overruns, there were under-estimates.
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Aug 27, 2013, 11:34:57 PM
Posted to F-35 Cost Estimates Drop; AvWeek Makes Motorboat Sounds