Home » Aviation » Bogdon: F-35C Tests Offer Proposed Fixes to Catapult Problem; Carrier Trials to Continue This Fall


Bogdon: F-35C Tests Offer Proposed Fixes to Catapult Problem; Carrier Trials to Continue This Fall

An F-35C Lightning II carrier variant, assigned to the Salty Dogs of Air Test and Evaluation Squadron (VX) 23, performs a touch-and-go landing on the flight deck of the aircraft carrier USS George Washington (CVN-73). US Navy Photo

WASHINGTON, D.C. – The Navy has completed testing on potential solutions to solve a ‘must fix’ catapult launch problem on the carrier version of the Lockheed Martin F-35 Lighting II Joint Strike Fighter, the head of the JSF joint program office said on Wednesday.

Now the service and the JPO are set to test the fixes during the next set of underway carrier trials for the fighter in the fall, Air Force Lt. Gen. Christopher Bogdon said during the McAleese/Credit Suisse defense conference.

During F-35C testing on USS George Washington (CVN-73) late last year, pilots were buffeted in the cockpit when after launch the fighter would excessively bob up and down on the nose gear as the JSF was catapulted down the flight deck.

“This is a very stiff airplane, even though the oscillations about the same magnitude as you would see in a Super Hornet, it beats the pilot up pretty good,” Bogdan said.
“He’s hurting after doing three or four of these [launches] and in some instances even banging his half-a-million dollar helmet on the canopy. That’s not good for the canopy or the helmet. So we knew we had an issue there.”

According to a December Pentagon’s director, Operational Test & Evaluation report,
“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.”

The report said the Navy had told the JPO the problem was a “must fix,” deficiency.

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 in December.

In February, Bogdon told Congress the Navy would test potential fixes at Joint Base McGuire-Dix-Lakehurst, N.J. at the Navy’s land-based test catapults.

“What we wanted to try and figure out was do we need a complete redesign of the nose gear or can we do other things? Well, the testing at Lakehurst has shown us that there are a couple of things we can do to mitigate this problem,” Bogdon said.

Those were changes on securing the pilot in the cockpit and adjusting the tension of the pull back bar on the catapult that compresses the strut of the nose gear.

“We were pulling that down to the max load of the airplane, not recognizing that was causing the biggest oscillations and you can actually launch this thing at low weight with a lot less tension on that catapult bar,” Bogdon said.
“We’ve proven that out. Whether that reduces that enough, I don’t know. We have to take that out to the field and check it out. If [it doesn’t work] we have to take it back to the drawing board and structurally look at what else we need to do.”

The Navy and the JPO will tests the fixes at sea later this year. If they don’t work the Pentagon and Lockheed may have to begin an estimated years-long effort to redesign the nose gear.

 

  • DaSaint

    That fix should be borne by LM, not the taxpayer. That said, I wonder how much of this is caused by this giant helmet?

    • Duane

      LM most likely doesn’t design or manufacture the landing gear – there is a supplier that handles that as well as most other major components. The fix the Navy will test later this year is a low or no cost fix, as far as the hardware is concerned. The same problem happened a few decades ago with the Hornets too. If the adjustments described are not enough, then any hardware fix, if the gear doesn’t meet specifications, will be on the supplier, with one big caveat. It could also be an issue with the specs, if they weren’t particular enough as to the requirements, and anticipating a result like this. This problem should have been anticipated by the Navy, from the Hornet experience.

  • b2

    Where’s the Navy XO (aviator I hope) of this Joint Project Office on this F-35C yellow sheet problem? Not that I don’t trust the USAF, it’s just that I don’t believe an AF General knows squat about a cat shot or about over designed beefy carrier aircraft landing gear…

    • USNVO

      I good question although he is called the Deputy Program Executive Officer (not sure who comes up with these names) and not an XO. Since he probably wasn’t at the conference in question, he probably wasn’t interviewed, and hence wasn’t in the article but I am not sure I have every read anything he said. By his bio, RADM Winter was a A-6 NFO before becoming an acquisition guy. Having said that, I would guess there is a vast cornucopia of subject matter experts on all aspects of the aircraft to advise the PEO and DPEO (and the 3 SES level assistants as well). The important thing is they know which ones they can listen to.

      • Duane

        Yup – General Bogdan is the Program Manager for all variants … somebody has to serve in that role, but it certainly does not mean that the Air Force is designing the F-35C for the Navy and Marines, nor the F-35B for the Marines.

        We’ve got a Marine General serving as SecDef … that certainly doesn’t mean he’s designing F-35As for the Air Force.

        The Navy is just as involved in developing the F-35C as they have been in any prior aircraft development program … allowing for certain subsystems that are common to all three variants, such as the engines. There’s only about 35-40% parts commonality among the three variants.

        • USNVO

          The thing about commonality is that it really matters what systems are common. For instance, the really expensive parts and the ones that require replacement all the time are things like the engine, the radar, other combat systems, the cockpit, etc. Those are all common. It doesn’t really matter that bulkheads, tailplanes, and wing spars are different. Those don’t generally fail and last the life of the aircraft. And, aircraft structure are not that big of an expense, manufacturing is very advanced, and there is not that huge of a learning curve on them either.

          The biggest benefit is that the combat systems are the same. So for instance, if the Navy decides they want to integrate JASSM on the F-35C, say to strengthen long range strike, they can do so just by doing drop tests, the missile has already been integrated on the F-35A. It can be integrated on the F-35B just by changing the software since it has the same outer mold line as the F-35A. Dramatically faster, cheaper, and easier than say integrating it on the F-18E/F.

  • CharleyA

    While LM is fixing the gear, they can get a start on replacing the outer wings as well.

    • E1 Kabong

      Why?

      • CharleyA

        They are deforming when carrying loads on stations 1 & 11.

        • E1 Kabong

          I’d like to see that test report.

          Source?

  • Arthur Vallejo

    Problems always have solutions. Our nation is not short on engineering and scientific talent. What is needed is faith, perseverance and lots of hard work.

  • Hugh

    Perhaps adjustable dampening of the strut for takeoff……..?

  • PHtaxpayer

    Seems to me like a simple problem…get Koni, Bilsteins or Ohlins to design a better damping suspension system. Lockheed probably scrimped on the design.

    • USNVO

      I am sure the did, the hired Northrop Grumman to design it!

  • tteng

    I googled ‘f-35c carrier launch’ and noticed, in the YouTube clip, there was a nose dip in the very beginning to counter the jerk moment arm (me guess: to protect the plane); the pilot gets pulled down with it, the nose then bounced up, and the pilot came up and hit the glass top. Compare to ‘f-14 carrier launch’, again via YT, the f-35 nose dip looks more ‘severe’.

    Now I can see, one of many, the benefit of linear motor launch over steam; the acceleration profile management to lessen the initial counter jerk moment.

  • Ike_Kiefer

    This problem is as old as launch bar cat shots. Nose strut is compressing as shuttle pulls the launch bar forward in first instants of the stroke and rebounding sharply when the holdback releases. EA-6B nosegear was stiffened for cat shot by electrically controlled mechanism that temporarily reduced oleo travel. Lockheed just needs to copy the solution Grumman figured out 30 years ago.