# 2 skydiving questions **URL:** \ **Category:** Factual Questions\ **Created:** [September 9, 1999, 9:50pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170 "1999-09-09T21:50:00Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Strainger](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/strainger/32/244_2.png) [@Strainger](https://boards.straightdope.com/u/Strainger)\ **Post date:** [September 10, 1999, 9:04pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/21 "1999-09-10T21:04:00Z")
BTW, my last 2 posts were in response to **E1skeptic’s** post, even though he didn’t think of _me_ ::sniff:: ---
**Author:** ![Omniscient](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omniscient/32/3290_2.png) [@Omniscient](https://boards.straightdope.com/u/Omniscient)\ **Post date:** [September 10, 1999, 9:24pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/22 "1999-09-10T21:24:00Z")
E1, I gave you the speed of sound at the two altitudes so you don’t need to calculate it with the temps. FYI at the altitude we’re concerned with here it gets warmer as you get higher. If you want it here they are: T(o-f)=228.5K-224.5K (o=initial alt, f=final alt of free fall) ---
**Author:** ![E1skeptic](https://avatars.discourse-cdn.com/v4/letter/e/3da27b/32.png) [@E1skeptic](https://boards.straightdope.com/u/E1skeptic)\ **Post date:** [September 10, 1999, 10:20pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/23 "1999-09-10T22:20:00Z")
Thanks **Strainger** , I was too lazy to go grab my Aerodynamics book. Hey, **Omni** , I was oversimplifying, ok? I know that the temperature at the tropopause is a (supposedly) constant of -56.4°C, remaining there until up to about 12 miles, and then increasing slowly (all this within the stratosphere) before reaching half way into the mesosphere where it begins to decrease again, and… shall I continue? ---
**Author:** ![E1skeptic](https://avatars.discourse-cdn.com/v4/letter/e/3da27b/32.png) [@E1skeptic](https://boards.straightdope.com/u/E1skeptic)\ **Post date:** [September 10, 1999, 10:22pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/24 "1999-09-10T22:22:00Z")
But thanks to both of you anyway. 🙂 ---
**Author:** ![Whammo](https://avatars.discourse-cdn.com/v4/letter/w/8dc957/32.png) [@Whammo](https://boards.straightdope.com/u/Whammo)\ **Post date:** [September 10, 1999, 11:26pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/25 "1999-09-10T23:26:00Z")
swept wings are needed because you have to keep them within the “cone” of the air wave that comes off of the nose of the plane and spreads out around it. OR. you need short stubby wings kept in the cone, hence, the first sound barrier breakers. * * * The wisest man I ever knew taught me something I never forgot. And although I never forgot it, I never quite memorized it either. So what I’m left with is the memory of having learned something very wise that I can’t quite remember. -George Carlin ---
**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:** [September 11, 1999, 12:39am UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/26 "1999-09-11T00:39:00Z")
> [@](#): > > The wisest man I ever knew taught me something I never forgot. And although I never forgot it, I never quite memorized it either. So what I’m left with is the memory of having learned something very wise that I can’t quite remember. -George Carlin Dang, that actually makes sense! ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [September 11, 1999, 3:37am UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/27 "1999-09-11T03:37:00Z")
B-12: Exactly. And that’s why the F-104 doesn’t have swept wings. ---
**Author:** ![dkgreath](https://avatars.discourse-cdn.com/v4/letter/d/bbe5ce/32.png) [@dkgreath](https://boards.straightdope.com/u/dkgreath)\ **Post date:** [September 11, 1999, 12:58pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/28 "1999-09-11T12:58:00Z")
I personally am amazed at how many people skydive (or bungie jump). My rule regarding such activities: 2 things fall out of the sky…Bird shit and fools. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [September 11, 1999, 6:53pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/29 "1999-09-11T18:53:00Z")
Do you have any statistics to back up your assertion that skydiving is foolish? Is it more dangerous than car racing? How about playing football? Mountain climbing? Going on a cross country holiday drive? Just where does it fit in? And if you don’t know, why do you feel compelled to judge people? ---
**Author:** ![Nickrz](https://avatars.discourse-cdn.com/v4/letter/n/bbce88/32.png) [@Nickrz](https://boards.straightdope.com/u/Nickrz)\ **Post date:** [September 12, 1999, 2:15pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/30 "1999-09-12T14:15:00Z")
So, to sum up… We know people don’t breathe through their skin, water clouds don’t suffocate us, and a few of us have jumped out of perfectly good airplanes… but we’re still not sure if anyone has broken the sound barrier while in freefall. ---
**Author:** ![Omniscient](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omniscient/32/3290_2.png) [@Omniscient](https://boards.straightdope.com/u/Omniscient)\ **Post date:** [September 12, 1999, 10:08pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/31 "1999-09-12T22:08:00Z")
I wish I could find this link that I read a while back (looking up this same topic) that discussed the Russian Cosmonaut who supposedly broke the sound barrier and jumped from a higher altitude than Kittenger. I searched on a handful of engines and can’t find the link I found last time, IIRC he jumped from slightly higher, but reached speeds in excess of 700 mph. Granted Russian records around this time are dubious at best so I imagine Guiness needs more reliable data (or maybe not). ---
**Author:** ![zuma](https://avatars.discourse-cdn.com/v4/letter/z/e9c0ed/32.png) [@zuma](https://boards.straightdope.com/u/zuma)\ **Post date:** [October 21, 2001, 7:05pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/32 "2001-10-21T19:05:14Z")
Hrm… apparently a skydiver, in a pressurized suit, is planning to jump from 130,000 feet, breaking kittinger’s 40-year old record. One odd quote from the article: “He appears undaunted by warnings from scientists that the descent through near-space could be so fast that his head will explode.” His head might explode? That sounds rather silly to me. [http://www.sunday-times.co.uk/news/pages/sti/2001/10/21/stifgnaus01001.html](http://www.sunday-times.co.uk/news/pages/sti/2001/10/21/stifgnaus01001.html) ---
**Author:** ![postcards](https://avatars.discourse-cdn.com/v4/letter/p/8e8cbc/32.png) [@postcards](https://boards.straightdope.com/u/postcards)\ **Post date:** [October 21, 2001, 7:33pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/33 "2001-10-21T19:33:08Z")
That sounds perfectly reasonable to me. His head just might explode. I was starting to think what might happen to your unprotected eardrums at the speed of sound when I came to this post. And just where the heck has **Coach** been for the last two years? ---
**Author:** ![micco](https://avatars.discourse-cdn.com/v4/letter/m/5f8ce5/32.png) [@micco](https://boards.straightdope.com/u/micco)\ **Post date:** [October 22, 2001, 3:41am UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/34 "2001-10-22T03:41:10Z")
Here’s another team working on a high altitude jump. [http://www.stratoquest.com/default.cfm](http://www.stratoquest.com/default.cfm) Their goal is actually to set the high-altitude record, and freefalling faster than Mach 1 may nor may not be a side effect of that. Their FAQ says: > [@](#): > > Q: Will Cheryl break the sound barrier? > A: There is currently no information on this subject and no human has ever broke the barrier without an external vehicle. The speed that Cheryl will be traveling (1.3 mach ) infers that she will break the barrier, although we are not sure that she will have the mass to actually make this happen. ---
**Author:** ![Popup](https://avatars.discourse-cdn.com/v4/letter/p/94ad74/32.png) [@Popup](https://boards.straightdope.com/u/Popup)\ **Post date:** [October 22, 2001, 12:49pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/35 "2001-10-22T12:49:44Z")
> [@](#): > > \*Originally posted by dhanson \* > **Do you have any statistics to back up your assertion that skydiving is foolish? Is it more dangerous than car racing? How about playing football? Mountain climbing? Going on a cross country holiday drive? Just where does it fit in?** Not that I agree with **dkgreath** (I would love to take up skydiving again, but there are other constraints), but skydiving **is** dangerous. This list came from a post here a long time ago, and I found it so interesting that I kept it locally: ```auto code:Activity # Fatalities per 1,000,000 exposure hours -------------------------------------------------------- Skydiving 128.71 General Aviation 15.58 On-road Motorcycling 8.80 Scuba Diving 1.98 Living (all causes of death) 1.53 Swimming 1.07 Snowmobiling .88 Passenger cars .47 Water skiing .28 Bicycling .26 Flying (scheduled domestic airlines) .15 Hunting .08 Cosmic Radiation from transcontinental flights .035 Home Living (active) .027 Traveling in a School Bus .022 Passenger Car Post-collision fire .017 Home Living, active & passive (sleeping) .014 Residential Fire .003 This is taken from the Bicycle Helmet Statistics page, which quotes it from "Failure Analysis Associates, Inc." whatever that is. ``` [Edited by UncleBeer on 10-22-2001 at 12:52 PM] ---
**Author:** ![RM\_Mentock](https://avatars.discourse-cdn.com/v4/letter/r/e274bd/32.png) [@RM\_Mentock](https://boards.straightdope.com/u/RM_Mentock)\ **Post date:** [October 22, 2001, 4:17pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/36 "2001-10-22T16:17:38Z")
> [@](#): > > \*Originally posted by tc \* > **Not that I agree with dkgreath (I would love to take up skydiving again, but there are other constraints), but skydiving is dangerous. This list came from a post here a long time ago, and I found it so interesting that I kept it locally:** Very interesting. Do you mean it was posted to the SDMB? I searched on it, and it seems to have come from this thread: [http://boards.straightdope.com/sdmb/showthread.php?threadid=58139](http://boards.straightdope.com/sdmb/showthread.php?threadid=58139) scr4 said it came from the [Bicycle Helmet Statistics page](http://www.bhsi.org/webdocs/stats.htm). It seems to support my [Safety thesis](http://www.teemings.com/issue07/safety.html)–although I wondered about the General Aviation category. In that other thread, Dr. Lao pointed out that General Aviation does not include regularly scheduled commercial flights, so it is odd that the list includes Passenger Cars, but not Commercial Airline Flights. ---
**Author:** ![audient](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@audient](https://boards.straightdope.com/u/audient)\ **Post date:** [October 22, 2001, 5:34pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/37 "2001-10-22T17:34:19Z")
fascinating data on the dangers of ordinary life. > [@](#): > > \*Originally posted by tc \* > > ```auto > > code:Activity # Fatalities per 1,000,000 exposure hours > > -------------------------------------------------------- > Home Living, active & passive (sleeping) .014 > Residential Fire .003 > > ``` this is intriguing. I’ll have to find a full explanation of these entries. It looks to me like I’m safer with my house on fire, then when I’m asleep. I guess I’ll have to torch the old place before I knock off tonight. But then, what’ll I do to keep safe _tomorrow_ night?? ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [October 22, 2001, 6:12pm UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/38 "2001-10-22T18:12:59Z")
I assume the fires are somewhat safe because people actively flee a burning house and are usually able to get out. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [October 23, 2001, 2:47am UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/39 "2001-10-23T02:47:04Z")
**tc:** Those statistics are misleading. They count the risk ‘per hour of activity’. But is that a reasonable measure? Not really, because you are comparing a very concentrated activity to one that is more diffuse. A more reasonable number would be event-based. Like, “What are the odds that I’ll be killed in a single skydiving jump” as compared to, say, “What are the odds that I’ll be killed driving to the airport?” If it takes 2 hours to drive to the airport, but the actual skydive jump only takes 3 minutes, then the odds of dying in the car are about 1 in a million, and the odds of dying in the jump itself are about 6.4 in a million. So there’s a six-times greater chance that you’ll be killed in the skydiving jump than in the 2-hour drive to get to the airport. But then, if you drive your motorcyle to the airport, the odds of being killed on the way to the jump to 17.6 in a million. So, if we use your numbers, then if you take a two-hour trip to the airport on your motorcyle to go skydiving, you are almost three times more likely to be killed on the trip to the airport than in the actual jump. That looks a little different than the way you stated it, doesn’t it? Here’s another one: Let’s say you become a skydiving fanatic, and get 1,000 jumps under your belt over your lifetime. Let’s assume that each jump takes 3 minutes. So you’ll spend a grand total of 50 hours skydiving over your life, and your chance of being killed in a skydiving accident in your lifetime is about 6435 in a million, or about .64% Now, let’s assume that you can do two jumps in a full day, so you spend 500 full days in your life engaged in your skydiving hobby. Your neighbor Bob thinks you are a risky idiot, and prides himself in engaging in ‘safer’ hobbies. So every time you go skydiving, he takes his motorcyle out and goes for a Sunday drive for 4 hours. So he’ll spend 2000 hours driving around during the time that you are skydiving. His odds of being killed engaged in his hobby is about 17,600 in a million, or about 1.76%. Your prudent neighbor just made a choice that will result in it being almost three times more likely that he’ll be killed engaging in his hobby than you will be engaging in yours. And of course, the REALLY safe guy who never ventures out of his house, and therefore doesn’t get as much exercise and stimulation as the two of you is making the riskiest choice of all. Because while those other activities have risks that hover around the 1% mark for lifetime engagement, the odds of dying from heart disease are about 1 in 3 - THIRTY times higher. Just focusing on raw statistical numbers can cause one to lose perspective. ---
**Author:** ![audient](https://avatars.discourse-cdn.com/v4/letter/a/ad7895/32.png) [@audient](https://boards.straightdope.com/u/audient)\ **Post date:** [October 23, 2001, 3:30am UTC](https://boards.straightdope.com/t/2-skydiving-questions/3170/40 "2001-10-23T03:30:07Z")
my earlier dry humor aside, I still say those fire figures look fishy. Of course the number is low “because people run out of fires”. One would guess that the amount of time actually spent exposed to any one fire is measured in seconds, or a few minutes at most. but we’re looking at “Fatalities per million exposure hours”. The data implies that someone divided the number of deaths due to residential fires by an estimated amount of time americans spent actually in fires. (adding up all those 10 second dashes, etc). At .003, that means that for _each_ fire death, there were - 333 _million_ hours spent in burning houses! WHOA DUDE. But actually, fire deaths number in the thousands, anually, which makes the exposure hours … um, something really big. Now I haven’t spent any time in a burning residence, perhaps everyone else is, to keep the average up, OR… some statistician is counting all hours spent in residences. [Previous page](https://boards.straightdope.com/t/2-skydiving-questions/3170.md?page=1) [Next page](https://boards.straightdope.com/t/2-skydiving-questions/3170.md?page=3)