HDTenEightyP/NetNews huggingface dataset:
From: ghee@vision.larc.nasa.gov (Terry A. Ghee)
Newsgroups: sci.aeronautics
Subject: Re: Flying Car--Innovative Lift System?
Date: 17 Dec 1992 13:20:54 GMT
Organization: NASA Langley Research Center, Hampton, VA  USA
Distribution: world
NNTP-Posting-Host: vision.larc.nasa.gov



Craig Meyer writes:
Hi, folks.  I'm the one that wrote about a lift system using driven air and a
stationary wing.  I've gotten some responses, but I want to make sure you all
know what I'm talking about.  So here goes:

Below is a super-sorry rendition of a airfoil, with an duct coming out of the
upper leading-edge.  High-speed air (from some central centrifugal blower or
something) shoots out of this duct, and over the wing.

Lift is produced by the resulting static-pressure difference between the top of
the wing (with the driven air flowing over it) and the bottom of the wing,
where the air is still.

Thrust is produced, too, becuase the air is being blown BACK, (action-reaction,
ya know).

Once you got going, you could retract the duct into the leading edge of the
wing, and blow the air out some ducts in the very back, for thrust only (since
you'll be getting lift naturally becuase you're moving)


             ------      LOW PRESSURE
           /   <- air comes out here   Flows out t

 leading /      ------------------------------\    h
  edge /                     / \                 \   i
       \                      |        ------>      \   s
         \                    |lift    thrust          \  w
           \--------------------------------------------- \  a
                        HIGH PRESSURE                          y
 
So that's it.

Please tell me whatever you think about it (if I'm a genius, an idiot, a
plagariser, whatever..)

Thanks all,

End, Craig Meyers





Your leading edge blowing concept has been around (I actually
wnated to do my MS research on leading edge blowing with a
circulation control trailing edge, had to settle for unsteady
circulation control instead :-)).  Anyhoot, there is not to
many jets available that would provide all the lift you want in 
the manner you describe.  Currently, folks in my branch are looking
into leading edge blowing, but only for vortex control not for
providing all the lift.

Just as an aside, you'll get more lift out of a circulation control
trailing edge than leading edge blowing (but you will still need
some freestream flow).  If you ever want references on circulation
control, let me know and I'll give you some good'uns.  I might also
still have some references on leading edge blowing, I'd have to look.
Hope this helps.

T.A. Ghee
Newsgroups: sci.aeronautics
From: rdd@cactus.org (Robert Dorsett)
Subject: Speed of sound (Re: MACH 8)
Organization: Capital Area Central Texas UNIX Society, Austin, Tx
Date: Wed, 16 Dec 1992 10:17:47 GMT

In article <10302@ncrwat.Waterloo.NCR.COM> tjgerman@53iss6.Waterloo.NCR.COM (Trevor German) writes:

>	I have been following the thread about the Mach 8 spy plane
>	and have a general question. What exactly is MACH 1. I understood
>	it to be the speed of sound at sea level (or more accurately at
>	an air pressure defined to be sea level). Is this the case or is
>	MACH 1 the speed of sound at any pressure, ie is MACH1 a higher
>	ground speed at 100,000 than it is at sea level. 

The reference frame for mach speed comparisons is the ground.  This isn't an
"indicated vs. true" issue.

The speed of sound is hinged on *temperature*, not altitude.  On a cold
day, the speed of sound will be lower; on a warm day, it will be higher.

Therefore, as altitude increases, the speed of sound will drop.  HOWEVER, 
as we enter the thermosphere, the ambient temperature *increases*, so the 
speed of sound will increase.

For your reference, the speed of sound at sea level is about 661.5 knots,
ICAO Standard Day.  At 100K, it's 583.3 kts, same restrictions.  1 knot = 1.15
mph.  The speed of sound can be approximated by the equation:
	a = 29.04 * SQRT(T),
where T is the ambient temperature, in Rankine. 

Mach is simply the ratio of the airplane's true airspeed to the ambient
speed of sound.


If there's any more interest in this, I could dig up the archived articles
from the last three or four times it was discussed.  I believe we got it
right, the last time. :-)


Lastly, a nit:

>       If it is the later (ie pressure dependend) how fast would a
>       Mach 8 plane be going in ground speed.

Ground speed is a navigation term, the resultant of an free-stream (true)
airspeed and the prevailing wind vector.  



---
Robert Dorsett
rdd@cactus.org
...cs.utexas.edu!cactus.org!rdd
Newsgroups: sci.aeronautics
From: ecf_stbo@jhuvms.hcf.jhu.edu (The intricate progressive rock of Hatfield and the North)
Subject: Re: zero angle of incidence...
News-Software: VAX/VMS VNEWS 1.41    
Organization: The Johns Hopkins University - HCF
Date: Fri, 11 Dec 1992 18:02:00 GMT

In article <-0d2gwf@rpi.edu>, leonam@aix.rpi.edu (Marcus B. Leonard) writes...
>You probably mean 0 angle of attack, in which case the answer is yes.
 Yes that's what I mean..
> 
>The conventional measure of angle of attack is the angle between the
>chord line of the airfoil (line from leading to trailing edge) and
>the direction of the oncoming air.
> 
>Any (?) airfoil with a positive camber (i.e, curved, with the concave
>side down) will generate lift at zero angle of attack.

Thanks everybody who responded here and by email. I think I maybe understand
it. I have read some of Marchaj's "Aerohydrodynamics of Sailing" and basically
get the circulation theory. Is it because at the trailing edge the attached
flow has a downward direction so a starting vortex is created similarly to a
flat plate with a tilted downward angle of attack? Could a thing like this
produce lift at 0 degrees (assuming attached flow all the over the foil (or is
that a bad assumption?))? A foil with camber but with a flat aft part so the
airflow leaves parallel to the free stream? Sorry that this is so basic, at
least it's not about bread!

        =     =
    =               =
 =                       =    =  =   =


Tom O'Toole - ecf_stbo@jhuvms.hcf.jhu.edu - JHUVMS system programmer 
Homewood Computing Facilities, Johns Hopkins University, Balto. Md. 21218 
>Here comes a jet ski.
>weuh weeuhh weeuhh weeuhh WEEUHH WEEUHH WEEUHH WEEUHH weeuhh weeuhh weeuhh weuh
From: tjgerman@53iss6.Waterloo.NCR.COM (Trevor German)
Newsgroups: sci.aeronautics
Subject: TAIL ROTORS
Date: 15 Dec 92 14:19:11 GMT
Organization: Imaging Systems Division, NCR Corp, Waterloo, Ont., CANADA


	I am an engineer and think I understand all the reasons why helos
	have tail rotors, however, it seems to me that they may not be 
	as nessecary as they appear. 

	I remember seeing a real low speed film of a dragonfly in flight
	and watching with fascination how the beast uses a pair or weighted
	pendulums behind the wings that swing in anti-phase to the main wings
	counteracting the up and down forces on the critters body caused by 
	the wing beats. Why can't a similar thing be done in helocopters.


	The problem, as I understand it, is that the torque of the engine 
	driving the rotor is balanced by the tail rotor pushing the other
	way. By adjusting the pitch of this rotor the balance is modified
	to swing the tail in either direction.  

	My question is why not put the torque adjusting in line with the
	main rotor. Granted there are counter-rotating rotor machines but
	these are complicated and expensive. Why not have a higher RPM 
	ducted vertical fan driven through a gearbox on the main shaft 
	pumping air down under the craft. The design of the fan should be
	done in a way that makes it very viscous, that is, a lot of torque
	required to move air.  The speed of the fan would 
	obviosly be greater than that of the main rotor. The pitch of the 
	fan would again be adjustable, or maybe just a damper in the airflow
	could suffice.

	This may have already been tried, or maybe I am missing something
	fundemental, but I am intrested in any comments or knowledge of
	similar schemes that have been tried.



--
       >|  "Only average people            | Trevor J German BSc    |<
       >|        never make mistakes."     | NCR, Waterloo, Ontario |<
       >| tjgerman@53iss6.Waterloo.NCR.COM | Canada.                |< 
Xref: sparky sci.aeronautics:2574 sci.space:17544
Organization: Arizona State University
Date: Sunday, 13 Dec 1992 12:45:39 MST
From: <AUJAM@ASUACAD.BITNET>
Newsgroups: sci.aeronautics,sci.space
Subject: Re: Mach 8+ Space/Spy Plane?
Distribution: na

In article <1992Dec11.002726.712137@locus.com>, rich@locus.com (Rich (the Wiz)
Silva) says:
>
>    Apparently reported in some English Aeronautic Journal was
>    a story claiming that the US has a new spy plane capable of
>    Mach 8+ (at least) in test.  Apparently said plane has a
>    glide path over Catalina while landing in Nevada.  The story
>    claimed that this plane was responsible for the periodic
>    "mysterious sonic booms and window shaking" (Thursday mornings?)
>    that have been occuring here in Southern CA.
>
>    Anyone know anything more?
>
>

I was in Joshua Tree national forest last May when I saw a plane in the upper
atmosphere fly across the sky about as fast as metors do I didn't here any
sonic booms but I't couldn't have been a jet airliner it was moving too fast
I did notice it's contrail was lumpy like -+-+-+-+-+-+ like a pulse.

>--
>Rich Silva
>Locus Computing Corporation                rich@LOCUS.COM
>                  {uunet,ucivax,trwrb}!lcc!rich
>       {randvax,ucbvax,trwspp}!ucla-se!lcc!rich
Newsgroups: sci.aeronautics,sci.space
From: schumach@convex.com (Richard A. Schumacher)
Subject: Re: Mach 8+ Space/Spy Plane?
Organization: CONVEX Computer Corporation, Richardson, Tx., USA
Distribution: na
Date: Tue, 15 Dec 1992 01:28:55 GMT
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

>>sonic booms but I't couldn't have been a jet airliner it was moving too fast
>>I did notice it's contrail was lumpy like -+-+-+-+-+-+ like a pulse.

>[no boom because]
>be in an acoustical shadow zone.  the same phenomenon exists in the ocean.  of
>course, maybe you really didn't see anything at all   :)     -ken

But that pulsed contrail has been described before, in Av Week. Sounds
to me like he saw the genuine article.
From: 01crmeyer@leo.bsuvc.bsu.edu (Craig Meyer)
Newsgroups: sci.aeronautics
Subject: Flying Car--Innovative Lift System?
Date: 17 Dec 92 00:47:14 GMT
Organization: Ball State University, Muncie, In - Univ. Computing Svc's

Hi, folks.  I'm the one that wrote about a lift system using driven air and a
stationary wing.  I've gotten some responses, but I want to make sure you all
know what I'm talking about.  So here goes:

Below is a super-sorry rendition of a airfoil, with an duct coming out of the
upper leading-edge.  High-speed air (from some central centrifugal blower or
something) shoots out of this duct, and over the wing.

Lift is produced by the resulting static-pressure difference between the top of
the wing (with the driven air flowing over it) and the bottom of the wing,
where the air is still.

Thrust is produced, too, becuase the air is being blown BACK, (action-reaction,
ya know).

Once you got going, you could retract the duct into the leading edge of the
wing, and blow the air out some ducts in the very back, for thrust only (since
you'll be getting lift naturally becuase you're moving)


             ------      LOW PRESSURE
           /   <- air comes out here   Flows out t
 leading /      ------------------------------\    h
  edge /                     / \                 \   i
       \                      |        ------>      \   s
         \                    |lift    thrust          \  w
           \--------------------------------------------- \  a
                        HIGH PRESSURE                          y
 
So that's it.

Please tell me whatever you think about it (if I'm a genius, an idiot, a
plagariser, whatever..)

Thanks all,

CM
-- 
       Craig Meyer                 01CRMEYER@LEO.BSUVC.BSU.EDU
       Indiana Academy for Science, Mathematics, and Humaities.
       Muncie, IN  47306                          317-285-7433

       Opinions expressed are mine alone, and not necessarily
       shared by the Indiana Academy.
From: br105@cleveland.Freenet.Edu (Jeffrey A. Del Col)
Newsgroups: sci.aeronautics
Subject: Talking to a mach 8 airplane
Date: 14 Dec 1992 15:39:28 GMT
Organization: Case Western Reserve University, Cleveland, OH (USA)
Reply-To: br105@cleveland.Freenet.Edu (Jeffrey A. Del Col)
NNTP-Posting-Host: hela.ins.cwru.edu


Okay, let's assume that there is a manned mach 8 airplane( It certainly
seems to be true)  Wouldn't there be a problem getting radio messages
through the ionized air that would form around it at those speeds?
Or is mach 8 not fast enough for such problems to occur?

I used to wonder how they got guidance information through to the 
extremely fast Sprint ABM's.  I can recall pictures of them being 
surrounded by an envelope of incandescent air as they streaked up through
the atmosphere during tests.  Surely they must have had to transmit
course correction data to them, no?

J. Del Col
-- 
Jeff Del Col      *   DECONSTRUCTION--- the critical method invented      
A-B College       *                      by Procrustes  
Philippi, WV      *                             
                  *         
Newsgroups: sci.aeronautics
From: cid@athena.mit.edu (Derek H Cedillo)
Subject: Re: SILENT HELICOPTER
Organization: Massachusetts Institute of Technology
Date: Wed, 16 Dec 1992 02:29:37 GMT

In article <921215011849@avistic.demon.co.uk> lorcan@avistic.demon.co.uk writes:
>In article <1992Dec6.235739.9736@athena.mit.edu> cid@athena.mit.edu
>(Derek H Cedillo) writes:
>
>> And, damn was that an impressive sight.  Id love to see the Mi-24 hind.
>> Only one bigger than the 53 series 
> 
>Don't you mean the Mi-26 Halo? The Hind is a helicopter gunship and
>considerably smaller than the 53.
> 
>Lorcan

Oops, sorry, I gotta quit typing so fast.
that sould have been "the Mi-24 *AND* the only one bigger than the 53 series"
Thanks for giving me the name and correcting the mistake...

Derek
-------------------------------------------------------------------
"He lived a life of going-to-do, 
   and died with nothing done"	       
		-J. Albery	     

In other words---JUST DO IT!
Xref: sparky sci.aeronautics:2629 sci.environment:13707
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: sci.aeronautics,sci.environment
Subject: Re: High-flying Perseus research aircraft ready for rollout [Re
Date: Sat, 19 Dec 92 00:10:26 PST
Organization: The Portal System (TM)

Hey, this plane sounds like it would be a great weapon, especially in the
role of a recce platform for third-world nations.  It would be cheap, and
few adversary third-world nations can shoot down a robot flying above 80K
feet.
Newsgroups: sci.aeronautics
From: lorcan@avistic.demon.co.uk (Lorcan Mongey)
Reply-To: lorcan@avistic.demon.co.uk
Subject: Cd of  open "box" shape...
X-Mailer: ReaderS for the Acorn Archimedes
Date: Tue, 15 Dec 1992 01:29:55 +0000

In article <1992Dec9.234916.10094@retix.com> bmartin@retix.com writes:

> Has anyone knoledge of the Cd value of an open box shape, with the
> open side toward the airflow? Is it better/worse than a flat plate,
>for example? 
 
Worse (ie higher drag). If you've ever seen pictures of a Pelton wheel
(a type of water turbine) the "paddles" are specially-shaped buckets
which accept the incoming jet of water and turn it back on itself, thus
maximising the momentum change and therefore the drag. These buckets are
much more efficient than a flat-bladed water wheel.
 
Lorcan
From: k.h.goodrich@larc.nasa.gov
Newsgroups: sci.aeronautics
Subject: Re: Paul Moller/One in every garage
Date: 14 Dec 1992 13:21:57 GMT
Organization: NASA-Langley Research Center
Distribution: usa
NNTP-Posting-Host: b1298amac7.larc.nasa.gov

In article <1992Dec13.224145.17989@gn.ecn.purdue.edu> gpayne@gn.ecn.purdue.edu
(Gregory A. Payne) writes:
>Has anyone heard any recent news on Paul Moller (sp?) and his vtol
>aircraft.  They were 'small' 4-place vtol craft that had eight engines
>and could fit in a garage.  They were also designed to be flown with
>little or none piloting experience if I remember correctly. Last I
>has heard was an article in Aviation Week and the cover article in Popular
>Mechanics, but these were about a year or two ago.

Not to be a pessimist (I love the idea), but I think he gets a cover
article in PM about every 5-10 years and nothing seems to change.

Newsgroups: sci.aeronautics,sci.space
From: kdrolt@athena.mit.edu (Kenneth D Rolt)
Subject: Re: Mach 8+ Space/Spy Plane?
Organization: Massachusetts Institute of Technology
Distribution: na
Date: Mon, 14 Dec 1992 15:58:06 GMT

Rich Silva [rich@locus.com] wrote:
>I was in Joshua Tree national forest last May when I saw a plane in the upper
>atmosphere fly across the sky about as fast as metors do I didn't here any
>sonic booms but I't couldn't have been a jet airliner it was moving too fast
>I did notice it's contrail was lumpy like -+-+-+-+-+-+ like a pulse.

a possible reason why you didn't hear anything {i.e. no sonic boom, and no
thrust noise} was that the sound from the mach cone and from the jet was
refracted too much away from the ground due to a sound speed profile in the
atmosphere:  the sound speed for the *aircraft* altitude was slower than the
speed of sound on the ground, so the sound waves refracted enough for you to
be in an acoustical shadow zone.  the same phenomenon exists in the ocean.  of
course, maybe you really didn't see anything at all   :)     -ken
     -----------------------------------------------------------------
    |    R  2	      Real Monza	     kdrolt@athena.mit.edu    |
    |    |__|					grad student !!       |
    |    |  |	'64 Corvair Convertible      mit ocean engineering    |
    |    1  3					underwater sound      |
     -----------------------------------------------------------------



Newsgroups: sci.aeronautics
From: prasanth@gn.ecn.purdue.edu (Ravi K. Prasanth)
Subject: Re: Mach 1 is also density dependent
Organization: Purdue University Engineering Computer Network
Date: Wed, 16 Dec 92 23:52:24 GMT

In article <1gnjaoINNgnh@bigboote.WPI.EDU>, gandalf@wpi.WPI.EDU (James Michael Sambrook) writes:
> 									
> What's REALLY neat about this equation is that it says that, in a totally
> incompressible substance, the speed of the compression wave is INFINITE!!! 
> This fact does make sense, in a manner of speaking.  If the medium cannot be
> compressed, then each molecule will react to the disturbance at the same time,
> and the entire substance will move at the EXACT same time!!!
>

Hmmm. So there are some compressible mediums where sound
travels faster than light. Where is the mistake ?

> Just thought I'd add my ideas to this discussion...
> 
> James Sambrook...A Nuclear and Aerospace Engineer at WPI
> 

RKP
Newsgroups: sci.aeronautics
From: jfb200@cbnewsd.cb.att.com (joseph.f.baugher)
Subject: Re: Speed of sound (was MACH 1)
Organization: AT&T Bell Laboratories -  Naperville, Illinois
Date: Sun, 20 Dec 1992 02:34:00 GMT
Keywords: formula

Most of the formulae I have seen posted here for the speed of sound in 
air are wrong.  In fact, some of them are not even dimensionally 
correct.  

Here's what Resnick and Halliday (a well-known freshman physics text) 
have to say.  

The formula for the speed of sound in an elastic medium (either liquid 
or gas) is 

		c = sqrt (B/rho) 

where B is the bulk modulus of the material (the ratio of the change 
in pressure to the resulting fractional change in volume) with units 
of newtons/m^2 or, equivalently, kg/(m.sec^2), and rho is the density 
with units of kg/m^3.  

If the material is a solid, the formula is quite similar, but the bulk 
modulus is replaced by Young's modulus Y.  

Therefore, the more dense the material, the slower the speed of sound.  
Also, the higher the bulk modulus the more difficult it is to compress 
the material and the higher the speed of sound.  So the people who have
said that the speed of sound depends on the density of the air are
correct, but that is not all there is to it.  The bulk modulus of air
also varies and must also be considered.  

For an ideal gas, the formula for the speed of sound is given by 

		c = sqrt(gamma*P/rho) 

where it is assumed that the passage of a sound wave through a gas is 
an adiabatic process.  Here, gamma is the ratio of specific heats 
(Cp/Cv), P is the pressure, and rho is the density.  Except of course
for the factor gamma, this formula could have been derived by using a
simple dimensional analysis. 

Let us now look at the well-known ideal gas formula: 

		PV = nRT 

where n is the number of moles enclosed in a volume V, T is the absolute
temperature in Kelvin (K), and R is the universal gas constant, units 
of joules/(mole*K).  Solving for P gives 

		P = (n/V)RT 

The factor n/V is the number of moles per cubic meter.  Substituting 
this into the formula for the speed of sound in a gas, we get 

		c = sqrt( gamma*(n/(V*rho))RT ) 

The factor n/(V*rho) is simply the inverse of the molecular weight of 
the gas (MW), so the formula for the speed of sound in a gas is 

		c = sqrt( gamma*R*T/(MW) ) 

The ratio of specific heats is for all practical purposes a constant.  
R is a universal constant of nature, so the speed of sound depends 
only on the absolute temperature and on the molecular weight of the 
gas.  

Since the temperature of the air decreases with altitude in the 
troposphere, the speed of sound decreases with altitude.  

Hope this helps.  

Joe Baugher			**************************************
AT&T Bell Laboratories		*  "You see, something's going to    *
2000 North Naperville Road	*   happen.  Something wonderful!"   *
P. O. Box 3033			**************************************
Naperville, Illinois 60566-7033		
(708) 713 4548				
ihlpl!jfb                   Who, me?  Speak for AT&T?  Surely you jest!	
jfb200@cbnewsd.att.com
Newsgroups: sci.aeronautics
From: fwing@leland.Stanford.EDU (Stephen James Morris)
Subject: Re: PARAGLIDING; cheapest Icarussyndrome medicine?
Keywords: flight, joy, paragliders, looking stupefying fluorescent and all
Organization: DSG, Stanford University, CA 94305, USA
Date: Fri, 18 Dec 92 21:49:47 GMT

Ther is a mailing list for people interested in hang gliding and paragliding.
To subscribe, send E-mail to <hang-gliding@virginia.edu> and ask to be put
on the list.

Steve Morris
Stanford, CA