Testing the F-35C Tailhook
the-engi-nerd.github.io
the-engi-nerd.github.io
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.
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.
Too often in the land of software we underestimate the potential negative impact the traditional "move fast and break things" approach to product development can have when it comes to real world use in mission critical systems.
Move fast and break things brings you to the Moon in a decade using primitive tech, where is total process compliance can't do that even in 50 years using much more advanced tech.
It's also quite important to remember how many lives were lost (or nearly lost) because of "breaking things" in the Apollo program. Something that's not nearly as acceptable today than it was at the height of the cold war. Something that directly implies moving more slowly and being more sure that everything works the first time, every time.
It can and did happen again, twice, on the shuttle project. Both the O rings and the ice damage were documented.
Ultimately, any process (or lack of process) can be subverted by a bad culture. And unreasonably excessive process - as perceived by the participants - can damage culture as much as not enough.
The problem is that culture is ineffable, so we try to nail it to the ground with whatever we can think of.
move fast and break things worked real well for the folks who got literally creamed while they were viewing the titanic.
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 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.“
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.
If your project started 30 years ago, that means DOS, or Network or maybe one of the IBM behemoths?
Then the maintenance includes pacing OS updates and dependency changes?
In the 10 years after release that I was on that project, we went through multiple OS upgrades from Windows NT to XP Embedded, to Windows Embedded Industry (replacement for XP Embedded) and a number of replacement x86 CPU boards had to be qualified as one manufacturer after another exited the market. Since the device is validated as a complete system, we often had to buy a year or two stockpile of existing product to give us time to start the Validation process for replacement hardware.
You usually have plenty of warning from a supplier that a product (Windows or a CPU board) is going EOL at a certain point, so you need to start validating whatever the next replacement will be well ahead of time.
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.
Again, maybe not enough to really matter, but enough to at least take into consideration.
Since the relative speed of the aircraft to the ship will be reduced.
Or are all of those tail hooks bespoke designs because reasons?
As far as the little lip at the very tip of the hook- it looks to me like the initial design was trying to minimize any risk of digging into the flight deck and causing damage- this is just a guess though.
The next morning I went up on the flight deck before flight ops started and walked to the aft edge of the deck. I was looking for something and found it.
About one foot from the end, there was a single, shiny, brand new, solitary hook imprint in the deck.”
Each plane costs ~$100 million and the entire program will cost over $1 trillion when it's done. Performance needs are extreme: They need to land in all sorts of adverse, imperfect conditions - damage to the plane, the carrier, the wire, the personnel; bad weather; bullets and missiles flying around. It seems worthwhile to design the highest-performing tailhook for this plane, rather than to save a few bucks.
Also, IME people doing something this sophisticated don't miss those really simple, obvious issues that we happen to be able to observe and grasp from the outside.
The model provided by -the manufacturer- correction NAVAIR (thanks OP!), stated that the cable will bounce up after having been hit by the landing gear. Thus the hook design made sense. The cable jumps up and over the hook. Plane arrested.
Instead, again as the article states, the cable is actually being pressed tightly against the flight deck and the elevated hook nose makes the entire hook get thrown up in the air when drawn over the tight cable, back towards the plane and would even destroy some parts of the monitoring mechanisms, so violently did that happen.
They also provide the new design, which is basically the old design and that is also why the techs that saw the new hook for the very first time (and know about the cable I presume) instantly said "That ain't gonna work!".
It's all in there.
I would actually love to know if someone on the hook design team questioned the model. I guess we won't know but I also it doesn't hurt to ask.
Like did someone go: odd, why would that cable go up and not tighten when waves are sent through it towards the outward attachments? But was inevitably shut down and didn't have "access to the customer" to ask/verify.
Like one of the first things to ask for when having to design this that comes to my mind is: I want high speed camera footage of current arrestor in action at the customer site!
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
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.
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".
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.
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.
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.
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...
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.
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.
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.
Since you're the author: can you remember any cases where the person with "common sense" thought "this crap ain't gonna work" but it worked anyway? Surely people only remember those cases when common sense won, and selectively forget those where it didn't?
I have one! Totally different field though. Cruise ships (and roro ferries) look sooo ungainly in water that regular people frequently ask how do they not just roll over. The Icon of the Seas goes 9 meter underwater and 20 stories over the water. It does not feel or look right. Yet it is right, and keeps upright :), because it does not have uniform density. The engines and machinery, and tanks at the bottom of it keeps the center of gravity low enough to make it stable.
The funny twist is that vehicle carrier ships also look unstable the same way and there the intuition is more correct. There have been multiple accidents where such ships capsized. But the intuition there is still not correct about the reasons why they flip over. (It is not that they don’t have enough draft, but due to free surface effects and the cargo destabilising).
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.
They intend for there to be endless war, which is what these machines produce. It is the only thing they can be used for..
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.
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.
Not spend very large sums of money on things piloted by 1-2 people that can end wars relatively quickly.
>Canada expects to receive its first four F-35As beginning in 2026, another six in 2027, and six more in 2028, with the full fleet to arrive in time to enable the phase out of the CF-18s by the end of 2032. But its CF-18 fleet, even bolstered by the purchase of 18 ex-Royal Australian Air Force F/A-18A-Bs, may not be able to effectively hang on until then.
They wasted a lot of time and money setting up supply chains and training pipelines for a fleet of near-end-of-life airframes that required constant maintenance, provide only the bare minimum capabilities and won't end up in service for very long. And they're having so many retention issues with their pilots that even that is wasted.
Now Canada has bigger problems and needs to better interoperate with NATO allies. Many countries switched their plans to F-35's after Russia invaded Ukraine.
So there was no point at all, we could've just bought actual replacements (f-35 or not) that would last for an entire generation back in 2p15. But hey, problem solved for the current government so who cares about what happens in 10 years! But then the issue got too big and we ended up circling back to buying the exact same f-35 that we wanted to have for the past 20 years. Just with a worse deal and even more clapped out f18 and pilot accidents.
So a couple old multi-role fighters are sort of okay for what they are doing. Mostly air to ground missions and demonstration flights. They need to up their defense spending a bit to meet NATO obligations, but not that much honestly. No one is going to kick out Canada, especially after the USA dragged them into Iraq.
That makes the mistake in not buying the F-35 the first time around all the worse.
>especially after the USA dragged them into Iraq
This is so not right, it's not even wrong.
[0] https://www.defensenews.com/industry/2022/11/18/f-35-costs-h...
I've heard this argument before about Canada's F-35 saga and it is now what it was then, massive copium overdose. By this logic Canada ought to wait until the F-35 is obsolete and other nations are selling airframes off for cheap.
That Canada did not have to use its air force in war during the Trudeau years does not mean that its 100% politically driven decision to shirk on the F-35 buy, then jump back on it again, was not a mistake.
Shimooka has a number of works chronicling the Canadian F-35 decision making process, e.g. https://macdonaldlaurier.ca/assessing-damage-canadas-fighter...
Billie Flynn discussing the F-35 and the current state of the CAF on "The Merge" podcast: https://youtu.be/kibWNHr9hdg
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...
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.
I suppose that hard landing might have, in some ways, replicated the hard slam-down this would produce. Author, is that the case? Was the hard landing judged to have been a decent proxy for the wire-only arrestment?
I just don’t think anyone had the risk appetite to chance a test asset against a very difficult to achieve test point.
Program management does not take decisions like this by themselves.
Kind of both: it was too dangerous to test a wider range of parameters, and the testing was therefore "successful" because it was crystal clear that going beyond the point where they had the problem would not be safe. So in this case "giving up"/stopping and "determining the limits of the landing envelope, were reached at the same time.
Based on other comments (or re-reading the authors comment carefully), it turns out that "wire only" mean that the wire catches before the wheels touch the ground. (This puts additional strain on the wire and airframe.)
There are brakes on the wheels (that can slow a plane moving at flying speed)? That's a lot of force. I assumed the wheels merely prevent friction between the plane body and the deck, and the engines and control surfaces, and the wire, did the braking.
If the cross-deck pendant snaps, the engines don't have time to throttle up before you go over the edge. And of course if you don't catch a wire you really don't want to be trying to stop.
No reverse thrust in carrier aircraft.
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.
IRIG 106, Chapter 4 PCM telemetry covers what we were doing in this process, along with Chapter 9.
Sometimes it's just the path of least resistance to use what you already have.
I remember putting in a request to install Python. It took me 6 months to get a response of no. I had the opportunity to appeal with more information on the use case, but I just did it in VB for Excel at that point.
Granted, I've also seen a piece of software denied because it has USB in the name (even though it had nothing to do with USB), so YMMV.
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.
They can fit into the CMV-22B variant of the Osprey, which is grounded for now, and I believe the CH-53K King Stallion. But they those aircraft didn't exist until recently.
edit:
I meant to say that the C-2 couldn't carry F-35 engines in particular because they don't fit, not that they couldn't carry replacement engines in general.
First off, there are CTOL airplanes which can deliver replacement engines to aircraft, just not F-35 replacement engines (because of their large blade diameter). USN had previously used C-2 Greyhounds for these sorts of duties, but they have too small a fuselage, and were being decommissioned. There was talk of converting some decommissioned S-3B for COD, exchanging their fuselage for a wider one to accommodate the F135, but this was not pursued. https://archive.ph/20150209193642/http://www.defensenews.com...
Second, lots of helicopters can carry F-35 replacement engines, including the Boeing Sea Knight. https://en.wikipedia.org/wiki/Boeing_Vertol_CH-46_Sea_Knight I believe that the USN didn't want to depend on conventional helicopters because of their relatively short range.
Other helicopters could deliver replacements to the carriers, as you said, but the carrier would have to be relatively close to shore.
Other side note: the V-22 isn't pressurized, so they have to stay at a relatively low altitude.
The lack of ability to do it during a "Real War" means that if the engine has problems, that fighter is now sitting in the hangar useless, except for parts to cannibalize.
In terms of the F-35 engines they under-speced them, so they have to run twice as hot[0] to cool the electronics:
"The original program engine specification allocated 15 kW [kilowatts] of bleed air extraction to support system cooling requirements, and the F135 engine was designed, tested, and qualified to this specification with a level of margin available for future growth," Schmidt wrote. "During the final stages of initial aircraft development, air vehicle cooling requirements grew to exceed planned bleed air extraction."
"To provide the necessary bleed air, the engine is required to run hotter, and the program is realizing the effects of this through an increase in operating temperature, and a decrease in engine life, which is driving earlier depot inductions and an increase in lifecycle cost,"[1][2]
[0] https://www.defenseone.com/threats/2023/03/f-35s-need-more-p...
[1] https://www.twz.com/f-35-engine-running-too-hot-due-to-under...
[2]https://www.pogo.org/newsletters/the-bunker/the-bunker-hardw...
If it has problems severe enough that the engine can't be repaired and must be replaced, and they don't have sufficient replacement stock, yes. But what I was trying to get at with my question about replacing the wing is that having an aircraft return to the carrier damaged severely enough that it's unflyable and unrepairable must be a somewhat routine/normal occurrence during "real war". (Of course the more you can repair while underway the better, all else being equal).
A whole wing replacement, I'm actually not sure but it wouldn't surprise me at all.
You might not see a port for nine months or a year -- that's not an acceptable amount of time to just have a plane or multiple planes down waiting on parts that are available. There's no way to get them off the ship other than a crane pierside if they can't fly.
The entire reason for the switch from the C-2 to the MV-22 for Carrier resupply was to be able to bring an F35 engine replacement aboard.
Does that mean that manufacturers don’t field test the hardware? If so, that is scary.
[0] The F-35B _can_ take off vertically, but it can't do so with any reasonable weapons or fuel load.
[1] Many non-Navy planes have tailhooks to work with emergency arresting wire systems at Air Force bases, but those are for emergencies and are rarely used, whereas the Navy uses tailhooks all day every day
The C is meant to do carrier takeoffs and landings. Landing on a carrier the traditional way is more reliable than trying to land vertically every time.