This is really cool, thanks for sharing. What's wild to me is that the program started in the late 90s and only now is the F35 fleet up to originally specified? operational capacity.
Since then I graduated high school, got a degree, got married etc etc. The time span is mind boggling. Would be interesting to see how continuity is maintained for so long. In software it feels like if a project is more than 6 months old, we throw it out and rewrite it.
> In software it feels like if a project is more than 6 months old, we throw it out and rewrite it.
I think that would be a bad way to operate, but what's worse is what we _actually_ do, which is write the project like it's gonna be replaced in 6 months and instead keep that poorly-documented untested duct-tape contraption around for a decade as the central load-bearing component of critical infrastructure.
The F-35 contract was awarded on October 26, 2001. I was in my freshman year of undergrad, 18 years old.
I started on the program in August, 2010. I was 26 years old.
The program has just completed its Initial Operational Test & Evaluation, including its runs for score in the Joint Simulation Environment. I am 40 years old.
> In software it feels like if a project is more than 6 months old, we throw it out and rewrite it.
“The Phoenix pay system is a payroll processing system for Canadian federal government employees, provided by IBM in June 2011 using PeopleSoft software, and run by Public Services and Procurement Canada… By July 2018, Phoenix has caused pay problems to close to 80 percent of the federal government's 290,000 public servants through underpayments, over-payments, and non-payments.“
You write shit down and you have career engineers that enforce continuity
It's trendy in software to complain about doing annoying work like writing reports and documenting things. But most hard tasks require writing reports and documenting things.
I work on software that has a lifetime once installed of about 30 years, and if a safety critical error is found during that time, ideally it needs to fixed with a minimal patch, so we have to maintain the capability to do so.
I guess the ethos is quite different to top tech company. We don't get the pay or perks that you would get in Silicon Valley, but we are unionised, and it's a viable option to spend your entire career just on one project so it's very stable.
Partly it depends on documentation, but also on thinking long term. There are certain people who are the technical authority for a particular area, and they know that about 5 years before they retire or move on they need to find someone who can take on their role for at least the next decade, to keep their knowledge rolling forward.
Was there ever any consideration given to building a "testing harness" to physically simulate the F35 landing? Something like the "dead load" testing that the EMALS undergoes. Just in reverse. Anyway, that was great read.
There was a lot of static load testing done, and things like a drop test [0] of a full scale article. But to my knowledge, the only way to test the dynamics of a carrier arrestment is to actually do an arrestment. We do them on land; NAS Patuxent River and NAS Lakehurst (among others) have a full set of Mark 7 arresting gear like you would find on a Nimitz class. Lakehurst also has the advanced arresting gear present on the Ford class.
They designed for the F-35B as the "baseline" with carrier requirements secondary. Also, the engineers knew but, "their concerns would have just as likely been ignored." This reference was 2012, when they knew it was a problem but before OP was fixing it.
First of all, thank you for the super interesting read!
Now, as a Ukrainian I do have a philosophical question of sorts. What we have seen here in a real full-scale combat is that some of the modern machines are way too delicate for actual operations on the ground. For example, I have heard some feedback about the Abrams tank: way too finicky for real use, not durable, not reliable. The same goes about many other western items. (Some hardware demonstrated exceptional reliability, like Bradleys and HIMARS)
My question is about modern fighter jets like F-35.
Does that level of engineering and the amount of delicate electronics somewhat limit the durability and reliability of the airplane compared to much simpler designs?
The F-35 was never really intended to be durable or reliable for ongoing use in long wars of attrition. It was designed to be survivable on penetrating strike missions against near-peer adversaries. Essentially to "kick the door in" and destroy high value targets such as air-defense systems during the first few days of a conflict. War games and simulations have shown that simpler designs can't accomplish that mission anymore so concerns over F-35 durability and reliability are somewhat misplaced (although there is certainly room to improve mission readiness rates).
No one is even remotely contemplating sending F-35s to Ukraine. Besides and costs and security risks, the Ukrainians unfortunately have nowhere near the infrastructure and logistics to sustain such a complex platform.
Yes, there are pendants that are supposed to keep the wire above the deck, but the short space between the F-35C main landing gear and the tail hook point means that there's not enough time for the pendants to raise the wire above the deck in the manner that the original (erroneous) wire dynamics model would have suggested.
> “Boss,” he says to me, “This fucker ain’t gonna work. Look at this thing. It’s short, it’s too close to the wheels, and look at this dumbass hook shoe they got on it. If the wire don’t hit it exactly right, it’s just gonna go under the hook and you’ll bolter.”
Did nobody with practical experience with arrested landings look at the arresting hook design prior to this? Obviously computer models can and do predict extremely novel solutions to existing problems, but it's worth double-checking the model when someone with practical experience says "it will never work"
In this case, it seems like a simple slow-motion video of an arresting wire going under the wheels of an F-18 would have been enough to debunk the model.
Random thought: this is a case where someone's intuition matched what actually happened, making us think "why don't they listen to people with common sense?".
But what about the many other cases where someone with "common sense" said "this fucker ain't gonna work" but the thing worked as predicted by simulations? Surely they must have happened too.
> Did nobody with practical experience with arrested landings look at the arresting hook design prior to this?
I mean... it's very likely that the answer is no. The last new carrier aircraft made was the Super Hornet - and that design was basically done by 1995 (the F-35 tests in question were in 2011/2012). That expertise would also be at McDonald Douglas/Boeing. Northrop Grumman has a long history of carrier aircraft development, but it would have been long dormant by that point.
I'm sure there's all sorts of reasons the model's inaccuracy wasn't caught before hand, but sometimes... if you're given a model that's someone says that's been V&V'd, and it produces a result that's only a little weird, you just go with it. There are only so many things you can add extra testing onto in a project. Sometimes you choose wrong.
Anyhow, consider that the model results were probably exactly what they were expecting. Remember that the designers would be honing in on the shorter tailhook. You can imagine their mental model going - "ok on legacy aircraft, we have flatter tailhooks because there's enough time for the cable to settle". And then going "ok, with a shorter tailhook, there won't be enough time to settle". And then their model comes out and say "ya, with the shorter tailhook, it won't have enough time to settle - it'll be UP IN THE AIR". Whereas reality is "ya, with the shorter tailhook, it won't have enough time to settle - it'll still be displaced DOWN".
Unfortunately, my decade plus as a military aircraft tech has taught me that no, practical knowledge does not make it through the system nearly as fast as engineering "expertise".
The F-18 tailhook geometry is far different than the F-35 tailhook geometry. F-18 hooks are much farther back from the main landing gear, and are also much longer.
They all came out of a book that anyone can buy called "F-35: From Concept to Cockpit". That book is a compilation of papers presented at an AIAA conference in 2018.
I love hearing about these engineering challenges. Media loves to point to these design iterations as proof that the F-35 is over-hyped or inferior to existing jets. But what I see is innovation and trying new stuff. Sometimes failing, but in the end making an amazing jet.
I just kind of wish we lived in a world where we didn't NEED a new fighter jet and could instead invest this time and effort into peaceful pursuits.
It's true, and it often forgets that most other aircraft go through the same teething problems.
As the article skillfully shows, there's a lot of work that goes into seemingly simple things like a hook. Other elements can be really complex to work out. The F-35's integrated power pack[1] was the source of quite a few issues if I recall correctly. But it was developments like that which allowed the plane to keep weight under control such that we now have a supersonic STOVL jet in the F-35B.
It's a pet peeve of mine when commentators say "that's stupid, they should just do <this>!" . Well, if it were so easy...
I get your sentiment regarding the need for new fighter jets. At the very least, some of these engineering developments end up helping commercial applications as well. A good example is the C-5 Galaxy, which went through torturous development. But lead to the development of the TF-39 engine, which was revolutionary in concept. It then became the CF6, which then went on to power a long line of successful airliners.
> It's a pet peeve of mine when commentators say "that's stupid, they should just do <this>!" . Well, if it were so easy...
Why don't they just put windows in the submarine...
It's good to remind ourselves and occasionally others that if the answer to a problem in a domain we don't have much knowledge on seems simple. Chances are the people with the knowledge are well aware of your answer and know why it won't work.
But what I see is innovation and trying new stuff.
I like your positive attitude. Though I think there were some engineering shortfalls that should have been avoided with common sense.
Eg. The original hook didn't work because the shoe was angled up too high to catch the wire. The engineers designed it based on a flawed simulation model. The guys field testing took one look and knew it wouldn't work. Heck, I showed this photo to my partner (non-engineer) and the first thing she said was "it's not pointing right".
My first class in Calculus based physics, my professor did an interesting thing. We would be asked to intuit the answer to problems before we did the math to know for certain. Physics is simply not intuitive.
Now, with regards to the simulation, the thing I think they failed on wasn't a lack of common sense. I think what they should have done is reproduce the results in real life using a similar jet. They relied on the model a bit too much and "Tested in production."
However, as far as mistakes go, this is a pretty small one.
Looking at the image, and knowing designers assumed the cable would rebound before being cought by the hook, the original design of the hook itself makes sense: catch the cable in the air and make sure it doesn't slip down the hook.
Obviously it doesn't work to catch cable lying flat on the ground. Which was, again, not the initial design requirement.
In another thread about Boeing, the topic of good sources to learn about real engineering came up. Well, this is a great example. Just assume the engineers designing the initial hook were not complete clueless idiots.
> The guys field testing took one look and knew it wouldn't work.
You have a hearsay, hindsight story (no offense to the author) that one person thought it wouldn't work.
And now we have a hindsight HN comment that they would have known it all along. I'm guessing the people who worked on it weren't idiots, though people seem to delight in supposing they are smarter than all the dumb people whose plans don't work out perfectly.
Yeah it's amazing how it is currently the best jet in the world considering how reviled and criticized it was in the media. And said criticism had real consequences, here in Canada we basically got stuck buying 1970s trash just because the f-35 became a taboo and a meme due to projected costs, even if it means that we will pay even more for the alternatives for much much less capabilities.
To be honest, I think the F/A-18 is an excellent jet for Canada's needs. Also Canada currently has 88 F-35s on order and will get their first ones in 2026.
Who benefited? I assumed that while criticism is healthy, some calls for cancelling the aircraft were from adversaries. Easiest way to defeat the plane is to get Congress to kill it.
Making a new experimental jet design is great. It's the committing to buy and pay for thousands of them before you've even confirmed whether that design works that I object to.
This is literally the only way you can do these mega projects. Otherwise they just wouldn't happen. If the design doesn't work, then they just move on to the next one.
EG: The Future Combat System, RAH66 Comanche, The Airborne Laser, The Kinetic Interceptor, The Expeditionary Fighting Vehicle, etc...
The cost of a single F35 could fund so much peace in the world. The only reason this isn't happening is because the people making sure the American people keep endlessly funding these programs have no intention whatsoever to make peace. They just don't have the intention to do so.
They intend for there to be endless war, which is what these machines produce. It is the only thing they can be used for..
I abhor war. I believe the only way to secure peace is to be very good at war. That's why I participated in flight testing the F-35, and why I work on electronic warfare simulations now.
I wish I lived in a world where there's no need for any of this, but as far as I know, war is as old as the species.
I would love to live in a world where I can know for a fact that war will never again happen. However, the path to that world is a very long one. In the meantime I want to know that the acquisitive psychopaths that run many of the countries in the world have a very good reason to not line me up in front of a wall and shoot me.
Should we be taking steps to a more peaceful world that we aren't right now? Yes, very much so. However, unless you want to imitate the path of Tibet or Ukraine, then you better spend some money on guns and fighter jets.
> The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments.
What does this mean? That the F-35C can only hook correctly when it lands very close to center? And what does "wire only" mean? Aren't all arrested landings on carriers "wire only"?
The whole purpose of this series of tests was to try to exercise the arresting gear in the most punishing ways. One way that's usually done is to try to arrest far off the centerline (where the arresting force will be applied far more intensely to one side) and also to try to have the arresting hook grab the wire while the jet is still wheels above deck (this slams the aircraft down, HARD)
After this incident it was determined that we had fulfilled the intent of the test plan.
Also, instrumented aircraft capable of doing arrestments were in short supply: the program only had two of them, and we pushed one to its very limit.
(BTW, the twitter link on your blog is mistakenly going to twitter.com. I think you meant to link to your account: https://twitter.com/the_engi_nerd Cheers!)
> After this incident it was determined that we had fulfilled the intent of the test plan.
Ok, so it was considered good enough? (This quote made it seem like the testing had failed and they were giving up: "The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments.)
Also, I still don't understand what wire-only arrestments are. Aren't all arrestments wire only?
I think every engineer has been burned by faulty test equipment. and I think every senior engineer has been burned by not trusting test equipment that IS working properly!
Great read. Looking forward to more!
I was once a Harrier mechanic, and I was told very often that I'd be learning to work on the F-35Bs during my 2002-2007 enlistment, which obviously didn't happen. So, as a former mech and current engineer, I am very interested in hearing more about it's development.
> Engineers, saving your program time and money out of the sheer laziness of not wanting to make a new XML format for an instrumentation project. This is how progress is made in the world, I guess.
I've worked in healthcare, fintech, and ads and this is one thing I've done in all three fields. I swear i've written or debugged XML parsers in 20 different languages at this point just so I didn't have to get consensus on a new format.
We made our XMLs with, horror of horrors, a Visual Basic script that ran in Excel and digested several input documents to generate a map template that we could then tweak by hand and turn into an XML through another VB script.
I went from doing things like I describe in the blog post, to verifying and validating the most complex electronic warfare simulation the DOD has ever done, to being a developer of one of the enabling technologies of that simulation.
I believe what I do now is important, but getting an issue past test and into the release that's sent to customers isn't nearly as satisfying as "I fixed the tailhook last night, which let today's flight test happen". I miss having an aircraft that I can touch.
Since the new aircraft carriers have this new fancy electromagnetic catapults. Why don't they just use regenerative braking like the hybrid cars? They could save a lot of energy recharging those catapult accumulators.
Readit News
Since then I graduated high school, got a degree, got married etc etc. The time span is mind boggling. Would be interesting to see how continuity is maintained for so long. In software it feels like if a project is more than 6 months old, we throw it out and rewrite it.
I think that would be a bad way to operate, but what's worse is what we _actually_ do, which is write the project like it's gonna be replaced in 6 months and instead keep that poorly-documented untested duct-tape contraption around for a decade as the central load-bearing component of critical infrastructure.
I started on the program in August, 2010. I was 26 years old.
The program has just completed its Initial Operational Test & Evaluation, including its runs for score in the Joint Simulation Environment. I am 40 years old.
“The Phoenix pay system is a payroll processing system for Canadian federal government employees, provided by IBM in June 2011 using PeopleSoft software, and run by Public Services and Procurement Canada… By July 2018, Phoenix has caused pay problems to close to 80 percent of the federal government's 290,000 public servants through underpayments, over-payments, and non-payments.“
https://en.wikipedia.org/wiki/Phoenix_pay_system
It's trendy in software to complain about doing annoying work like writing reports and documenting things. But most hard tasks require writing reports and documenting things.
I guess the ethos is quite different to top tech company. We don't get the pay or perks that you would get in Silicon Valley, but we are unionised, and it's a viable option to spend your entire career just on one project so it's very stable.
Partly it depends on documentation, but also on thinking long term. There are certain people who are the technical authority for a particular area, and they know that about 5 years before they retire or move on they need to find someone who can take on their role for at least the next decade, to keep their knowledge rolling forward.
[0] https://www.youtube.com/watch?v=lGPseVNfZO0
Or are all of those tail hooks bespoke designs because reasons?
https://www.f-16.net/f-35-news-article4494.html
Deleted Comment
Wildly different. For one the f14 is massive! And it's tail hook is like the size of a medium man
So yeah tail hooks vary wildy
Now, as a Ukrainian I do have a philosophical question of sorts. What we have seen here in a real full-scale combat is that some of the modern machines are way too delicate for actual operations on the ground. For example, I have heard some feedback about the Abrams tank: way too finicky for real use, not durable, not reliable. The same goes about many other western items. (Some hardware demonstrated exceptional reliability, like Bradleys and HIMARS)
My question is about modern fighter jets like F-35.
Does that level of engineering and the amount of delicate electronics somewhat limit the durability and reliability of the airplane compared to much simpler designs?
No one is even remotely contemplating sending F-35s to Ukraine. Besides and costs and security risks, the Ukrainians unfortunately have nowhere near the infrastructure and logistics to sustain such a complex platform.
Did nobody with practical experience with arrested landings look at the arresting hook design prior to this? Obviously computer models can and do predict extremely novel solutions to existing problems, but it's worth double-checking the model when someone with practical experience says "it will never work"
In this case, it seems like a simple slow-motion video of an arresting wire going under the wheels of an F-18 would have been enough to debunk the model.
But what about the many other cases where someone with "common sense" said "this fucker ain't gonna work" but the thing worked as predicted by simulations? Surely they must have happened too.
I mean... it's very likely that the answer is no. The last new carrier aircraft made was the Super Hornet - and that design was basically done by 1995 (the F-35 tests in question were in 2011/2012). That expertise would also be at McDonald Douglas/Boeing. Northrop Grumman has a long history of carrier aircraft development, but it would have been long dormant by that point.
I'm sure there's all sorts of reasons the model's inaccuracy wasn't caught before hand, but sometimes... if you're given a model that's someone says that's been V&V'd, and it produces a result that's only a little weird, you just go with it. There are only so many things you can add extra testing onto in a project. Sometimes you choose wrong.
Anyhow, consider that the model results were probably exactly what they were expecting. Remember that the designers would be honing in on the shorter tailhook. You can imagine their mental model going - "ok on legacy aircraft, we have flatter tailhooks because there's enough time for the cable to settle". And then going "ok, with a shorter tailhook, there won't be enough time to settle". And then their model comes out and say "ya, with the shorter tailhook, it won't have enough time to settle - it'll be UP IN THE AIR". Whereas reality is "ya, with the shorter tailhook, it won't have enough time to settle - it'll still be displaced DOWN".
I just kind of wish we lived in a world where we didn't NEED a new fighter jet and could instead invest this time and effort into peaceful pursuits.
As the article skillfully shows, there's a lot of work that goes into seemingly simple things like a hook. Other elements can be really complex to work out. The F-35's integrated power pack[1] was the source of quite a few issues if I recall correctly. But it was developments like that which allowed the plane to keep weight under control such that we now have a supersonic STOVL jet in the F-35B.
It's a pet peeve of mine when commentators say "that's stupid, they should just do <this>!" . Well, if it were so easy...
I get your sentiment regarding the need for new fighter jets. At the very least, some of these engineering developments end up helping commercial applications as well. A good example is the C-5 Galaxy, which went through torturous development. But lead to the development of the TF-39 engine, which was revolutionary in concept. It then became the CF6, which then went on to power a long line of successful airliners.
[1] https://www.defenseadvancement.com/feature/3-aircraft-system...
Why don't they just put windows in the submarine...
It's good to remind ourselves and occasionally others that if the answer to a problem in a domain we don't have much knowledge on seems simple. Chances are the people with the knowledge are well aware of your answer and know why it won't work.
I like your positive attitude. Though I think there were some engineering shortfalls that should have been avoided with common sense.
Eg. The original hook didn't work because the shoe was angled up too high to catch the wire. The engineers designed it based on a flawed simulation model. The guys field testing took one look and knew it wouldn't work. Heck, I showed this photo to my partner (non-engineer) and the first thing she said was "it's not pointing right".
https://the-engi-nerd.github.io/posts/welcome/images/clipboa...
You can see the original (blue) vs revised (red):
https://the-engi-nerd.github.io/posts/welcome/images/clipboa...
Now, with regards to the simulation, the thing I think they failed on wasn't a lack of common sense. I think what they should have done is reproduce the results in real life using a similar jet. They relied on the model a bit too much and "Tested in production."
However, as far as mistakes go, this is a pretty small one.
Obviously it doesn't work to catch cable lying flat on the ground. Which was, again, not the initial design requirement.
In another thread about Boeing, the topic of good sources to learn about real engineering came up. Well, this is a great example. Just assume the engineers designing the initial hook were not complete clueless idiots.
Deleted Comment
You have a hearsay, hindsight story (no offense to the author) that one person thought it wouldn't work.
And now we have a hindsight HN comment that they would have known it all along. I'm guessing the people who worked on it weren't idiots, though people seem to delight in supposing they are smarter than all the dumb people whose plans don't work out perfectly.
Who benefited? I assumed that while criticism is healthy, some calls for cancelling the aircraft were from adversaries. Easiest way to defeat the plane is to get Congress to kill it.
EG: The Future Combat System, RAH66 Comanche, The Airborne Laser, The Kinetic Interceptor, The Expeditionary Fighting Vehicle, etc...
They intend for there to be endless war, which is what these machines produce. It is the only thing they can be used for..
I wish I lived in a world where there's no need for any of this, but as far as I know, war is as old as the species.
Fighter planes are a significant export earner for the USA - it isn't just domestic demand.
Should we be taking steps to a more peaceful world that we aren't right now? Yes, very much so. However, unless you want to imitate the path of Tibet or Ukraine, then you better spend some money on guns and fighter jets.
Not spend very large sums of money on things piloted by 1-2 people that can end wars relatively quickly.
What does this mean? That the F-35C can only hook correctly when it lands very close to center? And what does "wire only" mean? Aren't all arrested landings on carriers "wire only"?
After this incident it was determined that we had fulfilled the intent of the test plan.
Also, instrumented aircraft capable of doing arrestments were in short supply: the program only had two of them, and we pushed one to its very limit.
Ok, so it was considered good enough? (This quote made it seem like the testing had failed and they were giving up: "The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments.)
Also, I still don't understand what wire-only arrestments are. Aren't all arrestments wire only?
Thanks.
that was a pleasant read
> https://twitter.com/the_engi_nerd/status/1758633498464952414 Labeling everything I could see in the cockpit > https://twitter.com/the_engi_nerd/status/1757243336941871159 a discussion of my primary job in flight test, aircraft instrumentation. > https://twitter.com/the_engi_nerd/status/1747803565987381495 riffing along with chapter one of "F35: From Concept to Cockpit", a compilation of papers written by Lockheed-Martin employees at the conclusion of F-35 system design/development.
I've worked in healthcare, fintech, and ads and this is one thing I've done in all three fields. I swear i've written or debugged XML parsers in 20 different languages at this point just so I didn't have to get consensus on a new format.
Since leaving the government to work at various software startups, I miss real world engineering like this.
I believe what I do now is important, but getting an issue past test and into the release that's sent to customers isn't nearly as satisfying as "I fixed the tailhook last night, which let today's flight test happen". I miss having an aircraft that I can touch.
I'm joking, of course.