Why so long to make a fighter jet?

Inspired by this thread, in which the claimed maximum possible production rate of modern fighter aircraft is a tiny fraction of what it was during WW2.

Why is this? The US population now is more than twice what it was in WW2, and presumably has a comparable degree of general industrialization. Is it just a matter of not as much floor space and personnel devoted to the task?

Given that aircraft designs are already established and production tooling requirements are already known, could we not quickly build/tool new factories to jack up the production rate?

Or does it really and truly take longer for any given modern aircraft to go from “raw materials” to “airborne?” Is it the complexity of construction of the airframe? The avionics? The engine(s)?

The same reason it takes so much longer to make a modern car than it did to make a Model T Ford. A Model T Ford took about 90 minutes to go through the production line, while a modern car takes about 18-24 hours.

The reason is simply the increased level of complexity.

Modern fighter aircraft are orders of magnitude more complex than those used in WWII.

WW2 aircraft were simple machines, sometime and engine with wings and guns attached to them. Modern planes are near magical technical sophistication, made of exotic materials, with radar (rare in WW2) avionics and sensors, running on millions of lines of software, capable of far more than what could be dreamed in WW2, datalinks, jet engines, weapons suite…

Indeed it’s not much of an exaggeration to say the difference between WW2 P51and modern planes like Block 52 F16 is like the difference between an artillery rocket and the Saturn V.

I suspect however, that if the manufacturers wanted to (i.e. were sufficiently incentivized), they could speed that time up quite a bit.

I mean, right now they’re delivering according to a peacetime schedule, and so are their suppliers. But if the government said “We want new fighters as fast as you can produce them,and cost is no object”, they could probably shave a whole lot off of that time through various methods.

In other words, the complexity is indeed a whole lot greater, but there’s also no evidence that the pace at which the planes are being delivered is constrained by it. For all we know, not everyone in the supply chain is necessarily working three shifts and/or shipping things as fast as possible. Simple stuff like that could make a big difference.

One of the big issues is what are called “long lead time” parts. There are large castings that are sort of the backbone of a jet. They take months to make. They’re made of materials that themselves must be ordered months in advance because the capacity of the entire mining-to-refining chain for that metal is capacity constrained.

The big thing to consider is this:

Can 9 women working together make a baby in 1 month? No.

If one man can erect a 100sf garden shed in a day, can 100 men erect a 10,000SF warehouse in a day? Can 10,000 men erect a 1,000,000sf skyscraper in a day? The answers are “No!” and “Hell No!!”

We’re now building the aerial equivalent of skscrapers. There are just a couple aircraft factories with the relevant tools and skills. There are only a couple of tool factories with the tools and skills to build the tools for the aircraft factory. There are just a couple of tool tool factories with the tools and skills to build the tools to build the tools. etc.

To do a production ramp-up you need to start several layers back in the tool chain. The same thing applies to the parts supply chain. Both of which eventually lead back into the raw materials chain. And the skilled personnel chain.

Assembling iPads and such is fairly easy. Because they’re made by the million they’re designed, and their factories are designed, to use relatively few manhours per item, and most of that is fairly low-skilled.

Because fighter aircraft are built by the onesy-twosy, they’re designed to be built with lots of hand-work. Skilled handwork, smart tool-assisted handwork, but handwork nonetheless.

Boeing in the last 10 years has gone through a real revolution in trying to drive man-hours out of airliner construction. With some success. But they’re making a 737 every 18 hours. At it’s peak, General Dynamics was making one F-16 every 4 days. The highest rate expected for the F-35 is about one every 8 days.
If you consider the tooling industry, their production rates are glacial compared to the already slow aircraft production rates. How many 50 foot autoclaves or laser alignment devices do they sell to equip those factories? A handful per decade.

Isn’t that a pretty new phenomenon, though? Until the current generation of aircraft and their reliance on composite structural elements, even fighters were built out of relatively small sections riveted together. Though I suppose wing spars were still pretty big.

bear in mind that once we decided to go all-in on WWII, much of commercial manufacturing was re-purposed to make military hardware. Chrysler stopped building cars and started making tanks, Packard stopped making cars and started making license-built Rolls-Royce fighter plane engines, etc. International Harvester stopped making agricultural equipment and started cranking out rifles and other weapons, etc.

and to go along with that, the military machines they were making were still conceptually similar enough to what they were already making such that they could get up to speed quickly. Packard was already making piston-engined vehicles, so it wasn’t a stretch for them to start making larger V12 piston engines.

nowadays so much of our manufacturing has specialized to the point where it would take forever to get e.g. Ford to stop building F-150s and start cranking out F-35s.

As stated, the complexity of modern fighter aircraft is orders of magnitude greater than a WWII aircraft, on basically every level. Just some examples and thoughts:

  1. The airframe is often made of materials that are specialty metals, like titanium, or otherwise made by complex milling or forging processes. Take a look at this F-35 bulkhead. Compare that to a few pictures of the guts of a P-51, especially the first two with the airplane stripped down and in a jig.

  2. Making things efficiently means not having excess tooling or infrastructure for what you need to build at the rate you’re expected. Lockheed or whomever isn’t going to have huge amounts of tooling that isn’t being used to optimal capacity for the production rate, just sitting around waiting for the production rate to increase. The machines that make these big aluminum bulkheads (and other really complex structures) are big, expensive, not fast, and require lots of materials to be delivered at the right time. If you need, say, five machine tools to build enough bulkheads to deliver on-time to support a production rate of 100 aircraft per year, nobody is going to pay to have five more of those multi-million dollar machines just sitting around in case you want to start building 100 per year on the drop of a hat. That’s wasted money invested in overcapacity.

Similarly, no aircraft manufacturer in their right mind is going to invest in having a sitting stock of huge pieces of metal that they can’t charge to their customer. You aren’t just going to buy a whole bunch of $50,000 pieces of titanium to have them sit around in a warehouse if you don’t have firm orders for the aircraft they may eventually build.

  1. The electronics and engines are a similar story. You don’t go down to the store and buy an AESA radar: you gotta get the fancy materials like, gallium nitride, make the circuits, make the antenna, integrate those pieces, deliver to the factory for final assembly, etc. The supply chains for these things can be very, very complex, so it is not unusual to have a dime holding up a dollar.

  2. There is the potential that additive manufacturing could, over time, make significant improvements to the efficiency of building such complex machines. There’s a joke about most of aircraft manufacturing being about drilling holes, because there’s simply thousands upon thousands of things that need to be attached to each other, and the touch labor involved simply takes time to drill the hole to connect two pieces so that they can snap together somehow. As additive manufacturing technology progresses, not only can you make the finished product of, say, that aluminum bulkhead in a lot less time, you can also save a lot on materials because you don’t need to start with a huge block of aluminum and eliminate what you don’t need. Then imagine that the bulkhead comes with all the holes in the proper places so you don’t need to have a person touch that huge thing dozens to hundreds of times, each with a tiny risk of screwing something up. There’s already been significant advances in this area, but we’re really only at the beginning of what additive manufacturing could do.

For reference sake, if the government orders a full year’s worth of F-35 production today, including the time it takes to order long-lead materials, the first of that batch will deliver roughly two years from today, and the last of that batch will deliver roughly three years from today.

I would think the avionics would be at least as much a bottleneck as structural elements although I admit I may be wrong. For example, an AESA must be quite something to build in terms of exotic materials and assembly and they’re presumably extensively individually tested.

When it comes to non-avionics, do I take it that this is usually because the material needs to cure/change at a molecular level once applied or have to be applied in successive layers? Like, say, fiberglass or RAM paint?

Good answers but just on a first order level look at the costs. Say the ‘fly away cost’ (IOW without counting research and development costs) of the modern fighter is $100mil as a round number. Expensive WWII fighters cost order of $100k, for example $134k for the big twin engine P-38 in 1939-41 procurement. Costs when down significantly at higher production rates as the war went on (the P-51 several mentioned was around $50k by 1945), and this is another variable since even 39-41 is war time ramp up, whereas now we’re talking peacetime. OTOH fighters of the 1930’s produced in true peacetime conditions at lower rates were smaller and less complicated still than WWII fighters.

Anyway, take $100k and $100mil to avoid false precision, 1000 times more in nominal terms, the CPI was around 17 times higher in Jan 2016 than Jan 1940, so in ‘real’ terms 59 times more expensive. Of course we’d also have to correct for general and specific changes in productivity, as well as the technical specifics of materials and processes, plus the emergence of avionics as a major category alongside air frame and engine, as other posts have. But just on a top line cost basis a modern fighter is clearly a much bigger economic undertaking per unit.

I’m not aware of this being an issue. Why would it take a long time (like, I assume you mean weeks/months?) to cure paint in the factory when aircraft will have to go maintenance and painting throughout its lifetime – and you’re not about to take aircraft out of action for similarly long periods of time for paint.

Most of the long-lead parts are large hunks of plain old metal. Usually titanium.

The issue is that it can take a month of trying just to cast a big billet perfectly with no voids.

Then you chuck the billet up in a precision machining tool.

That may work 24/7 for a month or more just grinding off the material you don’t use to leave behind the shape you do. In some cases 90% of the raw material is scraped off. Then thrown away since it’s no longer aerospace quality. More precisely, it’s sold as aerospace scrap for barely 10 cents on the dollar of what it cost. Somebody buys the scrap, maybe remelts it, then uses it to make less fancy stuff.

A lot of this comes down to how we fight wars these days.

Back in the WWII days, we had very large numbers of fairly simple weapons. They cranked out guns and tanks and planes by the thousands, and thousands of men went into combat.

There’s a bit of a philosophical difference between the way that the US does things and the way the Russians do things. While both tend to have much lower numbers of much more high tech weapons, the US is focused on very small numbers of very high tech weapons, and Russians have much higher numbers of much simpler weapons. There’s a certain quality in quantity, as the old Russian saying goes.

With our focus being on very small numbers of very expensive and very high tech weapons, we can’t scale that up very easily or quickly.

In the past several decades, this strategy has worked very well. We haven’t been in any kind of all-out war like WWII, so we haven’t needed the huge numbers. Our high tech planes were able to completely destroy the Iraqi air force in a very short amount of time. In WWII, if you needed to take out a factory or a bridge, you sent hundreds of planes over that factory and carpet bombed it. Most of the bombs missed their target, but enough would hit close enough to take it out. These days, one plane with one or two well placed smart bombs can accomplish the same thing, with much less collateral damage.

There is a bit of a danger with this strategy, and the German King Tiger tank of WWII is the typical example given of why this can be a bad idea. The King Tiger was by just about every measure the best tank of the war. Put it face to face against a Sherman tank, and you could let the Sherman fire first if you wanted. The Sherman couldn’t penetrate the front armor of the Tiger. But the Tiger could easily put a shell in through the front and out through the back of the Sherman (which was very bad news for the crew and everything else inside it). The Russian tanks fared a bit better, but even they were under-gunned against the Tiger.

The problem was though that the Tiger was monstrously complex and very difficult to build. The Germans would have been much better off taking the same amount of manpower and making their less capable tanks with it. They would have been able to field a lot more of their “inferior” tanks and would have had a much better presence on the battlefield. The Tigers couldn’t be produced in large enough numbers to be useful on the battlefield. It took on average four Shermans to take out one Tiger, but we were cranking out ten Shermans to every Tiger. The Russian tanks were cranked out in huge numbers as well. The Tigers, despite their superiority, were simply outnumbered by staggering amounts. There was no way that the Tigers could win that fight.

The same sort of thing might happen if the US and China or the US and Russia went to war. We have the best weapons, but they are difficult to produce.

Many argue that an all-out war between us and China or Russia would likely end up nuclear, so our lack of producible weapons may not be that big of a deal after all.

One valid criticism of the stealth bomber though is that it is too expensive to risk using it in combat. They did use it a bit in the second Gulf war, but only when the risk was minimal.

I don’t know where you’re getting this, but the B-2 has been used in many conflicts, including Yugoslavia (1999), Afghanistan (2001), Iraq (2003), and Libya (2011).

Actually, Yugoslavia provides a good example, the rules of engagement were such that risk was minimised and effectiveness severely curtailed.

There is a very good chance that in a peer v peer war, modern planes will be like the Dreadnaughts of WW1, too precious to actually use.

I think this is a preposterous idea, as the only point of a stealth aircraft is to penetrate the air defenses of strategic competitors to attack things that cannot be attacked in other ways. I very much doubt that you’d find any credible sources that seriously believe that B-2s, F-22s, F-35s or similar advanced aircraft would not be used against peer competitors.

Everything is designed with a specific manufacturing process in mind. A chair designed to be hand-made by a craftsman looks very different from one that’s designed to be sold at Ikea and assembled with hand tools. A custom 1-off car may have a very different underlying structure than one designed to be manufactured in a fully automated factory.

Modern fighter jets are not designed to be mass-produced on an assembly line.

True, and the other thing to note is that production wasn’t instantaneously high overnight. Even though the mobilization started in 1940, most categories of war materiel didn’t reach maximum production until 1944.

If for some reason, the government placed wartime-style orders for lots of F-35s as fast as they could get them, they’d figure out a way to make them faster. Obviously not as fast as they cranked out P-51s in WWII, but almost certainly faster than they do today.

And it might take a while to get ramped up, but I’d be willing to bet they’d be able to drop the construction time per aircraft to something reasonable once they got rolling.

For various reasons we choose not to have million-man levees-en-masse anymore, so we don’t crank out planes in huge numbers, because we wouldn’t have the pilots to fly them if we did. We are much more selective about who we choose to fly these large chunks of taxpayers’ $$$.

More than selective is the fact that it takes a couple years to convert a newbie into a fighter pilot.

Despite considerable effort to quicken the process nobody anywhere on Earth has figured out how to do it much quicker & still produce a good product. That’s a real rate-limiting issue for ramping up the size of any tactical air force anywhere in the world.

Which is part of why DoD is so interested in autonomous air vehicles.