F-35 Cancelled, then what ?
Do a Hover - it avoids G
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glad rag
I don't know of a more modern western military aircraft programme. Therefore uncovering and solving problems on it seems leading edge to me.
I don't know of a more modern western military aircraft programme. Therefore uncovering and solving problems on it seems leading edge to me.
He normally was, cuefaye.
JF, the F-4 wasn't badly off for for fuel. We frequently did supersonic intercepts on those long exercise sorties and most of each intercept was most certainly pointing AWAY from base.
On your other point, Leading edge doesn't necessarily mean functional or successful. As this program is currently proving.
JF, the F-4 wasn't badly off for for fuel. We frequently did supersonic intercepts on those long exercise sorties and most of each intercept was most certainly pointing AWAY from base.
On your other point, Leading edge doesn't necessarily mean functional or successful. As this program is currently proving.
And the other consideration which is absolutely critical in the case of the 'B' is weight....any modification/redesign is going to be heavier !The 'B' is already heavy enough and does not have much 'spare' !!
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Doesn't stop the Marines from wanting to order 6 more with OCO funds - funds that should be applied to actual overseas contingencies, like the renewed fighting in Iraq and possible actions in Syria. This backdoor maneuver was first floated last year, and I guess the Marines (and Lockheed Martin's lobbyists) are trying to slide this one in before the end of the fiscal year. The premise is to replace the AV-8Bs lost in 2012, but surely the Navy has a few F/A-18s that have been SLEPed to tide the Marines over....
Ecce Homo! Loquitur...
I presume this is the "quick fix" to get the test aircraft flying again, not the longer term solution?
So, another couple of months delay in the program, presumably taking the planned carrier sea trails out of the plan till at least next year?
Pratt: F-35 Fix Could Begin Installation Before End of Year
NATIONAL HARBOR, MD — Engine manufacturer Pratt & Whitney believes it could begin retrofit fixes by November for the engine issue that caused an F-35A to catch fire this summer.
“Probably in the November timeframe, with some anticipated success, we would begin the retrofit with emphasis on the SDD [system development and demonstration] jets,” Bennett Croswell, Pratt’s head of military engines, told reporters at the Air Force Association’s annual Air & Space conference.....
So, another couple of months delay in the program, presumably taking the planned carrier sea trails out of the plan till at least next year?
Pratt: F-35 Fix Could Begin Installation Before End of Year
NATIONAL HARBOR, MD — Engine manufacturer Pratt & Whitney believes it could begin retrofit fixes by November for the engine issue that caused an F-35A to catch fire this summer.
“Probably in the November timeframe, with some anticipated success, we would begin the retrofit with emphasis on the SDD [system development and demonstration] jets,” Bennett Croswell, Pratt’s head of military engines, told reporters at the Air Force Association’s annual Air & Space conference.....
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Tale from the 1960s ...
This story might make a few chuckle, especially John Farley.
While walking the hills I infrequently bump into an old RN articifer (b.1942). We chat, exchange views, knowledge - you get the picture. For some reason I described the problems with the F-35A engine, i.e. excessive blade rubbing leading to eventual fire. My friend smiled knowingly and his eyes sparkled. With some delight he then told me that in the mid-1960s he was aboard the RN aircraft carrier first tasked with trialling the new Buccaneer S.2 with its new Spey engines. (Note: I should have asked for more details of ship and date.)
He said that the Speys were failing at an alarming rate and that he and other articifers were working round the clock replacing them. Because the engines were 'sealed units' no-one on-board was allowed to strip the engines to find the cause (not that that would have helped operationally). This went on for days; good engines running low; tempers high between enginering and flying staff.
Eventually a senior RN engineer was flown aboard. He waited for a flight of Buccaneers to return. There were engine failure(s). Engineer proceeded to strip a Spey, something my articifer friend had never witnessed before - it made a great impression. Anyway, eventually the senior engineer reports to all the witnesses to his butchery that he has found the cause of the failures....
...... rotor blades failing due to excessive rubbing against the surrounding engine casing.
Of course, a solution was found and, as we all know, the Buccaneer S.2 and Spey went on to great acclaim.
regards, Tanimbar
Update courtesy of David Parry: the carrier was HMS Victorious, 1966.
While walking the hills I infrequently bump into an old RN articifer (b.1942). We chat, exchange views, knowledge - you get the picture. For some reason I described the problems with the F-35A engine, i.e. excessive blade rubbing leading to eventual fire. My friend smiled knowingly and his eyes sparkled. With some delight he then told me that in the mid-1960s he was aboard the RN aircraft carrier first tasked with trialling the new Buccaneer S.2 with its new Spey engines. (Note: I should have asked for more details of ship and date.)
He said that the Speys were failing at an alarming rate and that he and other articifers were working round the clock replacing them. Because the engines were 'sealed units' no-one on-board was allowed to strip the engines to find the cause (not that that would have helped operationally). This went on for days; good engines running low; tempers high between enginering and flying staff.
Eventually a senior RN engineer was flown aboard. He waited for a flight of Buccaneers to return. There were engine failure(s). Engineer proceeded to strip a Spey, something my articifer friend had never witnessed before - it made a great impression. Anyway, eventually the senior engineer reports to all the witnesses to his butchery that he has found the cause of the failures....
...... rotor blades failing due to excessive rubbing against the surrounding engine casing.
Of course, a solution was found and, as we all know, the Buccaneer S.2 and Spey went on to great acclaim.
regards, Tanimbar
Update courtesy of David Parry: the carrier was HMS Victorious, 1966.
Last edited by tanimbar; 18th Sep 2014 at 07:54.
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So, knowing that such a thing was a problem 50 years ago, it still hapens now. O.K., different manufacturer, but still. Just a case of NIH Syndrome?
One wonders whether the F/A-18V(arious) had such problems, and how long they took to resolve. Same for the F-4, F-14, not to mention land-based fighter/attack aircraft of course.
One wonders whether the F/A-18V(arious) had such problems, and how long they took to resolve. Same for the F-4, F-14, not to mention land-based fighter/attack aircraft of course.
We are 50+ years down the road from Spey's etc...
Also aircraft like the Buccaneer or F18 do not have the weight problem of the F35 'B' !
Any added weight is a problem for any aircraft but it is a crucial area for the F35 B
Also - historically blade rubbing might be viewed as a problem during 'enthusiastic' handling - but unless I have misunderstood - the blade rubbing on the F35 happened whilst being flown fairly sedately !
Also aircraft like the Buccaneer or F18 do not have the weight problem of the F35 'B' !
Any added weight is a problem for any aircraft but it is a crucial area for the F35 B
Also - historically blade rubbing might be viewed as a problem during 'enthusiastic' handling - but unless I have misunderstood - the blade rubbing on the F35 happened whilst being flown fairly sedately !
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Hempy (and others)
I've been taking a long break abroad with Mrs. Engines, so not so much posting recently.
I don't think I can add much to John Farley's responses, which cover all the angles as far as I can see.
The only thing I would add is that people should understand that the F135 development programme was required to 'push the envelope' to a very high degree in terms of thrust/weight ratio as well as src, and many other demanding performance targets to support all three variants. It's a very large diameter engine, and I'd think I'd be safe in assuming that this might have contributed to the rubbing between the rotors and the casing - it could be that P&W's models for this effect didn't hold up under all loading conditions. But that's pure speculation. In any case, it's a much tougher issue to prevent than with smaller engines.
It should also be appreciated that the entire propulsion system is a separate programme between the DoD and P&W, with the results being supplied to LM as Government Furnished Equipment (GFE). As a result, this problem is firmly in the DoD's court with P&W to solve.
Given all the above, I'm quite surprised that the programme has not had more engine issues to date. Almost all combat jet aircraft programmes I have looked at have had significant if not serious engine problems at one time or another. The UK have had some especially bad ones, as have the US. This one is serious, no doubt about that, but as JF so wisely says, this event is 'pure engineering gold'. More so as no-one got hurt during it. It will definitely help the engineers at P&W deliver the best possible product to the front line as soon as possible.
Hope this helps, best regards as ever to all those exceedingly clever propulsion engineers who have to cover the 'hard yards' for real
Engines
I've been taking a long break abroad with Mrs. Engines, so not so much posting recently.
I don't think I can add much to John Farley's responses, which cover all the angles as far as I can see.
The only thing I would add is that people should understand that the F135 development programme was required to 'push the envelope' to a very high degree in terms of thrust/weight ratio as well as src, and many other demanding performance targets to support all three variants. It's a very large diameter engine, and I'd think I'd be safe in assuming that this might have contributed to the rubbing between the rotors and the casing - it could be that P&W's models for this effect didn't hold up under all loading conditions. But that's pure speculation. In any case, it's a much tougher issue to prevent than with smaller engines.
It should also be appreciated that the entire propulsion system is a separate programme between the DoD and P&W, with the results being supplied to LM as Government Furnished Equipment (GFE). As a result, this problem is firmly in the DoD's court with P&W to solve.
Given all the above, I'm quite surprised that the programme has not had more engine issues to date. Almost all combat jet aircraft programmes I have looked at have had significant if not serious engine problems at one time or another. The UK have had some especially bad ones, as have the US. This one is serious, no doubt about that, but as JF so wisely says, this event is 'pure engineering gold'. More so as no-one got hurt during it. It will definitely help the engineers at P&W deliver the best possible product to the front line as soon as possible.
Hope this helps, best regards as ever to all those exceedingly clever propulsion engineers who have to cover the 'hard yards' for real
Engines
] I think I shall do all the arm-waving I bloody well want, Frostchamber...
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Glad,
A slightly pedantic point on 'who is paying'.
On this engine issue, P&W are footing the bill. On the engine development, the UK's share of development costs is a fraction of what we would have paid RR to do the job. For what it's worth, I think the UK Government should have pressed the US Government much harder (and paid if necessary) to keep the F136 alternate engine option open. However, water under the bridge and all that.
Arm waving is, of course, a democratic right. Third Amendment and all that. Please arm wave without let or hindrance. As ever, all I'll try to do is provide information to help the discussion along.
Best Regards
Engines
A slightly pedantic point on 'who is paying'.
On this engine issue, P&W are footing the bill. On the engine development, the UK's share of development costs is a fraction of what we would have paid RR to do the job. For what it's worth, I think the UK Government should have pressed the US Government much harder (and paid if necessary) to keep the F136 alternate engine option open. However, water under the bridge and all that.
Arm waving is, of course, a democratic right. Third Amendment and all that. Please arm wave without let or hindrance. As ever, all I'll try to do is provide information to help the discussion along.
Best Regards
Engines
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RR & GE Alternative
Engines, I have it on good authority from a RR engineer, that both RR & GE offered to carry on and fund the development themselves; but the powers that be ordered it be canned.
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Fat,
It's true that the RR/GE team offered to continue F136 development at their own cost, but only up to a specified point. The F-35 programme and the DoD would have had to cover the full development costs as well as the costs of qualifying the F-35 with the F136.
As I've posted before, I had a brief but interesting 'ringside seat' on the alternate engine issue in the late 90s. There was a real tussle within the DoD between the engine technical experts, who were convinced that their funding and guidance was giving P&W the right solution, and the propulsion acquisition guys who were scarred veterans of the 'Engine Wars' of the 1970s and 80s, especially the PW100 saga. The JSFPO convened a special panel to review the situation, and at that time the alternate engine programme got a 'pass'.
Sadly, the UK MoD declined to positively endorse the F136, and left the issue to the USG. The result that was when the Obama administration came in and were looking for cost reductions to offset other areas of F-35 cost growth, the UK's late efforts to save the F136 were not viewed as credible.
Anyway, water under the bridge, it's the F135 and P&W to sort the issue out.
Hope this lot is of passing interest to someone,
Engines
It's true that the RR/GE team offered to continue F136 development at their own cost, but only up to a specified point. The F-35 programme and the DoD would have had to cover the full development costs as well as the costs of qualifying the F-35 with the F136.
As I've posted before, I had a brief but interesting 'ringside seat' on the alternate engine issue in the late 90s. There was a real tussle within the DoD between the engine technical experts, who were convinced that their funding and guidance was giving P&W the right solution, and the propulsion acquisition guys who were scarred veterans of the 'Engine Wars' of the 1970s and 80s, especially the PW100 saga. The JSFPO convened a special panel to review the situation, and at that time the alternate engine programme got a 'pass'.
Sadly, the UK MoD declined to positively endorse the F136, and left the issue to the USG. The result that was when the Obama administration came in and were looking for cost reductions to offset other areas of F-35 cost growth, the UK's late efforts to save the F136 were not viewed as credible.
Anyway, water under the bridge, it's the F135 and P&W to sort the issue out.
Hope this lot is of passing interest to someone,
Engines
Last edited by Engines; 17th Sep 2014 at 19:17. Reason: Spelling