[NSRCA-discussion] (no subject)

vanputte at cox.net vanputte at cox.net
Mon Oct 15 04:55:48 AKDT 2007 

The best analysis of the effects of a steady wind was published by a South African named Len Salter 25-30 years ago.  He wrote that all you need to understand what's really going on is an aircraft carrier steaming downwind at the same speed as the wind.  You stand on the carrier's deck and there's NO wind.  You fly your airplane and it flies just as it would on a calm day.   You loops are nice and round and you get perfect verticals by pointing the airplane straight up or down.  There's no dreaded "downwind turn" problem.

Now suppose you were instantaneously teleported to an adjacent island.  Your airplane would have no clue that you weren't still on the carrier's deck, but I'll bet your airplane would "fly dfferently".

Ron 
   
---- Mark Atwood <atwoodm at paragon-inc.com> wrote: 
> George,
> 
> I think Ron¹s point is that the ³moving pool² IS the same...except the water
> is not moving relative to the pool.  The water is moving just as fast if the
> giant (I can¹t believe you guys have sucked me into this conversation or
> worse, this analogy) was running down the street with the pool, as it would
> be if there was a river..it¹s just that the walls of the pool are moving
> with it.  
> 
> If the pool was SO big, that there was no frame of reference...the water
> could be flowing at any speed and you would never know...(until you finally
> got close to a side :)
> 
> -M
> 
> 
> On 10/14/07 1:33 PM, "george w. kennie" <geobet at gis.net> wrote:
> 
> > Ahaaaa ! .................for the first time in all these years I understand
> > the reasoning of my good friend Ron Lockhart with his swimming pool analogy,
> > but,........there's a fly in the ointment !!!!!!!!!!!!
> > Someone, maybe Nat, mentioned that air is a fluid. I agree !  Moving air is a
> > CURRENT !  In order for the swimming pool analogy to equate to our situation
> > of flying in a crosswind, the pool would need to be converted into a hot tub
> > with jets located all down one side and exhaust outlets on the other side so
> > that a cross CURRENT could be established (same as the crossing CURRENT we're
> > flying in ) whereupon the swimmer would then be pushed to the exhaust side of
> > the pool. He would certainly feel the force of the current exerting a
> > deleterious effect on his intended swimming direction and would have to
> > compensate and if he was in a boat with a rudder (with forward propulsion) he
> > would aquavane vectorially due to the combined effect of the CURRENT and the
> > forward propulsion. It will not make any difference whether you pick the pool
> > up and move it sideways, fore or aft, turn it around, raise it, or lower it as
> > long as the AC doesn't go out. :>)
> > Who else,...me 
> >  
> >  
> >  
> >>  
> >> ----- Original Message -----
> >>  
> >> From:  Ron  Lockhart <mailto:ronlock at comcast.net>
> >>  
> >> To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
> >>  
> >> Sent: Saturday, October 13, 2007 10:46  PM
> >>  
> >> Subject: Re: [NSRCA-discussion] (no  subject)
> >>  
> >> 
> >>  
> >> See comments at end of RJO post.
> >>  
> >>>  
> >>> ----- Original Message -----
> >>>  
> >>> From:  rjo626 at aol.com
> >>>  
> >>> To: nsrca-discussion at lists.nsrca.org
> >>>  
> >>> Sent: Saturday, October 13, 2007 4:55  PM
> >>>  
> >>> Subject: [NSRCA-discussion] (no  subject)
> >>>  
> >>> 
> >>>  
> >>> The 010 track
> >>> is caused not by a weathervane effect, but by the  body of air moving from
> >>> west to east while airplane progresses
> >>> through  it on north heading.
> >>> 
> >>> During this flight, (and in
> >>> Case 1 and 2) a  yaw string would be straight, no wind hits side of
> >>> airplane.
> >>> 
> >>> I'm  missing something here. The body of air moving from west to east is
> >>> not  hitting the airplane? Then what makes it go off course? Please
> >>> explain.
> >>>                                 RJO
> >>>  
> >>> Comments-      
> >>>  
> >>> The airplane is carried along in the west to east movement of the body  of
> >>> air.
> >>>  
> >>> Sort like swiming in north direction in a swimming  pool.   And a big giant
> >>> (wind) picked up the pool
> >>>  
> >>> and carried it in a west to east direction.  You would  wind up going west
> >>> to east, but would not
> >>>  
> >>> have been hit on your west side by water.  You would still be  swimming
> >>> north, so you would travel
> >>>  
> >>> north on account of your swimming (airplane airspeed) and at the same  time
> >>> be carried east by
> >>>  
> >>> by the giant (wind)
> >>>  
> >>>  
> >>>  
> >>> Another way of looking at it - a non powered  balloon in the same body of
> >>> air will be carried in the same west to east  direction, and same speed as
> >>> the wind.   If you were riding in the  balloon, you would feel zero wind,
> >>> cause balloon is not moving in the body  of air.  Your direction of movement
> >>> over the ground will be same  direction and speed as the wind.
> >>>  
> >>> If balloon had a yaw string, it would point  straight down, same as it would
> >>> if in no wind air, which means it would  not
> >>>  
> >>> be moving over ground.
> >>>  
> >>>  
> >>>  
> >>> This "wind doesn't hit the side of the airplane" discussion ignors  gusting
> >>> wind, random turbulence, etc. that might momentarily "hit" the plane  and
> >>> cause changes in heading, pitch and airspeed.  They are relatively  short
> >>> duration.
> >>>  
> >>>  
> >>>  
> >>> Later, Ron Lockhart
> >>>  
> >>>  
> >>>  
> >>>  
> >>> 
> >>>  Email and AIM finally together. You've gotta check out free AOL Mail
> >>> <http://o.aolcdn.com/cdn.webmail.aol.com/mailtour/aol/en-us/index.htm?ncid=A
> >>> OLAOF00020000000970> !
> >>>  
> >>> 
> >>>  
> >>> 
> >>>  
> >>> 
> >>> _______________________________________________
> >>> NSRCA-discussion  mailing  list
> >>> NSRCA-discussion at lists.nsrca.org
> >>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> >>  
> >> 
> >>  
> >> 
> >>  
> >> 
> >> _______________________________________________
> >> NSRCA-discussion  mailing  list
> >> NSRCA-discussion at lists.nsrca.org
> >> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> > 
> > 
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> 
>

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