# ­xkcd thread **URL:** \ **Category:** Cafe Society\ **Tags:** comic-strips\ **Created:** [May 28, 2020, 12:57am UTC](https://boards.straightdope.com/t/xkcd-thread/854574 "2020-05-28T00:57:03Z")\ **Posts on this page:** 20\ **Page:** 293
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [May 6, 2026, 12:38am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5843 "2026-05-06T00:38:19Z")
Before microprocessors made artificial stability possible, flying wing designs were bedeviled by the lack of conventional tail surfaces. Even some delta wing designs ended up needing canards for adequate stability. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [May 6, 2026, 1:17am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5844 "2026-05-06T01:17:57Z")
And with a half-life of over a billion years, a large block of isotopically pure potassium-40 wouldn’t give off enough energy to do anything but register on a Geiger counter. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 6, 2026, 1:31am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5845 "2026-05-06T01:31:12Z")
If it weren’t for potassium-40, we wouldn’t have any argon in the atmosphere and not have an important way to measure the age of rocks. So let’s not be denigrating this isotope. ---
**Author:** ![Tamerlane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tamerlane/32/7602_2.png) [@Tamerlane](https://boards.straightdope.com/u/Tamerlane)\ **Post date:** [May 6, 2026, 1:35am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5846 "2026-05-06T01:35:35Z")
> [@LSLGuy](#): > > In the very early days there really was a lot of barely-informed experimentation with different fin arrangements. Some of which came to become standards, some of which are actively avoided, and some of which proved harmless but also useless. When odd little experimentation with plane wing design comes up it always makes me think of the [F-104 with its stubby little wings and ‘T-tail flutter’](https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter#Early_problems). I guess they were very good at certain things, but from my only semi-educated seat they really come off as a dog overall. Little wonder Lockheed was [bribing government officials to buy them](https://en.wikipedia.org/wiki/Lockheed_bribery_scandals). ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [May 6, 2026, 8:10am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5847 "2026-05-06T08:10:09Z")
> [@Tamerlane](#): > > always makes me think of the [F-104](https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter#Early_problems) Ah, yes, _der Witwenmacher_ (widow maker). Further down the page you linked to: > A total of 116 pilots were lost in West German F-104 accidents, including 1 ground-crew passenger and 8 USAF instructors. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [May 6, 2026, 3:58pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5848 "2026-05-06T15:58:34Z")
The pilot began his walk-around inspection of his Rutan Long-EZ. “Duck!” yelled the mechanic. But the pilot spoke only French, and banged his head on the canard. ---
**Author:** ![Kron](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kron/32/12444_2.png) [@Kron](https://boards.straightdope.com/u/Kron)\ **Post date:** [May 6, 2026, 5:46pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5849 "2026-05-06T17:46:44Z")
I laughed. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 6, 2026, 7:51pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5850 "2026-05-06T19:51:36Z")
> **[Aperiodic Table](https://xkcd.com/3242/)** [![](https://imgs.xkcd.com/comics/aperiodic_table.png) ](https://imgs.xkcd.com/comics/aperiodic_table.png) “Scientists occasionally invent alternative periodic table layouts, which is usually a sign that they don’t have enough enrichment in their enclosures.” ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 6, 2026, 10:33pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5851 "2026-05-06T22:33:03Z")
In that heady era USAF had no problem asking for the impossible. Then when the engineers got sorta close on some parameters and really missed some others, there’d be a negotiation to move the goalposts close to what the engineers built, have them gussy it up a bit more, then USAF would declare victory and order a couple hundred (or a thousand) of them. The state of the art was moving so fast, and frankly being pushed by USAF’s nutty Musk-like demands, that it wasn’t really such a bad technique for industrial technology base management. But the few models USAF kept longer than a couple years before superceding / scrapping mostly developed a reputation for being problems. Selling those kinds of machines to countries that didn’t have the resources to throw them away for something else a couple years later was not a nice thing to do to allies. Especially those in countries with shitty weather & small air bases. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [May 7, 2026, 1:08am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5852 "2026-05-07T01:08:33Z")
I was motivated to actually see what the graphite rod out of an expended battery is like, if maybe it was usable as a large pencil “lead”. I was expecting it to be on the soft and crumbly side, but to my surprise it’s much harder than #2 pencil; apparently lots of ceramic was added to make it strong enough to withstand rough handling. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 7, 2026, 1:21am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5853 "2026-05-07T01:21:05Z")
I think that a typical banana has a lot more radioactivity from carbon 14 than from potassium 40. > [@Lumpy](#): > > I was expecting it to be on the soft and crumbly side, but to my surprise it’s much harder than #2 pencil; apparently lots of ceramic was added to make it strong enough to withstand rough handling. And I think that pencil leads also have additives to make them softer. Clay, I think? ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [May 7, 2026, 7:58am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5854 "2026-05-07T07:58:44Z")
> [@Chronos](#): > > And I think that pencil leads also have additives to make them softer. Clay, I think? No, the clay definitely makes them a lot harder. 8B is around 90% graphite, while 2H is around 60% graphite (and 35% clay, 5% wax) ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [May 7, 2026, 5:26pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5855 "2026-05-07T17:26:44Z")
The little, skinny leads in mechanical pencils – 0.5 to 0.9mm – have polymer plastic as a stiffener instead of clay. I have heard of, but not tried, using battery graphite electrodes for arc lamps. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [May 7, 2026, 5:53pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5856 "2026-05-07T17:53:02Z")
> [@Chronos](#): > > I think that a typical banana has a lot more radioactivity from carbon 14 than from potassium 40. Would depend on the abundance of C-14 in your typical banana; but quite possibly. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 8, 2026, 8:30pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5857 "2026-05-08T20:30:23Z")
> **[Crystal Gazing](https://xkcd.com/3243/)** [![](https://imgs.xkcd.com/comics/crystal_gazing.png) ](https://imgs.xkcd.com/comics/crystal_gazing.png) “‘Beyond that lies a vale of fire through which my vision cannot penetrate’ is the kind of fun thing geologists, heliophysicists, and early universe cosmologists have a lot of opportunities to say.” ---
**Author:** ![Toxgoddess](https://avatars.discourse-cdn.com/v4/letter/t/f08c70/32.png) [@Toxgoddess](https://boards.straightdope.com/u/Toxgoddess)\ **Post date:** [May 8, 2026, 11:05pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5858 "2026-05-08T23:05:10Z")
Now I wanna be an early universe cosmologist. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 9, 2026, 1:25pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5859 "2026-05-09T13:25:22Z")
Yet another cool occupation the guidance counselor in high school completely forgot to mention. Dang! The Beginning is nigh! 🤪 ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 12, 2026, 10:30am UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5860 "2026-05-12T10:30:33Z")
> **[Pullback Drive](https://xkcd.com/3244/)** [![](https://imgs.xkcd.com/comics/pullback_drive.png) ](https://imgs.xkcd.com/comics/pullback_drive.png) ‘“How does the spring not run out almost immediately?” “We pull it back REALLY far.”’ ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [May 12, 2026, 1:25pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5861 "2026-05-12T13:25:27Z")
They gloss over what the tow truck fees will be. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [May 12, 2026, 1:44pm UTC](https://boards.straightdope.com/t/xkcd-thread/854574/5862 "2026-05-12T13:44:38Z")
If you use a pullback tow truck, then it’s free. [Previous page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=292) [Next page](https://boards.straightdope.com/t/xkcd-thread/854574.md?page=294)