F35 – CONGRESSIONAL REPORT Analysis



Introduction


The public release of a major US Congressional Report (F-35 Joint Strike Fighter Concurrently Quick Look Review dated 29 November 2011) offers a nearly unprecedented level of detailed information on the world’s largest defence procurement programme. This article offers an independent analysis of the report and considers what it may mean for the most significant project for the world’s military aircraft industry.

The Report


The report was not intended for widespread release, as its markings (For Official Use Only (FOUO) US Only) indicate. It was prepared in by five senior Department of Defense officials, including no less than three Deputy Assistant Directors. It contains a level of detailed information and programme assessment that is quite unknown outside the United States, and reveals key issues that the F-35 has been battling with for some time.
A useful introduction (Section 1) describes the background to and rationale for the report, and includes a summary of a recent (and highly critical) Operational Assessment(OA) . This is a highly significant issue in its own right, as the DoD agency conducting these assessments is influential and maintains an aggressively independent stance within the US defence acquisition system.
The introduction is followed by Section 2, a description and analysis of the central issue of the report, which is the level of overlap (concurrency) between the F-35’s initial production and the aircraft’s technical development. Section 3 describes and analyses the key technical challenges facing the programme, and how they affect the concurrency issues, followed by a short set of conclusions at Section 4. A comprehensive Appendix with 33 pages of detailed technical information completes the report.
It is clear from the report’s executive summary, and the introduction, that the project is carrying a very high level of overlap between series production and ongoing technical development. Moreover, it is clear that the programme faces major challenges in achieving current dates for Initial Operational Test and Evaluation (IOT&E) in 2015. The analysis effectively starts with the results of the OA released in Oct 2011.

Operational Assessment


The results of the F-35’s first OA make sobering reading. There are shortfalls and risks against requirements in all key combat capability areas, including Air to Surface Attack (A/S), Close Air Support (CAS), Air to Air Warfare (AAW), Electronic attack (EA), Combat SAR (CSAR) and Reconnaissance. Worryingly, risks are also considered to exist in the important areas of Deployability, Mission Generation, Training and Fleet Support.

Concurrency Risk


If an aircraft starts production too early in its development cycle, early examples will have to have changes embodied after they are built. Structural changes are the hardest to retrofit, and can affect both weight and performance as well as airframe life. Mission systems issues can pose major capability problems, as shown by those experienced with Typhoon Tranche 1 aircraft. Finally, problems with vehicle systems such as cooling, landing gear and arresting hooks can impact aircraft performance and capability.

Section 2 of the report shows that the F-35 programme is carrying a high level of concurrency risk, mainly due to the decision to start production sooner than legacy programmes. There are a number of reasons for this. One was the use of a concept demonstration phase, which was intended to significantly reduce downstream programme risk. Another was the assumption that sophisticated modelling and simulation tools, along with modern design and manufacturing methods would bring the F-35 design to maturity more quickly than legacy projects.

Unfortunately, this has not happened, and the programme is now having to cope with a large number of changes while ramping up production rate. The rate of change is still increasing when it should be decreasing, and the reason for the changes is also of some concern. Just over half are aimed at achieving or supporting specification compliance – which in simple terms means that LM are still working to get the design right.

Changes are taking a long time to get into production, and as the number of outstanding changes builds, the costs of retrofit and rework are increasing. This is not a unique situation. All recent combat aircraft have suffered from concurrency risks to some extent, but the report shows that the F-35 has a higher level than other US projects. It would be instructive to be able to make a comparison with UK and European projects, but sadly the level of information released in this report is unlikely to be matched outside the USA.

At this stage, it must be considered highly likely that the F-35 production schedule for all variants will be further delayed during 2012 or 2013. If it is not, the costs of retrofit and rework of early aircraft will become prohibitive. It is also likely that early F-35 aircraft will lack key operational capabilities unless they can be fully upgraded.


Design and Technical Issues – Overview

Section 3 of the report contains a wealth of detail on major technical issues (and design risks) with the F-35 aircraft and its support systems. It splits the issues into four categories.

  • The first category is design risks that preclude further production. The good news in this report is that no such risks were identified. This is  a key statement, that is likely to be ignored by the programme’s more vocal opponents. However, it is balanced by the findings in the next three categories.
  • The next are known design issues that will cause major consequences for the programme but have not yet been solved. There are 5 of these, including the HMD, the fuel dump system, the Integrated Power Package (IPP), the Arresting Hook System (AHS) and a ‘classified’ issue.
  • Following this, three areas are described that could have major consequences, but which are not yet fully understood. These include airframe buffet, airframe fatigue life and (slightly confusingly)  the progress of the overall flight test programme.
  • Finally, there are 5 areas where likely consequences are assessed as only moderate, but taken together the number of issues presented generates a higher than desired level of programme risk. These include mission system software development, weight control, thermal management, the Autonomic Logistics Information System (ALIS) and Lightning protection.

It is not easy, nor may it be fair, without detailed technical knowledge of the programme, to pronounce on whether this is a ‘bad’ or ‘good’ report. However, it is quite clear that the F-35 design has not reached the level of technical maturity that was expected just a few years ago.
Most surprisingly, the F-35 is, in a few areas, failing to meet legacy levels of performance from such systems as Night Vision Goggles (NVG). There are also apparently risks in areas of structure, mission systems (particularly the Helmet Mounted Display)(HMD) and certain key air vehicle systems.
Finally, a coded set of references to a ‘classified area’ very probably indicates issues with the aircraft’s low observable signature. They may be in the Radio Frequency (RF) area as well as the thermal spectrum.
This is an important assessment that will affect near term decisions on the F-35. The OA, being produced by the OT&E area, carries a great deal of weight within both the US Government (DoD) and the Congressional committees that discuss and decide the funding allocated to the programme.

The Five Major Issues – The Known’s

Helmet Mounted Display (HMD)

The HMD system is still exhibiting a series of problems including display jitter, night vision system acuity and latency (delays) in the images presented from the aircraft’s electro-optical distributed aperture system (EO-DAS). These are serious because the HMD system is a primary flight display – the JSF has no conventional Head Up Display(HUD). The seriousness of the situation is shown by the recent start of a parallel investigation into an alternate helmet system. However, this solution, which builds on a UK design developed for Typhoon, is not yet fully compliant with all parts of the JSF Operational Requirements Document (ORD), so it is not going to be an ‘off the shelf’ solution.

This is a challenging problem that will lead to extensive and costly tests and assessments to solve. These may well include repeat ejection seat tests and, as the report points out, simulators are not able to reproduce all the issues. That will mean more flight tests.

Fuel Dump System

The fuel dump issue appears to be minor, but is clearly a tough nut to crack. This is probably due to the difficulty of getting the fuel clear of the airframe without compromising the LO signature. Retractable dump masts are an option, but would add weight and complexity. This is a more serious problem for carrier borne operations, where fuel is always dumped on return to the ship, and where fuel-coated aircraft are not a good thing to have on a crowded flight deck with weapons in close proximity.

Integrated Power Pack (IPP)


The IPP is a novel feature of the F-35, combining the functions of power generation, cooling, engine starting and environmental systems. It was intended to reduce weight and volume and improve reliability, but is apparently not yet delivering on the last of these aims. Of equal concern is that removal and replacement of the IPP is taking two days, which must be far longer than specified or wanted. Finally, apart from changes to IPP system software, no obvious fixes to the IPP system appear to have been identified or developed. It seems quite probable that some will now have to be.

Arresting Hook System (AHS)

The problems with the AHS are described in some detail. It appears to have failed its first series of land based tests, which involved taxying at fairly low speeds over arresting wires. The possible causes identified include the shape of the hook point (simple fix) and the setting of the hook damper that controls its movement when striking the deck (probably a fairly simple fix). However, if these do not work, the other cause is the location of the hook very close behind the main wheels, which is not giving the arresting wire time to bounce back up after being ‘trampled’. This would be a far harder issue to solve, as the aircraft design does not provide easy structural options for moving the hook system further aft. In terms of suitability for aircraft carrier operations, it can fairly be said that design issues don’t get much more central than this one. It’s a tough one because final proof of any fix must await carrier based deck trials that not will not take place for some time.




‘Classified’ – Signature


The fifth issue, labelled as ‘classified’ can be assumed to be linked to signature. However, no further speculation can usefully be offered apart from the observation that the aircraft’s operational capabilities are heavily dependent on achieving a robust and effective low signature across all wavelengths.

Taken as a whole, the report’s assessment that these issues are a serious set of design risks for the F-35 programme can’t be argued with. They span a number of areas, and it should be understood that fixing any one might well impact the others.



The Three ‘Unknowns’


These design risks are not yet fully understood, and so there is a little less detail presented than for the first five. However, what is presented is extremely interesting.

Buffet

Airframe buffet is, on the face of it, a slightly surprising issue for LM to have encountered. The F-35 is not a high agility design, and higher than expected buffet at around 10 degrees AOA and M0.85 to M0.90 must be a serious disappointment to the airframe and aerodynamics design teams. Any fixes could involve changes to aircraft shape. Some structural ‘beefing up’ might be required. Some will be minor, some could be major – and further tunnel and flight testing will be required which will take until around 2014. However, they must be addressed, as buffet is already causing issues for the HMD system, and will undoubtedly affect other mission systems and reduce airframe fatigue life.  Not least, this problem can cause pilot fatigue and performance issues.

Fatigue Life

Airframe fatigue life issues must be another disappointment to the team, and are an area that was expected to be mitigated through use of CAD and other advanced techniques. However, the challenge of designing a durable and weight efficient airframe while leaving large holes for weapons bays, making space for internal fuel and avionics, and handling the loads generated by carrier launch and recovery is considerable. Add in the demands of a STOVL layout and it becomes extremely difficult. Taken together with the programme’s previous weight issues, it might be concluded that F-35’s structural design teams have not always been able to meet all the challenges posed. The A model has completed less than one fifth of its required test programme, the B model less than one tenth. In many ways, the C model is the most challenging structurally, and testing has yet to start on this variant.
The report is at pains to point out that experiencing fatigue problems is not unusual in combat aircraft programmes, and the F-35’s issues are not by themselves especially serious. However, when set against the amount of testing yet to be carried out, and the fact that a large number of airframes have already been built which will now require substantial rework, the report has elevated the seriousness of the issue.

Flight Test Progress
The final area presented in this category is that of flight test execution. The report states that the programme is around 8% behind plan, but this apparently small shortfall must be set against a number of relatively recent reviews and re-working of the flight test schedule. Given this, shortfalls against the latest schedule are most unwelcome and it is not surprising that the review team picked up on this. The team also identified the circular relationships between flight test and development. Some flight tests have been delayed by technical issues, including software, but in other areas the slower pace of progress is impacting progress towards design fixes.

The Cumulative Issues


The final set of design issues presented in the report provide further insight into the multiple challenges still faced by the F-35 team and the accumulating complexity of managing the fixes required.

Software
Development of software for both the aircraft mission system and to support flight testing is behind schedule, and the rate of changes required appears to be rising despite the best efforts of the various teams involved. The delays are also probably linked to hardware standards, and the flight test team is now having to manage eight different software loads across the test aircraft fleet. As for physical aircraft build, delays in achieving sufficient software maturity generate an increasing level of rework and changes to earlier aircraft and systems. If not addressed, they have a serious potential to delay critical weapons capability clearances.

Weight Management
The news that weight management is still a ‘formidable challenge for the F-35’ means that the well-publicised and extensive weight reduction effort that took place a few years ago did not entirely succeed. The report contains detailed information on aircraft weight that shows all three variants to have low margins of available design weight left to the teams. The STOVL B variant must stay below its Not To Exceed (NTE) design weight to meet a Key Performance Parameter (KPP) for Vertical Landing bring Back (VLBB). However, it has only 53 pounds margin to NTE, which while below the current planned curve, leaves very little margin for further unplanned weight challenges. The report also reveals that STOVL CofG has moved beyond a critical position, and will have to be recovered – this could be an extremely challenging task.
The CTOL A model has always had as serious a weight challenge as the STOVL, although it has been less well publicised. The report reveals that while the aircraft is still 69 pounds below NTE, that NTE weight target is still limiting the aircraft’s maximum ‘g’ and contributing to a failure to meet a CTOL KPP for combat radius. (The same KPP is also under threat for STOVL). Any failure to meet a KPP has to be seen as a significant shortfall in the design, and will have to be either fixed or accepted by the customer.
The C variant has the lowest margin to NTE (26 pounds) but still has a margin of over 400 pounds to its maximum Carrier Landing Design Gross Weight (CLDGW). While this sounds like a more comfortable margin, it makes a number of assumptions on the approach speed used, and the complex geometry and dynamics of arrested landings. All these are subject to change during flight test, and the actual weight achieved will have a significant impact on approach speeds.
Of some concern is the report’s conclusion that the F-35 will require careful weight management throughout its service life. This will only come via ongoing modifications and consequent cost.

Thermal Management
This is always a challenge for small combat aircraft, and the problem is exacerbated with LO designs that have to minimise intakes and exhausts. The problem gets even worse for STOVL aircraft, and modern flight displays also generate more heat than their analogue predecessors. All these challenges have been recognised on the F-35, and an aggressive and well organised programme has been in place for some time to address them. That said, the report indicates that not all the challenges have been beaten yet. The new electrically powered flying controls are still causing some issues, along with more traditional suspects (e.g wheel brake units). Finally, a surprising and unwelcome discovery is heat damage to the horizontal tail surfaces behind the engine nozzle associated with use of the afterburner, which is currently limiting flight operations.

Autonomics Logistics Information System (ALIS)
The shortfalls in the ALIS system are another unwelcome problem, and are likely to attract unfavourable comment. The selection of LM as the ‘winner who took all’ on JSF gave the DoD a potential problem, as Boeing had laid heavy emphasis on their expertise in logistics IT systems. As a result, LM’s programme of work to develop the complex and vital ALIS system have been closely overseen by the JPO. Unfortunately, the report makes it clear that there is much work still to do, and the current system is failing to deliver some key capabilities. As in the UK, large Government IT projects can cause serious problems.

Lightning Protection
The F-35 team decided not to adopt the ‘passive’ Lightning protection system used on Typhoon and other aircraft, where a conductive mesh is incorporated into composite airframe structure. Instead, they adopted an ‘active’ solution that relied on an On Board Inert Gas Generating System (OBIGGS) to reduce the risk of fuel vapour explosion after a Lightning strike. There is still work required to fully develop and certify this system, and the current limitations on F-35 operations pose another risk to flight test progress. Suggestions of using an additional ground cart to supply nitrogen when parked (presumably because the OBIGGS system takes some time to fully charge aircraft fuel tanks) will be most unwelcome to the users who were promised a small logistics footprint for JSF.
The final area presented in this category is that of flight test execution. The report states that the programme is around 8% behind plan, but this apparently small shortfall must be set against a number of relatively recent reviews and re-working of the flight test schedule. Given this, shortfalls against the latest schedule are most unwelcome and it is not surprising that the review team picked up on this. The team also identified the circular relationships between flight test and development. Some flight tests have been delayed by technical issues, including software, but in other areas the slower pace of progress is impacting progress towards design fixes.

Responses and Possible Impact


Early official response to the report has been limited, but interesting. The F-35’s Grogram Executive Officer )PEO) is Vice Adm. David Venlet, who gave a wide ranging and frank interview soon after the release of the report. His statements are worth studying.
He admits to being ‘surprised’ by the amount of change and cost of hot spots that have arisen in the last 12 months. In a key passage, he said that:

“Most of them are little ones, but when you bundle them all up ….the cost burden of …sucks the wind out of your lungs. I believe it’s wise to ..temper production for a while …until we get some of these heavy years of learning under our belt and get that managed right. And then when we’ve got most of that known and we’ve got the management of the change activity better in hand, then we will be in a better position to ramp up production.”

This is a clear indication that the DoD will use the report to delay production rate builds up in 2012. A full stop to production probably cannot be ruled out at this stage.

Venlet’s comments on the effects of taking on too much concurrency in the F-35 programme were also startlingly frank:

“Fundamentally, that was a miscalculation,”….You’d like to take the keys to your shiny new jet and give it to the fleet with all the capability and all the service life they want. …we’re taking the keys to the shiny new jet, giving it to the fleet and saying, ‘Give me that jet back in the first year. I’ve got to go take it up to this depot for a couple of months and tear into i…because if I don’t, we’re not going to be able to fly it more than a couple, three, four, five years.’ That’s what concurrency is doing to us.”

However, other statements make it clear that the programme would, in his view, proceed.

“I have the duty to navigate this program through concurrency. I don’t have the luxury to stand on the pulpit and criticize and say how much I dislike it and wish we didn’t have it. My duty is to help us navigate through it.”

“The question for me is not: ‘F-35 or not?’….The question is, how many and how fast? I’m not questioning the ultimate inventory numbers, I’m questioning the pace that we ramp up production for us and the partners, and can we afford it?”

“Slowing down the test program would be probably the most damaging thing anybody could do to the program,…..The test program must proceed as fast as possible.”

But he also set down a clear marker to Lockheed Martin for the upcoming negotiations on the fifth production package (LRIP 5). As well as slowing production rate, which LM will bitterly oppose, he is clearly aiming to make the company bear the costs of what he probably sees as outright design failures. He has high level support. In August, DoD acquisition chief Frank Kendall issued a memo requiring Lockheed to bear a “reasonable” share of such costs in LRIP 5. Lockheed have responded, complaining last month that the government was refusing to reimburse it for parts the company was buying in advance for LRIP 5 aircraft as the price and terms of that next production contract are negotiated. Venlet’s comment on this aspect is revealing:

“We negotiated the LRIP 4 contract with a certain amount of resources considered to pay for concurrent changes,” …..”We were probably off on the low side by a factor of four. Maybe five.”

It appears very probable that LM will be required to take on a far more onerous financial burden for managing change in LRIP 5.

Conclusions and Summary


The F-35 programme is not in terminal trouble. But it is in trouble, all the same. The reasons for this conclusion lie in the origins of the F-35 programme.

It was deliberately designed as a ‘one aircraft fits all’ programme that would be too big to fail. The aircraft it is replacing (F-15, F-16, F/A-18C/D, AV-8B, Harrier) are all at or nearing the end of their service lives, and are being outpaced by designs such as Super Hornet, Rafale, Typhoon, Gripen and Flanker, and new Chinese designs. If the US were to halt the F-35, the key question would be ‘OK, so now what do we build?’. If the answer were ‘nothing but UCAVs’ the US would soon be out of the manned combat aircraft business, and that is not a position that would be politically (or industrially) acceptable. If the answer were ‘more of what we already have’ the US would face being outclassed by potential enemies with little obvious recourse. At this stage, the original logic appears to be holding – just.

The recent announcement of the F-35’s first export sale outside the current programme participants (to Japan) will also help keep the programme in existence.
However, it is clear that the original gamble on increased concurrency, that was designed to drive more rapid design maturity, has failed. Taking the continued existence of the F35 programme as a given, the future shape looks like roughly the same aircraft, but with a substantially lower rate of production in 2012 and later years than currently planned. There will very probably be some open tensions between the DoD and LM as the size, shape and most importantly cost of LRIP 5 are thrashed out.
This will take place against a backdrop of fairly solid US political support. With no obvious alternative, neither US party would support full cancellation, but economic realities will probably add to pressures for delays in production. A series of fairly highly charged House and Senate committee hearings is inevitable, although Adm. Venlet appears to have gone some way to ‘spiking their guns’ through his very frank public statements.
Technically, the aircraft’s design and core capabilities appear to be more or less settled, but the report makers it clear that LM (and their customers) have far more to do at this stage of the programme than they would ever have wanted. What is especially interesting is that one ‘elephant in the room’ failed to appear in the report  – the STOVL ‘B” ‘variant’. Instead, the problems reported generally affect all three variants, apart from the AHS issues on the C model. Software, HMD, IPP, fuel dump, buffet, fatigue and flight test progress appear to affect the A, B and C models in equal measure.
There is no obvious ‘killer’ risk that stands out above all others (they are all significant), but the problems with software, weight and ALIS do appear to have serious potential for causing long lasting damage to programme progress, and should be closely watched in coming months.

  • Software, because the aircraft has fearsomely complex flight and mission systems which are wholly dependent on their software loads for operational release. Fixing current issues and then accelerating software development will be a major challenge for an already hard worked team. Software development is also closely linked to flight test progress
  • Weight management, because the programme has already done one highly publicised weight reduction effort, and there cannot be any ‘low hanging fruit’ left for easy weight reduction. It’s more probable that some performance trade-offs will have to be accepted by the user, and these could be in terms of range and/or payload.
  • ALIS (Autonomic Logistics) does not, at first sight, look to be a massive issue, but the report makes it clear that it is already impacting the flight test programme, which is in turn a significant programme risk. It also has a major impact on the ability to field the aircraft to the user.

What does this mean for the UK? One could draw the conclusion that the SDSR’s decision to delay F-35 procurement significantly has been vindicated. This could point to a closer than previously publicised level of understanding between the Uk MoD and the US DoD. That would be welcome news. Or it could mean that the MoD has a very good understanding of the F-35 programme status and risk. That would also be very good news. In any case, the UK will watch the programme closely to check that the F-35 and the two new carriers are still lined up. That could lead to ‘interesting times’ for Philip Hammond.

Another angle of the F-35 debate that does not get so much scrutiny are the single service desires and tactics. The SDSR process dealt a severe blow to the carefully maintained facade of ‘jointery’ and it is highly probable that the RAF and the RN will seek to keep their own arguments ‘front and centre’ as the budget driven debates continue.  But what will those arguments be?

From the RN angle, fixed wing aviation is now the only real justification for the large carriers being built. They could credibly start deploying arguments (around ‘cat and trap’ training and currency) that call for both ships to be ‘cat and trap’ capable to give the UK an enduring and available maritime strike force. But much effort is now being deployed to get RN personnel trained up on F/A-18 Super Hornet operations with the help of the USN. It is possible that if the F-35C were to experience more problems, the RN could switch tack and go for a ‘more affordable maritime strike’ option using the Super Hornet (and possibly E-2).

Such a move would pose real issues for the RAF. From their viewpoint, the F-35C now constitutes the Tornado replacement that delivers their long desired ‘first day of the war deep strike’ capability. Furthermore, it should be taken as read that the RAF has no genuine interest in developing a credible maritime strike capability. Within their own air power doctrine, the F-35C’s land based capability would replace the need for carrier borne aviation. It is therefore probable that the RAF will continue to support the F-35C strongly, and continue to question the need for maritime strike from the CVF.


In summary, 2012 will be a very interesting year for the F-35 programme, with ever closer scrutiny. Fortunately for those who are interested in these matters, the US’s historic openness means that there will be plenty of detail to analyse over this coming year. Meanwhile, historic service divisions in the UK will ensure a continuing stream of comment and opinion to keep the debate simmering.

Get our updates FREE

0 comments:

Post a Comment

Tuesday, May 8, 2012

F35 – CONGRESSIONAL REPORT Analysis


Introduction


The public release of a major US Congressional Report (F-35 Joint Strike Fighter Concurrently Quick Look Review dated 29 November 2011) offers a nearly unprecedented level of detailed information on the world’s largest defence procurement programme. This article offers an independent analysis of the report and considers what it may mean for the most significant project for the world’s military aircraft industry.

The Report


The report was not intended for widespread release, as its markings (For Official Use Only (FOUO) US Only) indicate. It was prepared in by five senior Department of Defense officials, including no less than three Deputy Assistant Directors. It contains a level of detailed information and programme assessment that is quite unknown outside the United States, and reveals key issues that the F-35 has been battling with for some time.
A useful introduction (Section 1) describes the background to and rationale for the report, and includes a summary of a recent (and highly critical) Operational Assessment(OA) . This is a highly significant issue in its own right, as the DoD agency conducting these assessments is influential and maintains an aggressively independent stance within the US defence acquisition system.
The introduction is followed by Section 2, a description and analysis of the central issue of the report, which is the level of overlap (concurrency) between the F-35’s initial production and the aircraft’s technical development. Section 3 describes and analyses the key technical challenges facing the programme, and how they affect the concurrency issues, followed by a short set of conclusions at Section 4. A comprehensive Appendix with 33 pages of detailed technical information completes the report.
It is clear from the report’s executive summary, and the introduction, that the project is carrying a very high level of overlap between series production and ongoing technical development. Moreover, it is clear that the programme faces major challenges in achieving current dates for Initial Operational Test and Evaluation (IOT&E) in 2015. The analysis effectively starts with the results of the OA released in Oct 2011.

Operational Assessment


The results of the F-35’s first OA make sobering reading. There are shortfalls and risks against requirements in all key combat capability areas, including Air to Surface Attack (A/S), Close Air Support (CAS), Air to Air Warfare (AAW), Electronic attack (EA), Combat SAR (CSAR) and Reconnaissance. Worryingly, risks are also considered to exist in the important areas of Deployability, Mission Generation, Training and Fleet Support.

Concurrency Risk


If an aircraft starts production too early in its development cycle, early examples will have to have changes embodied after they are built. Structural changes are the hardest to retrofit, and can affect both weight and performance as well as airframe life. Mission systems issues can pose major capability problems, as shown by those experienced with Typhoon Tranche 1 aircraft. Finally, problems with vehicle systems such as cooling, landing gear and arresting hooks can impact aircraft performance and capability.

Section 2 of the report shows that the F-35 programme is carrying a high level of concurrency risk, mainly due to the decision to start production sooner than legacy programmes. There are a number of reasons for this. One was the use of a concept demonstration phase, which was intended to significantly reduce downstream programme risk. Another was the assumption that sophisticated modelling and simulation tools, along with modern design and manufacturing methods would bring the F-35 design to maturity more quickly than legacy projects.

Unfortunately, this has not happened, and the programme is now having to cope with a large number of changes while ramping up production rate. The rate of change is still increasing when it should be decreasing, and the reason for the changes is also of some concern. Just over half are aimed at achieving or supporting specification compliance – which in simple terms means that LM are still working to get the design right.

Changes are taking a long time to get into production, and as the number of outstanding changes builds, the costs of retrofit and rework are increasing. This is not a unique situation. All recent combat aircraft have suffered from concurrency risks to some extent, but the report shows that the F-35 has a higher level than other US projects. It would be instructive to be able to make a comparison with UK and European projects, but sadly the level of information released in this report is unlikely to be matched outside the USA.

At this stage, it must be considered highly likely that the F-35 production schedule for all variants will be further delayed during 2012 or 2013. If it is not, the costs of retrofit and rework of early aircraft will become prohibitive. It is also likely that early F-35 aircraft will lack key operational capabilities unless they can be fully upgraded.


Design and Technical Issues – Overview

Section 3 of the report contains a wealth of detail on major technical issues (and design risks) with the F-35 aircraft and its support systems. It splits the issues into four categories.

  • The first category is design risks that preclude further production. The good news in this report is that no such risks were identified. This is  a key statement, that is likely to be ignored by the programme’s more vocal opponents. However, it is balanced by the findings in the next three categories.
  • The next are known design issues that will cause major consequences for the programme but have not yet been solved. There are 5 of these, including the HMD, the fuel dump system, the Integrated Power Package (IPP), the Arresting Hook System (AHS) and a ‘classified’ issue.
  • Following this, three areas are described that could have major consequences, but which are not yet fully understood. These include airframe buffet, airframe fatigue life and (slightly confusingly)  the progress of the overall flight test programme.
  • Finally, there are 5 areas where likely consequences are assessed as only moderate, but taken together the number of issues presented generates a higher than desired level of programme risk. These include mission system software development, weight control, thermal management, the Autonomic Logistics Information System (ALIS) and Lightning protection.

It is not easy, nor may it be fair, without detailed technical knowledge of the programme, to pronounce on whether this is a ‘bad’ or ‘good’ report. However, it is quite clear that the F-35 design has not reached the level of technical maturity that was expected just a few years ago.
Most surprisingly, the F-35 is, in a few areas, failing to meet legacy levels of performance from such systems as Night Vision Goggles (NVG). There are also apparently risks in areas of structure, mission systems (particularly the Helmet Mounted Display)(HMD) and certain key air vehicle systems.
Finally, a coded set of references to a ‘classified area’ very probably indicates issues with the aircraft’s low observable signature. They may be in the Radio Frequency (RF) area as well as the thermal spectrum.
This is an important assessment that will affect near term decisions on the F-35. The OA, being produced by the OT&E area, carries a great deal of weight within both the US Government (DoD) and the Congressional committees that discuss and decide the funding allocated to the programme.

The Five Major Issues – The Known’s

Helmet Mounted Display (HMD)

The HMD system is still exhibiting a series of problems including display jitter, night vision system acuity and latency (delays) in the images presented from the aircraft’s electro-optical distributed aperture system (EO-DAS). These are serious because the HMD system is a primary flight display – the JSF has no conventional Head Up Display(HUD). The seriousness of the situation is shown by the recent start of a parallel investigation into an alternate helmet system. However, this solution, which builds on a UK design developed for Typhoon, is not yet fully compliant with all parts of the JSF Operational Requirements Document (ORD), so it is not going to be an ‘off the shelf’ solution.

This is a challenging problem that will lead to extensive and costly tests and assessments to solve. These may well include repeat ejection seat tests and, as the report points out, simulators are not able to reproduce all the issues. That will mean more flight tests.

Fuel Dump System

The fuel dump issue appears to be minor, but is clearly a tough nut to crack. This is probably due to the difficulty of getting the fuel clear of the airframe without compromising the LO signature. Retractable dump masts are an option, but would add weight and complexity. This is a more serious problem for carrier borne operations, where fuel is always dumped on return to the ship, and where fuel-coated aircraft are not a good thing to have on a crowded flight deck with weapons in close proximity.

Integrated Power Pack (IPP)


The IPP is a novel feature of the F-35, combining the functions of power generation, cooling, engine starting and environmental systems. It was intended to reduce weight and volume and improve reliability, but is apparently not yet delivering on the last of these aims. Of equal concern is that removal and replacement of the IPP is taking two days, which must be far longer than specified or wanted. Finally, apart from changes to IPP system software, no obvious fixes to the IPP system appear to have been identified or developed. It seems quite probable that some will now have to be.

Arresting Hook System (AHS)

The problems with the AHS are described in some detail. It appears to have failed its first series of land based tests, which involved taxying at fairly low speeds over arresting wires. The possible causes identified include the shape of the hook point (simple fix) and the setting of the hook damper that controls its movement when striking the deck (probably a fairly simple fix). However, if these do not work, the other cause is the location of the hook very close behind the main wheels, which is not giving the arresting wire time to bounce back up after being ‘trampled’. This would be a far harder issue to solve, as the aircraft design does not provide easy structural options for moving the hook system further aft. In terms of suitability for aircraft carrier operations, it can fairly be said that design issues don’t get much more central than this one. It’s a tough one because final proof of any fix must await carrier based deck trials that not will not take place for some time.




‘Classified’ – Signature


The fifth issue, labelled as ‘classified’ can be assumed to be linked to signature. However, no further speculation can usefully be offered apart from the observation that the aircraft’s operational capabilities are heavily dependent on achieving a robust and effective low signature across all wavelengths.

Taken as a whole, the report’s assessment that these issues are a serious set of design risks for the F-35 programme can’t be argued with. They span a number of areas, and it should be understood that fixing any one might well impact the others.



The Three ‘Unknowns’


These design risks are not yet fully understood, and so there is a little less detail presented than for the first five. However, what is presented is extremely interesting.

Buffet

Airframe buffet is, on the face of it, a slightly surprising issue for LM to have encountered. The F-35 is not a high agility design, and higher than expected buffet at around 10 degrees AOA and M0.85 to M0.90 must be a serious disappointment to the airframe and aerodynamics design teams. Any fixes could involve changes to aircraft shape. Some structural ‘beefing up’ might be required. Some will be minor, some could be major – and further tunnel and flight testing will be required which will take until around 2014. However, they must be addressed, as buffet is already causing issues for the HMD system, and will undoubtedly affect other mission systems and reduce airframe fatigue life.  Not least, this problem can cause pilot fatigue and performance issues.

Fatigue Life

Airframe fatigue life issues must be another disappointment to the team, and are an area that was expected to be mitigated through use of CAD and other advanced techniques. However, the challenge of designing a durable and weight efficient airframe while leaving large holes for weapons bays, making space for internal fuel and avionics, and handling the loads generated by carrier launch and recovery is considerable. Add in the demands of a STOVL layout and it becomes extremely difficult. Taken together with the programme’s previous weight issues, it might be concluded that F-35’s structural design teams have not always been able to meet all the challenges posed. The A model has completed less than one fifth of its required test programme, the B model less than one tenth. In many ways, the C model is the most challenging structurally, and testing has yet to start on this variant.
The report is at pains to point out that experiencing fatigue problems is not unusual in combat aircraft programmes, and the F-35’s issues are not by themselves especially serious. However, when set against the amount of testing yet to be carried out, and the fact that a large number of airframes have already been built which will now require substantial rework, the report has elevated the seriousness of the issue.

Flight Test Progress
The final area presented in this category is that of flight test execution. The report states that the programme is around 8% behind plan, but this apparently small shortfall must be set against a number of relatively recent reviews and re-working of the flight test schedule. Given this, shortfalls against the latest schedule are most unwelcome and it is not surprising that the review team picked up on this. The team also identified the circular relationships between flight test and development. Some flight tests have been delayed by technical issues, including software, but in other areas the slower pace of progress is impacting progress towards design fixes.

The Cumulative Issues


The final set of design issues presented in the report provide further insight into the multiple challenges still faced by the F-35 team and the accumulating complexity of managing the fixes required.

Software
Development of software for both the aircraft mission system and to support flight testing is behind schedule, and the rate of changes required appears to be rising despite the best efforts of the various teams involved. The delays are also probably linked to hardware standards, and the flight test team is now having to manage eight different software loads across the test aircraft fleet. As for physical aircraft build, delays in achieving sufficient software maturity generate an increasing level of rework and changes to earlier aircraft and systems. If not addressed, they have a serious potential to delay critical weapons capability clearances.

Weight Management
The news that weight management is still a ‘formidable challenge for the F-35’ means that the well-publicised and extensive weight reduction effort that took place a few years ago did not entirely succeed. The report contains detailed information on aircraft weight that shows all three variants to have low margins of available design weight left to the teams. The STOVL B variant must stay below its Not To Exceed (NTE) design weight to meet a Key Performance Parameter (KPP) for Vertical Landing bring Back (VLBB). However, it has only 53 pounds margin to NTE, which while below the current planned curve, leaves very little margin for further unplanned weight challenges. The report also reveals that STOVL CofG has moved beyond a critical position, and will have to be recovered – this could be an extremely challenging task.
The CTOL A model has always had as serious a weight challenge as the STOVL, although it has been less well publicised. The report reveals that while the aircraft is still 69 pounds below NTE, that NTE weight target is still limiting the aircraft’s maximum ‘g’ and contributing to a failure to meet a CTOL KPP for combat radius. (The same KPP is also under threat for STOVL). Any failure to meet a KPP has to be seen as a significant shortfall in the design, and will have to be either fixed or accepted by the customer.
The C variant has the lowest margin to NTE (26 pounds) but still has a margin of over 400 pounds to its maximum Carrier Landing Design Gross Weight (CLDGW). While this sounds like a more comfortable margin, it makes a number of assumptions on the approach speed used, and the complex geometry and dynamics of arrested landings. All these are subject to change during flight test, and the actual weight achieved will have a significant impact on approach speeds.
Of some concern is the report’s conclusion that the F-35 will require careful weight management throughout its service life. This will only come via ongoing modifications and consequent cost.

Thermal Management
This is always a challenge for small combat aircraft, and the problem is exacerbated with LO designs that have to minimise intakes and exhausts. The problem gets even worse for STOVL aircraft, and modern flight displays also generate more heat than their analogue predecessors. All these challenges have been recognised on the F-35, and an aggressive and well organised programme has been in place for some time to address them. That said, the report indicates that not all the challenges have been beaten yet. The new electrically powered flying controls are still causing some issues, along with more traditional suspects (e.g wheel brake units). Finally, a surprising and unwelcome discovery is heat damage to the horizontal tail surfaces behind the engine nozzle associated with use of the afterburner, which is currently limiting flight operations.

Autonomics Logistics Information System (ALIS)
The shortfalls in the ALIS system are another unwelcome problem, and are likely to attract unfavourable comment. The selection of LM as the ‘winner who took all’ on JSF gave the DoD a potential problem, as Boeing had laid heavy emphasis on their expertise in logistics IT systems. As a result, LM’s programme of work to develop the complex and vital ALIS system have been closely overseen by the JPO. Unfortunately, the report makes it clear that there is much work still to do, and the current system is failing to deliver some key capabilities. As in the UK, large Government IT projects can cause serious problems.

Lightning Protection
The F-35 team decided not to adopt the ‘passive’ Lightning protection system used on Typhoon and other aircraft, where a conductive mesh is incorporated into composite airframe structure. Instead, they adopted an ‘active’ solution that relied on an On Board Inert Gas Generating System (OBIGGS) to reduce the risk of fuel vapour explosion after a Lightning strike. There is still work required to fully develop and certify this system, and the current limitations on F-35 operations pose another risk to flight test progress. Suggestions of using an additional ground cart to supply nitrogen when parked (presumably because the OBIGGS system takes some time to fully charge aircraft fuel tanks) will be most unwelcome to the users who were promised a small logistics footprint for JSF.
The final area presented in this category is that of flight test execution. The report states that the programme is around 8% behind plan, but this apparently small shortfall must be set against a number of relatively recent reviews and re-working of the flight test schedule. Given this, shortfalls against the latest schedule are most unwelcome and it is not surprising that the review team picked up on this. The team also identified the circular relationships between flight test and development. Some flight tests have been delayed by technical issues, including software, but in other areas the slower pace of progress is impacting progress towards design fixes.

Responses and Possible Impact


Early official response to the report has been limited, but interesting. The F-35’s Grogram Executive Officer )PEO) is Vice Adm. David Venlet, who gave a wide ranging and frank interview soon after the release of the report. His statements are worth studying.
He admits to being ‘surprised’ by the amount of change and cost of hot spots that have arisen in the last 12 months. In a key passage, he said that:

“Most of them are little ones, but when you bundle them all up ….the cost burden of …sucks the wind out of your lungs. I believe it’s wise to ..temper production for a while …until we get some of these heavy years of learning under our belt and get that managed right. And then when we’ve got most of that known and we’ve got the management of the change activity better in hand, then we will be in a better position to ramp up production.”

This is a clear indication that the DoD will use the report to delay production rate builds up in 2012. A full stop to production probably cannot be ruled out at this stage.

Venlet’s comments on the effects of taking on too much concurrency in the F-35 programme were also startlingly frank:

“Fundamentally, that was a miscalculation,”….You’d like to take the keys to your shiny new jet and give it to the fleet with all the capability and all the service life they want. …we’re taking the keys to the shiny new jet, giving it to the fleet and saying, ‘Give me that jet back in the first year. I’ve got to go take it up to this depot for a couple of months and tear into i…because if I don’t, we’re not going to be able to fly it more than a couple, three, four, five years.’ That’s what concurrency is doing to us.”

However, other statements make it clear that the programme would, in his view, proceed.

“I have the duty to navigate this program through concurrency. I don’t have the luxury to stand on the pulpit and criticize and say how much I dislike it and wish we didn’t have it. My duty is to help us navigate through it.”

“The question for me is not: ‘F-35 or not?’….The question is, how many and how fast? I’m not questioning the ultimate inventory numbers, I’m questioning the pace that we ramp up production for us and the partners, and can we afford it?”

“Slowing down the test program would be probably the most damaging thing anybody could do to the program,…..The test program must proceed as fast as possible.”

But he also set down a clear marker to Lockheed Martin for the upcoming negotiations on the fifth production package (LRIP 5). As well as slowing production rate, which LM will bitterly oppose, he is clearly aiming to make the company bear the costs of what he probably sees as outright design failures. He has high level support. In August, DoD acquisition chief Frank Kendall issued a memo requiring Lockheed to bear a “reasonable” share of such costs in LRIP 5. Lockheed have responded, complaining last month that the government was refusing to reimburse it for parts the company was buying in advance for LRIP 5 aircraft as the price and terms of that next production contract are negotiated. Venlet’s comment on this aspect is revealing:

“We negotiated the LRIP 4 contract with a certain amount of resources considered to pay for concurrent changes,” …..”We were probably off on the low side by a factor of four. Maybe five.”

It appears very probable that LM will be required to take on a far more onerous financial burden for managing change in LRIP 5.

Conclusions and Summary


The F-35 programme is not in terminal trouble. But it is in trouble, all the same. The reasons for this conclusion lie in the origins of the F-35 programme.

It was deliberately designed as a ‘one aircraft fits all’ programme that would be too big to fail. The aircraft it is replacing (F-15, F-16, F/A-18C/D, AV-8B, Harrier) are all at or nearing the end of their service lives, and are being outpaced by designs such as Super Hornet, Rafale, Typhoon, Gripen and Flanker, and new Chinese designs. If the US were to halt the F-35, the key question would be ‘OK, so now what do we build?’. If the answer were ‘nothing but UCAVs’ the US would soon be out of the manned combat aircraft business, and that is not a position that would be politically (or industrially) acceptable. If the answer were ‘more of what we already have’ the US would face being outclassed by potential enemies with little obvious recourse. At this stage, the original logic appears to be holding – just.

The recent announcement of the F-35’s first export sale outside the current programme participants (to Japan) will also help keep the programme in existence.
However, it is clear that the original gamble on increased concurrency, that was designed to drive more rapid design maturity, has failed. Taking the continued existence of the F35 programme as a given, the future shape looks like roughly the same aircraft, but with a substantially lower rate of production in 2012 and later years than currently planned. There will very probably be some open tensions between the DoD and LM as the size, shape and most importantly cost of LRIP 5 are thrashed out.
This will take place against a backdrop of fairly solid US political support. With no obvious alternative, neither US party would support full cancellation, but economic realities will probably add to pressures for delays in production. A series of fairly highly charged House and Senate committee hearings is inevitable, although Adm. Venlet appears to have gone some way to ‘spiking their guns’ through his very frank public statements.
Technically, the aircraft’s design and core capabilities appear to be more or less settled, but the report makers it clear that LM (and their customers) have far more to do at this stage of the programme than they would ever have wanted. What is especially interesting is that one ‘elephant in the room’ failed to appear in the report  – the STOVL ‘B” ‘variant’. Instead, the problems reported generally affect all three variants, apart from the AHS issues on the C model. Software, HMD, IPP, fuel dump, buffet, fatigue and flight test progress appear to affect the A, B and C models in equal measure.
There is no obvious ‘killer’ risk that stands out above all others (they are all significant), but the problems with software, weight and ALIS do appear to have serious potential for causing long lasting damage to programme progress, and should be closely watched in coming months.

  • Software, because the aircraft has fearsomely complex flight and mission systems which are wholly dependent on their software loads for operational release. Fixing current issues and then accelerating software development will be a major challenge for an already hard worked team. Software development is also closely linked to flight test progress
  • Weight management, because the programme has already done one highly publicised weight reduction effort, and there cannot be any ‘low hanging fruit’ left for easy weight reduction. It’s more probable that some performance trade-offs will have to be accepted by the user, and these could be in terms of range and/or payload.
  • ALIS (Autonomic Logistics) does not, at first sight, look to be a massive issue, but the report makes it clear that it is already impacting the flight test programme, which is in turn a significant programme risk. It also has a major impact on the ability to field the aircraft to the user.

What does this mean for the UK? One could draw the conclusion that the SDSR’s decision to delay F-35 procurement significantly has been vindicated. This could point to a closer than previously publicised level of understanding between the Uk MoD and the US DoD. That would be welcome news. Or it could mean that the MoD has a very good understanding of the F-35 programme status and risk. That would also be very good news. In any case, the UK will watch the programme closely to check that the F-35 and the two new carriers are still lined up. That could lead to ‘interesting times’ for Philip Hammond.

Another angle of the F-35 debate that does not get so much scrutiny are the single service desires and tactics. The SDSR process dealt a severe blow to the carefully maintained facade of ‘jointery’ and it is highly probable that the RAF and the RN will seek to keep their own arguments ‘front and centre’ as the budget driven debates continue.  But what will those arguments be?

From the RN angle, fixed wing aviation is now the only real justification for the large carriers being built. They could credibly start deploying arguments (around ‘cat and trap’ training and currency) that call for both ships to be ‘cat and trap’ capable to give the UK an enduring and available maritime strike force. But much effort is now being deployed to get RN personnel trained up on F/A-18 Super Hornet operations with the help of the USN. It is possible that if the F-35C were to experience more problems, the RN could switch tack and go for a ‘more affordable maritime strike’ option using the Super Hornet (and possibly E-2).

Such a move would pose real issues for the RAF. From their viewpoint, the F-35C now constitutes the Tornado replacement that delivers their long desired ‘first day of the war deep strike’ capability. Furthermore, it should be taken as read that the RAF has no genuine interest in developing a credible maritime strike capability. Within their own air power doctrine, the F-35C’s land based capability would replace the need for carrier borne aviation. It is therefore probable that the RAF will continue to support the F-35C strongly, and continue to question the need for maritime strike from the CVF.


In summary, 2012 will be a very interesting year for the F-35 programme, with ever closer scrutiny. Fortunately for those who are interested in these matters, the US’s historic openness means that there will be plenty of detail to analyse over this coming year. Meanwhile, historic service divisions in the UK will ensure a continuing stream of comment and opinion to keep the debate simmering.

No comments:

Post a Comment

back to top