Recent content by Norman

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

  1. Norman

    Holes in Spoiler or Not

    Spoilers have holes to eliminate some nonliterary in their operation. Spoilers without holes have a delay in both the buildup of drag and loss of lift due to a starting vortex (there could even be some extra lift during the lag period). After a few seconds the vortex breaks up into random...
  2. Norman

    Profili 2 Airfoil Database for Harry Riblett GA Airfoils

    They probably could have been patented even though they were derived from NACA thickness forms. It is and always was common practice to start with a seed shape and tweak it untill you get the characteristics that you want. Airfoils are not generally patented because it's just not worth the...
  3. Norman

    Reducing drag on a kitfox

    A round tube makes as much drag as a symmetrical airfoil 9 or 10 times as thick so fairing the struts is definitely worthwhile. Also angle of climb is strongly dependent on wing loading so use the lightest materials possible for fairing blocks, wood is hardly ever necessary except for parts...
  4. Norman

    Profili 2 Airfoil Database for Harry Riblett GA Airfoils

    Just something I read a long time ago from someone who actually is an authority on this stuff. Riblett's " GA Airfoils" contains a bunch of photocopied articles and apparently not all with permission.
  5. Norman

    Profili 2 Airfoil Database for Harry Riblett GA Airfoils

    Why? He didn't respect the legitimate copyrights of others so why should people honor his unfounded claims? There is no copyright on data even though he claimed it. Authors can claim less IP protection than the law allows but they can't extend it to include new restrictions.
  6. Norman

    Profili 2 Airfoil Database for Harry Riblett GA Airfoils

    Copyright covers words, pictures, and software but not data or technology. A table of numbers is data so no copyright on the coordinates themselves although the compilation (the book and all its pages) are protected. In other words don't photcopy the pages. Airfoil shapes are technology which...
  7. Norman

    High aspect ratio wings

    Materials and money. Back when the only materials available were wood and steel it was found that spar weight started increasing really fast at AR>7 or 8 so most GA airplanes got that aspect ratio. The move to aluminum didn't change the weight to AR much so 7 or 8 is still typical...
  8. Norman

    Pinbal project

    I was expecting a thread about an Orange P-63. Boy was I surprised.
  9. Norman

    No one can explain WHY planes fly...

    Exactly, the kenetic energy of molecules of air is much higher than the gravitational attraction between them. If it weren't for the gravitational attraction of earth the atmosphere would just fly away.
  10. Norman

    No one can explain WHY planes fly...

    When two molecules bounce off eachother at 750 mph their velocity is much higher than required to ensure that gravity will never pull them back together. The mass of the wing isn't even enough to pull them back. The mass of the Earth is the only gravitational influence of importance here...
  11. Norman

    No one can explain WHY planes fly...

    Nothing wrong with Bernoulli's theorem except that it can't be used in a cause and effect argument because it's reversable. It also says nothing about viscosity which is a property of all fluids at normal temperatures. Euler's formulas do an OK job of describing the flow around an airfoil...
  12. Norman

    No one can explain WHY planes fly...

    No. There is no significant attractive force between neutral molecules. The springs that Feynman was talking about are the strong nuclear force which only affects the nucleus, not the bulk flow. The only interaction between molecules of a neutral gas is collisional. To contenu the traffic...
  13. Norman

    No one can explain WHY planes fly...

    Part two of this Vorticity lecture uses clips from Prandtl's film to illustrate the part of the lecture about lift and goes into more detail. Sorry I was only thinking about the starting vortex before and only searched for that term. It's only a subset of Vorticity so searching for that...
  14. Norman

    No one can explain WHY planes fly...

    It's a little easier to see what's going on in this CFD clip than the original aluminum powder on water film.
  15. Norman

    No one can explain WHY planes fly...

    Search YouTube for "starting vortex". I didn't find anything like Prandtl's original film but some college students try to approximate it with stuff in their dorm kitchens. There are also some CFD symulations. None with helpful voice or text. Here's a brief verbal explanation of the starting...
Top