Saturday, September 4, 2010

Wikipedia, wrong again

Wikipedia continues to disappoint. The most recent example of an incorrect entry is on the topic of "what is the densest element?"  Here's their answer:
"The measured density of [iridium] is only slightly lower than that of osmium, which is often listed as the most dense element known. However, calculations of density from the space lattice may produce more reliable data for these elements than actual measurements and give a density of 22650 kg/m³ for iridium versus 22610 kg/m³ for osmium. Definitive selection between the two is therefore not possible at this time."
"So," you ask, "how can you so definitively say that such a non-definitive answer is wrong?"

Simple. Because the correct answer is neither of those. The correct answer is.... well, I'll get to that.

First, I had to cut the second spar slot in the right side skin.

As you may infer from the fact that I'm wearing a sweatshirt, our heat wave has been replaced with unseasonably cold weather. Ohio weather is at best a study of extremes, best studied from more temperate states.

I used the nibbler again, and while I think it makes a cleaner cut than shears, it does present the down side of being somewhat difficult to hold on a completely straight cut. You won't have any trouble choosing the side that I cut versus the side that Van's cut.

I was wrong when I said that it was a waste of time to cleco the left skin onto the fuse. It turns out that the little gusset that needs to be riveted on is accessible even with the skin in place.

 My prediction regarding impending match drilling was proved correct pretty quickly. I thought this picture in the build manual was odd, though. That hatched part in the circle gets cut off once the longerons are drilled. I didn't think it was odd to have a piece on there that would later get removed; every now and then there is a tab that must be used to hold the part in whatever machine Van's uses to manufacture parts. I just thought it was odd that they had bothered to drill holes in it.

I can live with "odd" in the short term - I just move on with the stuff that isn't odd.

The skin gets clamped to the longeron. That's not odd at all.

Then drilled.

Each hole is clecoed as soon as it's drilled to hold the skin flat.

I didn't see any reason to drill for a part that's going to get cut off anyway.

Then, the next side. As I was drilling my way down the side, I noticed something wrong on the roll bar support plate:

The hole was marked for countersinking, but no countersinking had been done! I figured I'd finish drilling the longeron row and then fix the countersinking mistake. I eventually got to the end, where yet again I was confronted with the inexplicably over-engineered throw-away part. I mean really, why have us drill holes through a part that's just going to get cut off and thrown away? Then it struck me, and I have to confess that the simplicity of the answer embarrassed me: to put holes in the longeron for the tail cone to rivet into. The part of the skin that gets discarded acts as a drilling template.

So now you can see why I believe that neither iridium nor osmium is the densest element on Earth.

It's because I am.

Once all of the longeron holes were drilled, I went back to countersink the hole on the roll bar support.

For some reason I couldn't get the countersink bit to dig deep enough into the hole. After a couple of adjustments to the bit cage didn't help, I thought that maybe something was obstructing the part of the bit that goes through the hole. Well, I was right, in a way.

I hadn't match drilled those holes yet.

See? Iridium ain't got nothing on me when it comes to dense.

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