F-35 Cancelled, then what ?
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Maus92
Some not so good news about the Charlie: Testing was halted back in November after a "small crack" was found in the titanium wing spar, which was downplayed at the time by JPO spokesperson Joe DellaVedova, "Such discoveries are expected during a developmental test program." Note that the JPO was more or less forced to respond to press reports about the cracks - the JPO had not released news of the casualty publicly. Testing resumed in February after repairs, but was halted 3 days later after strain gauges detected further cracking.
Some not so good news about the Charlie: Testing was halted back in November after a "small crack" was found in the titanium wing spar, which was downplayed at the time by JPO spokesperson Joe DellaVedova, "Such discoveries are expected during a developmental test program." Note that the JPO was more or less forced to respond to press reports about the cracks - the JPO had not released news of the casualty publicly. Testing resumed in February after repairs, but was halted 3 days later after strain gauges detected further cracking.
Join Date: Sep 2007
Location: USA
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
Turbine D - The crack in the Ti spar was detected before it became a serious problem, and the aircraft continued to be flown after installing strain gauges to monitor propagation of the fracture. This tells me that they are doing a thorough job with the test program.
The aluminum die forgings used for the fuselage frames also had some fracture issues. Fixing those problems required some expensive changes to the massive die sets used to produce the aluminum forgings. However, I imagine the Ti wing spars are not produced from die forgings since the cost would be prohibitive. They are likely machined from shapes hammer or roll forged from wrought stock. Thus adding thickness in most areas of the spar to resolve the cracking issue would only require modification of the CNC machining program.
Titanium is very sensitive to surface flaws, which can result in fractures propagating from these defects. So the surface of a machined titanium part subject to high stress or fatigue conditions must be smooth and/or mechanically pre-stressed in compression by shot peening.
Titanium also tends to work harden when machined. So Ti parts that are subject to significant machining and stock removal require periodic stress relief treatments to produce a dimensionally stable finished component.
The aluminum die forgings used for the fuselage frames also had some fracture issues. Fixing those problems required some expensive changes to the massive die sets used to produce the aluminum forgings. However, I imagine the Ti wing spars are not produced from die forgings since the cost would be prohibitive. They are likely machined from shapes hammer or roll forged from wrought stock. Thus adding thickness in most areas of the spar to resolve the cracking issue would only require modification of the CNC machining program.
Titanium is very sensitive to surface flaws, which can result in fractures propagating from these defects. So the surface of a machined titanium part subject to high stress or fatigue conditions must be smooth and/or mechanically pre-stressed in compression by shot peening.
Titanium also tends to work harden when machined. So Ti parts that are subject to significant machining and stock removal require periodic stress relief treatments to produce a dimensionally stable finished component.
Join Date: Nov 2013
Location: Annapolis
Posts: 109
Likes: 0
Received 0 Likes
on
0 Posts
@RR: you might be talking about earlier cracking in a different aircraft - you mention that the aircraft was flown after adressing minor cracking. The F-35C that I'm referencing is a test article as mentioned in DOT&E written testimony to Congress last week:
"Structural testing. Major findings are continuing in the durability test articles, particularly in the titanium bulkhead in the F-35C test article. Significant limitations to the life of the fielded F-35C aircraft can only be addressed with intrusive structural modifications prior to the expected full service life, and show again the high cost of concurrent production and development. In the past year, discoveries of unpredicted cracks continued to occur, and in some cases required pauses in testing to determine root causes and fixes. This occurred in all three variants. Currently, only the F-35A structural test article can be tested; it is about to begin the third lifetime test phase, or the third series of 8,000 equivalent flight hours of testing. The F-35B test article is still down for repairs needed to complete the second lifetime. The F-35C test article restarted testing in mid-February but stopped three days later when strain gauges indicated cracking in a titanium bulkhead; it has not yet restarted."
"Structural testing. Major findings are continuing in the durability test articles, particularly in the titanium bulkhead in the F-35C test article. Significant limitations to the life of the fielded F-35C aircraft can only be addressed with intrusive structural modifications prior to the expected full service life, and show again the high cost of concurrent production and development. In the past year, discoveries of unpredicted cracks continued to occur, and in some cases required pauses in testing to determine root causes and fixes. This occurred in all three variants. Currently, only the F-35A structural test article can be tested; it is about to begin the third lifetime test phase, or the third series of 8,000 equivalent flight hours of testing. The F-35B test article is still down for repairs needed to complete the second lifetime. The F-35C test article restarted testing in mid-February but stopped three days later when strain gauges indicated cracking in a titanium bulkhead; it has not yet restarted."
Join Date: Aug 2007
Location: London, New York, Paris, Moscow.
Posts: 3,632
Likes: 0
Received 0 Likes
on
0 Posts
So that'll be 2020 then for RAF lightning II's then??
Muhahahah.
Not really, they'll just delete more testing benchmarks from the schedule and everything will be just fiinnee.
YAY More Good News!!!
Muhahahah.
Not really, they'll just delete more testing benchmarks from the schedule and everything will be just fiinnee.
YAY More Good News!!!
Join Date: Sep 2012
Location: England's green and pleasant land
Posts: 697
Likes: 0
Received 0 Likes
on
0 Posts
There aren't any "RAF" Lightnings glad rag, only UK ones that will be flown and operated Jointly by the RN and RAF and if there aren't any until 2020 that's news to a LOT of people!!
Join Date: Dec 2010
Location: Middle America
Age: 84
Posts: 1,167
Likes: 0
Received 0 Likes
on
0 Posts
The cracking of one wing spar was discovered on an aircraft being used for cyclic testing. The cyclic testing had accumulated the equivalent of 20 years of operational service towards a longer life goal. The problem has been identified as a design problem and not a subsequent manufacturing processing problem. Correcting the design will add one half pound to the weight of the spar. Of course, all assembled and deployed aircraft will require retrofitting the new beefed up spar at a convenient time, lets say short of 20 years.
The wings are bigger on the F35-C version than either the -A or -B versions. I would think the UK version would be good to go by 2018 assuming nothing goes wrong between now and then. Anyhow, what could possibly go wrong between now and then?
The wings are bigger on the F35-C version than either the -A or -B versions. I would think the UK version would be good to go by 2018 assuming nothing goes wrong between now and then. Anyhow, what could possibly go wrong between now and then?
Join Date: Aug 2007
Location: London, New York, Paris, Moscow.
Posts: 3,632
Likes: 0
Received 0 Likes
on
0 Posts
wink, wink and all that...
Join Date: Mar 2010
Location: UK on a crosswind
Posts: 262
Likes: 0
Received 0 Likes
on
0 Posts
On the general subject of battlefield vulnerability and all that, despite ISIS having a fair bit of portable technology, it seems the USAF is deploying several Broncos to mark targets for them in Iraq/Syria.
Join Date: Oct 2003
Location: Somewhere
Posts: 502
Likes: 0
Received 0 Likes
on
0 Posts
Well, according to the RAF website, the erstwhile Marham Staish, Harv Smyth, has been appointed OC Lightnings at Marham. Isn't it about time we renamed this thread, as the project, like the banks, is way too expensive to cancel?
Join Date: Sep 2012
Location: England's green and pleasant land
Posts: 697
Likes: 0
Received 0 Likes
on
0 Posts
Hey gr, I'd love to believe it was a purposeful phrase, but alas..! The correction was for the wider audience who perhaps don't appreciate the full extent of the Joint arrangement.
Join Date: Apr 2008
Location: The Whyte House
Age: 95
Posts: 1,966
Likes: 0
Received 0 Likes
on
0 Posts
Well, according to the RAF website, the erstwhile Marham Staish, Harv Smyth, has been appointed OC Lightnings at Marham. Isn't it about time we renamed this thread, as the project, like the banks, is way too expensive to cancel?
*instead of -Mates
Join Date: Sep 2007
Location: USA
Posts: 601
Likes: 0
Received 0 Likes
on
0 Posts
@Maus92- Thanks for correction. I went back and re-read the article. The wing spar crack was in the fatigue structural test airframe and occurred at the equivalent of 6,850 flight hours. It was noted the issue had no impact on current F-35 flying operations.
The previous cracking issue I noted was with the die forged aluminum bulkheads used on the F-35B. Similar to the situation above, the cracking was discovered on the fatigue structural test airframe at 9,400 hours, which is beyond the design requirement of 8,000 hours. People should appreciate that the aluminum die forgings used for the bulkheads are very impressive pieces of manufacturing engineering.
The previous cracking issue I noted was with the die forged aluminum bulkheads used on the F-35B. Similar to the situation above, the cracking was discovered on the fatigue structural test airframe at 9,400 hours, which is beyond the design requirement of 8,000 hours. People should appreciate that the aluminum die forgings used for the bulkheads are very impressive pieces of manufacturing engineering.
Join Date: Dec 2006
Location: UK
Posts: 799
Likes: 0
Received 0 Likes
on
0 Posts
Snafu,
Perhaps I can help a little - I can confirm that I'm not an employee of LM, nor am I paid to post here ( I understand the term is 'a shill').
To be clear, I was employed by BAE and worked on the F-35 programme for a few years - I don't think I've ever tried to hide that. I left BAE about 10 years ago, and they don't pay me to post either.
Hope this helps
Best wishes as ever to those of any opinion,
Engines
Perhaps I can help a little - I can confirm that I'm not an employee of LM, nor am I paid to post here ( I understand the term is 'a shill').
To be clear, I was employed by BAE and worked on the F-35 programme for a few years - I don't think I've ever tried to hide that. I left BAE about 10 years ago, and they don't pay me to post either.
Hope this helps
Best wishes as ever to those of any opinion,
Engines
Join Date: Sep 2010
Location: Neverland
Posts: 59
Likes: 0
Received 0 Likes
on
0 Posts
@Engines. Your postings reflect the statement you make. As far as this outside observer can tell they are factual and present interesting information that contributes to general knowledge. My original post was mostly directed at another posters comments which were coming across very close to a party line to the detriment of the intent behind them, in my opinion.
@Ken V none of which I (or anybody else really) has actually said. You wish people were actually saying those things because it might make your desire to dismiss opinion that does not coincide with yours easier to achieve in reality.
@Ken V none of which I (or anybody else really) has actually said. You wish people were actually saying those things because it might make your desire to dismiss opinion that does not coincide with yours easier to achieve in reality.
Join Date: Aug 2014
Location: New Braunfels, TX
Age: 70
Posts: 1,954
Likes: 0
Received 0 Likes
on
0 Posts
@Ken V none of which I (or anybody else really) has actually said. You wish people were actually saying those things because it might make your desire to dismiss opinion that does not coincide with yours easier to achieve in reality.
Join Date: Jan 2003
Location: Leicestershire, England
Posts: 1,170
Likes: 0
Received 0 Likes
on
0 Posts
In the absence of any 'really good' news...