Sea fang vs Sea fury vs XP-72

GregP said:

Me 262 was 6,400 man-hours in the only place I found it.

P-47started off at 22,000 man-hours and fell to 9,600 man-hours by the end of the war.

I'd say the XP-72 was back up in the 20,000+ man-hour area because it was a prototype and not a production airframe, but I have never seen an actual man-hour number for it. Hand-built airplanes aren't quick to assemble.

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Greg,

Does that 6400 hours include slave labor? I'm not trying to stir the pot but am curious if the Germans counted slave labor hours.

Cheers,
Biff

Shortround6 said:

Immm, what was unit cost of the Me-262???

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Is that an answer to my question?

Man hours, are a rough estimate of airframe cost.

But airframe cost is not unit cost. Unit cost often includes power plant cost. Or includes armament costs.

And that is really simple accounting, once you are counting hundreds (thousands) of parts per airframe things can get complicated .

The cost of a Me262, with engines was about 107,000 RM.

I have not seen a unit cost for a MK108, but it was of simple design and would have cost less than comparable weapons.
The cost of the electronic equipment and related gear, I have no clue.

Hi Biff and Dedalos.

All I could find was one reference to man-hours for the Me 262, and it was many years back. I put it down in a spreadsheet.

You could equate the man-hours to labor costs, but the actual cost would also include material and management / overhead.

I have a Bf 109E at 7,900 man-hours and a cost of 68,340 U.S. Dollars. The cost includes labor and material and profit.

I have a B-17, for instance, in January 1943 at 35,400 man-hours and a costs of $204,370. A year later, the man-hours for the same aircraft were down to 18,600.

I do NOT have a breakdown of costs and hours for the entire war.

Clayton Magnet said:

I for one would love to see what could have been, if the Spitfire Mk.III had actually made it into service

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Me too.

Man hours to build is just as bad a metric for cost as £,$,RM. Without context it's a meaningless figure. Did the USAAC give a man hour figure covering everything from mining the Bauxite to polishing the windscreen with a Chamois ready for the pilot to step in and press the button. Did the German figure include slave labour and the cost of the engine. Did the British figure include fitting the teacup holder.

fastmongrel said:

Did the British figure include fitting the teacup holder.

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The bloody well did, by Jove

No.

Man-hours was and is the man hours required to build the airframe, exclusive of GFE (Government Furnished Equipment). Man-hours is a VERY GOOD yardstick of the difficulty in building an aircraft.

GregP said:

No.

Man-hours was and is the man hours required to build the airframe, exclusive of GFE (Government Furnished Equipment). Man-hours is a VERY GOOD yardstick of the difficulty in building an aircraft.

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Or perhaps the experience of the workers building them? The B-17 cutting build-time in half within a year seems to reflect at least in part a more-experienced workforce.

No it doesn't. It reflects a normal learning curve used by almost any manufacturer of man-made goods where manual labor is the main labor..

If you start at 35,400 hours and experience a 7.7% learning curve, you will be at 18,600 hours exactly 4,179 iterations of building a B-17. Not coincidentally, that's exactly how many B-17s were built in 1943.

The equation is: Y = a X^b, where Y = average time of the period measured, a = time to complete the first task, X = number of attempts completed, and b = the slope. For our example above, b = -.077; X = 4,179 B-17s built in 1943; a = 35,400 hours, and Y = 18,600 hours at the end of the attempts. The curve is NOT infinite. At some point, you get a minimum time and it bounces around a bit since workers are replaced when they quit, get sick, die, or get promoted, and they have to learn the process from scratch.

Standard manufacturing engineering.

Edit:
OK, technically, the above isn't quit right. The slope turns out to be the natural log of the learning percent over 100 divided by the natural log of 2. So, rather than a 7.7% learning curve, it's really a 94.79% learning curve. I forgot the "slope" is a composite term composed of a quotient of natural logs ... mostly because it is now in a spreadsheet. I just looked at the slope, when I said 7.7%, not the actual learning curve percentage.

My bad, but the result is the same for the manufacturing time. Most manufactured goods with manual labor experience anywhere from an 85% to 95% learning curve, or slope around -.077 give or take a bit. You might want to look up manufacturing learning curves.

GregP said:

Range: 1,200 mi

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That seems suspiciously high for a plane with a R-4360. It's hauling around a lot more weight (most of it in the engine I assume) and one imagines self-consumption of the engine is higher with all those pistons, so that seems off. Do we know how much tankage it had? None of the articles I find mention it.

Maury Markowitz said:

That seems suspiciously high for a plane with a R-4360. It's hauling around a lot more weight (most of it in the engine I assume) and one imagines self-consumption of the engine is higher with all those pistons, so that seems off. Do we know how much tankage it had? None of the articles I find mention it.

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The F2G 'Super Corsair' have had the range of 1955 miles @ 185 mph at 15000 ft, with 309 gals internal fuel + 2x150 gal drop tanks. On just internal fuel, range was 1190 miles @ 190 mph at 15000 ft.
Data sheet for F2G can be had here.

GregP said:

No it doesn't. It reflects a normal learning curve used by almost any manufacturer of man-made goods where manual labor is the main labor..

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Hi, Greg -- aren't "experience" and "learning", in this context, just two different terms for the same phenomenon of learning how to put the thing together in a more efficient manner?

Maury Markowitz said:

That seems suspiciously high for a plane with a R-4360. It's hauling around a lot more weight (most of it in the engine I assume) and one imagines self-consumption of the engine is higher with all those pistons, so that seems off. Do we know how much tankage it had? None of the articles I find mention it.

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According to Joe B's site - "Normal range was 1200 miles at 300 mph and maximum range was 2520 miles at 315 mph with two 125 Imp. gall. drop tanks." Now if this was an estimate or actually flown, I don't know but I don't think it's suspicious.

It seems like the range listed for the XP-72 sounds about right.

The Douglas AD, which weighed about the same as the XP-72, had a range of about 1,300 miles - even though it had the R-3350.

It might have been estimated range.

One source says the first prototype held 370 gallons which is the exact capacity of a later P-47.
The same source says product versions would have used P-47N wings.

I have seen one book saying 535 gallons of internal fuel but didn't say how it was arranged.

The two XP-72 Prototypes were more proof of concept than finished operational aircraft.

I understood the trade off was the longer the production line the more tooling was justified, which brought down the number of man hours per unit. Ford Willow Run did more tooling than the other B-24 lines but had trouble recovering the costs due to the regular changes.

As people have noted the continual problem is what man hours or costs are being counted. Like depreciation of both the buildings and factory equipment. What overheads are counted if the company is also making other items plus of course pushing for other business and so on. Sample data

Figures from Buying Aircraft by Halley,

Time and dollar costs encountered while making 73 modifications to a group of 1,000 P-38,
P-38F-5, 10,450 engineering hours, 6,200 tooling hours, $4,650
P-38G-1, 23,250 engineering hours, 23,760 tooling hours, $18,000
P-38G-3 to 5, 5,000 engineering hours, 4,000 tooling hours, $3,000
P-38G-10, 19,200 engineering hours, 18,480 tooling hours, $13,800

Joe Baugher's web site says 100F-5, 80 G-1, 12 G-3, 68 G-5, 548 G-10, total 958.

B-25 direct engineering hours to give an idea on how often design change actually was
1940 - 329,415 hours
1941 - 419,060 hours
1942 - 695,488 hours
1943 - 461,213 hours
1944 - 200,321 hours

In the end 25 to 50% of the man hours turning out military aircraft were performed at the modification centres. Nearly all bombers and transports needed modification, along with 30 to 50% of fighters. Some 58,741 AAF aircraft were reworked.

Ford Willow run began production in September 1942, as of January 1943 it took 5.03 direct man hours per pound of airframe accepted, it was 2.52 in February and 1.03 in May, 0.56 in January and May 1944, and 0.32 in September 1944. B-24E built September 1942 to August 1943 (plus 1 in August 1944), B-24H June 1943 to April 1944, B-24J April to September 1944, B-24M August 1944 to January 1945, B-24M from December 1944 to end of production. Note total acceptances of B-24J in September 1944 and B-24M in January 1945 was 1 each, so effective end of production was the previous month.

Republic Farmingdale in January 1943 had a ratio of 3.82 direct man hours per pound of airframe accepted, that was down to 1.9 in May 1943, and 1.02 in September 1944, it then spiked to 1.61 in December 1944. The last P-47C and first P-47D were accepted in February 1943, the 130 P-47M were built October to December 1944. The first 2 P-47N were accepted in October 1944, followed by 68 in December. P-47D production in January 1945 was 45 and 1 more was accepted in February to end production.

When the US measured airframe build efficiency in WWII it seems productivity followed a curve that said it took 16 to 18 man hours per pound of aircraft for the first production example, dropping to around 7 man hours by aircraft 10, 3 by aircraft 100, 1.2 by aircraft 1000 and 0.52 man hours per airframe pound by aircraft 10,000.


(There is a total of 262 stinking boring data points, different aircraft, different times, different cost methods) Factory costs Boeing Renton $22,771,000 (There is a total of 220 stinking boring data points, including engine, airframe, propeller and Nordern bombsights buildings costs), $2.62 billion 1940's dollars.

British War Production by Postan. Effort in man hours, Spitfire production, mark / design / jigging and tooling
I / 339,400 / 800,000
II / 9,267 / unknown
III / 91,120 / 75,000
V / 90,000 / 105,000
VI 14,340 / 50,000
IX 43,830 / 30,000
XII / 27,210 / 16,000
VII / 86,150 / 150,000
VIII / 24,970 / 250,000
XIV / 26,120 / 17,000
21 / 168,500 / unknown
PR XI / 12,415 / unknown
Seafire I / 10,130 / 18,000
Seafire II / 3,685 / 40,000
Seafire III / 8,938 / 9,000
Seafire XV / 9,150 / unknown
Spitfire on floats 22,260 / 35,000

Figures as of September 1943 for Supermarine works in Southampton.

UK production reports, cost of 201st production aircraft, man hours, Lancaster 74,319, Halifax 98,246, Stirling 129,944

In May 1942 a Lancaster was estimated to cost 84,800 pounds ready to be sent to a combat unit, a Stirling in June 1942 140,800 pounds.

The Australians did a break down of the costs of Beaufort production, including an allowance for office fittings and fixture depreciation. Another stinking boring set of data no doubt.

The US Maritime Commission notes the average price for a Liberty ship was $1,822,000 per shipsworth, where a shipsworth equals 1 if the ship was fully completed and a fraction if delivered incomplete. There were 20 yards that built Liberty Ships, lowest average cost yard was $1,544,000 highest was $3,923,000.

fastmongrel said:

Man hours to build is just as bad a metric for cost as £,$,RM. Without context it's a meaningless figure. Did the USAAC give a man hour figure covering everything from mining the Bauxite to polishing the windscreen with a Chamois ready for the pilot to step in and press the button. Did the German figure include slave labour and the cost of the engine. Did the British figure include fitting the teacup holder.

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My understanding is the US man-hour count (and probably the British) would include the amount of direct and indirect labor required to build the product from processed raw materials, that is the amount of labor required to produce extrusions, rivets, nuts, bolts, and screws, and (probably) tires (Commonwealth tyres) would not be included, but sub-contractors performing machining and forming operations would. So would the overhead labor involved in supervision, engineering change orders, quality control, inventory management, sweeping the floors, and watering the plants in the CEO's office. Capital expenditures (replacing English wheels with stamping presses or manual lathes with automatic screw machines), better employee training, and more efficient work flow can all reduce labor hours. So can technological advancements, like welding vs riveting or investment casting vs machining.

PAT303 said:

As a former Mechanical engineer this situation is something that is often glossed over, maintenance heavy equipment is a massive burden on your crews and the more they have to do it the more pissed off they get and the reliability suffers as a consequence. Having to constantly work, on a plane in this case causes resentment and the care factor starts to wane especially having to remove so many plugs so often resulting in the chances of damaging the threads likely meaning more work to fix it and more swearing and more resentment and moral suffers. Lastly looking at the fuel system, ammunition and supercharger layout the plane is ''full'' of things to be hit, all late war German and British aircraft had switched over to cannons and there's very few places on a Thunderbolt that a API/SAPI round can hit that won't cause a fire or explosion, the things a flying fuel tank surrounded by ammunition.

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Isn't the thunderbolt supposed to be the most durable fighter in WW II?