A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Home Built
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

The Impossibility of Flying Heavy Aircraft Without Training



 
 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
  #11  
Old March 4th 06, 04:23 PM posted to rec.aviation.piloting,rec.aviation.homebuilt,rec.aviation.student
external usenet poster
 
Posts: n/a
Default lift, wings, and Bernuolli


Jose wrote:
The flying wing has some horizontal momentum which is secondary here,

How much?


mv

The air thrown forward (or, if you will, the higher pressure ahead)
tries to reduce that, the engine presumably makes up for it.

Energy is 'pumped' into the air by the plane.


Yes, and what form does that energy take?


Heat.

I maintain that it takes the
form of a net increase in mv^2/2 over all the air molecules.


Yes.

Since m
doesn't change, and 2 only changes in a pentium, that leaves v to
change. This changes mv, thus momentum.


Mass and energy are scalers but velocity is a vector.
You can increase the average velocity of the air molecules
without changing the momentum of the air mass. Indeed,
that is exaclty what happens when you heat air.


We agree that there is (microsocopic) momentum transfer at each
collision. We disagree as to whether the net is zero, and I think that
part of that disagreement has to do with just how much of the system we
are looking at.


More importantly we disagree on what causes lift.

If there is lower pressure on the upper surface of a wing than there
is underneath there will be an upward force on that wing. I think
we agree on this.

You argue that the presssure difference and resulting force
is secondary, lift is actual caused by the reaction of the wing
to the momentum change it induces in the air. But suppose
the wing creates low pressure on the upper surface by throwing
air sideways? You still have a pressure differential and the
resultant force but the only downwash is the air flowing
toward the upper surface of the wing from above to fill in
the rarefied region.

For that matter, consider the common demonstration using a
notecard, thumbtack and a straw. Put the tack through the
middle of a 3x5 index card or something similar. Put a drinking
straw over the thumbtack. Hold the aparatus with the straw
vertical and the notedard down. Blow through the straw and
let go of the notecard. The notecard will be supported by the
Bernouli effect.

The only downwash is through the straw, directed at the notecard,
pushing it down. There is no downwash from the card. The card
does not deflect any air down, it deflects the air sideways.
Yet the card is supported by the pressure differential created
by the Bernouli effect. Horizontal flow accross the upper surface
of the card creates that pressure difference.

Downwash does not cause lift. Downwash is a secondary effect
caused by the same phenomenum that causes lift.

--

FF

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
AOPA Stall/Spin Study -- Stowell's Review (8,000 words) Rich Stowell Aerobatics 28 January 2nd 09 02:26 PM
GAO: Electronic Warfa Comprehensive Strategy Needed for Suppressing Enemy Mike Naval Aviation 0 December 27th 05 06:23 PM
Washington DC airspace closing for good? tony roberts Piloting 153 August 11th 05 12:56 AM
Sport Pilot pilots not insurable? Blueskies Piloting 14 July 12th 05 05:45 AM
USAF = US Amphetamine Fools RT Military Aviation 104 September 25th 03 03:17 PM


All times are GMT +1. The time now is 02:14 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.