Supersonic speeds could cause big problems for the F-35’s stealth coating

By: Valerie Insinna and David B. Larter    16 hours ago

An F-35C flies over the U.S.s Navy’s stealth guided-missile destroyer Zumwalt as the ship transits the Chesapeake Bay on Oct. 17, 2016. (Andy Wolfe/U.S. Navy)

WASHINGTON — At extremely high altitudes, the U.S. Navy and Marine Corps’ versions of the F-35 jet can only fly at supersonic speeds for short bursts of time before there is a risk of structural damage and loss of stealth capability, a problem that may make it impossible for the Navy’s F-35C to conduct supersonic intercepts.

The Defense Department does not intend to field a fix for the problem, which influences not only the F-35’s airframe and the low-observable coating that keeps it stealthy, but also the myriad antennas located on the back of the plane that are currently vulnerable to damage, according to documents exclusively obtained by Defense News.

The F-35 Joint Program Office has classified the issues for the “B” and “C” models as separate category 1 deficiencies, indicating in one document that the problem presents a challenge to accomplishing one of the key missions of the fighter jet. In this scale, category 1 represents the most serious type of deficiency.

Click here for more on the hidden troubles of the F-35.

Both deficiencies were first observed in late 2011 following flutter tests where the F-35B and F-35C both flew at speeds of Mach 1.3 and Mach 1.4. During a post-flight inspection in November 2011, it was discovered the F-35B sustained “bubbling [and] blistering” of the stealth coating on both the right and left sides of the horizontal tail and the tail boom.

During similar tests of the F-35C in December 2011, “thermal damage” that compromised the structural integrity of the inboard horizontal tail and tail boom were apparent.

Vice Adm. Mat Winter, who leads the F-35 program on behalf of the Pentagon, told Defense News that the department has taken steps to mitigate the problem with an improved spray-on coating, but added that the government will not completely fix it — instead accepting additional risk.

As justification for the decision, Winter noted that the issue was documented while the jet was flying at the very edge of its flight envelope. He also said the phenomenon only occurred once for both the B and C models, despite numerous attempts to replicate the conditions that caused the problem.

“How often do we expect something like that to occur?” he said. “It’s very, very small.”

Greg Ulmer, Lockheed Martin’s F-35 program head, said there have been no cases of this problem occurring in the operational fleet and that incidents have been limited to the “highest extremes of flight testing conditions that are unlikely replicated in operational scenarios.”

Winter acknowledged that the deficiency could keep the Navy from accomplishing its supersonic intercept mission — as the documents charge — if similar issues were being experienced more widely across the F-35C inventory.

“If you had that performance on all of your fleet, then you would have a problem. That’s not the case,” he said.

“We have put into place what we believe are the appropriate technical fix to ensure that our F-35Cs have the full envelope and capability to do the high-speed mission, if needed. That’s where we are. Right now, our United States Navy and Marine Corps flying the sea agree with that,” he said.

The new coating, which was introduced in Lot 8, allows the jet to withstand hotter temperatures caused by the afterburner, the documents stated. Winter characterized the material as able to withstand “what we call the thermal shock wave,” but declined to specify how the coating works or how much protection it provides.

“It may be some future advanced materials that can withstand the pressure and the temperature,” Winter said. “Then we see that, and we go, ‘Hey, look, we’ve got this on the book,’ [and] we do a test check to see if that new material solves that problem.”

The Defense Department has also instituted time limits on the number of seconds the F-35B and F-35C can fly at speeds in excess of Mach 1.2 while at full afterburner.

However, those restrictions are somewhat complicated, and it is unclear how pilots are expected to monitor their compliance to the limits while in flight.

For example, an F-35C can only fly at Mach 1.3 in afterburner for 50 cumulative seconds, meaning that a pilot cannot clock 50 seconds at that speed, slow down for a couple seconds and then speed back up. However, the time requirements reset after the pilot operates at military power — an engine power setting that allows for less speed and thrust than afterburner — for a duration of three minutes.

The F-35B can fly for 80 cumulative seconds at Mach 1.2 or 40 seconds at Mach 1.3 without risking damage.

But for both the C and B models, flying at Mach 1.3 over the specified time limits poses the risk of inducing structural damage to the aircraft’s horizontal stabilizer.

It is infeasible for the Navy or Marine Corps to operate the F-35 against a near-peer threat under such restrictions, the documents acknowledge.

“Pilot observed timers are not practical/observable in operationally relevant scenarios,” one document read. Another document said that “pilots will be unable to comply with time limit in many cases due to high mission workload, resulting in lost missions due to aircraft damage.”

And when those timer violations occur, they will result in “degradation of [stealth], damage to [communications, navigation and identification] antennas, and/or significant [horizontal tail damage],” one document explained.

How significant is this problem?

The limitations on the afterburner, when combined with another deficiency pertaining to the plane’s maneuverability, could prove deadly in close-combat scenarios.

The concept of operations for the F-35 is to kill an enemy aircraft before it can detect the fighter jet, but relying on long-range kills is a perspective that, for historical and cultural reasons, naval aviation distrusts. In the Vietnam War, when air warfare began heavily relying on missiles and moved away from the forward gun, it caused a spike in air-to-air combat deaths.

The lesson naval aviation took away was to prevent the latest and greatest technology from offsetting the learning of fundamentals, and it was the impetus behind the formation of Top Gun 50 years ago, a naval strike fighter course for training and tactics development.

“The solution is: ‘Hey, we’ll just limit the afterburner to less than a minute at a time,’ ” one retired naval aviator said, when told of the issue. “Which, with what the aircraft is supposed to do and be capable of, that’s a pretty significant limitation.”

“If you want to use it on the first or second day [of a conflict], it has to be stealthy, so you can’t hang a lot of external stores, which means you have to use internal fuel and internal weapons. And that means you have to launch fairly close in and you’ve got to be close enough to do something to somebody. And that usually means you are in a contested environment,” the aviator said.

“So you’re saying that I can’t operate in a contested environment unless you can guarantee that I’m going to be however far away from the thing I’m trying to kill,” the aviator added. “If I had to maneuver to defeat a missile, maneuver to fight another aircraft, the plane could have issues moving. And if I turn around aggressively and get away from these guys and use the afterburner, it starts to melt or have issues.”

The issue is compounded for the Navy, which must operate forward for months at a time, because any significant issues with coatings or the structure of aircraft would require a depot-level repair. And so a damaged aircraft would remain damaged until its host ship return to home port, reducing the combat effectiveness of the air wing.

“We might have to be operating at sea for eight months, so if you damage something on week one, guess what? It’s damaged for the rest of the deployment. And it affects your ability to evade detection by the enemy — you just degraded that asset permanently until you can get it somewhere where it can be fixed, at great expense and time,” the aviator said.

However, a naval aviator currently in service said the afterburner problem may not be that troubling to pilots, who must frequently work around a jet’s limitations. The key, he said, is understanding how often the issue occurs.

“I think you’d do well to go back and look at all the times they used the afterburner and that didn’t happen,” he said. “We’re talking about tens of thousands of sorties at this point that this aircraft has flown.”

Other aircraft that the Navy operates also have afterburner limits, he explained.

“I think that number needs context,” he said. “It looks scary on its own, but [the Super Hornet] has afterburner limits. They’re not that restrictive, but they have them. The aircraft has an afterburner, you want it to work.

“But I would want to get context for that number: Does this represent 0.002 percent of all sorties? If that’s the case, I don’t give a sh–, and I’ll probably have 15 other things fail before that.”

Bryan Clark, previously a top aide to former Chief of Naval Operations Adm. Jonathan Greenert and now an analyst with the Center for Strategic and Budgetary Assessments, likened the limitation on the afterburner to similar restrictions on submarine and ship operations.

“I think the operational impact is not huge, since it only applies during a small fraction of the jet’s operational profile. In subs and ships, we have a ‘safe operating envelope’ that defines where the platform is engineered to operate reliably for a long time. We can operate outside the safe operating envelope for a short time, but there are risks to doing so. The operator or commander needs to balance those risks against the benefits,” he said.

“That is similar to this situation,” he added. “The pilot can be on afterburner as long as needed to evade a threat but has to know the risk of structural damage increases. The pilot can balance that against the risk of getting shot down because he or she didn’t evade fast enough.”

The most important piece will be how well trained the pilot is on the aircraft, he continued.

“As a submariner, I knew the risks of being outside the safe operating envelope and how those risks increased over time and would impact ship performance.”

Source: Defense News “Supersonic speeds could cause big problems for the F-35’s stealth coating”

Note: This is Defense News’ report I post here for readers’ information. It does not mean that I agree or disagree with the report’ views.


J-20’s PL-10, PL-15 Air-to-air Missiles Superior to F-22, F-35’s

Mark Epikopos’ late 2018 article on National Interest titled “Mic Drop, Stealth Style: The Real Reason China’s J-20 Fighter Is a Threat” describes US fear of J-20’s air-to-air missiles superior to the AIM-9X and AIM-120D AMRAAM missiles carried by F-35 and F-22.

Epikopos is a research assistant at the Center for the National Interest. He says that not much is known about J-20 due to its confidentiality kept by China, but he has quite detailed information about J-20’s PL-10 and PL-15 air-to-air missiles with more advanced technology than the AIM-9X and AIM-120D

I have a post titled “F-22 Pilots Will Be Scared to Death if WS-15s Are Used on J-20” on March 13 on how F-22 pilots are scared by J-20’s PL-10 dogfight missiles. The article shows the writer’s concern that the US has failed to develop air-to-air missile rival to PL-10 and PL-15.

The article says, “PL-10 can be fired at off boresight angles of 90 degrees using the J-20’s Helmet Mounted Display (HMD). In other words, the PL-10’s on the J-20 can be fired in the direction that the pilot points their head.”

That is precisely what F-22 pilots are scared by as described in my March-13 post.

For beyond the vision air combat, PL-15 has a much longer range than AIM-120D.

Moreover, AIM-9X and AIM-120D are vulnerable to modern digital radio frequency memory (DRFM) jamming techniques but PL-10 and PL-15 are built with the latest anti-jamming technology to resist such jamming.

China is developing WS-15 engine for J-20 but due to secrecy, Epikopos does not know what progress China has made in the development. He has seen the rolling and climbing J-20 performed in Zhuhai Airshow. That was not surprising in a fifth-generation fighter jet. He believes J-20’s air-to-air missiles are real reasons for J-20 being a threat.

Comment by Chan Kai Yee on National Interest’s article, full text of which can be viewed at

JASDF F-35s made 7 emergency landings before crash. However Japan assures U.S. it will continue to buy the jet.

By Dario Leone -Apr 22 2019

JASDF F-35s made 7 emergency landings before crash. However Japan assures U.S. it will continue to buy the jet.

Two of the emergency landings involved faults in the F-35 that later crashed.

Takeshi Iwaya, Japan’s Minister of Defense, has assured acting U.S. Defense Secretary Patrick Shanahan that Tokyo will continue to buy more F-35s despite the crash of a Japan Air Self-Defense Force (JASDF) Lightning II belonging to 302 Hikotai from Misawa Air Base on Apr. 9, 2019.

“At this point, we have no specific information that would lead to a change in procurement plans,” Iwaya was quoted as saying.

Japan has received 13 F-35As so far, of which four were built in the U.S. and the rest assembled in Japan from American components. The government plans to procure six more this fiscal year. Going forward, Tokyo will stick to importing finished jets, as it is more cost-effective.

But the recent crash could derail these plans, the Nikkei says.

The mishap aircraft, F-35A #79-8705 (construction number AX-05), is the first Japanese-assembled F-35A, and was rolled out in Nagoya on Jun. 5, 2017.

The stealth fighter crashed while on a training flight 135km away from Misawa Air Base. It was flying over the Pacific Ocean then.

Little is known about the crash as both the US and Japan scour the Pacific off the northeast coast of Japan to look for wreckage of the jet. The pilot, who is still missing, had called for the mission to end before his plane went down. Should the incident turn out to have been caused by a defect in the plane, Tokyo could face calls to stop buying them.

According to the Defense Ministry, five of Japan’s 13 F-35As have been involved in seven emergency landings between June 2017 and January 2019. Two of the incidents involved faults in the plane that later crashed. Four of the planes that experienced problems had been assembled by Mitsubishi Heavy Industries, under a partnership with Lockheed Martin. The other jet was made in the US.

“Unplanned returns to base were made after the planes reported issues with systems relating to fuel, hydraulics and other parts,” Japanese daily Mainichi quoted Iwaya as saying. “Excluding one case of an error by the aircraft’s monitoring systems, the remaining six saw the fighters inspected and parts replaced before they were confirmed safe.”

While the jets were inspected each time to confirm they were safe to fly, the ministry is checking again to see if there might be any links to the accident.

The US has not disclosed details of the F-35’s state-of-the-art technology to other countries, and there are worries that China or Russia could get their hands on the wreckage and unlock some of its secrets, including the jet’s capability to shoot down ballistic missiles. This is among the reasons why Washington is sending a deep-sea search vessel to the site of the incident to help find the wreckage.

If the cause of the crash turns out to involve sensitive information about the plane, the U.S. could be reluctant to share it with even its close ally Japan.

Source: The Aviation Geek Club “JASDF F-35s made 7 emergency landings before crash. However Japan assures U.S. it will continue to buy the jet.”

Note: This is Aviation Geek Club’s article I post here for readers’ information. It does not mean that I agree or disagree with the article’s views.

F-35 crash shows problems still lurk behind stealth fighter

Oxygen supply system raises questions as search for pilot and plane continues

TETSURO KOSAKA, Nikkei senior staff writer
April 23, 2019 12:16 JST

TOKYO — In the weeks since a Japanese F-35A stealth fighter jet crashed into the Pacific Ocean, the U.S. and Japan have not yet found either the plane or the cause of the incident. But it could be linked to a system that has bedeviled the American military for years.

All F-35s have onboard oxygen generation systems, or OBOGS, which draw oxygen from the surrounding air and supply it to the pilot at the high concentration necessary to operate at high altitudes. The U.S. Air Force, Navy and Marine Corps have used OBOGS for more than three decades, in models including the F-16 and F/A-18 as well as certain training planes.

But since the U.S. began using OBOGS in the F-22 in 2008, there have been more than 20 cases of F-22 pilots experiencing symptoms indicating a lack of oxygen, apparently due to problems with the system. An F-22A crashed in November 2010 in an incident that may have resulted from an oxygen shortage.

Low levels of oxygen in the bloodstream — known as hypoxia — can cause sweating, headaches and dizziness, followed by vision problems and trouble making decisions, and eventually loss of consciousness. After the 2010 crash, the U.S. military temporarily stopped using OBOGS in the F-22 while it worked to address the issue, in part by replacing components in the system.

But the problem persisted in multiple jet models, including the F-35A. The military has not worked out the cause but reportedly has increased the emergency oxygen supply provided to pilots in case the OBOGS fails, among other precautions. Put bluntly, it is employing every trick it can think of to keep using the system.

With the Japan incident, the Air Self-Defense Force pilot called a halt to his training exercise just before the crash. This suggests that he realized something was wrong, after which the situation quickly deteriorated. That would fit with hypoxia caused by an OBOGS malfunction.

Such problems are a risk in the modern era. These days, all aircraft, civilian or military, are filled with electronics requiring complex software to run. As such, new planes must be put through a series of test flights to find and correct any problems in the code.

Test pilots, as well as the first pilots to operate new models after their rollout, must fly without knowing whether bugs might still lurk in their planes’ programming. The task is a dangerous one.

The ASDF grounded all of its F-35As after the crash. At this point, it is impossible to tell whether the OBOGS might have been involved in the incident. But whether or not this turns out to be the case, given the long-running issues with the system in the U.S., Japan must also consider it suspicious.

But the ASDF cannot simply modify the planes to remove the OBOGS and use liquid-oxygen systems like those in the F-15, its current mainstay, because that would break the terms of its deal with Washington. This is a major downside to buying foreign jets.

There is one other concern. In June 2017, the USS Fitzgerald, an American destroyer equipped with the Aegis missile defense system, collided with a Philippine containership off the Japanese coast, killing seven people on board. The captain and another officer were court-martialed for criminal negligence. But the U.S. Navy recently made the unusual decision to withdraw the charges.

Like modern fighter jets, Aegis-equipped vessels are full of electronics. The accident prompted speculation that the Fitzgerald could have been hacked or hit with an electromagnetic pulse attack that caused systems to malfunction.

With military secrets involved, the truth remains a mystery. But the strange decision to withdraw charges over an incident that caused multiple deaths raises the possibility that hacking was found to have been involved, leading the military to conclude that the officers were blamed in error.

There are worries that the F-35A and the F-22 could be hacked — perhaps during system updates — to plant the seeds for future software problems. The U.S. military is believed to be looking into this risk with respect to the OBOGS malfunctions.

A national security source said of a recent piece on the American scramble to keep the F-35’s secrets safe from Russia and China: “I agree with it, but the situation is more serious than that,” the source said. What that could mean remains a mystery of its own.

Source: Nikkei Asian Review “F-35 crash shows problems still lurk behind stealth fighter”

Note: This is National Interest’s article I post here for readers’ information. It does not mean that I agree or disagree with the article’s views.

China’s New J-11 Variant Better than Su-35

The Diplomat says in its article “Why is China Developing a New J-11 Variant?” that China has developed a new variant of J-11 the J-11D “4++ generation” air superiority fighter superior to Russia’s Su-35 that China has imported.

According to the article, Su-35 was developed in 2000s with technologies developed in the 1990s while the J-11D as a later development with newer technology is considerably more sophisticated so that it will very likely surpass Su-35 in its combat performance.

J-11D integrates some of the most capable Russian military aviation technologies. It uses more composite materials for a stronger but lighter airframe. Its electronic warfare systems and sensors are the latest development comparable with J-20’s and more advanced than Su-35.

It has better situation awareness than Su-35 as it uses a miniaturized active electronically scanned array (AESA) radar better to detect at range than Su-35’s passive electronically scanned array radar. Moreover, the article says, “The J-11D could potentially integrate a Distributed Aperture System, a cutting edge technology currently deployed only by the J-20 and American F-35.”

In addition, some stealth technologies are adopted in J-11D, such as radar absorbent coatings to reduce its radar cross section.

J-11D uses WS-10A three dimensional thrust vectoring engines to make it highly maneuverable.

It carries China’s new PL-15 air-to-air missile with a 150km engagement range longer than the R-77 and extended range variants of the R-27 used by Su-35.

Compared with China’s new 5th-generation stealth fighter jet J-20, it can carry larger missiles with far wider range than those carried in J-20’s internal weapon bay such as the ship hunting YJ-12 and ramjet powered PL-21 “AWACS hunter”.

With comparable electronic warfare systems and sensors, and with some stealth technologies of its own, J-11D is an effective next generation complement to the J-20 for decades to come. Moreover, it is likely to be considerably cheaper to operate and easier to maintain.

As for whether J-11D is the best of its kind, the article says, “How the aircraft will compare to Boeing’s F-15X, an advanced “4++ generation” air superiority platform currently on order for the U.S. Air Force, which is in many ways conceptually similar to the J-11D, remains to be seen.”

Comment by Chan Kai Yee on The Doplomat’s article, full text of which can be viewed at

Safety Worries due to Japanese Crash Delays Singaporean Order for F-35

TOC says in its report “Mindef Singapore to ensure safety of F-35 Joint Strike fighter jets prior to acquisition, in the aftermath of Japanese crash” today, “Singapore’s Ministry of Defence (Mindef) assured that the F-35 Joint Strike Fighters will be ‘safe to operate’ prior to obtaining them.”

The cause of the recent April-10 crash of a Japanese F-35 remains unknown as the crashed warplane lies down 1,500 meters under water and its pilot has disappeared. However, we can be sure that there was problems in the crashed F-35 as before the crash Hosomi, the pilot of the crashed F-35, “instructed the other pilots participating in the exercise to terminate the training portion of the flight, according to Defense News.”

Hosomi certainly found some problem that caused the crash. If Hosomi has been found alive he, as an experienced Japanese pilot, might tell what problem he has found in the crashed F-35 and caused him to instructed other pilots to terminate the exercise.

It is obvious that F-35 has quite serious problems so that the program of its development was $163 billion in excess of budget and seven years behind schedule. However, those are not big problems as the US is rich and can afford such excessive spending and it has no urgent need to use F-35 to start any war of aggression.

However, killing experienced pilots will be a serious problem. Hosomi’s inability to escape to safety when he found some problem indicated some problem with F-35’s ejection system. It seems the US has to ground all the F-35s to fix the ejection system in order to ensure pilot safety as good pilots like Hosomi are more valuable than F-35s.

Comment by Chan Kai Yee on TOC’s report, full text of which can be viewed at

F-35 Too Poor, Japan to Develop Its Own Stealth Fighter

National Interest says in its report “Meet the Mitsubishi F-3: Japan’s 6th Generation Fighter Jet”, “Japan’s 2019 Mid-Term Defense review quietly revealed that after years of hesitation, Tokyo has decided to press ahead with development of its own domestically designed sixth-generation Mitsubishi F-3 air-superiority stealth fighter, rather than purchasing an additional foreign stealth design to supplement its growing fleet of F-35s.”

Recent crash of the F-35 made by Japan proves F-35 is not a reliable fighter jet so that Japan has to incur lots of costs to develop its own F-3 stealth fighter jet.

Japan certainly has the technology to develop its own advanced weapons. It purchases F-35 as the joint funding in the development of F-35 by various US allies cost less than development entirely on its own. However, the crash proves US inability to make the best fighter jet. As a result, Japan has to rely on itself.

I have published quite a few posts on US inability to win arms race with China. Japan seems to realize that now so that in the future, it will rely on itself or buy from Europe as Europe’s Germany and France have also decided to develop their own advanced fighter jets instead of buying unreliable F-35.

Poor America! It remains the richest country but it does not know how to spend its money.

Comment by Chan Kai Yee on National Interest’s report, full text of which can be viewed at