from Hacker News

How tall can a Lego tower get?

by jofo25 on 12/4/12, 10:39 AM with 46 comments

• by bediger4000 on 12/4/12, 3:11 PM

  Speaking as an ex-aerospace-stress analyst, I found the article lacking. 2x2 Lego bricks individually fail by plastic deformation. The weight of an unreasonably tall tower could cause it, but we know that such an unreasonably tall tower can't exist because of stability concerns. So: what actually limits the height of a Lego tower? Elastic buckling, or some other kind of buckling, or is it something weird because of the friction fit of Lego bumps in the bottom of the block above? That's where the really interesting stuff comes into play. The Prague tower in the picture appears to have a square cross section, but is it hollow, or solid? What special construction techniques did they use, or is it just a matter of craftsmanship and selecting exactly nominal bricks for construction?

• by meaty on 12/4/12, 5:17 PM

  A friend and myself managed a slightly less epic 9.45m in 1989. We did it in the gap in the stairwell of our old flats. The base was only 8x8 and tapered every couple of meters and it was essentially hollow (to reduce weight and because we didn't want to run out of bits). We provided horizontal stabilisation with some string between the banisters to stop it falling during construction.

  It was stopped by one of the whingy old fart neighbours wondering what we were doing and threatening to complain to the management company. We had a good 5m left and probably enough bits left to cover it!

  Smashing it was awesome and made one hell of a mess which took hours to clear up.

  Most of the Lego came from a car boot sale in two large bins and was purchased for a mere 5 GBP. Went on ebay in 2001 for nearly 200 GBP (good investment!)

• by ComputerGuru on 12/4/12, 11:45 AM

  I'm a little confused. That's the weight that a single Lego brick can withstand, correct? So assuming you made a "tower" that was essentially a vertical line of 2x2 Lego bricks, it'd collapse after 3,591m.

  But that's not how we build towers. If you create a proper foundation with Lego bricks and distribute the weight evenly across them, and taper the tower as it goes up, am I wrong in assuming it could go a lot more than that? The entire weight of a structure never rests on a single brick...

• by sp332 on 12/4/12, 12:50 PM

  If you're curious about the engineering that goes into a large Lego structure, James May ("Captain Slow" of Top Gear fame) built an entire house out of Legos. http://www.youtube.com/watch?v=qR2YqMrS_pM It's an hour long story, but if you want to skip to the final product: http://www.youtube.com/watch?v=qR2YqMrS_pM#t=2600s

• by dhx on 12/4/12, 12:27 PM

  The current record is 32.5m and was set in Prague over the days of 5-9 September 2012.

  Refer to the following site for a comprehensive list of historical LEGO records:

  http://www.recordholders.org/en/list/lego.html

• by UnoriginalGuy on 12/4/12, 12:56 PM

  Is anyone else excited by the fact that your average Lego brick can easily hold a human's weight? So if you built things out of LEGO you could, at least in theory, stand on them.

• by coroxout on 12/4/12, 12:43 PM

  This seems to simulate the pressure due to the weight of the bricks, but I wonder how much the height comes down by if you factor in the extra pressure you have to put on the top brick to get it to clip on.

  Does this add non-negligibly to the pressure on the bottom brick, or is it almost nothing once dispersed through the whole tower?

  (You may be able to tell that I have very little knowledge of the physical sciences, so apologies if this is a stupid question!)

• by cadab on 12/4/12, 11:37 AM

  They mention that there "There has been a burning debate on the social news website Reddit.". Yet that reddit debate was over a year ago!

• by ggchappell on 12/4/12, 8:05 PM

  > The average maximum force the bricks can stand is 4,240N.

  Ah, but that's not quite the issue, if the question is how high of a tower you can build.

  If a tower is 3.5 km tall, then the lower 100m (to pull a number out of the air) are all supporting pretty much the same weight. And that 100m is about ... 10,000 bricks thick? If one of those bricks goes, then the tower goes. So what you want to know is not the average strength of a brick, but the expected strength of the weakest brick out of 10,000. I imagine that's significantly less.

  Exercise for the reader: Given the probability distribution of brick strength, how do we compute the height at which we expect a one-brick-wide tower to fail? (Assume that vertical compression of bricks is the only issue; there are no lateral forces, the tower is perfectly balanced, etc.)

• by SolarNet on 12/4/12, 6:35 PM

  Wow, bbc is really hard up for news huh?

  I really loved this quote:

  '"... it's the typical height at which people ski in the Alps," Ian Johnston says (though many skiers also ski at lower altitudes).'

  Really? I would never have guessed...

• by bpratdesaba on 12/4/12, 1:43 PM

  Actually in Spain we have Teide, a mountain taller than the Lego tower. http://en.wikipedia.org/wiki/Teide

• by skylan_q on 12/4/12, 1:58 PM

  It looks like a space elevator to me.

• by IheartApplesDix on 12/4/12, 2:19 PM

  Does anyone here have enough 2x2 bricks to try getting it several meters high?

• by Zedronar on 12/4/12, 1:23 PM

  Those resources could have been spent in something more useful.