HDTenEightyP/NetNews huggingface dataset:
From: ckp@netcom.com (Charles Pooley)
Subject: Re: Stink Bombs
Date: Sat, 22 Aug 92 01:02:52 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Summary: Annonia stink bomb


A fairly safe stink bomb with a built-in delay is made by mixing in
a paper bag 1 part NaOH with 2 parts NH4NO3, dry.   The reaction, which
requires water, goes slowly from atmospheric moisture and small amount
of water in the AN (which is hydroscopic), then rapidly, as the water
produced wets the mass.  After 2-15 minutes (not accurate timer, but rel-
iable), the stuff becomes a boiling hot gurgling mess which is rapidly
evolving ammonia.  Ammonia isn't too dangerous compared to some other stink
chemicals.
Another that a friend tried--a dead animal was placed in the squirrel-cage
blower of an air conditioning system...  It was slow, but they took a while
to find it...
-- 
Charles Pooley                  ckp@netcom.com    GEnie  c.pooley
EE consultant, Los Angeles, CA
Newsgroups: rec.pyrotechnics
From: firebird@cbnewsk.cb.att.com (larry rosen)
Subject: Re: a.p cookbook idea
Organization: AT&T
Distribution: usa
Date: Fri, 14 Aug 1992 22:07:10 GMT
Summary: safe&sane???

In article <1992Aug14.195246.9385@samba.oit.unc.edu>, cptully@med.unc.edu (Christopher P. Tully) writes:
> In article <1992Aug9.024732.9293@uoft02.utoledo.edu> aschlie@uoft02.utoledo.edu (A.Schliesser) writes:
> >With all the bitching about what to do and what not to do  when mixing
> >chemicals to make explosives. What I would like to see is the "experts" write a
> >small cookbood about the safe way to make the fun toys.  Yes, given that safty
> >depends on the maturity of the chemists, others of us who have extensive
> >chemistry background (eg. 1yr of inorganic and 1 year of organic) are
> >interested in the "how to" part.  Practically, very few will make the stuff,
> >other would like to know the whys and hows (eg. short cuts).
>**********
 
> Try going to your local army surplus store.  They (should) have old army
> manuals that give a lot of simple and SAFE compositions along with more
> detailed instructions than anyone with a BS should need.  I'm refering
> to such little wonders as the _Handbook_of_Improvised_Gorilla_Warfare_.
> Wonderful title, but it gives good and safe info.
> 
> Enjoy.
> Chris Tully


Good and Safe info??  You've got to be kidding.  Look at the key word in the
title, "Inprovised" which means not neccesarily safe.  Gorilla warfare 
seems to imply that accidents will happen.

Alive and well 

Newsgroups: rec.pyrotechnics
From: cptully@med.unc.edu (Christopher P. Tully)
Subject: Re: a.p cookbook idea
Organization: UNC-CH School of Medicine
Date: Fri, 14 Aug 1992 19:52:46 GMT

In article <1992Aug9.024732.9293@uoft02.utoledo.edu> aschlie@uoft02.utoledo.edu (A.Schliesser) writes:
>With all the bitching about what to do and what not to do  when mixing
>chemicals to make explosives. What I would like to see is the "experts" write a
>small cookbood about the safe way to make the fun toys.  Yes, given that safty
>depends on the maturity of the chemists, others of us who have extensive
>chemistry background (eg. 1yr of inorganic and 1 year of organic) are
>interested in the "how to" part.  Practically, very few will make the stuff,
>other would like to know the whys and hows (eg. short cuts).
>
>Any takers for such a task??
>
>Thanks,
>
>Tony

Try going to your local army surplus store.  They (should) have old army
manuals that give a lot of simple and SAFE compositions along with more
detailed instructions than anyone with a BS should need.  I'm refering
to such little wonders as the _Handbook_of_Improvised_Gorilla_Warfare_.
Wonderful title, but it gives good and safe info.

Enjoy.
Chris Tully
From: JDurand@cup.portal.com (Gerald Joseph Durand)
Newsgroups: rec.pyrotechnics
Subject: Re: Rocket Fuel question
Date: Sat, 22 Aug 92 09:24:24 PDT
Organization: The Portal System (TM)
Distribution: usa
  <1992Aug17.193146.19257@hplabsz.hpl.hp.com>
  <1992Aug20.140942.23181@b30.ingr.com>

>>
>>cheers...bic
>>
>Hey Bic! 
>Had a great time at the convention, especially running out in the desert
>putting out ROCKET FIRES! :)
Bic, I was wondering if our 1,600 gallon water tank will be big enough for
testing your rockets, or should I have the forestry department on standby?
8-) 8-) 8-)

To the rest of PGII, great show, can't wait to see the 60 foot version of
the wheel next year.

Jerry Durand
From: u8705114@cs.uow.edu.au (Anthony Thomas Cusack)
Newsgroups: rec.pyrotechnics
Subject: Stink Bombs
Keywords: stin bombs
Date: 21 Aug 92 01:26:21 GMT
Organization: Dept of Computer Science, Wollongong University, Australia

Why bother on the path of dangerous chemicals and the like - 
apart from the fact that they are fun.

When I was in high school a lab assistant was pouring the contents of
small dropper bottles down the drain, by and large they were
hydrocarbons, mostly short chain etc... although there was a small 
amount of acids (various) in some of the bottles.

The result as that buteric acid (?) was made and diffused through the 
drains in the building coming out of each sink. The smell is like
vomit / sour milk, and dispersed eventually.

From memory no one was killed, and only 2 - 3 hours of class time was 
missed while the lab was aired.

I'm sure that some smart chemist could tell you the 
appropriate chemicals to mix for the appropriate result

Hope this helps someone in gat a good laugh.

Anthony Cusack
u8705114@cs.uow.edu.au
Newsgroups: rec.pyrotechnics
From: fernee@newton.physics.uq.oz.au (Mark Fernee)
Subject: Re: Stink Bombs
Organization: Physics Dept. The University of Queensland
Date: Thu, 20 Aug 1992 03:07:38 GMT


This is just a possibility, but it sounds like a solution
of sodium polysulfide made by dissolving sodium sulfide
in water and then adding an excess of sulphur and mixing
them together untill the sulphur dissolves. This solution
turns a yellowish brown and smells of hydrogen sulphide.

By the way, hydrogen sulphide is more toxic than HCN and 
many orders of magnitude more pungent. Peolple have died
in Rotorua from this gas.

Any acid mixed with this polysulfide solution increases the
evolution of the gas. Phewww..

Mark.


 
Newsgroups: rec.pyrotechnics
From: grabenst@umbc4.umbc.edu (Mr. Michael Grabenstein; ACS (GUEST))
Subject: Re: Flash powder ....
Organization: Univ. of MD, Baltimore County
Date: Tue, 18 Aug 1992 21:44:49 GMT

In article <1992Aug18.081316.24885@usenet.ins.cwru.edu> cd353@cleveland.Freenet.Edu (Norman Spiney) writes:
>
>I have just tried the KMnO4 Al mixtures and find them very easy
>to ignite. I am using "Silver powder" from an art supply shop.
>to touch and is easily fluidised). The KClO4 Al mixtures seem to
>barbecue skewer). However mixtures of KMnO4 KClO4 Al have shown
>
>Mark.
>

	Mark or anyone else -- What is KMnO4 and KClO4 ???
What is it found in?
Thanks.

Later,
	Mike
	ZMEG@AACC.bitnet
	or grabenst@umbc3.umbc.edu
Newsgroups: rec.pyrotechnics
From: mark@lenti.med.umn.edu (Mark Olson (CDC))
Subject: Rocket Fuel question
Organization: University of Minnesota
Date: Wed, 12 Aug 1992 13:48:07 GMT


   I've got a question regarding the HTPB (polybutadiene) component
of a composite rocket propellant - how does one degass the mixture
and avoid the foaming problem?  When I try to vacuum degass the mixture
it expands to more than 10x its original size before many bubbles
come out.  I suppose a vacuum stirrer would obviate the problem but I
don't have access to one.  Would a large flat container work?  I don't
have a lot of resin to experiment with - I'm hoping someone else has
already solved this problem...
  
  Thanks!
  
mark olson
mark@lenti.med.umn.edu

Newsgroups: rec.pyrotechnics
From: mvp@netcom.com (Mike Van Pelt)
Subject: Re: a.p cookbook idea
Date: Sun, 16 Aug 92 00:37:49 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

In article <1992Aug14.195246.9385@samba.oit.unc.edu> cptully@med.unc.edu (Christopher P. Tully) writes:
>Try going to your local army surplus store.  They (should) have old army
>manuals that give a lot of simple and SAFE compositions along with more

NOT

Actually, the "Improvised Munitions" handbooks are a much better source
than suicide manuals like the Anarchist's Cookbook, but think long and
hard about the phrase "field expedient".  The IM book assumes that some
lossage of personell is just a part of the job.  This is something a
professional soldier might, in a sticky situation where he's otherwise
going to be killed or otherwise fail to accomplish his mission, do
once in his career.  Not something for a basement bomber to do on a
regular basis.

Caveat detonator.
-- 
Mike Van Pelt          | What happens if a big asteroid hits Earth?
mvp@netcom.com         | Judging from realistic simulations involving a
                       | sledge hammer and a common laboratory frog, we
                       | can assume it will be pretty bad. -- Dave Barry
From: mcaldwel@netcom.com (Michael Caldwell)
Newsgroups: rec.pyrotechnics
Subject: Re: Stink Bombs
Keywords: stin bombs
Date: 21 Aug 92 20:28:45 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

In my chemistry set I remember what it called a stink bomb was sodium
bisulfite and sodium bisulfate and water.  This also worked well and sounds
like it has the required sulpher.  As I remember it was equal parts and you
added water as long as it bubbled.  I interested in knowing what the actual
gas produced is.

Michael
Newsgroups: rec.pyrotechnics
From: fernee@newton.physics.uq.oz.au 
Subject: Re: a.p cookbook idea
Organization: The University of Queensland
Date: Sat, 15 Aug 1992 10:03:32 GMT

In article <1992Aug14.195246.9385@samba.oit.unc.edu>, cptully@med.unc.edu (Christopher P. Tully) writes:
|> In article <1992Aug9.024732.9293@uoft02.utoledo.edu> aschlie@uoft02.utoledo.edu (A.Schliesser) writes:
|> >With all the bitching about what to do and what not to do  when mixing
|> >chemicals to make explosives. What I would like to see is the "experts" write a
|> >small cookbood about the safe way to make the fun toys.  Yes, given that safty
|> >depends on the maturity of the chemists, others of us who have extensive
|> >chemistry background (eg. 1yr of inorganic and 1 year of organic) are
|> >interested in the "how to" part.  Practically, very few will make the stuff,
|> >other would like to know the whys and hows (eg. short cuts).
|> >
|> >Any takers for such a task??
|> >
|> >Thanks,
|> >
|> >Tony
|> 
|> Try going to your local army surplus store.  They (should) have old army
|> manuals that give a lot of simple and SAFE compositions along with more
|> detailed instructions than anyone with a BS should need.  I'm refering
|> to such little wonders as the _Handbook_of_Improvised_Gorilla_Warfare_.
|> Wonderful title, but it gives good and safe info.
|> 
|> Enjoy.
|> Chris Tully

I'd watch some of these cookbook recipes as some are notoriously
unreliable and/or highly unstable. For instance The Handbook of
Improvised Munitions mentions a technique for making RDX which
requires bringing the nitration mixture upto a temperature of
50 degrees Celsius. However reputable sources on the chemistry
of explosives state that THIS nitration mixture is highly
unstable above 28 degrees Celsius and undergoes rapid and
sometimes (explosive) decomposition. I would think twice before
trying any of these recipes! There are many great and reliable
books on pyrotechnics, practice and safety, maybe someone can
post a list.

There have been many tales of tradjedy posted to this group.
I would like to see a compendium of such stories posted so
as to keep us in mind of the real dangers involved in
recreational pyrotechnics.

Mark.

Newsgroups: rec.pyrotechnics
From: cptully@med.unc.edu (Christopher P. Tully)
Subject: Re: Flash powder ....
Organization: UNC-CH School of Medicine
Date: Fri, 14 Aug 1992 19:45:46 GMT

In reference to KMnO4 and gylcerol-

It does self-ignite, just doesn't always do it right away.  I like to pour a
small pile of KMnO4 on the ground (~ 1in dia by 1/2 in high) and douse with 
1/2 - 1 tsp. glycerol. (Yes I have tried this, so stand back; the flame is not
particularily large, but it is HOT [burns Mg nicely!] and spews in a wide
pattern.)  I did this on a small board in the snow once and got a purple 
(ofcourse) patch right around the KMnO4, and a large (1 1/2 - 3 ft dia) 
pattern of green specks on the snow.

Enjoy
From: th2_oate@csd.brispoly.ac.uk (Tom Oates)
Newsgroups: rec.pyrotechnics
Subject: Re: Stink Bombs
Date: 20 Aug 92 16:17:56 GMT
Organization: Bristol Polytechnic, England

The liquid in `stink-bombs' is hydrogen sulphide. Hydrogen sulphide
is poisonous. It's not likely to kill/injure by inhaling the fumes from a
single shop-bought stink bome in a large room. However, if you were to let 
off lots of them in a small space there might be trouble if the 
concentration of gas built up. To put it in perspective, during the First 
World War hydrogen sulphide saw limited use as a chemical weapon until it 
was superseded by Phosgene etc. Needless to say, don't drink the contents of
a stink bomb, and try not to home-build a really big one (ie. one the size
of a soda bottle) for use at your local nightclub. Might kill someone.

When I was a nasty schoolboy and the Americans were bombing Vietnam, I 
remember sneaking out of class during a lesson and placing a stink bomb 
on top of the bells which signalled the end of the lesson. I used 3 in all.
Come the end of the lesson the bells rang. Their vibration dislodged the 
stinkbombs which tumbled to the floor and cracked open. The resulting chaos 
can easily be imagined. There was an 'investigation', but the headmaster never
did find out who did it.

Now if you want a *really* unpleasant smell (ie. one which would make a 
billy goat cringe) try using mercaptan. 

-- 
*************************************************************************
*  Tom Oates  (Bristol Poly, England)    *   DISCLAIMER:-               *
*  JANET: th2_oate@csd.brispoly.ac.uk    *   I speak only for myself.   *
*************************************************************************
Newsgroups: rec.skydiving
From: CHAROLYN_BABICHUK@darwin.biochem.ualberta.ca
Subject: Re: First jump - T-minus 8 days
Organization: University of Alberta
Date: Fri, 14 Aug 1992 21:56:46 GMT

In article <l8o2opINN6id@exodus.Eng.Sun.COM> james@cadillac.Eng.Sun.COM (James
Mangin) writes:
>Much to my horror, I'm going to do it.  8^]  Heading up to Davis, Calif. next
weekend to go through
>level 1 training and freefall.  
>
>I'm scared...but I can't wait.
>
>Is it appropriate to party like wildmen after we've done it?
>

Forever and ever.  But don't forget the wildwomen, either.

>---
>James Mangin                                     

Charolyn Babichuk
From: bdh@csd.cri.dk (Bent Dandanell)
Newsgroups: rec.skydiving
Subject: PS
Keywords: Postscript,logbook
Date: 17 Aug 92 12:53:24 GMT
Organization: Computer Resources International A/S

Dear Friends,

Are there any of you that has a postscript file/description of those
little men we'are using when writing/stamping in  our logbooks?  I would
appreciate a postscript file containing a definition for such a `little
man' for an article which I'm writing.


Bent DanDanell
e-mail: bdh@csd.cri.dk
From: drp40@cd.amdahl.com (Douglas R Puchalski)
Newsgroups: rec.skydiving
Subject: Hard landing?
Date: 17 Aug 92 21:45:22 GMT
Reply-To: drp40@cd.amdahl.com
Organization: Amdahl Corporation, Sunnyvale, CA

Just to add some levity to a serious situation:

This weekend we were talking about a student who had died (Yolo?)
from a very hard landing (actually a spinning canopy, which 
we didn't mention at the time).

Jumper #1:  "Yeah.  I guess he died from severe internal injuries
             from the hard landing."
Jumper #2:  "What, you mean like 120mph??"

Aren't they all just hard landings?

-- 
Doug Puchalski						drp40@cd.amdahl.com
From: SKYDIVE@f15.n233.z1.fidonet.org (SKYDIVE)
Newsgroups: rec.skydiving
Subject: Re: Lost Prairie
Date: 17 Aug 92 19:31:46 GMT

Reply-to: Bill.Caefer@p0.f853.n102.z1.fidonet.org (Bill Caefer)
Fido-To: bleck@mobot.ai.mit.edu

 b> to: bleck@mobot.ai.mit.edu (Olaf Bleck)

|> >one last thing, anyone know if Delta has a policy concerning 
|> >rigs abord their craft as carry-on?
|> 
|> Hmmm,  It might make the other passengers a little nervous!

 b> I just tell them with a smirk that I wouldn't get on a plane without!

Another good line is:

"Didn't they give YOU one?"


--- Maximus 2.00
--- eecp 1.45 LM2 

 * Origin: <X> Infinity Ltd.  HST/DS (1:102/853)
--  
SKYDIVE - via FidoNet node 1:233/13
internet: SKYDIVE@f15.n233.z1.FIDONET.ORG
-- Check Source BBS, (217) 244-6954, HST, V.32, V.42bis ---
Newsgroups: rec.skydiving
From: bleck@theta.ai.mit.edu (Olaf Bleck)
Newsgroups: rec.skydiving
Subject: Re: LORAN System for Spotting
Date: 22 Aug 92 21:59:44 GMT
Reply-To: bleck@ai.mit.edu
Organization: MIT Artificial Intelligence Laboratory

In article <1992Aug21.203232.23668@nntpd.lkg.dec.com>, koning@koning.enet.dec.com (Paul Koning) writes:
|> I agree.  People who spot with Loran, or similar electronic hackery, in order
|> to jump through a solid cloud deck are -- in my opinion -- reckless maniacs,
|> and I wouldn't want to have anything to do with them.
|> 
|> Incidentally, both the pilot and the jumpers are in clear violation of
|> FAA part 105 by doing such a thing, and the pilot could suffer the
|> consequences (like losing his/her license).


Well, first off, if your 20-way is riding up in an Otter, and you get to an 8
grand cloud layer with your 16 ticket, you might just be tempted in a fit of
annoyance to change your mind suddenly.

Secondly, it clearly doesn't make sense to do this over a DZ where the air
traffic isn't well controlled, for the obvious reason that you can't see what
you might be jumping past.  At Quincy for example, Loran spotting happened
fairly often, but they had a temporary air traffic control center set up to
keep loads from dropping on each other, and to keep other air traffic out
from the spot.   So the risk of something being in your way, except for a
raindrops and ice crystals, was minimal, in this sport of risk management.

Third, sure, it's illegal (isn't that a sick bird?), but if *you* never do
*anything* illegal, I "wouldn't want to have anything to do with [you]"
either!!  I'd get bored stiff!

Fourth, traffic/transportation rules are there to protect the ordinary
average person from posing a danger to himself or to others under average
circumstances.  However, the old "rules are there to be broken" addage
applies whole-heartedly to many things, particularly when the persons
involved have made provisions to minimize the failure modes, either by better
training, traffic control, or whatever.  For example, I speed on the highway
because I personally am confident enough that I have better situation
awareness and handling ability than 95% of the people on the road, so does
that make me a "reckless maniac?"  Maybe if you're in the lowest 5
percentile...

Fifth, more of an example: those people that got out over lake ??? were
clearly taking a *big* risk--one of the failure modes here clearly is/was
that the LORAN could be busted over a large body of water.  So, doing a LORAN
spot near a large body of water is pretty dumb--but if you're out in the
middle of Illinois corn fields, even if you miss by a long way, you'd be hard
pressed to land in anyplace remotely dangerous!  At best some lone cow might
glance at you.

Sixth: I heard maybe a dozen first hand complaints of near misses during
opening in "novice" big-ways, and not one of "reckless mainiacs" jumping
through clouds, so maybe your sense of recklessness is not well thought out...

Enough...

Phlpzlpzlplz!!!
-Olaf  DBC804
Newsgroups: rec.skydiving
From: jvilhube@diana.cair.du.edu (Jan Vilhuber)
Subject: Re: First jump - T-minus 8 days
Organization: University of Denver, Denver, Colorado
Date: Fri, 14 Aug 92 23:41:10 GMT

In article <1992Aug14.215646.5000@kakwa.ucs.ualberta.ca> CHAROLYN_BABICHUK@darwin.biochem.ualberta.ca writes:
>In article <l8o2opINN6id@exodus.Eng.Sun.COM> james@cadillac.Eng.Sun.COM (James
>Mangin) writes:
>>Much to my horror, I'm going to do it.  8^]  Heading up to Davis, Calif. next
>weekend to go through
>>Is it appropriate to party like wildmen after we've done it?
>

Some make more of a religion of the partying (hi tim;)
>Forever and ever.  But don't forget the wildwomen, either.
>
No! Never forget the women. Not that many in skydiving (percentually).
-- 
 Jan Vilhuber            | Internet: jvilhube@du.edu or jvilhube@[130.253.1.4]
 (The skydivin' Bass)      | Bitnet  : jvilhube@DUCAIR
--------------------------------------------------
From: sl9b4@cc.usu.edu (Deep Six)
Newsgroups: rec.skydiving
Subject: Questions about (military) chutes
Date: 20 Aug 92 15:17:39 MDT
Organization: Utah State University

Hello, 

Have some questions for some of you ``vetrans'' (literally). I need information
on the T10 series of military parachutes.

First, what is the T10 like? Where is it worn? Is it steerable? How much
does it weigh? If I was buy one, how much would I expect to pay?

Second, what is the difference in the T10 and T10-A? Where is the T10-A
worn and how much does it weigh? Price?

Third, what about the T10-B and T10-C? What are their differences? What
would you expect to pay for them?

Do military parachutes have reserves built in (or included)? What kinds 
of reserve chutes are there?

Can static line parachutes (like the T10's) be fitted with manual rip 
cords?

What is the Para-Commander like? Where is it mounted and what are some
good esitmates on price and weight? Is it static line or rip cord 
operated (or either/both)? What makes it ``the Cadillac ride of all''?

Now what about the para-foil? Are these always worn on the back? What
about reserves? Are they included? Price? Weight? (For an average
quality set-up). 

Post if you want, but email responses would be better for me. Thanks
for any info.

Okay,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Chadd VanZanten SL9B4@CC.USU.EDU + ``Ahm just a hunka' hunka' burnin' luv.''
--Elvis, Burning Love
From: stephen@moclips (Stephen L Nicoud)
Newsgroups: rec.skydiving
Subject: Jumps from Jets
Summary: jumps from 737
Keywords: jet, 737, static line
Date: 17 Aug 92 22:42:03 GMT
Reply-To: stephen@boeing.com (Stephen L Nicoud)
Organization: Boeing Computer Services Research and Technology, Bellevue, WA USA
Originator: stephen@atc.boeing.com

Regarding parachute jumps from jets, I have Boeing test flight footage
showing the (first?) test of jumping from a 737.  For the test, they
first tossed a dummy out on a static line through the starboard rear
door.  After that was successful, two skydivers ("real dummies" as one
senior Boeing engineer put it :-) jumped.

Stephen
-- 
Stephen L Nicoud  <stephen@boeing.com>  bcstec!bcsaic!stephen
Boeing Computer Services Research and Technology, Computer Science
Bellevue, Washington  USA
"I ask unanimous consent to revise and extend my remarks."
From: U50281@uicvm.uic.edu
Newsgroups: rec.skydiving
Subject: Re: 727 loads
Date: 14 Aug 92 16:54:01 GMT
 <1992Aug13.025600.1696@zia.aoc.nrao.edu> <92226.182657U50281@uicvm.uic.edu>
 <1992Aug14.021220.9683@mercury.cair.du.edu>
Organization: University of Illinois at Chicago

In article <1992Aug14.021220.9683@mercury.cair.du.edu>,
tjreynol@zephyr.cair.du.edu (The Jumpin Dude) says:
>
>um, i don't understand how the dude figured out that his loop broke
>and then managed to keep his stuff inside his container,
>
>could you elaborate on that?
>
>
>also, was there a preferred body position for exit? like a maybe cannonball?
>:-)
>
>
>tim
>
I don't know how he figured it out.  I'm sure I wouldn't have known about it
until I figured out the horseshoe.  Preferred exit?  Whatever works...

Jeff Hauser
Sky Knights SPC
East Troy, WI
Newsgroups: rec.skydiving