# WW II production and engineering cost

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##### Well-Known Member
Most interesting link if you haven't seen it before:
British Production Costs
American Production Costs

I'm not that surprised by the building time for a Spitfire or Lancaster. What's most interesting though are the hours put in engineering. All too often we hear that "in the past they didn't do all that fancy math and just build a good plane". Well, over half a million hours on design alone halfway the war for the Spitfire.

"When Rolls Royce brought over the Merlin blueprints, the American officer who's job was to bring it to Washington thought he would be able to fit it into a briefcase and carry it to Washington. The British escort just shook his head, and pointed towards a couple of crates. Two tons of paperwork"

#### Marc Bourget

The program for the Golden State Airshow two years ago gave the production costs of the various US WW-II aircraft. I think the contract cost for an end of the war P-38 was $40K and a P-51 around$15K. A B-17 might have been $105K, But this is from memory only and I'm well in to the age range of CRS disease. Looked for the program, but I may have tossed it. FWIW #### RJW ##### Well-Known Member It’s hard to imagine that it took longer to build a Spitfire than a Hurricane. I guess the time it takes to pound 40 or 50 thousand rivets really adds up. Sobering info for the guy who wants to build a replica warbird in his garage. Rob #### fly2kads ##### Well-Known Member HBA Supporter Impressive investment considering the short life expectancy of fighting equipment. i recall a passage from a memoir of a German engineer (Kurt Tank, I think), from a book review. The gist of it was that he knew Germany was going to lose the war when he inspected the disassembled engine of a captured P-47. He knew they could not compete with a country that could afford to put such meticulous machining in an essentially disposable engine. #### Aircar ##### Banned The production cost of the B24 built by Ford at Willow Run would be of interest since they re engineered the aircraft production more along automotive lines -- one aircraft was rolling off the line around every hour from what I recall reading . The shape of the learning curve and it's effect on price is shown by the P38 figures --and the volumes are 'only' around the 10 000 total figure --compared to up to 20 000 000 in cars of a single model eg VW beetle Golf Model T etc . The most produced single design aircraft was something like 47000 for the Cessna 172 and a Russian Policarpov WW2 -- the number of aircraft prototypes that were not produced in any numbers is far higher than in the car field also . Depending on handbuilt homebuilts where often the builder is also learning the skills for the first time is thus just about the least efficient route to cheap flying machines (in time costed terms) and hand finished moldless composite is at the top of the hand hours scale -- metal construction is more amenable to trading machine hours for man hours and with bonding can be much less labour intensive . I toured the GippsAero factory a few weeks ago -building the GA 8 8 seat utility aircraft and was told they use 4000 hours -they were taken over by an Indian conglomerate to keep going though and the composite Cirrus was taken over by the Chinese similarly -- volume production and volume techniques are the key to getting affordable and viable costs yet the miniscule light aircraft market is fragmented into dozens of essentially similar products. The most revolutionary advance in light aviation will be from price reduction rather than slightly more speed or styling although the lesson of mass production is that expensive tooling is needed to cut manufacturing costs and also allows sophisticated shapes (look at the smoothness and shapeliness of a car body compared to a light airplane and compare the prices as well ) #### Aircar ##### Banned Not sure what the moral is but the P51 was supposedly built from design specification to first flight in 120 DAYS --probably some caveats on this figure and no idea how many engineers and tradesmen were involved but it is astonishing . One story goes that Curtiss had conducted an extensive study of a new fighter and was committed to building transports and sold the design information to North American so had a "head start" --the British provided the research for the low drag Meredith duct cooling system as well --given the huge development times on new aircraft now (HITC excepted:gig: ), it is hard to see how computer design has reduced development times since the WW2 or or even the 1950s and the Lockheed Skunk works rapid prototyping -- the Rutan/SCALED development man hours would also be of interest (they had 177 staff last I looked ) #### wsimpso1 ##### Super Moderator Staff member Log Member Some corrections... Well known numbers for a P-51D ready to go to war was$56k, complete. Remember that North American built them with specified source hardware that was included in that price. That included a Packard built Merlin (and the generous royalty check that helped keep the British Empire afloat), the propeller, six M-2 machine guns, radios, the reflector gunsight, and a mandatory amount of flight test and gun sighting. Now maybe the airframe itself cost \$15k to build, but there is a bunch of other industry in the rest of the airplane, and you have to include all of that too.

B-17's and B-24's in the first year of the Eighth Air Force's prosecution were north of one million 1943 dollars. Same issues as the Mustang. Engines, all of those M-2's in their gun turrets, bomb sight, radio and navigation gear, engines, props. Each airplane had a bunch of industry in it that was not built in the airplane factory. Then there is the cost of flight test, gun zeroing, etc.

And the Hurricane being less costly to build than the Spitfire - that was only part of why to build both. Geez. Britain knew that they needed modern fighters, and a bunch of them. At the time of the selections, both airplanes used the same prop and engine (by edict) and the Spit only slightly outperformed the Hurry. But the Hurry was less expensive, used a lot less strategic materials, and most of the manpower that would be needed came from the furniture industry already trained, while Supermarine was going to have train huge numbers of folks in aluminum fabrication. Think about it, the country had to arm in a hurry, and airplanes were just part of the deal. The Spit took a lot of nearly precious aluminum and huge man hours to first build the tools and then to stamp out all of the parts and jig them, rivet them up into assemblies, and many of the structures were ridiculous fabrications. The Hurry had a fuselage of mild steel tubing, simple wooden parts and either thin plywood skins or fabric skins. Much of the wing was also wood. Many airfame parts could be farmed out to small furniture building companies all over Britain and Scotland to further smooth the supply situation. The tooling was simpler and less complex, and it all could be changed easily too. In the end the RAF knew that they needed a lot of airplanes, and deciding to buy both meant a lot more airplanes sooner. Damned good strategy it was too, as they only barely had enough fighters by the summer of 1940, when both airplanes proved to be an adequate radar guided tool for gutting the Luftwaffe.

The really surprising one to me on AR's list is the small arms. There must be some mistake. I can understand 5 hours for an M-1 Rifle. It is a bunch of parts, some kind of fancy. Fascinating to strip and re-assemble. But the Enfield rifle being five times that much? The British had been building it since 1888. Well, maybe they were so proud of it that allowing huge hours to build one was acceptable.

Billski

#### Georden

##### Well-Known Member
Wikipedia says the hurricane airframe was heavily based on the Hawker fury biplane, thus making the transition to hurricane production much smoother as the workers were already familiar with the construction methods.

#### Marc Bourget

##### Well-Known Member
I was privileged to attend a meeting of Chap 7 EAA in the early 70's where Edgar Schmud, chief designer of the P-51, gave a talk.

Sat next to a guy who was an electrical engineer and designed the avionics at North American. His whispered comments really fleshed out Mr. Schmud's story.

I recall that the aircraft was designed in 90-91 days. I guess it took 30 days to tool it up and make the first copy.

mjb

#### Battson

##### Well-Known Member
It’s hard to imagine that it took longer to build a Spitfire than a Hurricane. I guess the time it takes to pound 40 or 50 thousand rivets really adds up.
I though that's the whole reason they were so plentiful, successful, and basically won the battle or Britian - they were easier/faster to produce and repair than a Spitfire's metal body.

#### PTAirco

##### Well-Known Member
Some corrections...

And the Hurricane being less costly to build than the Spitfire - that was only part of why to build both. Geez. Britain knew that they needed modern fighters, and a bunch of them. At the time of the selections, both airplanes used the same prop and engine (by edict) and the Spit only slightly outperformed the Hurry. But the Hurry was less expensive, used a lot less strategic materials, and most of the manpower that would be needed came from the furniture industry already trained,

The Hurry had a fuselage of mild steel tubing, simple wooden parts and either thin plywood skins or fabric skins. Much of the wing was also wood. Many airfame parts could be farmed out to small furniture building companies all over Britain and Scotland to further smooth the supply situation. The tooling was simpler and less complex, and it all could be changed easily too. In the end the RAF knew that they needed a lot of airplanes, and deciding to buy both meant a lot more airplanes sooner. Damned good strategy it was too, as they only barely had enough fighters by the summer of 1940, when both airplanes proved to be an adequate radar guided tool for gutting the Luftwaffe.
Have to be pedantic again and make some corrections: The Hurricane fuselage was not made of mild steel tubing; it used all kinds of high strength, high carbon tubes, many roll-formed into octagonal tube shapes. There was no welding to speak of. All tubes were joined with various fittings, some machined, some simple stampings.

The only wood in the fuselage was stringers on plywood fairings to give it shape - none of it was structural.

And the wing was all- metal; no wood was used in its construction. The prototype was partially fabric covered, but all production models were metal skinned over spars made of the same high-strength, roll-formed tubing. The tooling was actually pretty complex, but the point was, Hawker already was set up for this type of construction for several years - their biplanes used the same technique. Hence it was a relatively simple affair to build Hurricanes, very little had to be added to the production lines. Strategically it was a right move; it provided an immediate good supply of an adequate fighter while others were working on the next generation of designs.

The furniture industry did play a big part in Britain, especially when the Mosquito came along, but also for a lot second-line aircraft and trainers like the Airspeed Oxford and Avro Ansons etc. But not so much for the Hurricane.

In general, British engineering at the time placed quality and performance above cost and time, but during the war became much more pragmatic in its approach.

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#### Aircar

##### Banned
Just to second PTAirco on the steel used in Hawker aircraft --it was high tensile and referred to as "1025" -- sometimes as '50ton' quolloqiaully (you know what I mean ..) -I guess 100,000 psi . There was an old warehouse full of second world war surplus run by two old bachelors who had a treasure trove of original instruments,wheels and engines materials etc in the north of Melbourne in the 80s - we bought two RAF target towing winches from them to convert a couple of Pipers for towing gunnery targets for the NAVY (ship or shore to air ) They were extremely paranoid about guarding their horde and who got to go inside --we called them Heckle and Jekyl (after the cartoon crows) but must be long gone by now.

I had a Hawker Demon under reconstruction in my workshop --free space in return for the use of a lathe and mill --and got to see the fuselage in detail (this one used the original stainless steel 'fishplates' and some 'new' tubing from the secret stash --the internal bracing wires and turnbuckles , hollow rivets and bolted splices etc etc were impressive but must have taken hordes of hours )

On the P51 development time I looked it up and it seems it was about 8 months from the notional start till 1st flight --25 Feb 1940 to 26 Oct 1940 --with various signings and contract dates in between and still some vagueness about Curtiss' role in the design studies that preceded it.

On the subject of masses of paperwork I can reccomend as a good read James Follet's "Mirage" which is "faction" - a fictionalized account of how the Israeli government got hold of the complete production drawings for the Dassault Mirage and the ATAR engine -- not to spoil the story but it seems that all the drawings could barely fit in a VW Kombi Van ....

#### Dana

##### Super Moderator
Staff member
Just to second PTAirco on the steel used in Hawker aircraft --it was high tensile and referred to as "1025" -- sometimes as '50ton' quolloqiaully (you know what I mean ..) -I guess 100,000 psi .
Unless you mean "1025" under some entirely different numbering system, 1025 steel is hardly "high tensile"; it's more like 55,000 psi.

I'm sure part of the Mustang's fast development time was due to extremely motivated workers... given the state of the world at that moment...

-Dana

We never really grow up, we only learn how to act in public.

#### PTAirco

##### Well-Known Member
Here is a definitive list of steel used in British aircraft during the 30s and 40s, for those of you who like this kind of stuff:

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#### Battson

##### Well-Known Member
I guess it makes sense that the fuse wasn't welded steel - that would be very hard to repair quickly when arriving back at base full of bullet holes. It was probably faster / easier to knock out pins/bolts and replace tube sections with no hot-work involved.

#### wsimpso1

##### Super Moderator
Staff member
Log Member
Hmm, we seem to have caught something that I remember wrong on the joints. When I think about my viewing of the Smithsonian's Hurricane being rebuilt (at the Paul Garber facility in the early 1990's), I never did see the fuselage naked, but i did see plenty of tubes through places where covers were not in place. Another airplane must have impressed me with its welded construction.

I did see the plywood formers/ribs/etc supporting plywood covering the forward fuselage and front portions of wing, and conventional fabric covering everything. Linen was being applied to be completely authentic. And the control surfaces, like many of the WWII airplanes, were definitely fabric covered. Then there fabricated wooden pieces for everything from turtledeck and cockpit fairings to inspection panels to faired doors for access to all sorts of stuff. A lot of wood and fabric was in places where the Spitfire was aluminum. I saw the turtledeck after they opened the wooden box dated with a month and year from the war (don't remember which year). Both the inside of the crate and the turtledeck smelled of wood chips and glue. Amazing. There were formers fore and aft and wood strips longitudenally. This was all attached to the steel tube fuselage and then the restorers covered it with linen and dope too.

Anyway, there was little aluminum and a lot of wood and fabric in the bird.

Billski

##### Well-Known Member
If I recall correctly (I don't recall the source I'm citing), the long build-times for British aircraft reflected the industrial attitude of the time. With the Depression still on their minds and probably advocated by worker unions, British aerospace products were, quite frankly designed, to keep as many people employed as possible.

I think this attitude is reflected by how long it took the British to embrace welding. Although it may have been that they just didn't trust the strength of the process, riveting a steel frame (like with Hurricane fuselage shown above) keep more people employed because it was way more labor intensive.

Although the British Production page doesn't show the progression of man hours needed to build an airframe as the war went on, Building Spitfires, Slowly | The Daily Planet other sources seem to imply that it didn't go down by much. Assuming 15k hours for the Mk1 and 13k hours for the MkV (as stated in the blog above).

In contrast, I think the most comparable airframes to the Spitfire (in terms of geometry and mission) are the P-47 (because of its elliptical wings) and the Bf-109. The P-47, as indicated by the American Production Cost page, took around 9600 hours to make and managed to cut down around 500 hours by the end of the war. The Messerschmitt started off with build times resembling that of the Spitfire at 12000 hours and was able to reduce it by a whopping 6 times to around 2000 hours. Granted, the quality of the German fighter was abysmal by that time, but it can clearly be seen that this was a production compromise in order to deal with their severe fighter shortage. The P-51, perhaps the closest to the Bf-109 and Spitfire in terms of weight and complexity, started off at 12,000 man hours and ended up at barely over 2000 hours at the end of the war.

So with these numbers in mind, I think what is implied is that American and German aircraft were gradually optimized for extreme producibility while British aircraft manufacturers never let go of the artisan mindset that aircraft should be constructed by highly skilled craftsman. There's nothing wrong with that, as evidenced with the British having some of the finest combat aircraft ever constructed at the end of the war, other than being forced to slowly build up numbers.

I think when you look at quality, producibility, and performance of aircraft during the World War II, its hard to hold a candle to American wartime production. The British had quality and performance, as evidenced by extremely effective aircraft such as the Spitfire, Mosquito, and Tempest. The Germans had performance and producibility, epitomized by the late mark Bf-109G-K. The Russians had extreme producibility and decent to good performing aircraft at the end like the Yak and MiG series, though their stuff was clearly not designed to last.

Thoughts?

##### Well-Known Member
Thoughts?
Mostly surprise that none of the mentioned aircraft were particularly optimized for fast/efficient production.

Except for the Mosquito, I can't think of any (important) airframe that had the problems of fast production and rare resources as a priority?

#### PTAirco

##### Well-Known Member
Mostly surprise that none of the mentioned aircraft were particularly optimized for fast/efficient production.

Except for the Mosquito, I can't think of any (important) airframe that had the problems of fast production and rare resources as a priority?

The Messerschmitt 262 used large amounts of steel which was in much greater supply than aluminium in Germany. By the time it was produced, this was obviously a major concern. The Heinkel 162 Volksjäger was another example deigned to use mostly wood. The 109 ended up with wooden tailplanes as aluminium became scare and scarcer.

There was a British single seat fighter prototype, the Miles M20, also designed for fast production with minimum use of strategic materials. Wood wings and partially wooded fuselage, with some welded steel tube structure and a Merlin. All put together in little over two months.

Had the war dragged on for a few more years, many of these ideas would probably have been used more extensively. Although by the end of the war one would think Germany's supply of aluminium should have been increasing by salvaging all the shot down allied aircraft! They didn't lose a lot of their own abroad any more by that time.

#### Topaz

##### Super Moderator
Staff member
Log Member
...Except for the Mosquito, I can't think of any (important) airframe that had the problems of fast production and rare resources as a priority?
PT beat me to some good examples, but pretty much every German WWII aircraft design after 1942 was designed to minimize the use of 'strategic materials' - in other words, anything that was useful but becoming scarce, either because of limited supply or the supply lines being disrupted by Allied activity.

Aside from the examples PT gave, there are other, more extreme ones:

The Ba-349 "Natter" - A rocket-powered semi-expendable vertical-launch point-defense interceptor with an all-wood airframe, that was actually starting production in cabinet- and piano-maker shops across Germany when the war ended.

The Go-229 flying wing jet fighter - Plywood-covered steel-tube center section structure, all-wood wings.

The Lippisch P.13a - A mostly-wood delta-winged supersonic interceptor powered by a ramjet burning granulated coal. Conventional fuels were becoming very scarce, but coal was plentiful.

And so on. The Volksjäger and Miniature Fighter designs - of which the He-162, as the winning contender of the Volksjäger competition, is the most famous, were all designed for a minimum use of aluminum and other strategic materials. Whether these aircraft were "important" depends on how you define importance. None had any significant effect on the war, but they were all significant designs from an engineering standpoint. The He-162 was the first purpose-built single-engine jet fighter to fly, for example, and certainly the first to enter combat. You could also say it was the first "light" jet fighter, of which the F-16 and F-35 are modern examples.

The Germans were the most ardent about this work, since their production capacity and supply lines from mid-war onwards were being heavily disrupted. The British also looked at this type of thing, but they had a huge convoy "pipeline" of ships carrying equipment and raw material across the Atlantic from the USA, and by mid-war the U-boat threat was beginning to be reduced.

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