1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Maximum endurance at higher altitude

  1. Nov 11, 2011 #1
    As a first year aerospace engineer student I had a problem today.

    The question was :

    Does the altitude effect the endurance of an aircraft (provided that the aircraft engines can generate enough trust at this higher altitude).

    Maximum endurance is minimum fuel flow [N/s] F = Ct T

    in a steady, horizontal, symmetric flight F = Ct D

    D = Cd (1/2) rho V² S

    D: Drag
    T: Thrust
    Cd: Drag coefficient
    Cl: lift coefficient
    Rho: air denisty
    V: velocity
    S: wing area

    So higher altitude = lower density = lower drag = lower fuel flow = higher endurance.

    But also true is that F = Ct (Cd/Cl) W and none of these parameters are effected by the altitude.

    Which one is correct and why? And why is the other one wrong?

    Kind regards,
    Alex

    Edit:
    D = Cd (1/2) rho V² S
    but V is sqrt (W*2*1/(S*rho*Cl))
    so the rhos cancel eachother out.

    Is there a delete button somewhere?
     
    Last edited: Nov 11, 2011
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: Maximum endurance at higher altitude
  1. Maximum altitude (Replies: 7)

Loading...