tisdag 25 september 2012

NASA: What Keeps Planes in the Air?

                                             Dad, what keeps the airplane in the air?

To check if someone understands a physical phenomenon it is often instructive to study how it is presented to young innocent minds. As an example, let us see how NASA Glenn Research Center in its Beginners Guide to Aeronautics, explains how an airplane is kept in the air by an upward lift force generated by the wings balancing gravitation:
  • How is lift generated? 
  • There are many explanations for the generation of lift found in encyclopedias, in basic physics textbooks, and on Web sites. 
  • Unfortunately, many of the explanations are misleading and incorrect. 
  • Theories on the generation of lift have become a source of great controversy and a topic for heated arguments for many years.
  • The proponents of the arguments usually fall into two camps: (1) those who support the "Bernoulli" position that lift is generated by a pressure difference across the wing, and (2) those who support the "Newton" position that lift is the reaction force on a body caused by deflecting a flow of gas.
  • Which camp is correct? How is lift generated?
After this challenging start NASA disappoints the curious young mind by:
  • The real details of how an object generates lift are very complex and do not lend themselves to simplification.  
  • To truly understand the details of the generation of lift, one has to have a good working knowledge of the Euler Equations.
NASA thus has no explanation of lift to offer, only a mathematical Euler Equation mystification, and so in a desperate move to maintain scientific authority and credibility resorts to presenting, instead of any correct theory, three incorrect theories: "equal transit time", "Venturi" and "skipping stone".

But if NASA would learn about the New Theory of Flight then NASA would be able to fill its mission to reach young minds with essential science, instead of as now delivering only mystical or incorrect science.

I have tried before to get the attention of NASA (see Interview with Glenn Research Center from  2009) and will now make a new try and report...

PS In a last attempt to save face NASA throws in circulation theory:
  • From a Newtonian perspective, lift is generated by turning a flow of air. 
  • The flow turning that occurs in the creation of lift also creates bound vorticity within the airfoil.
  • The existence of the bound vortex (or vortices) within the airfoil created an important theoretical problem when it was first proposed.
  • With a bound vortex within the object, there would then have to be another vortex of opposite strength present within the flow domain.
  • It took some very careful experimental work by Ludwig Prandtl to actually "catch" the other vortex on film (the so-called starting vortex)
Computer drawing of an airfoil showing the bound vortex
 and the shed vortex.
The New Theory of Flight shows that this 2d picture does not describe actual real 3d physics, only fictional physics which only Prandtl could "catch" in his mind, as a mystery to generations of aerodynamicists flocking at NASA.


2 kommentarer:

  1. " (1) those who support the "Bernoulli" position that lift is generated by a pressure difference across the wing, and (2) those who support the "Newton" position that lift is the reaction force on a body caused by deflecting a flow of gas."

    is (1) not essentially the same as (2), just a diferent way of describing the same phenomenon??

    SvaraRadera
  2. Anonym:
    (1)happens every time air flows around a wing. If the wing is to fly the flow has to be sufficiently large so that (2) is equal to airplane weight.
    Therefore (1) is the basic function of the wing.
    Unfortunately for Bernoulli though, he has very little to do with it.

    D

    SvaraRadera