Results 1 to 3 of 3

Thread: Concorde like nose design for modern jets

  1. #1
    Member
    Join Date
    Apr 2005
    Posts
    302

    Exclamation Concorde like nose design for modern jets

    My question is why are new generation jets (such as the 787 and A380) designs are not making use of the almost needle shaped noses? I never understood that. I mean, I would think a sharper nose would create less drag, increase speed and enable the aircraft to use less fuel.

    Am I missing something here?

  2. #2
    JPElite Member! Dmmoore's Avatar
    Join Date
    Jan 2008
    Location
    Prescott, AZ, USA, Earth, Sol Solar System, Milky way Galaxy
    Posts
    1,336

    Default

    Quote Originally Posted by Dantheman View Post
    My question is why are new generation jets (such as the 787 and A380) designs are not making use of the almost needle shaped noses? I never understood that. I mean, I would think a sharper nose would create less drag, increase speed and enable the aircraft to use less fuel.

    Am I missing something here?
    What you are missing is the difference supersonic and subsonic airflow. At subsonic speeds airflow is moved aside without encountering excessive drag from moving the air aside. As long as the shape is smoothly curved, the drag is minimal.

    As speeds approach the transonic range, air begins to compress as air moves around the airfoil. At this point a sharper leading edge begins to become more efficient than the blunt nose version. Above MACH 1 sharper leading edges are required. The higher the MACH number, the sharper the leading edges need to be. At supersonic speeds, any structure of any shape causes the air to compress as it passes through. The sharper the leading edge of the structure, the less drag (from compression).

    At subsonic airflow does not compress to any significant amount. It is the compression of the air that causes the sonic boom associated with supersonic flight.

    A pointed nose increases weight while generating unusable or less usable space.
    Don
    Standard practice for managers around the world:
    Ready - Fire - Aim! DAMN! Missed again!

  3. #3
    Senior Member Gabriel's Avatar
    Join Date
    Jan 2008
    Location
    Buenos Aires - Argentina
    Posts
    6,880

    Default

    Right Don.

    I'll add to that that in subsonic flight with any reasonably streamlined shape, the friction drag is a more important component of the drag than the pressure drag.

    While a pointi nose could still reduce the pressure drag in just a fraction of a bit, it would increase the friction drag. Why? Pointi noses have more wet area. Think ho long would the nose of an A380 be to reach from a dimeter of zero in the tip to the full fusselage diameter at a constant small angle!

    At supersonic speeds the pressure drag becomes so important that you are glad to increase the friction drag if that can help reduce the former in any significant degree.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •