Sunday, April 15, 2012

CVF and JCA: why i'd go CATOBAR

F35B and F35C: the airplane situation

Of immense interest is the 2011 Department of Defence Annual Report for the Office of the Director, Operational Test & Evaluation which gives us an up to date major picture of the current F35 development and testing situation. In the detail, it tells of everything that still does not work with the F35, and details the progress of the program in 2011. 

It is very useful to draw some well-informed conclusions, and contains some interesting data. For example, it emerges that: 

- F35A is 11% behind schedule with its test and validation campaign
- F35B is 9% behind schedule
- F35C is 32% ahead of schedule

We must, of course, look at the 32% ahead of schedule data with the awareness that the C is the variant who entered trials last. The other two variants are ahead of the F35C with their programs of development, testing and validation as they are closer to entering active service. For example the B already went at sea, while the C won't go on an aircraft carrier until next year.
However, A and B are lagging considerably in terms of test points cleared, while the F35C has cleared 32% more test points than planned, which is very reassuring. Having started later also means that more corrections have been incorporated into the C at build, thanks to discoveries made on the other two variants.

The planning, updated to December 2011, is for the three variants to complete their development and testing with many more flights. In each flight, a number of tests are run, in order to validate long lists of requirements. Each airframe requirement makes for 1 or several "test points". As of December 2011, maturity of the F35C was 1002 test flights away, with 12.442 test points yet to clear.
The A still has 827 flights and 10.257 test points to go.
The B 1,437 flights and 15.045 points.

These values of course change rather frequently when a change proves necessary and needs to be flown and trialed, adding new flights and points to clear to the count, but they are indicative of the current plan. 

Regarding the F35B trials at sea on USS Wasp, which were presented by the STOVL prophets as having proven that the B has "no issues" and that the jet blast hazard claims were "nonsense" and that everything actually works perfectly well, well, the reality is actually a bit different. The F35B jet blast does not hole the deck as someone had (rather extremely) prophetized, no, but a jet blast issues exists and the trials at sea only confirmed it. A 75 feet danger radius is reported. 

Jet blast from the F-35Bs is expected to produce unsafe forces on flight deck personnel up to 75 feet from the short take-off line.
This is going to make another serious dent, along with Ship  Borne Rolling Vertical Landing, in the flaunted advantages of STOVL when conducting simultaneous jet and helicopter operations on deck, which some describe as indispansable for the success of Carrier Enabled Power Projection. 
With jet blast hazard and landing runs on the deck, the differences between F35B and F35C in deck usage during ops are getting smaller and smaller.  

Among the F35B issues, is the cracking of a wing carry-through bulkhead cracked before 2,000 hours of airframe life. The required airframe lifetime is 8,000 hours. Repair of the bulkhead on the test article was completed in November 2011, and F-35B durability testing should have restarted in January 2012.

Following the bulkhead crack in the F-35B test article, analysis verified the existence of numerous other life‑limited parts on all three variants. The program began developing plans to correct these deficiencies in existing aircraft by repair/modifications, and designing changes to the production process. The most significant of these in terms of complexity, aircraft downtime, and difficulty of the modification required for existing aircraft is the forward wing root rib on the F-35A [which failed after some 3000 hours] and F-35B aircraft.

The F35C's own durability testing are due to start in the next while, if it hasn't already. By August last year the C had completed all of its structural test points, including drop tests to simulate rough carrier landing stress on the airframe. 

The F35B has had  a large number of parts re-designed and replaced and corrected, and the reports notes that, so far, there's no plan in place for rolling in the modifications in production airplanes. The report acknowledges: 

The program has not completed the final re-designs and plans to correct deficiencies through modifications of F-35B production aircraft intended for the fleet, which cannot be monitored in-flight because these aircraft are not instrumented. Production aircraft will be restricted from STOVL-mode flight operations until Service airworthiness authorities grant a flight clearance. A significant amount of flight test and development of system maturity of the final STOVL-mode door and propulsion system designs remains to be accomplished. A system mature enough for unmonitored STOVL-mode flight may be needed as early as late 2012 to coincide with the delivery of lot 4 F-35B aircraft to the Marine Corps at Yuma, Arizona. If testing of the changes is not complete and needed modifications are not installed by late 2012, aircraft at Yuma will fly in CTOL‑mode only.

The full extent of issues so far detected in the airframe doors and STOVL propulsion assembly is reported in a table, and makes for rather depressing reading, with some of the solutions in development already planned not to be ready before LRIP 7 while other solutions have yet to be determined, tested, and planned for adoption on production standard airplanes. 

The table of the F35B propulsion and door issues, as presented in the report.
There is also serious problems with overheating of the clutch that can prevent the STOVL mode to be angaged (how do you land at that point if your only runway is the carrier, or is just too short for a CTOL landing???) for which a real solution does not yet exists, and the driveshaft has to be redesigned. 

Besides, the F35B has a margin for growth of sole 230 pounds before it breaks its not-to-exceed weight planned for 2015. An additional 142 pounds might be secured by a greater descent rate to touchdown, but it is far from certain, and even so that means just 372 pounds of weight growth margin available, before the deadly line is crossed, with several years of testing and development yet to go, and no military service at all done. 
Talk about constrained airframes... 

The report notes: 

This additional weight [the 142 additional pounds of margin, to 372 total] increases the margin to 1.2 percent of current weight and allows for 0.36 percent weight growth
per year. Managing weight growth with such tight margins for the balance of SDD will be a significant challenge, especially with over 70 percent of the scheduled F-35B flight sciences test flights remaining to be accomplished in the next 60 months. For comparison, weight growth on the F/A-18 E/F was approximately 0.69 percent per year for  the first 42 months following first flight.

Again, undesirable wing roll-off, airframe buffet, and sideslip occurred in transonic flight regimes, and handling characteristics as a consequence do not meet requirements. It is likely that no more changes will be made to the plane, and it will be the requirements that are reviewed and reduced, in order for the plane to "meet" them!

The final word on the F35B can be identified in this passage: 

In October 2011, the program successfully conducted initial amphibious ship trials with STOVL aircraft in accordance with the new, restructured plan for 2011; however, significant work and flight tests remain to verify and incorporate modifications
to STOVL aircraft required to correct known STOVL deficiencies and prepare the system for operational use.

Regarding the F35C, the report says: 

F-35C Flight Sciences
• As F-35C flight sciences focused on preparation for and execution of carrier launch and landing testing at Lakehurst, a limited amount of other envelope expansion occurred in 2011.
The F-35C flight sciences test points accomplished thus far are approximately 15 percent of the total expected in SDD.

• The lack of available flight envelope in the transonic regime currently constrains testing of F-35C aircraft handling qualities. In limited testing using flight control software that
benefitted from F-35A and F-35B testing, the F-35C aircraft performance in the transonic flight regime demonstrated the predicted intensity of uncommanded rolls but higher buffet
levels. The F-35C aircraft was expected to have the greatest challenge of the three variants in the transonic flight regime, which led to the decision to incorporate structural provisions for the installation of external spoilers in one test aircraft.
(Buffet is a problem of all three variants, it seems, and indeed a common problem in american naval jets, since the F-18 notoriously had this kind of issues too!) 
• The carrier launch and landing testing at Lakehurst provided valuable lessons regarding the impacts of these dynamic environments on the aircraft early in the testing.
Corrections and regression testing are needed as a result of the discoveries listed below. The program is also working to correct other performance problems such as excessive
nose gear oscillations during taxi, excessive landing gear retraction times, and overheating of the electro-hydrostatic actuator systems that power the flight controls. The program will subsequently evaluate the need for modifications of production aircraft for these items.
• Discoveries included:
-- Flight test aircraft could not engage the arrestment cable
during tests at the Lakehurst, New Jersey, test facility. The
tail-hook point is undergoing a redesign and the hold-down
damper mechanism requires modifications to enable
successful arrestments on the carrier. Resolution of these
deficiencies is needed for testing to support F-35C ship
trials in late 2013.
-- Hold-back bar and torque arm components, which keep the
F-35C aircraft from moving forward when tensioned on the
catapult at full power, require a redesign due to the use of
incorrect design load factors. Actual loads are greater than
predicted. The impact of these greater‑than‑predicted loads
on strength and fatigue characteristics is under analysis by
the program.
-- Loss of inertial navigation and GPS inputs to pilot displays
occurred during a catapult launch. Root cause analysis was
in progress at the time of this report.
-- The test team conducted initial testing in the transonic
flight regimes with one version of air vehicle software on
aircraft CF-2. Problems similar to the other variants were
observed, such as excessive buffeting and roll-off, at times
making the helmet-mounted displays unreadable.
-- Higher than predicted temperatures exist in the
electro‑hydrostatic actuator system during flight testing
of the aircraft in a landing configuration. This component
provides the force to move control surfaces.

In addition, the F35C acceleration is inferior to the hoped value.

The F35B is still far from its maturity, with several thousand test points more than the other variants to clear and with a huge variety of very serious issues to fix and with a significant amount of changes and redesigning already having taken place.
The F35C has its problems too, but is in a remarkably better shape and, save for the arrestor hook issue, which is said to be due for fixing in the next few months, has not revealed problems potentially show-stopping. The B's extremely low growth margin, with associated Bring Back weight issues, is instead a very serious menace to its viability as embarked plane for CVF. 

CATOBAR reasons and issues 


- Maximum interoperability. Rafale, F-18, F-35C but also STOVL F35B can work from a big CATOBAR deck. The opposite is not true. 

- Future proof. Any kind of naval drone which will be developed in the coming years will be able to operate from the carrier. We will also be able to benefit from research and development done by the US Navy, and benefit of their support and investments into EMALS, AAG, and compatible platforms. 

- Compatible with future adoptions of better COD, AEW and tanker platforms. 

- Maximum military performances. It makes it possible to use the most capable embarked airplanes, and it fits into the operations of the two main allies of the UK. 


- Cost. EMALS and AAG add up-front cost to the carriers, and come with a personnel and training penalty. 

I've tried to quantify the extent of the training penalty connected to CATOBAR ops, but it is not easy at all.
I've discovered that a Sea Harrier FA2 pilot was a Naval All Weather Fighter Pilot after 100 day and 80 night landings on deck, but i've been unable to find a figure for the number of day and night landings necessary to re-certify for ops when the pilots are assigned to active service on the carrier.

On the other side of the barricade, i don't have a figure for the number of landings required for initial pilot certification, but i know that France's carrier pilots re-certify for carrier ops currency by making 6 daytime arrested landings and 4 night time arrested landings. A direct comparison in this latest value would be invaluable in assessing the feasibility of having RAF pilots, initially certified to CATOBAR ops, getting current again quickly to reiforce the naval strike wing embarked on the carrier.

The STOVL prophets say that re-certification with the Harrier required far fewer landings, and was much more readily achievable. They say that with CATOBAR, it wouldn't be possible to have one naval squadron plus 2/3 land squadrons able to reinforce the embarked complement in case of crisis, but we'd need a CATOBAR cadre of at least 3 naval squadrons.
Assuming they are right and it is true,  my reply is: that's how things should have always been.

While there's several clear and rationale reasons for having a naval fixed wing element [provide air defence for the fleet and independent, full spectrum air power even when airbases are not available], which brings to the table some very unique capabilities, i believe the rationale for a separate land based fleet of "deep penetrating" strike planes to replace Tornado has never been weaker. And in many ways it is a duplicate of the carrier strike fleet.

The RAF's JCA plan so far has been to get a land fleet of planes, capable to, at a stretch, migrate on the carrier when necessary. But considered the difficulties of getting land pilots to operate from ships, it will always make more operational sense to have naval pilots instead, who can readily work from land bases if the situation calls for it.
It is much easier to put a naval squadron ashore than a land squadron at sea, it is undeniable.

If CATOBAR requires a greater focus on naval operations, so be it, i say. France does not do bad at all with its own naval aviation, considering that they deployed a sizeable and capable force at sea for Libya ops, even though Charles De Gaulle was back from four months of ops over Afghanistan by less than one month.
They did especially well considering that their naval air force at the time had a single Rafale squadron, 12F, with an establishment of 15 airplanes, plus two Super Etendard squadrons, 11F and 17F.
Now, finally, 11F is converting to Rafale as part of the progressive retirement of the Super Etendard. The naval fixed wing complement is of course completed by 4F squadron, with the 3 E2C Hawkeye. Numerically, if the UK is really to order 50 F35s, the numbers are similar, as France has so far ordered 48 Rafale M, and has lost 3 to accidents, giving them a fleet of potentially just 45 airframes, even if once they were hoping for 60.

Looking at France's small but efficient CATOBAR naval aviation, i say that Britain could no doubt at least match it, standing up three naval-focused, if not naval-owned, squadrons of 14 F35C each (as 2 would normally be roled as Buddy-Buddy tankers).
France trains its naval pilots in the US, where they fly and "trap" on the T-45 Goshawk. When they come back, as few as 12 hours on the Rafale simulator are sufficient to achieve conversion to type. Much like with the F35, there is not a (naval) two-seat Rafale trainer. Differently from the F35, which pretty much never envisaged it, the Rafale N was planned (naval two-seat) and the airforce has the two-seat B variant. From late 2010, the Armee de l'Air has formed a large Rafale training squadron (2/92 Aquitanie) which offers some 4 slots a year for naval pilots to exploit some hours on the two-seat Rafale for combat system advanced training.
The RAF and RN hope to cover this requirement for the F35 with the Hawk T2 and with the simulators.  
On land, carrier landing practice is done by french pilots without a carrier-shaped runway with wires: a standard runway, with a marked "square" area the same size of the one that on a carrier would sport the wires is sufficient for good practice prior to embarkation on the aircraft carrier.

Keep in mind that the F35 promises to come with the best and most realistic simulators ever developed, and much of the training is to be done on sims, so matching what France does with the Rafales is the minimum i expect.

I do not think CATOBAR represents such an insurmontable challenge, if the decision is eventually taken to go ahead with it.
The problem is financing the conversion of the two carriers, essentially. And accepting that naval aviation is a serious trade, that should not be half-assed with part-time solutions.    


  1. Hi Gabriele

    Good article, no doubt the RAF centric STOVL groupies will attempt to discredit it. However as you say dspite all the spin about Wasp trials and off probation, much of the issues about the type that prompted the 2010 switch are still valid. The F-35B has alot of issues to overcome before it can become a warfighter and even then how viable it then is will still need to be answered.

    If F-35C remains the JCA choice then yes in effect all aircrew need to be Naval Aviators to ensure we can utilise the force as and when needed, with a regular complement of Carrier based aircraft it shouldn't prove too difficult to rotate the units to keep them upto speed.

    Geoff B

  2. Hello Gabriele,

    a well researched article as usual.

    You may find section 6.2 of this document useful:


  3. That seems to be an immensely interesting document, thank you! Definitely will be looking into it tomorrow.

    And i'm glad you appreciated the article.

  4. Stovl is completely ugly and lacks interoperability. The UK needs Catobar.


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