bring_it_on said:Pentagon’s cost assessment and program evaluation shop presented analysis to the Air Force supporting the move.
LowObservable said:The FY19-20 SuperBug flyaway costs have the MYP confound.
Confound? This means what, in English?
LowObservable said:Latest news:
http://www.airforcemag.com/Features/Pages/2019/January%202019/Think-of-F-15X-In-Context-Of-Fighter-Recap-Donovan-Says.aspx
Donovan seems to have a fair number of F-15X-related talking points close to hand: "I can't tell you that we're buying more F-15s, but here's why we are doing it."
LowObservable said:Thanks.
I hate doing math in public, but I'm sure that the use of a more expensive raw material for ~20% of the structure will totally drive the cost through the roof, even including engines and avionics. Particularly when much of the Ti is SPF/DB, which has the offsetting merit of reducing parts count.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.850.3043&rep=rep1&type=pdf
lastdingo said:Those figures sure don't apply to individual airframes.
marauder2048 said:lastdingo said:Those figures sure don't apply to individual airframes.
They do. The buy-to-fly ratio for titanium is....bad.
https://www.f-15.nl/hist.htmlThe F-15 airframe {classic} contains 25.8 percent titanium by weight, most of it concentrated around the engines and in the inboard sections of the wings.
SpudmanWP said:Um, that F-15E (ie 70k) number is wrong. The empty weight of an F-15E is around 32k for EVERYTHING so 70k for Titanium is impossible.
LowObservable said:I guess we'll see when the budget documents appear. By the way, both the F-15E and F/A-18E/F have forged and machined Ti bulkheads, which are the worst in terms of buy-to-fly. And even if the difference is 56,000 lb, it takes a pretty high raw material price to hit more than a few per cent of the total airplane.
malipa said:Since the production rate is pretty low, why not 3D print them?
Depends. Back when the F-15E bulkheads were being made they started with a solid block but modern systems like the F-35 start with a forging that is almost done.For titanium, a very small fraction of the raw material (buy weight) ends up as a finished part (fly weight) on the airframe.
I know the F-35 wasn't designed to be a true air-superiority fighter but could the same be done for a fighter designed for that role? Have composites come that far or are the specs for aircraft like the F-15 and F-22 so demanding that titanium is still king?marauder2048 said:The titanium buy-to-fly ratio on the F-35 CTOL is better than just about any other fast jet
and there was a very deliberate effort (per repeated and emphatic DOD guidance) to de-spec titanium
as much as possible.
LowObservable said:FWIW, remember that Ti has to be at $100/lb to make a $5m difference to unit cost, if M2048's numbers are accurate.
LowObservable said:But that's a component cost, not a raw material cost.
LowObservable said:But that's a component cost, not a raw material cost.
TomS said:LowObservable said:But that's a component cost, not a raw material cost.
Commercially pure Ti is running around $25 a pound these days. Aviation-specific alloys could easily be significantly more, especially with the DoD traceability/accountability requirements. I don't know specific pricing, but $100 per pound doesn't seem impossible.
marauder2048 said:bring_it_on said:Pentagon’s cost assessment and program evaluation shop presented analysis to the Air Force supporting the move.
Which tells you that it wasn't AF initiated since that analysis would have come from AFCAA.
“Our budget proposal that we initially submitted did not include additional fourth-generation aircraft,”
Air Force Secretary Heather Wilson told reporters during a Feb. 28 roundtable at the Air Force Association’s Air Warfare Symposium.
Wilson’s comments confirm reporting by Defense News and other outlets who have reported that the decision
to buy new F-15X aircraft was essentially forced upon the Air Force.
Melting down titanium shavings back into ingot seems complicated considering how much titanium loves oxygen, but I'm no metallurgist so I dunno if that's a minor wrinkle or it's in "Might be cheaper to start with raw material" territory.SpudmanWP said:Depends. Back when the F-15E bulkheads were being made they started with a solid block but modern systems like the F-35 start with a forging that is almost done.For titanium, a very small fraction of the raw material (buy weight) ends up as a finished part (fly weight) on the airframe.
Besides, they collect and reuse the shavings.
Why would they use it non structurally when it's so strong and expensive? Nanotubes I imagine would outstrip the cost of carbon fiber with the same risk of rejection while also having similar health hazards as asbestos, that has to be super expensive. All I can think of is to get information on how it weathers, unless this is their weatherproof RAM? Is it a radar absorbing material?SpudmanWP said:Take a look at CNRP.
It's already being used in non-structural components of the F-35.
marauder2048 said:It's also not like you see a ton of composite sub-structure on fighters either.
What often keeps advanced materials out of those areas is lack of ballistic tolerance: it's what kept
the high-temperature aluminum off the F-22 though IIUC the latest alloys are better in this regard.