Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place • Hacker News Board

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#41

Post by anonymouz » Sat, Jun 08, 2013, 6:53 AM UTC

gmrple wrote: post #37

priv_acy wrote: post #31

In the aerospace business there is a guy known as the Mass Properties Engineer who gets to rule the project with an iron fist. He is responsible for knowing the estimated, calculated or measured weight of every part on the spacecraft from concept through to launch. It's not a very fun job, but it's very important. Some people actually made careers out of it. You simply cannot get this stuff wrong and not pay dearly f…

My electrical engineering professors were constantly trying to ingrain in us the tendency to estimate the solutions to problems long before solving them. Why? because if you know the ball park solution you'll be able to catch gross errors before they happen. Thus you will be less likely to pull a Homer Simpson at the power plant or end up transmitting too much power from your antenna. I'm thankful to be in an industr…

Without more details it's hard to say what exactly went wrong, but it is not at all clear that a ballpark estimate would be of any help here: The submarine weighs 2200 tons, and they think it's 70 tons too heavy.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#42

Post by coldarchon » Sat, Jun 08, 2013, 7:46 AM UTC

anonymouz wrote: post #41

gmrple wrote: post #37

Earlier quoted context omitted.

My electrical engineering professors were constantly trying to ingrain in us the tendency to estimate the solutions to problems long before solving them. Why? because if you know the ball park solution you'll be able to catch gross errors before they happen. Thus you will be less likely to pull a Homer Simpson at the power plant or end up transmitting too much power from your antenna. I'm thankful to be in an industr…

Without more details it's hard to say what exactly went wrong, but it is not at all clear that a ballpark estimate would be of any help here: The submarine weighs 2200 tons, and they think it's 70 tons too heavy.

Actually it is 75 tons too heavy, they stretched the sub out to get more buoyancy but now they have NO IDEA how heavy it really is ..

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#43

Post by lmm » Sat, Jun 08, 2013, 8:12 AM UTC

mikekij wrote: post #36

Is there such a thing as submarine unit testing?

You can't exactly unit test the buoyancy - the hull is the only part that floats on its own[1], all the other crap you put in would sink. The two need to balance when you combine them, but there's no way to test that at the unit level.

[1] Ok technically a few other parts like air tanks would float.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#44

Post by omegant » Sat, Jun 08, 2013, 8:45 AM UTC

lmm wrote: post #43

mikekij wrote: post #36

Is there such a thing as submarine unit testing?

You can't exactly unit test the buoyancy - the hull is the only part that floats on its own[1], all the other crap you put in would sink. The two need to balance when you combine them, but there's no way to test that at the unit level. [1] Ok technically a few other parts like air tanks would float.

But you don't have to unit test a radio throwing it to the water. Just sending messages.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#45

Post by ingve » Sat, Jun 08, 2013, 9:01 AM UTC

oneye wrote: post #29

kryptiskt wrote: post #3

> “Apparently somebody in the calculations made a mistake in the very beginning and nobody paid attention to review the calculations,” he said. Supporting the old software engineering folklore that the earlier a bug is introduced (and the later it is found) the harder and more expensive it is to fix.

> Supporting the old software engineering folklore that the earlier a bug is introduced (and the later it is found) the harder and more expensive it is to fix. I wouldn't call it folklore as there are numerous studies supporting it. EDIT: I decided to crack open Code Complete for anyone who is interested [1]. [1] "Researchers at Hewlett-Packard, IBM, Hughes Aircraft, TRW and other organizations have found that purgin…

The studies supporting it have apparently been somewhat hard to confirm, a lot of the source material used by McConnell seems to be from secondary sources and self-referential. [1] is a detailed blog post where the author tries to track down the original sources:

[1] http://blog.securemacprogramming.com/2012/09/an-apology-to-r...;

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#46

Post by irremediable » Sat, Jun 08, 2013, 9:14 AM UTC

mikekij wrote: post #36

Is there such a thing as submarine unit testing?

As I* understand it the only "traditional" engineering field with anything close to unit testing is electronic engineering. Lots of chip or circuit design packages let you automatically test small parts of your design.

For mechanical/civil projects, this approach is less common. I think that's partly because of the projects' nature (good luck unit testing a submarine!) and partly because of the engineers being more traditional, and further from the software industry.

This said, I can envision some cool things you might do by taking a CAD package and associating some (automatically updating) equations with various parts' critical dimensions. This might act a bit like unit testing. A check of total mass would be another such useful check.

* Engineering student with some work experience, but by no means a blooded engineer.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#47

Post by berkut » Sat, Jun 08, 2013, 10:43 AM UTC

mikekij wrote: post #36

Is there such a thing as submarine unit testing?

Depends - as it's designed (using GRC's Paramarine - http://www.qinetiq.com/what/capabilities/maritime/Pages/nava...) you can virtually unit test things like propulsion, stability and buoyancy.

Once it's been assembled into one complete system, it's very difficult to do that - individual systems on-board from a systems perspective could be unit tested, but actual physical items - not so much - generally they only find out about mismatches when they try and assemble the warship/sub from different sections (sometimes built by different companies) and they discover their tolerances were off.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#48

Post by damoncali » Sat, Jun 08, 2013, 12:55 PM UTC

anonymouz wrote: post #41

gmrple wrote: post #37

Earlier quoted context omitted.

My electrical engineering professors were constantly trying to ingrain in us the tendency to estimate the solutions to problems long before solving them. Why? because if you know the ball park solution you'll be able to catch gross errors before they happen. Thus you will be less likely to pull a Homer Simpson at the power plant or end up transmitting too much power from your antenna. I'm thankful to be in an industr…

Without more details it's hard to say what exactly went wrong, but it is not at all clear that a ballpark estimate would be of any help here: The submarine weighs 2200 tons, and they think it's 70 tons too heavy.

The bigger point is that 70 tons should not sneak up on you. They should have been managing weights carefully throughout the process.

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#49

Post by Someone » Sat, Jun 08, 2013, 2:59 PM UTC

anonymouz wrote: post #41

gmrple wrote: post #37

Earlier quoted context omitted.

My electrical engineering professors were constantly trying to ingrain in us the tendency to estimate the solutions to problems long before solving them. Why? because if you know the ball park solution you'll be able to catch gross errors before they happen. Thus you will be less likely to pull a Homer Simpson at the power plant or end up transmitting too much power from your antenna. I'm thankful to be in an industr…

Without more details it's hard to say what exactly went wrong, but it is not at all clear that a ballpark estimate would be of any help here: The submarine weighs 2200 tons, and they think it's 70 tons too heavy.

On the one hand, you are right. Preventing things like this (a 3% budget overrun) in large projects is very, very difficult.

On the other hand, if this really is a single off by ten error, this was not a death by a thousand cuts, but someone must have reported that his 80 ton part only weighed 8 tons. That must have been noticeable, even if it got reported for a 'part' where nobody has a natural feel for its weight (for example, what do living quarters, with kitchen, supplies, and water for the showers weigh?)

Re: Spain builds submarine 70 tons too heavy by putting a decimal in the wrong place

#50

Post by dm2 » Sun, Jun 09, 2013, 2:34 AM UTC

D-Coder wrote: post #30

dm2 wrote: post #21

Earlier quoted context omitted.

Even if it costs hundreds of millions of dollars, big woop. How much have we spent on F-35 research, trillions? And those things don't even work in space.

Or under water!

Not really practical for an aircraft to operate underwater, but someday operating in space might not be inconceivable. My point was that for trillions of dollars, the aircraft better do some cool shit. Yes, crash avoidance is awesome, but not trillions awesome.

The sea is arguably more valuable than space in terms of military value, an underwater vehicle is practically invisible and can deliver massive amounts of firepower to any region in the world. Not to mention the secret mission capabilities of submarines such as tapping undersea fiber and special forces delivery.