HDTenEightyP/NetNews huggingface dataset:
From: prichard@devon.larc.nasa.gov
Subject: Re: Sonic Boom stuff; N-waves
Organization: Lockheed Engineering & Sciences Co.
	<PRICHARD.92Apr16132943@devon.larc.nasa.gov>
	<kurjaqINN59v@appserv.Eng.Sun.COM>
Date: Fri, 17 Apr 1992 13:02:34 GMT


 fiddler@concertina.Eng.Sun.COM (steve hix) writes:

   Unless the supersonic object is quite a long distance away, it's been my
   experience that a sonic boom is normally heard as boom-boom.

yes, I think this is due to the classic N-wave phenomenon.  one minor
detail I didn't mention in my last post is the tail shock.  the various
tail shocks also coalesce away from the vehicle. by the time this wave
train hits the ground, all the contributing wavelets have sorted themselves
out into a bow shock and tail shock.

crude ASCII graphics;



^ pressure
|                        |\
|                        | \
|                        |  \
|                        |   \
|-----> time   ----------|    \     |-----------
                               \    |
                                \   |
                                 \  |
                                  \ |
                                   \|

as my officemate can tell you, this sort of pressure time history is often
seen in measurements.

reference; "Aeroacoustics of Flight Vehicles: Theory and Practice", 
NASA RP 90-3052, Volume 1, chapter 10.

--
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 | Devon Prichard                     The four phases of public office; |
 | Designated Scapegoat                           Nomination, Election, |
 | Lockheed Engineering & Sciences Co.          Indictment, Conviction. |
 | prichard@devon.larc.nasa.gov                                         |
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From: geoffm@purplehaze.Corp.Sun.COM (Geoff Miller)
Newsgroups: sci.aeronautics
Subject: Re: Northrop Flying-Wing
Date: 13 Apr 92 21:02:01 GMT
Followup-To: sci.aeronautics
Organization: Sun Microsystems, Menlo Park, Ca.
NNTP-Posting-Host: purplehaze.corp.sun.com



In article <2148@transfer.stratus.com> kvk@questor.sw.stratus.com 
(Ken Koellner) writes:

>What was the number designation of the Northrop Flying-Wing
>prototype bomber (prop version)?

XB-35.  (The jet version was the YB-49.)


>It was a pusher prop wasn't it?

Yes.


>It had four engines, yes?

Yes.  I don't know what type offhand, but I suspect that it used the P&W
R-4360 4-row radial that was also used in the B-36 and (K)C-97.  It also
has contrarotating propellers, the gearboxes for which proved troublesome.




Geoff


-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Geoff Miller                    + + + + + + + +        Sun Microsystems
geoffm@purplehaze.Corp.Sun.COM  + + + + + + + +     Menlo Park, California
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From: slagle@lmsc.lockheed.com (Mark Slagle)
Subject: Re: Sonic Boom stuff.        :-)
Reply-To: slagle@lmsc.lockheed.com
In-reply-to: rone@carina.usc.edu's message of 12 Apr 1992 23:50:49 -0700
Organization: Lockheed Missiles and Space Co., Sunnyvale, Ca.
	<1992Apr13.020133.25790@yuma.acns.colostate.edu>
	<kuibq9INN5ir@carina.usc.edu>
Date: Wed, 15 Apr 92 03:19:16 GMT

In article <1992Apr13.020133.25790@yuma.acns.colostate.edu> jb026939@longs.LANCE.ColoState.EDU (Jeffrey Bathke) writes:
   >Concerning sonic booms, I've always wondered what would happen if you could
   >fly a second plane "in" the shock wave cone of another plane.  (Both planes
   >are moving the same speed).  I first wondered about this when I thought about
   >hearing a "continuous" sonic boom.  By definition, that couldn't happen, 
   >since the "boom" is the abrupt pressure change as the shock wave moves past
   >an observer.
   >Would the second plane be able to fly in the shock wave -- or would there be
   >so much turbulence that the plane would fall apart?

----
The air flow within the shock cone, behind another plane,
will have been accelerated to approximately the free-stream
velocity.  Any airplane that created a zone of subsonic flow
that extended much behind itself would likely be unable to
fly even if it could carry enough fuel to overcome the drag
for long enough to get to supersonic speeds.  Plowing through
the air is restricted to low speed vehicles like cars and
trucks.  There would be some disturbance to the stream,
but probably would not cause a serious problem.  

Flying "in the shock wave" would be somewhat difficult 
given that the thickness of the shock wave is negligible 
from a macroscopic view.

--
----
Mark E. Slagle                                 PO Box 61059
slagle@lmsc.lockheed.com                       Sunnyvale, CA   94088
408-756-0895                                   USA
Newsgroups: sci.aeronautics
From: montefus@ghost.dsi.unimi.it (diego montefusco)
Subject: Super Cockpit infos needed
Organization: Computer Science Dep. - Milan University
Date: Wed, 15 Apr 1992 14:36:18 GMT

Hi!
	I know that probably this isn't the proper newsgroup to address this 
question to (sci.virtual-worlds would be more appropriate), but I would like
to have some informations about the Super Cockip Project, made by Air Force.
If anyone has any information, or knows where to find some, please e-mail me.

Thanks in advance,

			Diego Montefusco 
-- 


--------------------------------------------------------------------------------
Diego Montefusco	Dipartimento di Scienze dell' Informazione
From: fiddler@concertina.Eng.Sun.COM (steve hix)
Newsgroups: sci.aeronautics
Subject: Re: Sonic Boom stuff.        :-)
Date: 16 Apr 92 18:54:18 GMT
Organization: Sun Microsystems, Mt. View, Ca.
NNTP-Posting-Host: concertina

In article <PRICHARD.92Apr16132943@devon.larc.nasa.gov> prichard@devon.larc.nasa.gov writes:
> bdd0066@zeus.tamu.edu (Bryan, kick the tire and light the fire, Duke) writes:
>
>   It was my understanding that *every* nook and cranny make it's own
>   shockwave.  This would mean that the intakes, nose, rivits, wings, etc.
>
>yes, every longitudinal shape change will create at least an infinitesimal
>strength wave, either expansion or compression.
>
>from the distant ground observer's viewpoint, the various shocks have
>already coalesced.  

Unless the supersonic object is quite a long distance away, it's been my
experience that a sonic boom is normally heard as boom-boom.

Growing up in southern california may have warped my experience in that
regard, though.








--
-----------------------------------------------------------------------
Of making many books there is no end...  |  What's wrong with chasing 
                       -- Eccl. 12:12    |  nebulae till 3 am?  |-(
-----------------------------------------------------------------------
Newsgroups: sci.aeronautics
From: prichard@devon.larc.nasa.gov
Subject: Re: Sonic Boom stuff.        :-)
Organization: Lockheed Engineering & Sciences Co.
Date: Thu, 16 Apr 1992 18:29:43 GMT


 bdd0066@zeus.tamu.edu (Bryan, kick the tire and light the fire, Duke) writes:

   It was my understanding that *every* nook and cranny make it's own
   shockwave.  This would mean that the intakes, nose, rivits, wings, etc.
   would each make their own wave.  I have a picture of a XF-17 (or
   a model of) in a windtunnel at various mach #'s and *many* waves are
   clearly visable.  Howwever, I think the biggest were from 
   the wing and nose--so the above post would be mostly/sorta correct.  If
   you were standing on the ground, the wave would move over you so fast
   that your ears/brain could not tell any of the waves apart.  

yes, every longitudinal shape change will create at least an infinitesimal
strength wave, either expansion or compression.

from the distant ground observer's viewpoint, the various shocks have
already coalesced.  remember that the sound speed changes across a shock,
(recall a^2 = gamma R T, and temperature increases behind a shock)
so that the following shocks travel thru air with higher sound speed
and catch up to the ones ahead.

if the aircraft is so low that the shocks haven't coalesced at that
distance from the aircraft, I don't think the observer will be able
to count shocks. ;)

--
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 | Devon Prichard                     The four phases of public office; |
 | Designated Scapegoat                           Nomination, Election, |
 | Lockheed Engineering & Sciences Co.          Indictment, Conviction. |
 | prichard@devon.larc.nasa.gov                                         |
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From: roy@alanine.phri.nyu.edu (Roy Smith)
Newsgroups: sci.aeronautics
Subject: Re: falling dynamics
Date: 8 Apr 92 15:37:52 GMT
Organization: Public Health Research Institute (New York)

hsong%asylum.utah.edu@cs.utah.edu (Hwal Song) writes:
> when you drop a metal ball, it will fall straight.  but when you drop a
> piece of paper or glass, the falling path will be affected by air
> resistance.  for the piece of paper, it will be deformed.

	Along those lines, there is a cute gizmo that's been showing up in
small grocery/deli/bodegas here in New York.  There is a plexiglass cylinder
about 6 inches in diameter and 2 feet long standing up on one end, filled
with water.  At the bottom, is a smaller solid cylinder about 1.5 inches in
diameter and 2 inches tall.  If you can drop a quarter into the top and get
it to come to rest on top of the pedestal, you win something (typically
either $5 or a free sandwich).  I'll leave it to the lawyers to argue about
illegal gambling, but judging from the huge piles of change at the bottom of
these things, I'd guess lot's of people try it.  I'm sure it's almost
impossible to win.  Here's what it looks like in cross section:


                  |         |
                  |         |
                  |         |
                  |         |
                  |         |
                  |         |
                  |         |
                  |    _    |
                  |___| |___|

	I would guess that just like Hwal's piece of paper or glass falling
in air, the coin will take a fairly random path down through the water.
Since the ratio of the area of the bottom of the tank to the pedestal is
probably 10:1 or more, you only have a 10:1 chance of getting the coin on
the pedestal at random.  But, I would imagine that if the coin were properly
lined up with the pedestal and getting near it, it would see a high pressure
area just above the pedestal and a lower pressure area off the edge of the
pedestal and would be actively pushed away from landing properly.  I havn't
tried it, but my guess is that because of that effect, it is virtually
impossible to win, let alone just difficult.  Some of these also have two
small nubs sticking up at diametrically opposed points on the edge of the
pedestal.  I'm not sure why they are there, but I would imagine that somehow
they further reduce your chance of winning.
-- 
roy@alanine.phri.nyu.edu (Roy Smith)
Public Health Research Institute
455 First Avenue, New York, NY 10016, USA
"This never happened to Bart Simpson."
Newsgroups: sci.aeronautics
From: tjz20735@uxa.cso.uiuc.edu (Tom Zych)
Subject: Re: Question About Sonic Booms
Organization: University of Illinois at Urbana
Date: Fri, 10 Apr 1992 18:58:36 GMT

john@newave.mn.org (John A. Weeks III) writes:

>Are sonic booms only created when an object passes through
>the speed of sound, or does an object create a sonic boom
>the entire time the object is moving faster than the speed
>of sound.  In the first case, there would be a single boom
>heard for a moment, while in the second case, there would
>be a sonic boom `traveling' along with the object as it
>moves across the country side.

The sonic boom is created as long as the aircraft is moving over Mach 1.  It
is heard as a 'boom' because the Mach cone/pressure wave is moving with the
aircraft and therefore to a stationary observer on the ground, the passing
of this wave creates the 'boom'.

>Are sonic booms only associated with the speed of sound,
>or are there other types of sonic booms created at other
>speeds.  For example, does an airplane create a second
>sonic boom when it passes through Mach 2, Mach 2.2, or
>everytime it passes a Mach number?  (I picked Mach 2.2
>because I recall that early high speed aircraft had great
>difficulty with control problems around Mach 2.2.)

There is only one pressure wave created, at the Mach cone angle 'mu'. 
(mu = arcsin(1/M)) So as the aircraft moves faster, the Mach cone angle
decreases and the strength of the pressure wave increases, but there is
still only one wave.  (I think.  I'm sure someone will correct me if I'm
mistaken)

The early control problems at high M, I believe, had to do with tuck-under
and control reversal as the aerodynamic center moved aft, eventually getting
behind the center of gravity and making the aircraft uncontrollable.  I'm not
that sure about this one.  Hopefully someone else can give a better explanation
of this...

Tom   tjz20735@uxa.cso.uiuc.edu

Aero/Astro Engineering, University of Illinois   BS 1992
From: geoffm@purplehaze.Corp.Sun.COM (Geoff Miller)
Newsgroups: sci.aeronautics
Subject: Re: XB-70 Valkyrie (was: Re: Sonic Boom stuff.        :-)
Date: 16 Apr 92 15:13:18 GMT
Followup-To: sci.aeronautics
Distribution: usa
Organization: Sun Microsystems, Menlo Park, Ca.
NNTP-Posting-Host: purplehaze.corp.sun.com



In article <1992Apr16.143341.22282@athena.mit.edu>
brndlfly@m37-332-5.MIT.EDU (Matthew T Velazquez) writes:

>One of the pilots managed to eject (there were two, sorry but I don't 
>remember their names).  

The AC was Ed White, who would later be killed in the launchpad fire 
aboard Apollo 1.  The copilot was a USAF major whose name I forget, but
who was supposedly a highly experienced test pilot. 


>Also, what kind of heat supression stuff did the Valkyrie use?  
>Certainly not black paint!

Not sure about the heat suppression mechanism, but it so happens that I
saw the Wings episode about the XB-70 last night (what a magnificent
machine that is!), and learned that during the first flight, the airframe
flexed so much (as it was designed to do) that a lot of the white paint
flaked off.  By the time the plane landed, it looked as though it had
been sitting in the desert sun for 20 years.  

I missed the first part of the show because of a late meeting :-(, so I
didn't see anything relating to details of the XB-70's construction.  Was
it made primarily of titanium like the Blackbird?



Geoff


-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Geoff Miller                    + + + + + + + +        Sun Microsystems
geoffm@purplehaze.Corp.Sun.COM  + + + + + + + +     Menlo Park, California
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Newsgroups: sci.aeronautics
From: dtice@avd23.larc.nasa.gov (David C. Tice)
Subject: Re: Sonic Boom stuff.        :-)
Organization: NASA Langley Research Center, Hampton, VA  USA
Date: Thu, 16 Apr 1992 12:42:24 GMT

In article <1992Apr16.032849.22379@zoo.toronto.edu> 
henry@zoo.toronto.edu (Henry Spencer) writes:

>In article <1992Apr14.124031.9795@news.larc.nasa.gov> 
>dtice@avd23.larc.nasa.gov (David C. Tice) writes:
>>The "compression lift" you refer to was a nice little technical white lie 
>>perpetuated by North American Aircraft and the Air Force to make the XB-70 
>>sound even more gee-whiz than it was...
>
>I think Alfred Eggers of NASA Langley, who discovered compression lift,
>would be more than a little offended at this characterization.  That
>"little technical white lie" more than doubled L/D ratio at Mach 3.
>It wasn't just marketing hype.  

My point was that the contribution of compression lift was very small on 
the XB-70, even though that seems to be what people remember most about
the aircraft (as evidenced by responses in this group).  It was played
up by the PR people to get Congressional and public support for the 
program.

If you think the engineers who actually worked on XB-70 performance at NAA 
are wrong, maybe I should pick up the phone and let them know how misinformed 
they've been all these years.

I don't dispute that compression lift has been shown in theory and highly
controlled wind tunnel tests.  However, if you know of any functional aircraft
that has used it as a major contributor of lift, I'd like to know about it.

---------------------------------------------------------------------------
David Tice                                          uu   uu sssssss ccccccc
Lockheed Eng. & Sci. Co.     beat  the             uu   uu  ss     cc     
NASA/Langley                 spAztecs!            uu   uu    ss   cc
Hampton VA                   (9/5/92)            uuuuuuu sssssss ccccccc

The above comments do not reflect those of LESC or the Lockheed Corp.
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Newsgroups: sci.aeronautics
From: raymond@jupiter.ame.arizona.edu (Raymond Man)
Newsgroups: sci.aeronautics
Subject: Re: XB-70 Valkyrie (was: Re: Sonic Boom stuff.        : -)
Date: 17 Apr 92 17:02:08 GMT
Organization: University of Arizona, Tucson

I wonder if the F-104 chase plane getting too close to the XB-70 was
because of the drag characteristic of the Starfighter. I read about some
pilots said that due to the very slander shape, the drag is so low that
if one F-104 follows another exactly, ie. in the wake, it can easily
fly into the other's tailpipe.

It is not hard to imagine a big plane like the XB-70 can generate a
wake large enough to blanklet the very small frontal shape of the
fighter.
-- 
Just call me `Man'. 
"And why take ye thought for "    --   Matt. 6:28
raymond@jupiter.ame.arizona.edu
From: stiles@quik.clearpoint.com
Newsgroups: sci.aeronautics
Subject: FBW for GA aircraft
Date: 6 Apr 92 15:06:50 GMT
Reply-To: stiles@quik.clearpoint.com
Distribution: sci.aeronautics
Organization: /usr4/stiles/.organization






I'm curious - is there anything happening with development of fly by
wire systems for general aviation aircraft?  What type of sensor input is
used for an FBY system?
From: Charles.K.Scott@dartmouth.edu (Charles K. Scott)
Newsgroups: sci.aeronautics
Subject: XB-70 Valkyrie (was: Re: Sonic Boom stuff.        :-)
Date: 17 Apr 92 12:09:40 GMT
Organization: Dartmouth College, Hanover, NH

In article <1992Apr16.143341.22282@athena.mit.edu>
brndlfly@m37-332-5.MIT.EDU (Matthew T Velazquez) writes:

> Piloting the F-104 was Joe Walker, former X-15 test pilot.  For some unknown
> reason (at least I don't knowwhat it was), the F-104 got up too close to the
> Valkyrie and probably got caught up in its starboard tip vortex.

Chuck Yeager in his first book claimed that Walker was a civilian test
pilot who was good as a stick handler but had little experience with
close in formation flying.  He implied that it was this inexperience
that resulted in the accident.  Yeager was taking shots at the
civilians who were getting big bucks to be a test pilot while the
military pilots who were doing the same flight schedules were doing it
for standard flight pay.  This is what I remember from reading the
book, it is not necessarily my opinion.

Corky Scott
From: dlevy@viper.engin.umich.edu (David W Levy)
Newsgroups: sci.aeronautics
Subject: Re: Whatever happened to prop-fans?
Date: 3 Apr 92 13:49:29 GMT
Organization: University of Michigan Engineering, Ann Arbor
Originator: dlevy@viper.engin.umich.edu


In article <1992Apr3.045046.3891@julian.uwo.ca>, mann@csd.uwo.ca (Robert Mann) writes:
> I seem to recall that 10 or so years ago NASA, M-D and maybe some other
> engine makers were working on jet engines that were sort of a cross
> between turboprops and turbofans.  The engines had odd shaped propellors
> on the front or back of the engine.  They supposedly provided better
> fuel economy than existing engines but had slightly lower top speeds than
> existing engines.  Were these for real?  Did they work - ie. provide
> better fuel economy?  What happened to them?
> 
I spent last summer at Boeing and part of the time I spent helping
out with a summer intern project aimed at exposing the interns
to a larger picture of the company than they were seeing during their
normal work assignments.  As a case study, the development of the 7J7 was
followed.  For those who don't know this airplane, it was to use the
UnDucted Fan (UDF) by GE.  This isn't quite the same thing as a propfan,
but I think most of the conclusions apply to propfans as well.

To start, GE was claiming a 15% or greater improvement in fuel consumtion
for this engine, but everything went downhill from there.

First, when the engine was integrated into the airframe, it's efficiency
went down because of the effects of the airframe.

Next the drag of the airframe went up because of the effects of the engine.

Third, the engine was heavier than a comparable turbofan.

Fourth, can you say NOISE?  What? I can't hear you . . .
More weight to keep the cabin noise to tolerable levels.

All this weight is at the back end of the body, so the c.g. moves back
and the tail gets bigger and so on.

The bottom line was that the final airplane design, when all the problems
were worked out, was marginally more efficient on a per seat mile basis
than the turbofans.  Also, there is the stigma of propellers as being
low tech.  When they took it to the Paris Airshow and didn't get a single
order, the project was cancelled.
Newsgroups: sci.aeronautics
From: lind@eng.umd.edu (Charles A. Lind)
Subject: Re: Sonic Boom stuff.        :-)
Date: Tue, 14 Apr 92 12:05:15 GMT
Organization: College of Engineering, University of Maryland, College Park
Originator: lind@mustang.eng.umd.edu


In article <1992Apr13.232037.8500@wdl.loral.com>, zeke@wdl50.wdl.loral.com (Solly Ezekiel) writes:
>As I recall, the XB-70 (huge mach 3+ 1960's aircraft) more or less flew on
>top of _its own_ shock wave.  It had a pair of canards just aft of the
>cockpit, which generated shock waves.  The shocks were then channeled under
>the main wings, whose wingtips folded down to keep the shocks there.
>Apparently this added something like 60,000 lbs of lift to the aircraft
>for virtually no penalty in fuel!
>
>  +--------------------------+---------------+---------------------------+
>  | "Asps!!  Very dangerous. |               | My opinions are not those |
>  |     ...You go first."    |  Sol Ezekiel  |      of my employer,      |
>  |          -- Sallah       |               |    Space Systems/Loral    |
>  +--------------------------+---------------+---------------------------+

The XB-70 did indeed ride its own shock wave.  Nowadays we refer to such
a vehicle as a "waverider".  Waveriders, because they contain the high
pressure underneath the vehicle (due to the attached shock) will have
higher lift than other such vehicles.  In fact, a hypersonic waverider can have L/D
as high as 10!!

Charles Lind
Dept. of Aerospace Eng.
University of MD, College Park
Newsgroups: sci.aeronautics
From: vkochend@isis.cs.du.edu (vance kochenderfer)
Subject: Re: fly-by-wire
X-Disclaimer: Nyx is a public access Unix system run by the University
	of Denver for the Denver community.  The University has neither
	control over nor responsibility for the opinions of users.
Organization: Nyx, Public Access Unix at U. of Denver Math/CS dept.
Date: Thu, 16 Apr 92 04:11:15 GMT

In article <1992Apr15.234757.25031@athena.mit.edu> chuang@athena.mit.edu 
Weihaw Chuang) writes:
>
>	What are the benefits of "fly-by-wire" controls beyond greater 
>manuverability?  More specifically why are the civillian jets starting u
ing
>digital controls systems.


Well, basically, it cuts down on a lot of weight.  Also, you could
say that it also is less complex, but you're trading off electronic
complexity for mechanical...  It also allows the computer control
to prevent the pilot from putting the aircraft through maneuvers
for which it was not designed, but this feature is not well-liked
by pilots and I believe was implicated in one of the Airbus crashes.

Vance "Look, Ma, no hands" Kochenderfer
Virginia Tech                     |        'But these go up to eleven.'
ae313406@vtcc1.cc.vt.edu          |                     -Nigel Tufnel
vkochend@nyx.cs.du.edu <-New Address, try it first..