Home » Aviation » Navy to Test Fix for F-35C Catapult Problem Next Week


Navy to Test Fix for F-35C Catapult Problem Next Week

F-35C Launches from an aircraft carrier. US Navy Photo

F-35C launching from a test range in Lakehurst, N.J. US Navy Photo

WASHINGTON, D.C. — The Navy is starting tests next week for a fix to a critical safety issue found on the F-35C Lighting II Joint Strike Fighter, the head of F-35 Joint Program Office told reporters on Thursday.

During testing in 2016 on USS George Washington (CVN-73), F-35C pilots complained when the aircraft was catapulted from the carrier, the aircraft excessively bobbed up and down on its nose gear on its trip down the carrier’s deck making it impossible to read instruments, difficult to reach emergency controls and causing a certain amount of pain in pilots.

“Fleet pilots reported that the oscillations were so severe that they could not read flight critical data, an unacceptable and unsafe situation during a critical phase of flight. Most of the pilots locked their harness during the catapult shot which made emergency switches hard to reach, again creating, in their opinion, an unacceptable and unsafe situation,” read a December from the Pentagon’s director, Operational Test & Evaluation report.
“The U.S. Navy has informed the Program Office that it considers this deficiency to be a ‘must fix’ deficiency.”

According to a late December report on the issues — first obtained by Inside the Navy” multiple factors are contributing to the problem, including the pilot’s seat restraint and hand-hold (grab bar) locations, the mass and center-of-gravity of the F-35 helmet and display unit, the physical characteristics of the nose landing gear strut (load vs. stroke, damping), and the length and release load of the repeatable-release hold-back bar.”

In an evaluation of the pilot discomfort following 105 test launches on George Washington (CVN-73), 74 resulted in moderate pain, 18 caused severe pain, reported Inside the Navy.

On Thursday, F-35 JPO head Air Force Lt. Gen. Christopher Bogdan told reporters testing to fix the problem would begin at Joint Base McGuire-Dix-Lakehurst, N.J. at the Navy’s land-based test catapults.

“The first fix that we’re looking at… is when you first hook up the airplane to the catapult there’s a pullback mechanism and we pullback really hard and that compresses the strut a lot and when you launch you get the oscillations,” Bogdan said.
“What they’re trying to figure out is can they reduce some of that tension on the pullback, still get the effective energy they need to get the plane of the deck but without compressing the strut so much on the pullback. They’re doing multiple tests out there to figure out the range of pullback capability. We should know by the March timeframe if that’s going to help.”

A Navy official told USNI News the testing was set to start on Feb. 21.

Rear Adm. Mat Winter, deputy program executive officer for the F-35 said if the pullback fix worked, it would be easily translated to the ship.

“The important point is the Lakehurst testing is 100 percent representative, so we’ll know the technical fix and take it to the ship,” he said.

The up and down oscillations issue is similar to one pilots suffered in early testing of the F/A-18 Hornet that was fixed, a Navy official told USNI News on Thursday. The service was able to adjust the pullback force during launch of the aircraft that corrected the issue with the Hornets.

However, if the early attempts at a fix don’t work, it may require the Navy more extensive fixes to the nose gear and the helmet display, according to the December paper.

The last ditch effort would be to redesign the entire nose gear for the F-35C which could take years and further delay the program.

“A redesign could incorporate all the benefits of the advanced modeling efforts, but is expected to require a multiyear effort to re-qualify a major redesign,” according to the December paper.

  • b2

    Good. I hope it works and really corrects the problem. This “fix” is postulated to work on both on steam or mag-lev cat shots, right?
    A Navy catapult shot, night or day, requires a pilots 110% attention to the task at hand or people get hurt…. Anticipating or actually receiving “severe” pain during an act requiring all your senses is a killer/no-go.

    • RDF

      not much the pilot can do on the cat stroke. like to see good airspeed at the end and + VSI. those are the critical dohickeys…

      • b2

        Yeah.. I’ve felt several hundred of ’em, day and night, in all seas. I can tell you that the sooner you un-cage the better, especially if the shot was less than optimum or you have any other issues going on with the jet…. BTW I never experienced “severe pain” as seen at 2:59 on the video. Light loaded or not this is a problem.

        • Rocco

          What did you fly sir?

          • b2

            YGBSM

          • Rocco

            ???

          • NeilMarshall

            You’ve Gotta Be Shittin’ Me…..

          • Rocco

            Evidently b2 couldn’t tell me what he flew so he says!!

          • muzzleloader

            If I’m not mistaken, I think his online name tells what he flew…

          • Rocco

            Well the way he was talking about how a jet takes off from a carrier made me think he was a naval pilot! I guess it went over my head with his avatar posted b2 should be B-2!! I would of figured it!

  • Ed L

    After watching video of F-14 and F/A-18 launches The front strut F-35C really allows a lot of bounce in it compare to (what I could see) no bounce on the Tomcat and Hornet.

    • Rocco

      The Tomcat squats down really low on take off!! The hornet doesn’t have the height the F-35C does.the hold back bar was adjusted to suit.i don’t know if this is the solution.eventually this will be ironed out

      • b2

        OK Rocco, your “eventually this will be ironed out” sounds good but isn’t that what the article said. There is “something to see here”. This is not an issue that can be shrugged off or mitigated by hopeful expectations or LM marketing. I hope the “fix” alluded to works but redesign of the entire NLG and launch bar system will take a while (years?) and regression testing is inevitable. As you know an aircraft is an entire system and impact to one affects others and in a jet like this all is controlled by software.. millions of lines of code.

        • Rocco

          Yes I know the old can of worms syndrome!!🤓

        • Duane

          This won’t affect the code … it’s a purely mechanical action. The pull back force will be tweaked and tested as this post says it will. If that fixes it, as will shortly be known, it’s done. If not, then the gear design will likely have to be modified, but that could be as simple as changing out the orifice in the damper mechanism.

          In the meantime the “issue” only shows up with no weaps and a known, light fuel load. Load more fuel than that known amount, or add weapons, problem disappears. The only question is how long and expensive the fix will be, short and effectively zero (but for the cost to test), or anywhere from a few months to two years and progressively more expensive. LM’s gear supplier will have to eat the cost to fix.

    • Corporatski Kittenbot 2.0

      Were the Tomcats and Hornets empty?

      Cos that is the only situation where the Lightning bounces so vigorously at launch.

      • Ed L

        Years ago I got to see Tomcats and Hornets doing Carrier Quals. I didn’t remember them bouncing, We saw one bounce and the Naval Aviator Commander, shook his head and picked the headset and called someone on the Deck and quietly reminded them about the tension setting, Which was explain to me by the LT I was standing next to. I was a staff puke back then, Never care for Carriers, too big, Even after serving on 3 ships, I would always get a bit lost. it must have been the couple of hundred extra frames that threw off my internal navigation.

        • RDF

          up and forward starboard side, down and aft port side.. :-]

          • Ed L

            That did work on the 5 ships I was on, but when TAD to a Perry class Frigate. Well that was a different story. First time I heard the title ship control officer and then saw the Helm on the bridge. I wonder What the you know what.

  • old guy

    Does anyone know if the linear motor (rail gun) catapult is now, or will be, installed?

    • Horn

      Yes. EMALS is installed on the USS Ford and is planned to be installed on all future Ford-class aircraft carriers. I believe the Navy decided not to retrofit EMALS into existing Nimitz-class carriers.

      • Ctrot

        As far as I know retrofitting EMALS to Nimitz class was never a consideration.

      • old guy

        Thanks. When we (NAVSEA 003/03R ) worked the linear accelerator in 1977, with the DOE, we determined its best use was as a catapult. So we transferred the program to Lakehurst, which, apparently did a great job. The unique feature of the system, as I have heard, is its ability to program the acceleration and eliminate “pull back”. It could also be a great decelerator.
        We rejected it as a rail gun because of high energy requirements and the ease of rocket launch. The “sexy” high speed projectile speed could easily be matched by an ETC gun that we actually demonstrated, could be a retrofit to existing guns.

      • Rocco

        Because it can’t be done!!

    • Rocco

      Really!!!

    • Secundius

      I don’t if its the Right Answer, but as of January 2016. DOI: 10.1515/SBEEC-2016-0016 Coaxial Linear Motor and a Type 6101-T64 Aluminum Linear Induction Launcher…

    • RDF

      They are going with the non-linear one. 1G ACCEL until last 20 feet and then 200G. Few issues still. :-]

      • old guy

        THANKS! I just hope that they emphasize. this and retrofit to all carriers and reduce the need for steam generation, which is costly, cumbersome, and inefficient

  • PRONESE

    As far as the Helmet issue goes, perhaps a restraint device similar to the HANS system used by todays race car drivers could be implemented to attenuate the vertical motion of the helmet during the initial catapult release. the restraint mechanism could then be detached from the helmet after launch to allow for a full range of motion for the pilot.

    • RDF

      more weight for the helmet. non-starter.

      • PRONESE

        1 oz of Titanium for the hardware. I don’t know…

        • RDF

          They are shaving grams off that helmet.

  • Bob Hickok

    A plane like the f-35 needs a bouncy nose gear for vertical landings. Perhaps the Navy can incorporate two modes in strut pressure for vertical and for catapult launches. Sports cars have this as part of normal equipment.

    • RDF

      F4 and F14 had their own answers to this problem. Navy will solve it. When you take an aircraft aboard you ‘carrierize’ it which involves lots of things. some of which are increased strut pressures and tire pressures.

      • muzzleloader

        The F-4 was before my time, but I remember the issues with the Tomcat after it’s fleet intro. The variable geometry wing, the leading edge glove, and the under powered TF30 Engine led to numerous aircraft losses. It was still a great air superiority aircraft and later refinements made it even better. I am confident the F-35 will pan out to be the warplane that it’s current and future pilots will be proud to fly.

        • RDF

          Let’s hope so. It costs plenty.

          • muzzleloader

            That it does.

        • RDF

          The F-4 extended the nose strut in the shuttle. and it was a bridle launch. more forgiving. The F14 kneeled to compress the nose strut and used a launch bar. nastier shot.

    • Bob Bitchen

      The F35c is not a vertical take off aircraft, the F-35b is the V/STOL version. The fix need only apply tp the F-35c model.

      • Duane

        Yup – and the B model being STOVL doesn’t therefore need to be certified for cat launch. It flies off the deck without assistance.

  • captlou

    Suggest that you study the video at around 2:55 and check out the pilot’s head bob up-and-down during the cat shot. Ouch, that not only looks painful but most significantly, very dangerous.

  • RDF

    said pilots are locking their harness for the shot. I used to lock mine for arrestment only. different strokes.

  • omegatalon

    Lockheed Martin’s F-35A variant scored a 15-to-1 kill ratio at the latest Red Flag wargame at Nelllis AFB against legacy (F-15, F-16 and F/A-18) fighter jets which means the US Navy needs to do whatever is necessary with Lockheed Martin engineers to get their variant of the F-35 flying.

    • Patrick Bechet

      Actually it was 19:1.

  • USNVO

    Just a couple of observations on what is one of the better discussions of the problem.

    If there were 12 pilots and 10 landings and takeoffs apiece, why wasn’t there 120 surveys. Or did only 105 of the 120 launches result in the oscillations. In any event, 105 is a strange number in that it is not a multiple of 12.

    The F/A-18 suffered from a similar problem but that was not disclosed in the DOT&E report. To be fair, that was a long time ago so perhaps the testers were not aware of it. Of course the DOT&E didn’t indicate it only happened at light loads either. So much for objectivity.

    • Duane

      The oscillations were only excessive in a no weaps/very light fuel load configuration at launch. The Navy determined the minimum fuel load necessary to eliminate the issue. As explained in the article, the holddown force compressing the strut is excessive for the gear design as it stands. If the holddown force can be reduced and still get a good launch, it will fix the issue. If, however, the holddown force correction isn’t sufficient to let the launch work OK, then they have to tweak the gear design. It’s highly unlikely that a complete new gear would need to be designed and certified … most likely all that is needed is to tune the damping, such as by changing the orifice size.

      • USNVO

        I agree, my point was more the sensationalistic problem description that was used in the DOT&E report. Since DOT&E doesn’t actually do any testing, rather they look at the ongoing testing by the program, it is not like they did not have access to the information. They could have specified that the oscillation only occurs at lighter loads (like, I don’t know, perhaps CLQs?) but they chose not to. They also could have indicated that the F-18 had similiar developmental issues and the Navy was going to try a similiar fix, but again, they chose not to. Perspective is important and it makes you wonder who wrote the report and why.

        It reminded me of the tailhook shape issue, especially with the much hyped “unprecedented” MLG to tailhook distance report from NAVAIR which was a clear hit piece from the beginning. A report discussing a single engine fighter aircraft that doesn’t include the A-7 or F-8 in your analysis but includes the E-2, right. After all, why would you look at similiar aircraft before putting you credibility on the line. Especially in such an easily spotted way. Interestingly enough, the current F-35C tailhook works great and appears to closely mimic the one used on the F-8, A-7, and A-4. Who would have thought.

        Or the report by Captain Hendrix on CVW range for the Center for a New American Security. Really, did he really think anyone wouldn’t notice when he shifted from quoting range to quoting radius when he talks about the F-35C and how it has short legs? You can whine about all manners of issues with the F-35C but range is not one of them. Again, it makes you question the integrity of the source and question why they would place their credibility on the line with such glaring errors of omission.

        Is DOT&E giving a fair assessment of the program, are they trying to sensationalize everything for some other purpose, or are they just incompetent? Makes you wonder.

        • Duane

          I didn’t read the Hendrix piece you mention, but it’s ridiculous for anyone to complain about short legs for the F-35C … in terms of effective combat radius, it’s already the longest legged carrier attack aircraft we’ve had since the A-6 … 60% longer than the Super Hornet, and 25% longer than the Tomcat on internal fuel. When the new GE variable bypass engines are fielded by 2020, GE says we’ll get another 35% boost in combat radius on top of that, to upwards of 850 nm.

          btw – effective combat radius on internal fuel is what really matters … some planes claim artificially high range but only if loaded up with drop tanks to the max, which severely limits the weaps loadout. The F-35C as it stands has an effective combat radius of 630 nm on internal fuel and a full weaps loadout of 18K.

  • Charles Pierce

    As I have been saying all along this is a TFX part 2. All aircraft for all thing that will do nothing and cost a great deal of money. It took 9 year before the aircraft was any where near what it was supposed to be, I can see an F/A18 buy.

    • Duane

      You cannot determine the actual performance during a cat launch unless and until you do the detailed cert testing at all possible loading configurations, including those that will rarely if ever be used (i.e., no weaps and very light fuel load, which is the only configuration at which the bouncing occurs). The detailed cert testing on a carrier was not performed until late last year. Just as was done on the Hornet back in the 80s where a similar problem was encountered. Armed with the testing results, they’re tweaking the process, not the hardware, to see if the same result obtains that occurred with the Hornet 30 some years ago.

      The F-35C is still in development and is not yet operationally certified.