[NSRCA-discussion] Airplane angle of attack

[Bob Richards]

That makes sense to me. The AOA depends on the load. In an extreme case, very lightly loaded, I don't think you would want to fly with the fuselage in a nose down attitude, that would probably be inefficient. Better to have it slightly nose up in cruise with a full load. JMHO.
   
  Of course, the reason WE would trim wing incidence would have more to do with overall flight characteristics during aerobatics, particularly with pitch coupling in knife edge flight.
   
  Bob R.
  

chris moon <cjm767driver at hotmail.com> wrote:
      .hmmessage P  {  margin:0px;  padding:0px  }  body.hmmessage  {  FONT-SIZE: 10pt;  FONT-FAMILY:Tahoma  }    Tried to post this before but it did not go through. 

The optimum cruise angle of attack for jetliners is somewhere between 
2.5 and 5 degrees nose up. Usually closer to 2.5 or 3 degrees for an 
econ cruise. As fuel burns off and the gross weight goes down, the 
airplane will need a lower angle of attack to maintain flight which 
will take us away from our optimum angle (lower). So, we will either 
climb to where the air is "thinner" and require a higher aoa (angle of 
attack) to get us back to the 2.5 or 3 degrees or, slow down and 
maintain the lower altitude thus requiring us to increase the aoa back 
to optimum. The answer to your question is yes, a jetliner flies at a 
nose high aoa in cruise. Lift from the fuselage would probably be 
negligible other than "impact" lift - the force of the relative wind 
against the raised fuselage bottom. 

Chris 


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