HDTenEightyP/NetNews huggingface dataset:
From: latyr@IASTATE.EDU (Leslie A Tyrrell)
Subject: Re: Scratching
Reply-To: latyr@IASTATE.EDU (Leslie A Tyrrell)
Organization: Iowa State University
Date: Mon, 5 Oct 1992 03:01:54 GMT

In article <gaynier.718246437@s1.elec.uq.oz.au>, gaynier@elec.uq.oz.au (Ron
Gaynier) writes:
> In <1992Oct4.172422.28354@abo.fi> HAHLLUND@finabo.abo.fi (Hans Ahllund Inf)
writes:
> 
> "|"Hello Fellow glider-pilots...
> 
> "|"I would like to add my own opinions in your scratching diskussion...
> 
> "|"The first thing you have to realise is that thermals below a certain 
> "|" altitude, depending on the day , tend to be Bubble-shaped.

<part ommitted for brevity>

> "|" If you fly into the bubble from the middle, it will feel almost like you
> "|" have encountered a "thermal-pipe" (formed by a cloud). This is the
easiest
> "|" option. Just bank hard and climb. Do not change thermal when the lift
> "|" decreases a bit. The decrease only indicates that you have reached the
top
> "|" of the bubble. At this point lift is equal to the speed of the bubble    
>     going upwards.
> "|" 
> 
> I have often heard people talk about climbing to the top of a rising bubble
> of air, I don't think this is possible. Remember that a glider is normally 
> sinking through the air mass even when thermaling. What causes us to climb is
> the fact that the air mass is rising faster than the glider is sinking and
> the net affect is an increase in altitude. If we could climb faster than the
> air mass is rising then we wouldn't need thermals at all. If you stay in
> a rising bubble of air you will eventually come out the bottom as it rises
> faster than you do.
> 
> Ron Gaynier


I've also read about this.  I believe Hans is describing a situation where
the thermal is in the form of a ring vortex.  The air in the center of the
vortex rises faster than the ring, thus it is still possible for a glider
circling in the fast-rising core to climb to the top of the thermal, which
is only rising as fast as the vortex ring.

I do not yet have the enough flight experience to actually confirm this,
though I can recall encountering situations which this would explain rather
nicely.  Either that, or I'm good at flying out of strong lift well below
cloudbase.

I would also reccomend reading through back issues of the British Gliding
Association's magazine, Sailplane and Gliding.  An article concerning
just this phenomena written by John Williamson appears in the Feb/March 1987
issue, and is very informative.

Les Tyrrell

p.s. anyone know how I could get some Wave imported to Iowa?
From: raveling@Unify.com (Paul Raveling)
Newsgroups: rec.aviation.soaring
Subject: Re: Hunting for thermals.
Date: 5 Oct 92 19:50:48 GMT
Organization: Unify Corporation (Sacramento)

In article <RCG.92Oct2093719@delphi.delphi.dseg.ti.com>, rcg@delphi.dseg.ti.com (bob gibbons) writes:
> In article <10504@uqcspe.cs.uq.oz.au> colin@cs.uq.oz.au (Colin Millerchip) writes:
> 
> >   I'd like to start a discussion on how people hunt for thermals.

	A pretty good summary of techniques.
> 
> >    - heat sources and "triggers": on blue days (ie, a cloudless sky), 
> >   look for ground sources that are likely to be hot (for eg, large black
> >   paddocks), and then look for the trigger point -- some obstacle,
> >   usually slightly downwind of the source, which initiates the thermal.  
> 
> On blue days, I have never found ground triggers to be of much use
> except when low (below, say, 600m). By and large, I just fly straight on
> course until I hit something, with two general guidelines, 1.) if sink
> seems to be long lasting, try a 45 deg course deviation, you might be in
> a sink street, and 2.) try to stay to the high ground, you determine
> this by watching stream beds, usually shown by tree lines along the
> beds. ...

> Of course these guidelines are for flat land soaring. My principal
> soaring area is northeast Texas, very flat.

	Good advice.  A couple additions that depend on local situations
	might be...

	--  Look for dust devils (did I miss a reference to them?).
	    In blue-sky areas, such as most deserts, these usually
	    are the most visible markers for boomers.

	--  In non-flat land, compare geography and surface wind
	    direction.  This is a variation on earlier comments, but
	    one configuration that often generates thermals is a
	    valley that's sheltered from the wind by a ridge at
	    its side.  It can act enough like an oven to spawn
	    a resident thermal (example:  A house thermal near Crystal,
	    between a foothill ridge and the higher ground of the
	    San Gabriel Mts).  On the other hand look out for
	    the same place if the wind turns 90-degrees, converting
	    the valley to a wind tunnel & breaking up would-be thermals.

	Beyond that I can only second the thoughts about looking
	for sunlit dark areas and contours that help local wind to trigger
	a thermal.  Looking for places that may develop orographic
	lift often works for finding thermals.


------------------
Paul Raveling
Raveling@Unify.com
From: jim@fjolsvid.css.gov (Jim Wang)
Newsgroups: rec.aviation.soaring
Subject: Re: Scratching
Date: 6 Oct 92 15:56:58 GMT
Reply-To: jim@fjolsvid.css.gov (Jim Wang)
Organization: Science Applications Int'l Corp./Geophysics Div.
In-reply-to: ludeman@astroatc.uucp (Weekend Pilot)

In article <1992Oct5.155640.22184@astroatc.uucp>, ludeman@astroatc (Weekend Pilot) writes:
>
>Clarence See, in the course of forty or more years of flying sailplanes,
>told me that exactly *twice* he has thermaled up in the blue to  the 
>condensation level and had a cumulus start to form all around him -- i.e.
>he was indeed at the very top of the bubble.  This is possible if the thermal
>follows the torroidal bubble model, the sailplane is well centered in the
>core and the core rate of rise exceeds the overall rate of rise by more
>than the sink rate of the sailplane.  Pretty neat.  
>-- 

I'm a little puzzled by this account because when a blue bubble
reaches the condensation level, it is not at the top of its climb.  In
fact, since the latent heat of vaporization is being released by the
condensation, the ambient lapse rate only needs to exceed the
saturated pseudo-adiabatic lapse rate (SALR) rather than the dry
adiabatic lapse rate (DALR) to continue the climb.  Since the SALR
(5C/km) is less than the DALR (10C/km) the "bubble" would actually
tend to accelerate after it reaches the condensation level.

Also, in my much more limited experience in soaring, I've often
climbed to the condensation level and noticed clouds start to form
(they form quickly, and it can be quite scary).  I would think that
this would be an even more common occurence in the East than here in
the arid West.  What's the explanation?

Jim
From: steckner@lri.uwo.ca (Michael Steckner)
Newsgroups: rec.aviation.soaring
Subject: World class gliders
Date: 4 Oct 92 14:35:04 GMT
Article-I.D.: lri.9210041435.AA03617
Organization: Relayed-by-Sendmail
To: rec.aviation.soaring@julian.uwo.ca

I understand that the world class fly off is currently in process somewhere
in Germany. Is there anyone out there who can tell us what is going on there?
Newsgroups: rec.aviation.soaring
From: martin@kaa.desy.de (Martin Gasthuber)
Subject: Re: Hunting for thermals.
Organization: UNI-Hamburg I Institut f. Exp-Physik
Date: Fri, 2 Oct 1992 10:51:06 GMT

In article <10504@uqcspe.cs.uq.oz.au>, colin@cs.uq.oz.au (Colin Millerchip) writes:
|> Hello to r.a.s!
|> 
|> I'd like to start a discussion on how people hunt for thermals. Here in
|> Oz I'm spoiled rotten, but I'm returning to the UK in the
|> not-too-distant future, and anticipate a tougher time. I'm still a
|> novice, having only recently gone solo, but am privileged to have
|> started cross-country training with Allan Latemore, a pilot of some
|> standing in Australia. So far I've been exposed to a couple of
|> techniques, and I'm wondering if there are any others around.  
|> 
very good idea ....
|> The two techniques that I've met are: 
|> 
|>  - clouds; cu-s often have thermals under them, so on clouded days 
|> here in Oz thermal hunting can be fairly straightforward. Other factors
|> have been mentioned/alluded to, such as overdevelopment of the day, or
|> the day "cycling".  
|> 
|>  - heat sources and "triggers": on blue days (ie, a cloudless sky), 
|> look for ground sources that are likely to be hot (for eg, large black
|> paddocks), and then look for the trigger point -- some obstacle,
|> usually slightly downwind of the source, which initiates the thermal.  
|> 
|> 
|> There are other general rules, like looking for soaring birds, chaff in
|> the air, and leeching off a good pilot >:-) As you can see, these
|> descriptions are woolly in the extreme (maybe that's what I like about
|> thermal hunting!). If anyone can add other techniques to this short
|> list, or comments on the effectiveness of these two, I'd love to hear
|> them (the associated theory as to why they work would also be
|> interesting). I'm obviously interested in any UK-specific techniques.  

sometimes on a windy day and good air (cold and dry), means high base
it's possible to catch a wave and climb. I've done so near Hamburg and
reached a maximum high of 4300 meters. Mostly the air is too dry, so
no chance to see (visually) such a wave.

Another trick (hopefully) at blue days are some invisible thermal-street's
so remember the wind direction and fly into that direction if reached some
thermals. At my location it works very often, and make life so easy..... 

Waiting for the next season (on the upside of the world) !!!!!  --))

-- 

/***************************************************************************\
|  Martin Gasthuber    I. Institut f. Experimentalphysik                    |
|                      Luruper Chaussee 149                                 |
|                      2000 Hamburg 50          Tel. 49-40-8998/2164        |
|     martin@kaa.desy.de I04GAS@DHHDESY3.BITNET r02gas@rec01.desy.de        |
\***************************************************************************/
Newsgroups: rec.aviation.soaring
From: orloff@surya4.cern.ch (Jean Orloff)
Subject: Rule for Base of Thermal Cu needs experimental confirmation
Organization: CERN, European Research Center for Particle Physics
Distribution: rec
Date: Mon, 5 Oct 1992 11:26:48 GMT

I started reading about micro-meteo recently, and as a physicist,
tried to cook-up a few formulae. One of these assumes only a small
early morning fog (ie ground-level saturation at the minimal
temperature) and says that the basis of thermal cumuli should be at

75 METERS * (GROUND TEMP. NOW - MIN. GROUND TEMP.) (in centigrades)

This follows from the dry adiabatic temperature gradient (+-95
meters/degree Cent) minus the equal saturation gradient (+- 20
meters/degree) and should hold if there is no humidity exchange
between the rising air and its surroundings (I assume water diffusion to
be too slow, just like heat conduction).

I would be most interested to hear the opinion of flying gods who ride
the sky with their eyes on an altimeter, watching for vertical
currents, and always know about ground temperatures from their meteo
bulletin: how correct/useful/well-known this rule of thumb might be????

Sincerely,
Jean
--
*************************************************************************
*	Jean Orloff		*	e-mail: ORLOFF@dxcern.cern.ch	*
*	TH-Division, CERN	*	phone:	(41-22) 767-3204	*
*	CH-1211 Geneva 23	*	fax:	(41-22) 782-3914	*
*************************************************************************
Newsgroups: rec.aviation.soaring
From: mgb5528@cc.utah.edu (Beck, Michael Gregory)
Subject: Soaring GODS!
News-Software: VAX/VMS VNEWS 1.4-b1  
Organization: University of Utah Computer Center
Date:  2 Oct 1992 18:50 MST  

Boy you guys are the guys I want to talk to!  I am an aspiring glider pilot, 
buI really want to get started.  How does one really get started.  Should Iake 
a regular ground school and go from there or are there special classes for 
gliders? 

Newsgroups: rec.aviation.soaring
From: rcg@delphi.dseg.ti.com (bob gibbons)
Subject: Re: World class gliders
Organization: Texas Instruments
Date: Mon, 5 Oct 1992 15:37:58 GMT

In article <9210041435.AA03617@lri.uwo.ca> Michael Steckner <steckner@lri.uwo.ca> writes:

>   I understand that the world class fly off is currently in process somewhere
>   in Germany. Is there anyone out there who can tell us what is going on there?

Dick Johnson is currently in Germany on the jury evaluating the World
Class gliders. He is due back later this week, I will ask if he can give
me a brief summary, if so, I will post.
--
Bob Gibbons				Texas Instruments
Internet: rcg@delphi.dseg.ti.com	Dallas, TX
Newsgroups: rec.aviation.soaring
From: gaynier@elec.uq.oz.au (Ron Gaynier)
Subject: Re: Scratching
Organization: Prentice Centre, University of Queensland
Date: Mon, 5 Oct 1992 00:53:57 GMT

In <1992Oct4.172422.28354@abo.fi> HAHLLUND@finabo.abo.fi (Hans Ahllund Inf) writes:

"|"Hello Fellow glider-pilots...

"|"I would like to add my own opinions in your scratching diskussion...

"|" The first thing you have to realise is that thermals below a certain 
"|" altitude, depending on the day , tend to be Bubble-shaped.
"|" Because of this, you first have to find out in wich part of the bubble
"|" you are, or , if you are in the vicinity of several smaller bubbles.
"|" 
"|" If you encounter weak lift that has very little sink when you enter, and
"|" it feels like you would be flying on a ball when trying to center, then
"|" you are on top of a bubble coming up. The thing is to keep centering and
"|" after a while you will slide into the core of the bubble.

"|" If you fly into the bubble from the middle, it will feel almost like you
"|" have encountered a "thermal-pipe" (formed by a cloud). This is the easiest
"|" option. Just bank hard and climb. Do not change thermal when the lift
"|" decreases a bit. The decrease only indicates that you have reached the top
"|" of the bubble. At this point lift is equal to the speed of the bubble going
"|" upwards.
"|" 

I have often heard people talk about climbing to the top of a rising bubble
of air, I don't think this is possible. Remember that a glider is normally 
sinking through the air mass even when thermaling. What causes us to climb is
the fact that the air mass is rising faster than the glider is sinking and
the net affect is an increase in altitude. If we could climb faster than the
air mass is rising then we wouldn't need thermals at all. If you stay in
a rising bubble of air you will eventually come out the bottom as it rises
faster than you do.

Ron Gaynier


Newsgroups: rec.aviation.soaring
From: petri@venus.iucf.indiana.edu (HOWARD PETRI)
Subject: Glider Waxing
News-Software: VAX/VMS VNEWS 1.3-4   
Reply-To: petri@venus.iucf.indiana.edu
Organization: INDIANA U. CYCLOTRON FACILITY, BLOOMINGTON, IN
Distribution:  world
Date: Tue, 6 Oct 1992 04:01:14 GMT


     I would like to wax my Pegasus, but as most of us know, the 
people who do glass repairs beseech us not to use a silicone based
wax. So does anyone know of a good non-silicone based wax that
can be used? I know the pure carnubas are OK , but I haven't found any
around here and I suspect they are hard to use. I have heard that
there are some teflon based waxes. Anybody know something about them?
Finally last year I read an article in a car magazine that evaluated
auto waxes. There are some auto waxes out there that claim not to have
any silicone in them, but when analyzed were found to contain silicone
after all. So reading wax labels won't help. Anybody know for sure
what is OK to use?

Howard Petri
Pegasus  (EJ)
From: hagood@sabre.den.mmc.com (Dave Hagood)
Newsgroups: rec.aviation.soaring
Subject: Re: World class gliders
Date: 5 Oct 92 17:18:30 GMT
Organization: Martin Marietta Astronautics Group

In article <9210041435.AA03617@lri.uwo.ca>, steckner@lri.uwo.ca (Michael Steckner) writes:
|> I understand that the world class fly off is currently in process somewhere
|> in Germany. Is there anyone out there who can tell us what is going on there?

	As I understand it, all aircraft that were not issued an airworthiness
certificate in their country of manufacture were prohibited from flying in
German airspace.  Since this competition is a fly-off, the inability to fly
has removed several (most?) of the designs from the competition.

	Specifically, the American entry was removed from the competition; I
believe all gliders designed and built specifically for the World Class Glider
competition were removed as well.

-------------------------------------------------------------------------
									|
David M. Hagood			Martin Marietta Astronautics Group	|
									|
Voice:  (303) 977-9657		When in danger, or in doubt,		|
E-mail: hagood@den.mmc.com	Run in circles, scream and shout.	|
Fax: (303) 977-1530							|
									|
-------------------------------------------------------------------------
     static char *disclaimer = "My opinions, not Martin Marietta's."    |
-------------------------------------------------------------------------
Newsgroups: rec.aviation.soaring
From: battlec@cs.rpi.edu (Clark Battle)
Subject: College hangin'
Date: Wed, 7 Oct 1992 01:15:28 GMT

I want to start a hg group at RPI but I am receiving flak about insurability.
RPI has scuba, flying, rock & ice climbing, and spelunking clubs but hg has
repeatedly been shot down.  What I need is support from any established and
college recognized (ie:funded) hg groups.  If RPI can see how it is done at
other colleges then maybe they'll ease up and fund us.
Newsgroups: rec.aviation.soaring
From: pt@geovision.gvc.com (Paul Tomblin)
Newsgroups: rec.aviation.soaring
Subject: Two dumb questions...
Date: 2 Oct 92 18:12:54 GMT
Reply-To: pt@geovision.gvc.com
Organization: Not officially GeoVision Systems Inc., Ottawa, Ontario

I've got two question about soaring:

1. Why do high performance sailplanes carry water ballast?  (I got asked this
question because a couple of the pictures posted to the net had water
streaming out of them.  I used to know, but I forgot.)

2. I live in Ottawa (near enough to the Gatineau Glider Club, I assume), and
I used to be mad keen about soaring - 15 years ago I used to have the book
"The Art and Technique of Soaring" out of the library constantly.  But that
was before the real world caught up to me.  What would it cost for me to
learn to soar, and what sort of money per year are we talking about to stay
reasonably active in the sport?

Thanks for any response.  If you'd rather email me, I'll summarize to the
net.

-- 
Paul Tomblin, pt@geovision.gvc.com
(This is not an official opinion/statement of GeoVision Systems Inc.)
"There is nothing wrong with making up .signature quotes, but... make *new*
ones." - Apologies to Henry Spencer and D.Sim
From: dls@genrad.com (Diana L. Syriac)
Newsgroups: rec.aviation
Subject: Re: Close Encounter - Balloon/Airplane
Date: 28 Sep 92 12:12:04 GMT
Organization: GenRad, Inc.


I have but one thing to say about this matter of whether or not "200 feet"
is clear enough.  For a SLOW airplane that is taking off at 60 knots, he
travels approximately 100 feet per second.  In other words 200 feet go by
in just two seconds.  Reaction time of a normal human is on the order of 
1-2 seconds (before they realize something must be done and acts to change
that).  How much time is left to avoid now?  I'll leave the math to the
net.


Diana


->Diana L. Syriac (Carlson) dls@genrad.com	Ham: KC1SP (Sweet Pea)      <-
->I'D RATHER BE FLYING!	P-ASEL, INST		CAP: CPT, Freedom 690 Mobile<-
->AD ASTRA, PER ASPERA				Airplane: C-172 N6513E	    <-
->GenRad, MS/6, 300 Baker Ave, Concord, Mass.  01742  (508)369-4400 x2459   <-
From: ron@topaz.bds.com (Ron Natalie)
Newsgroups: rec.aviation
Subject: Re: Recent flight experience
Date: 29 Sep 1992 22:28:43 GMT
Organization: BDS Systems
Distribution: world
NNTP-Posting-Host: topaz.bds.com
Keywords: PIC, logging

> For the purpose of meeting the requirements of the paragraph, a person may
> act as pilot-in-command of a flight under day VFR or day IFR if no persons
> or property other than as necessary for his compliance thereunder, are
> carried.

Eh?  For passenger carrying, this just means you can be PIC for going
around without passengers for getting your 3 landings.  Sure, you could
do this anyway, so why is it here?  It is there because 61.57(c) also
covers "aircraft certificated for more than one required pilot flight
crewmember."  If that out wasn't there, you couldn't ever get recurrent
because you couldn't make the landings unless you were pilot in command,
but you weren't legal to be PIC of this aircraft because you weren't
current.

Nothing in that statement says anything about "in lieu of" or "notwistanding"
the general exception language.  This specifically states conditions allows
for meeting the currency stated earlier in the paragraph.

-Ron
Newsgroups: rec.aviation
From: bdboyle@erenj.com (Bryan D. Boyle)
Subject: Re: $10 HEADSET: WILL IT WORK?           
Keywords: softcomm, headset
Organization: Exxon Research and Engineering Co., NJ
Distribution: usa
Date: Wed, 30 Sep 1992 19:47:41 GMT

In article <1992Sep30.185837.27406@eagle.lerc.nasa.gov> tostan@dumbo.lerc.nasa.gov (Stan Mohler) writes:
>
>One thing bothers me: aircraft headsets are a couple thousand ohms impedance.  
                                               ^^^^^^^^^^^^^^^^^^^^
No, the intercoms, audio panels, and most good (i.e. major brand) radios
are based on the (drum roll, please...) telco standard 600 ohm
impedance.  It should be ok...won't get the noise attenuation from
standard aircraft headphones, but it will work ok.  It won't damage it-
however, if you plug more than one in, the volume will definately go
down for all of them...


>But this thing is definately 8 ohms.  Will I damage the aircraft radio if I use 
>it more?  Until I know, I won't use it.  
>
>-- 
>
bottom line: don't worry about it...in the avionics shop I work in part
time, we have never seen a problem from using off-the-shelf commercial
headphones...enjoy.

Bryan D. Boyle    |opinions are mine, not Exxon's
Senior Engineer   |PVT/ASEL/IA
ER&E Co.          |bdboyle@erenj.com
From: junio@shadow.twinsun.com (Jun Hamano)
Newsgroups: rec.aviation
Subject: What did you do to the rest of your shirt?
Date: 27 Sep 92 06:21:36 GMT


  Today I was wearing my favorite T-shirt, washed clean and
perfectly ironed, which was very unusual.  My instructor cut the
back of it with scissors and hanged it on a wall of the FBO,
leaving me in the wrecked shirt.  The first thing I'm going to do
would be to wash it (the day was hot and I was sweating a lot),
but what would I do next?

  Do I hang it on a wall in my office?  May I ask net.aviators
what they did to theirs?

--
      i
   __-+-__      Jun Hamano
_-+ (\o/) +-_   junio@twinsun.com
  !   .   !
Newsgroups: rec.aviation
From: gregk@cbnewsm.cb.att.com (gregory.p.kochanski)
Subject: Re: The things controllers know...
Organization: AT&T
Date: Wed, 30 Sep 1992 03:25:13 GMT

In article <1992Sep27.235555.1@pomona.claremont.edu> jhenderson@pomona.claremont.edu writes:
>>>DATE:   Thu, 24 Sep 1992 05:20:25 GMT
>>>FROM:   Geoff Peck <geoff@peck.com>
>> ...Amusing transponder story deleted...
>> 
>>>still not see us?  Apparently not.  The controller said "that's funny -- we
>>>could see you on the way up to dinner, but we aren't getting a readout
>>>now."  (Duh.  I guess these controllers really _do_ know what we do with
>>>light aircraft.  :-) )

They may know what we're doing, but not always where we're doing it.
Back in July, I was flying up from NJ to Plymouth, New Hampshire (NH12),
with a stop at Manchester, NH to avoid the thunderstorms.
On departure from Manchester, the ground controller and one of the
approach controllers asked me where NH12 was, despite the fact it was
less than 50 miles away.  Of course, it *is* a 2000' grass runway
in a mountain valley that supports 6 airplanes...

Greg Kochanski   gpk@physics.att.com
AT&T Physics Research -- Physics for Fun and Profit