Boeing 787; in what units has been designed?

Do you think that the ease of conversion between different systems of units now makes it irrelevant what units are used? Or should people
strive to convert to SI?
I teach a course in Product Development and need to address the issue of different unit systems. Is it bad? is it irrelevant now? or maybe it is good (to use different unit than your competition)?
Do you know what system of units has been used to design 787, is this an issue at all?
Thanks
Paul
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Dear Paul,

We lost a satellite package on Mars, due to one assuming SI, and another assuming Imperial. It is critical that we read the entire message, and that the message contains intended units. "pounds-force" vs. "newtons. http://www.cnn.com/TECH/space/9911/10/orbiter.02 /

Imperial units have been tied to SI units since ~1900. Full conversion simply allows one to be be brainless about units.

Millions of dollars can be lost due to a single mistake.

No. It is relevant, just as any exercise in "full communication" and "reading for comprehension" are relevant.

If you are working on a vehicle desinged and built with a different set of tools (metric vs. SAE), it is irritating. But a sales feature... maybe a so many liter fuel tank sounds bigger than an equivalent volume gallon fuel tank. But somebody can sell anything to the ignorant.

Various components of aircraft are manufactured many places in the world. Defining the inferface is critical. I cannot answer for Boeing.
David A. Smith
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No. Many calculations are easier, and hence less prone to error, if you pick you unit system intelligently.

People should be fluent in both. A project should be done in one or the other but, ideally, not both at the same time.

No.
No.
I'm not sure if it gives you competitive differentiation, but it's good from the point of view that there is a lot of legacy technology that's going to be around for along time that is in multiple unit systems and it's good to be comfortable in all of them.

It's designed in inches. Although, since the design software is French, I suspect the system is actually storing the data in SI and just converting for display.
Tom.
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f'up to misc.metric-system
Hello Paul,

There is a special group for your topic: misc.metric-system
Greetings from Germany Joerg
--
http://www.joergei.de /
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From the few CAD drawings I have seen for contract machining by shops other than Boeing, I see the little cone at the bottom of the drawings to indicate conventional inch/ft/lb and actual dimensions in inch, ft.
I'm sure all calculations as to weight, thrust, horsepower, drag, speed and the like follow their traditional rules. Why go metric when your success has been in ft/lbs?
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wrote:

Because you may wish to take advantage of the world-wide source of engineering expertise, labour and products that only exist in metric. You may wish to cut your costs but find it impossible because you have limited yourself to a limited number of resources.
Why did every nation go metric when their ancient units served them fine?
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The reality is that in the US the vast majority of engineering resources are still denominated in the in-lb system. In the aerospace industy, heavily influenced by military contracting, there is still alot of reference material generated in the in-lb system. Unit systems are a matter of contract negotiations. We occasionally get "metric" specified in our contracts. The usual result is alot of work being done in in-lb (because all of the materials will be available that way) and then the drawings and documents will be "converted". Which unit system is actually used is a function of each individual program and to some extent the individual engineer. So much software is able to handle the conversions that it is a trivial decision and no one tries to force anything.
That said, the "troubles" start when there is an attempt at international cooperation. It isn't so much which dimensions get used, that's almost always expressed in metric. The problem comes in what actual hardware gets chosen. "Standard" sizes aren't exactly comparable and fastener diameters and sheet "gauges" and the like need to be chosen based upon what unit system one wants to be compatible with. It is hard to get metric fasteners of certain styles in the US. They have to be special ordered and often the lead times are excessive, not to mention minimum order sizes. Flip side is the in Europe, "standard" US styles and sizes can be almost harder to obtain. I was involved in one effort where we were sending US styles to Germany and they were sending us metric hardware because of the relative ease of each in obtaining them.

Because people got laws passed which forced them.
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Actually, I'm hearing that the rivets being used on Airbus are standard US sizes which is causing a shortage of supply for Boeing, putting them behind testing schedule because of it.

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wrote:

Imperialists are so upset that metric has taken over the world that the only two excuses they can find to justify the continued use of imperial is either culture or those few remnant industries still able to survive using imperial. When you consider the number of industries world-wide that are metric and prospering and the number of industries that started out in imperial and successfully switched to metric (as an example computers), there really is no reason to justify the continued use of imperial. These industries survive only because they have a niche product whose components have no use in other industries. Thus everything associated with these niche industries is specialized and very expensive.
Compare the profits earned in metric industries to those in imperial and you will see that metric by far produces the greatest economic gain for the most people. Thanks to American and British industries moving their engineering and production to metric countries like China, billions of products once designed and made in imperial are now designed and made in metric. Even products that carry inch trade names. I have yet to see a product with an inch trade name live up to the dimension it is named by.
It must be a living hell for an imperialist living in a metric country. They spend many a wasteful hour looking for things that no longer exist or searching shop after shop for a faint glimpse of an imperial product. Then only to find it is a metric product disguised as imperial.
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Dear Euric:
...

<snip rant>
Ever heard of "The Wizard of Oz"? Did you ever realize that it was a political satire, based on standardization of money (an ounce of gold). http://www.prosperityuk.com/prosperity/articles/wizzoz.html
Since the "Tower of Babel" fell, it has become necessary for Mankind to spend effort to understand one another. Standard units won't help someone that has no clue.
It isn't political systems. In fact, they'd love not having to maintain staffs of translators, whether language or dimensions. Funny how you'd proselytize *for* imperialists...
David A. Smith
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wrote:

Hmmmm...someone unsure of the concept.
Imperial measures were formerly used by the British - it was their Empire, once upon a time. They have long since decimalized their currency, and turned to metric measures. The only country left using non-metric measures is the US, and their measures are formally called "US Customary measures".
Brian Whatcott Altus OK
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In the history of metrication, it was industry that initiated the change and with the aid of government; laws were passed that made the change swift and painless, except for the US and UK. Metrication was almost complete in the UK when the imperialists, Luddites, lovers of the old empire (or whatever name you want to call them) applied enough pressure to get the metrication process halted before it was complete.
The US barely got started before pressure was applied to stop it cold.
But industry got something better as a compromise from the governments for not pushing metrication on the people. Ronald Reagan in the US and Margaret Thatcher in the UK set in motion the means by which companies wanting to produce metric goods could do so outside the US and UK, import the goods back into the US and UK tariff free. These very same leaders opened the gates to globalization at the very moment they closed it to further government supported metrication.
No matter how you look at it, the citizens of the UK and US lost the greater war. The resulting service economy in both countries produced a poorer class of citizen making less for longer hours. To maintain the illusion of the middle class dream, income that could not be earned then became borrowed. The result was that the US went from being the world's richest creditor nation, to the world's poorest borrower nation. The UK began to suffer under a heavy debt burden, which prevented it from joining the Euro. The UK could not join the Euro and be subjected to interest rate decisions from Frankfurt. They had to have interest rates higher then the eurozone in order to secure their increasingly heavy debts resulting from the exportation of their manufacturing and industry.
The US is in the same worsening predicament. The mortgage and sub- prime problems are just the tip of the iceberg. Each step the US and UK take to try to lessen the damage of relying on credit to purchase their living standard only assures a more quicker and painful end to the very living standard they are trying to preserve.
And to think it is all tied to giving into to anti-metrication.
An interesting article that touches on this very subject:
http://www.weeklygripe.co.uk/a486.asp
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|> Why go metric when your success has been in ft/lbs?
Exactly that attitude seems to have done substantial damage to the UK engineering industry (especially automotive) in the 1970s. The newly opening European markets expected metric products and standards and the Commonwealth was no longer a protectionistic guaranteed market for UK non-metric products, and so it became suddenly rather difficult to sell products that required exotic (for most customers) inch-based spare parts and tools to maintain.
Past performance is no indicator for future performance ... US industries may well face similar surprises in globalization.
But you are right in that the question is less about the units used, but more about the tools and component standards. The aircraft and oil industries are probably the only two industries worldwide that are still so much dominated by U.S. standards that at least inch-derived dimensions are going to stick around for quite some time. I am not so sure about non-length quantities (force, mass, pressure, etc.), which can be changed much more easily to global standards as they tend to play a much less significant role in backwards compatibility.
Markus
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["Followup-To:" header set to misc.metric-system.]

You forgot about gallons and barrels - or e.g. about karat?
- Martin
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Ease of conversion makes no difference. What makes a difference is what the majority in the market place use. 98 % of the people in the world use metric. The remaining 2 % should strive to convert, but since they won't, global business by-passes them when it comes to making purchases.
If you design a product using rounded metric units, and someone converts them into obsolete units, the numbers will not come out in a form that is useful to them. So although the conversion was easy, the result is difficult to use.

Using different units brings about a cost disadvantage and a huge potential for errors. Therefore you should only use one system, the one used by the majority of people in the world, which is SI. You shouldn't waste your time or your student's on different measurement units. If you do, then you are taking time away from learning concepts and theory. Thus, yes it is bad. You should use whatever units the majority in the world use. If someone chooses to use different units then let the burden of cost and errors be upon them.

Hard to say, but I would guess a mixture. At one time Boeing was only non-SI, but they do a lot of subcontracting especially from Asian countries and the Asians don't waste their time and resources on multiple systems. They use only metric. My experience with Asians is that if you send them a drawing not in SI, they will convert it before producing from it.

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http://seattletimes.nwsource.com/html/boeingaerospace/2003889663_boeing180.html
Fired engineer calls 787's plastic fuselage unsafe
By Dominic Gates
Seattle Times aerospace reporter
A former senior aerospace engineer at Boeing's Phantom Works research unit, fired last year under disputed circumstances, is going public with concerns that the new 787 Dreamliner is unsafe.
Forty-six-year veteran Vince Weldon contends that in a crash landing that would be survivable in a metal airplane, the new jet's innovative composite plastic materials will shatter too easily and burn with toxic fumes. He backs up his views with e-mails from engineering colleagues at Boeing and claims the company isn't doing enough to test the plane's crashworthiness.
Boeing vigorously denies Weldon's assertions, saying the questions he raised internally were addressed to the satisfaction of its technical experts.
Weldon's allegations will be aired tonight by Dan Rather, the former CBS News anchor, on his weekly investigative show on cable channel HDNet.
Weldon thinks that without years of further research, Boeing shouldn't build the Dreamliner and that the Federal Aviation Administration (FAA) shouldn't certify the jet to fly.
Boeing's current compressed schedule calls for a six-month flight-test program and federal certification in time for delivery in May.
Rather's show presents a letter Weldon wrote to the FAA in July detailing his view, as well as two e-mails to Weldon dated August 2005 and February 2006, expressing similar safety concerns, from unidentified senior Boeing engineers who are still at the company.
Weldon worked at a Boeing facility in Kent. Within Boeing, he led structural design of a complex piece of the space shuttle and supervised several advance design groups. He has worked with composites since 1973.
Weldon recently declined through an intermediary to speak with The Seattle Times.
Boeing confirms he was a senior engineer, but spokeswoman Lori Gunter said he is not specifically a materials expert.
He complains in his July 24 letter to the FAA that when he expressed his criticisms internally they were ignored and "well-covered up."
Weldon was fired in July 2006. He alleged in a whistle-blower complaint with the U.S. Occupational Safety and Health Administration (OSHA) that the firing was "retaliation for raising concerns throughout the last two years of his employment about the crashworthiness of the 787."
But according to a summary of OSHA's findings, Boeing told investigators Weldon was fired for threatening a supervisor, specifically for stating he wanted to hang the African-American executive "on a meat hook" and that he "wouldn't mind" seeing a noose around the executive's neck.
Weldon denied to OSHA investigators that he had referred to a noose and said the "meat hook" reference had not been a threat.
OSHA dismissed Weldon's claim, denying him whistle-blower status largely on the grounds that Boeing's 787 design does not violate any FAA regulations or standards.
FAA spokesman Mike Fergus said Monday the 787 will not be certified unless it meets all the FAA's criteria, including a specific requirement that Boeing prove passengers will have at least as good a chance of surviving a crash landing as they would in current metal airliners.
Rather said Weldon had spoken out publicly only with great reluctance.
"We approached Weldon. In the beginning, it was not at all certain he would cooperate," Rather said in an interview.
Rather said his show doesn't determine whether Boeing or Weldon is right. But referring to the e-mails from Weldon's peers, he said, "There are others who are still within the company who are concerned ... that Boeing could be destroyed by taking the 787 to market too soon and brushing aside these safety concerns too cavalierly."
The Seattle Times reviewed the program transcript and also the letter to the FAA. In the letter, Weldon alleges:
The brittleness of the plastic material from which the 787 fuselage is built would create a more severe impact shock to passengers than an aluminum plane, which absorbs impact in a crash by crumpling. A crash also could shatter the plastic fuselage, creating a hole that would allow smoke and toxic fumes to fill the passenger cabin.
After such a crash landing, the composite plastic material burning in a jet-fuel fire would create "highly toxic smoke and tiny inhalable carbon slivers" that "would likely seriously incapacitate or kill passengers."
Weldon also told the FAA this could also pose a major environmental hazard in the area around the crash site.
The recently conducted crashworthiness tests - in which Boeing dropped partial fuselage sections from a height of about 15 feet at a test site in Mesa, Ariz. - are inadequate and do not match the stringency of comparable tests done on a 737 fuselage section in 2000.
The conductive metal mesh embedded in the 787's fuselage surface to conduct away lightning is too light and vulnerable to hail damage, and is little better than a "Band-Aid."
Though aluminum airplanes are safe to fly through lightning storms, Weldon wrote, "I do not have even close to the same level of confidence" for the 787.
Boeing's Gunter denied the specifics in Weldon's Dreamliner critique.
"We have to demonstrate [to the FAA] comparable crashworthiness to today's airplanes," she said. "We are doing that."
The recently completed crash tests were successful but are only the beginning of a process that relies on computer modeling to cover every possible crash scenario, she said.
Tests so far have shown that shards of composite material released in a crash are not a shape that is easily inhaled, Gunter said, and the smoke produced by composites in a jet-fuel fire is no more toxic than the smoke from the crash of an aluminum plane.
The 787's lightning protection will meet FAA requirements, she said.
Gunter expressed frustration at Weldon's portrayal of the plane maker as taking shortcuts for profit.
"We wouldn't create a product that isn't safe for the flying public," Gunter said. "We fly on those airplanes. Our children fly on those airplanes."
Dominic Gates: 206-464-2963 or snipped-for-privacy@seattletimes.com
Copyright 2007 The Seattle Times Company
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