# Can a spider stop a 747 ? **URL:** \ **Category:** Factual Questions\ **Created:** [November 25, 2001, 9:21am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137 "2001-11-25T09:21:43Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![DarrenS](https://avatars.discourse-cdn.com/v4/letter/d/977dab/32.png) [@DarrenS](https://boards.straightdope.com/u/DarrenS)\ **Post date:** [November 25, 2001, 9:21am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/1 "2001-11-25T09:21:43Z")
A show on Discovery Channel a couple of weeks ago claimed that a “rope” made of spider silk (the stuff spiders use to make webs) of the same diameter as a pencil could stop a Boeing 747 flying at full speed. I really have trouble believing this - how could this possibly be?! I thought I was going crazy until I looked this up and saw a couple of other references to it. Search in Google for “spider thread strength 747” and you’ll find plenty. All the ones I looked at seemed rather second hand, though -very Urban Legend-like. ---
**Author:** ![Ell](https://avatars.discourse-cdn.com/v4/letter/e/e47774/32.png) [@Ell](https://boards.straightdope.com/u/Ell)\ **Post date:** [November 25, 2001, 9:59am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/2 "2001-11-25T09:59:32Z")
_Spiderman! Spiderman! Does whatever a spider can!_ [sub]Sorry. Nothing to add here.\* ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [November 25, 2001, 10:19am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/3 "2001-11-25T10:19:53Z")
Well, as far as I know, spider silk has the highest tensile strength of any material. ---
**Author:** ![TBone2](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TBone2](https://boards.straightdope.com/u/TBone2)\ **Post date:** [November 25, 2001, 12:39pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/4 "2001-11-25T12:39:47Z")
Wow! That’s quite a claim, **SenorBeef**!! You’ll pardon me if I don’t subscribe to _that_ level of ambition early on a Sunday morn… However, I distinctly recall reading in a grade school science text that spider web has roughly three times the tensile strength of steel. Of course, such a comparison would have to take into consideration things like cross-sectional area, etc. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 25, 2001, 1:18pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/5 "2001-11-25T13:18:26Z")
First off, the phraseology used by all the links produced by the [Google search](http://www.google.com/search?q=spider+thread+strength+747) are just too similar. It makes me think they are derived from one source, or each other. In fact, the first two links have many of the same diagrams and incorrect terms (see below). Secondly, most of the sites are religious in nature–either creationist claptrap or sermons. Nothing wrong with sermons, but not my first choice for scientific info. Even the first site, which appears to be scientific at first glance, is a bit too “gee whiz” for my tastes. Here is the relevant phrase. > [@](#): > > A thread of silk with the thickness of a pencil is able to stop a Boeing 747 flying at full speed. We are still unable to reproduce such a material with all our technological knowhow. But then the site goes on to say: > [@](#): > > The strength of a material is given in a unit called dernier. (1 dernier = 1 g per 9000 m) I’ve never heard of a “dernier,” especially with respect to the strength of a material. From this site: [http://www.ilcdover.com/Products/EngInf/terms.htm](http://www.ilcdover.com/Products/EngInf/terms.htm) > [@](#): > > **Denier** : A weight-per-unit-length measure of any linear material. Officially, it is the number of unit weights of 0.05 grams per 450-meter length. This is numerically equal to the weight in grams of 9,000 meters of the material. Denier is a direct numbering system in which the lower numbers represent the finer sizes and the higher numbers the coarser sizes. A site that can’t even spell units correctly, and is mixing up “weight-per-unit-length” with “tensile strength” is rapidly losing credibility with me. Sounds like B.S. to me… ---
**Author:** ![Patricinus\_Scriblerus](https://avatars.discourse-cdn.com/v4/letter/p/f07891/32.png) [@Patricinus\_Scriblerus](https://boards.straightdope.com/u/Patricinus_Scriblerus)\ **Post date:** [November 25, 2001, 1:50pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/6 "2001-11-25T13:50:21Z")
For strength of a spiders web… [http://boards.straightdope.com/sdmb/showthread.php?threadid=100786](http://boards.straightdope.com/sdmb/showthread.php?threadid=100786) As for could a spider stop a 747… Sure It depends on how. If one creeps through the cabin and a flight attendent loses it…panic ensues and so on…you get the idea. ---
**Author:** ![Hemlock](https://avatars.discourse-cdn.com/v4/letter/h/c5a1d2/32.png) [@Hemlock](https://boards.straightdope.com/u/Hemlock)\ **Post date:** [November 25, 2001, 2:15pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/7 "2001-11-25T14:15:02Z")
Or if it’s a tarantula and it kills the pilots. 🙂 ---
**Author:** ![PunditLisa](https://avatars.discourse-cdn.com/v4/letter/p/4af34b/32.png) [@PunditLisa](https://boards.straightdope.com/u/PunditLisa)\ **Post date:** [November 25, 2001, 2:18pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/8 "2001-11-25T14:18:05Z")
I believe James Dean tested this theory. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [November 25, 2001, 8:22pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/9 "2001-11-25T20:22:53Z")
> [@](#): > > \*Originally posted by Hemlock \* > \*\*Or if it’s a tarantula and it kills the pilots. 🙂 \*\* I didn’t think the tarantula was deadly to humans. The black widow is. And the brown recluse. Ahh, the spiders of my youth! 😃 ---
**Author:** ![Thrasymachus](https://avatars.discourse-cdn.com/v4/letter/t/ce73a5/32.png) [@Thrasymachus](https://boards.straightdope.com/u/Thrasymachus)\ **Post date:** [November 25, 2001, 8:41pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/10 "2001-11-25T20:41:43Z")
Ahh, this is more of a UL than anything else. Spider silk (webbing) is not “stronger than anything known to man” or even close. But they told me that in third grade too. There are two basic varieties - dragline silk (strong) and the regular stuff (sticky). Two basic cites: Spider’s silk 35 000 psi [http://www.plmsc.psu.edu/~www/matsc259/tensstren.htm](http://www.plmsc.psu.edu/~www/matsc259/tensstren.htm) Here 200 000 psi for dragline silk [http://www.harcourtcollege.com/chem/general/joesten/student/add/chapters/spiderwebs.html](http://www.harcourtcollege.com/chem/general/joesten/student/add/chapters/spiderwebs.html) For comparison, piano wire has about a 475 000 psi ultimate strength, and the steel used in common nails (mild steel) is more like 40 000 psi. So, nothing amazingly strong, although it’s up there with some of our better materials. But the kicker is that the spider silk elongates quite a bit (30% IIRC), so it can absorb a fairly large amount of energy before failure. I think one of the links above discusses that aspect in more detail. A fully loaded 747 weighs about 800 000 lbs, and can fly mach 0.85. I’m not sure how they made their calculation, but with the “factoid” presentation I’d have to say it sounds pretty iffy. I suppose if it were used as a tow line tied to something solid to stop the plane it might work. But I’m too lazy to figure it out this morning. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 25, 2001, 8:44pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/11 "2001-11-25T20:44:01Z")
I wanted to address this claim more directly: > [@](#): > > A thread of silk with the thickness of a pencil is able to stop a Boeing 747 flying at full speed. We are still unable to reproduce such a material with all our technological knowhow. From the data I posted in [this thread](http://boards.straightdope.com/sdmb/showthread.php?threadid=100786)\* for the tensile strength of a spider thread, the tensile strength for the “capture spiral” is 1338 MPa. A pencil has a diameter of 7.0 mm. Thus, a thread of spider silk with the diameter of a pencil has a max strength of 51,500 N (11,600 lb). Pretty impressive, but nothing compared to the max takeoff weight of a [Boeing 747-400](http://www.boeing.com/commercial/747-400/product.html) Passenger jet, which is 875,000 lb. Since this thread can’t even support the weight of the jet at rest, there’s no way it’s going to “stop [it] flying at full speed.” \*BTW, what was the rationale for starting an additional thread with such a similar topic? 😕 ---
**Author:** ![DPWhite](https://avatars.discourse-cdn.com/v4/letter/d/d26b3c/32.png) [@DPWhite](https://boards.straightdope.com/u/DPWhite)\ **Post date:** [November 25, 2001, 8:44pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/12 "2001-11-25T20:44:01Z")
A black widow or brown recluse can be deadly to humans, but not necessarily so. I have seen a number of news stories about how strong spider silk is, how some people want to make bullet proof vests out of it and how they are going to do genetic engineering on goats to make goats produce the stuff in their milk. Getting it from spiders just isn’t practical apparently. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 25, 2001, 9:04pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/13 "2001-11-25T21:04:29Z")
Wow! No activity on this thread all day (for more than 6 hours), and when I decide to revisit this thread, multiple simulposts! Great minds must think alike! 😃 Anyway, I hadn’t seen **Thrasymachus** ’ contribution when I posted, but considering these new figures, they seem to be comparable to mine. With the conversion 1 MPa = 145 psi, the 200,000 psi for dragline silk corresponds to 1380 MPa, which is on par with the figure I used above. Oh, and apparently **manhattan** has closed the other related [thread](http://boards.straightdope.com/sdmb/showthread.php?threadid=100786). ---
**Author:** ![donotprodme](https://avatars.discourse-cdn.com/v4/letter/d/43a26b/32.png) [@donotprodme](https://boards.straightdope.com/u/donotprodme)\ **Post date:** [November 25, 2001, 9:08pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/14 "2001-11-25T21:08:17Z")
The new bullet proof body armor is made out of spider silk. Or so I’ve heard 🙂 ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [November 25, 2001, 9:15pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/15 "2001-11-25T21:15:58Z")
> [@](#): > > \*Originally posted by donotprodme \* > **The new bullet proof body armor is made out of spider silk.** I don’t see why that would be advantageous. From **Thrasymachus** ’ link above, Kevlar 29 fiber has a tensile strength of 2700 MPa (400,0000 psi), which is twice that of spider silk. Also, **Thrasymachus** , the maximum extensibility of the capture spiral thread is an incredible **476%**. The weaker radial thread’s average extensibility is 39.4%. Source: [http://www.tiem.utk.edu/~mbeals/spider.html](http://www.tiem.utk.edu/~mbeals/spider.html) ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [November 25, 2001, 10:33pm UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/16 "2001-11-25T22:33:13Z")
> [@](#): > > …they are going to do genetic engineering on goats to make goats produce the stuff in their milk. Getting it from spiders just isn’t practical apparently… - - - So how are they going to get goat’s milk up a spider’s butt? Oh, wait: goat’s _milk_… So, goats are gonna be spinning webs with -, um, oh, man, the thought of this is getting pretty wierd right about now. - DougC ---
**Author:** ![RichLather](https://avatars.discourse-cdn.com/v4/letter/r/da6949/32.png) [@RichLather](https://boards.straightdope.com/u/RichLather)\ **Post date:** [November 26, 2001, 1:26am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/17 "2001-11-26T01:26:07Z")
> [@](#): > > \*Originally posted by donotprodme \* > \*\*The new bullet proof body armor is made out of spider silk. > > \*\* Just to nitpick: it’s bullet-_resistant_ body armor. If it were bullet_proof_ no bullets could get through it. I love throwing that out to the reporters and prducers I work with! ---
**Author:** ![Speaker\_for\_the\_Dead](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@Speaker\_for\_the\_Dead](https://boards.straightdope.com/u/Speaker_for_the_Dead)\ **Post date:** [November 26, 2001, 1:58am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/18 "2001-11-26T01:58:26Z")
> [@](#): > > \*Originally posted by RichLather \* > \*\* > > > [@](#): > > > > \*Originally posted by donotprodme \* > > \*\*The new bullet proof body armor is made out of spider silk. > > > > \*\* > > Just to nitpick: it’s bullet-_resistant_ body armor. If it were bullet_proof_ no bullets could get through it. I love throwing that out to the reporters and prducers I work with! \*\* That’s true, but it also depends on one’s definition of ‘bullet’, doesn’t it? 🙂 ---
**Author:** ![robinh](https://avatars.discourse-cdn.com/v4/letter/r/b77776/32.png) [@robinh](https://boards.straightdope.com/u/robinh)\ **Post date:** [November 26, 2001, 3:22am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/19 "2001-11-26T03:22:22Z")
> [@](#): > > \*Originally posted by robby \* > I’ve never heard of a “dernier,” especially with respect to the strength of a material. > > From this site: > [http://www.ilcdover.com/Products/EngInf/terms.htm](http://www.ilcdover.com/Products/EngInf/terms.htm) > > > [@](#): > > > > **Denier** : A weight-per-unit-length measure of any linear material. Officially, it is the number of unit weights of 0.05 grams per 450-meter length. This is numerically equal to the weight in grams of 9,000 meters of the material. Denier is a direct numbering system in which the lower numbers represent the finer sizes and the higher numbers the coarser sizes. > > A site that can’t even spell units correctly, and is mixing up “weight-per-unit-length” with “tensile strength” is rapidly losing credibility with me. > > Sounds like B.S. to me… \*\* I know nothing about spider webs or their relative strengths… however, I do know something about fibers. The term “denier” (just one “r”) does, indeed, refer to the thickness of a fiber. It was originally used to describe silks, but is also used for other fibers. This thickness is important for those who work with fibers; the tensile strength would be entirely dependant on the content of the fiber in question. [This site](http://home.att.net/~ssur/about.htm)-scroll down about a third of the way-gives a bit of an explanation. I couldn’t find anything much clearer. In any case, it is a term which is (I’m guessing) more useful to fiber artists than anyone else. ---
**Author:** ![clayton\_e](https://avatars.discourse-cdn.com/v4/letter/c/c57346/32.png) [@clayton\_e](https://boards.straightdope.com/u/clayton_e)\ **Post date:** [November 26, 2001, 3:33am UTC](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137/20 "2001-11-26T03:33:07Z")
Yeah, but that’s kinda like the same theory “Enough small pebbles piled in one spot can stop a train dead.” or something like that. If you put enough of something in one spot it will be able to do something you wouldn’t expect. I would be amazed if one spider could do that in a set time period, but the fact you propose does not impress me. If you get enough republicans in the way of a train… [Next page](https://boards.straightdope.com/t/can-a-spider-stop-a-747/95137.md?page=2)