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  1. Birdman100

    Minimum Composite Thickness/Layup

    If skins are stiff/strong enough I wouldnt worry about leading edge. LE is sharp and that shape gives extra rigidity itself, plus you have overlap there (upper and lower skin bond). As far as I know there is no additional reinforcement in LE in glider wings.
  2. Birdman100

    Playing with OpenFOAM

    Any progress with airfoils? some advises: -try to get good results with isolated foils first, comparing CFD results to experimental; this to "calibrate" your code -you need adequate turbulence model (that is transition) in order to capture both laminar and turbulent BL. Otherwise you will...
  3. Birdman100

    New Tool: 3DConnexion Space Pilot Pro

    How long does it take to get used to it?
  4. Birdman100

    Thinking about a human powered ornithopter

    good machine if you have kidney stone...
  5. Birdman100

    German 120kg class

    In this particular case he considered 35 kts as low. For a fast bird with a small wing this indeed can be hard to achieve...
  6. Birdman100

    "New" Hummel Bird? How?

    I will. I just say "fowler" but I mean double slotted fowler actually. Slot section is small enough and doesnt add any significant weight but it does contribute to flap effectiveness.
  7. Birdman100

    German 120kg class

    My design is very hard or even impossible to get down to 115 ew with 50-60 kg engine (HKS 700). That would leave 60 kg for the whole airframe... What are my options?
  8. Birdman100

    German 120kg class

    300 kg is take off, while 115 kg is empty or empty doesnt matters as long as take off is <300?
  9. Birdman100

    "New" Hummel Bird? How?

    Yes, it has sense. Looks like DG 200.. Ok, now how about airfoils ? What is currently "best" available (coordinates)...? Anything newer and better than HQ 17, HG 35, du89, ah93k, diana 2 sections...and still available (I guess am searching impossible now)? Then my next dilemma is related to...
  10. Birdman100

    Thoughts / questions on Jetman's (Yves Rossy) wing

    Main reason for sweep is stability - directional, lateral, longitudinal. See hang gliders, sub sonic as well and all with swept wings. Deficiency in tail must be compensated and the answer is swept back flying wing. In aerodynamic sense Ives Rossy flying wing is not any spectacular...
  11. Birdman100

    Junkers flaps

    Am looking forward to see your progress. You are using commercial mesher or trying to program your own? Long and bumpy road...
  12. Birdman100

    "New" Hummel Bird? How?

    Didnt know those speeds are that high, but I thought that flutter shown in videos above is artificially triggered for the sake of research.
  13. Birdman100

    "New" Hummel Bird? How?

    DZ, I get your point and I understand that flutter is a serious issue. I just cannot say anything with absolute certainty without serious analysis. My approach is to undertake proper research on the problem, put "on paper" and calculate and see what possible outcome is. Am just confident that...
  14. Birdman100

    "New" Hummel Bird? How?

    Actually the airplane evolved much, and Vne around 400 km/h is more realistic value.
  15. Birdman100

    "New" Hummel Bird? How?

    The problem is we often tend to draw general conclusion from single event. It is really important to be familiar with all circumstances before we induce some facts. Flutter is dangerous and trappy phenomenon, but there are ways to postpone it and to avoid it (up to reasonable Vn) with proper...
  16. Birdman100

    CriCri MC-15 in San Francisco

    michael, what is the thickness of canopy material? plexiglas? Looks very nice (post #22)
  17. Birdman100

    "New" Hummel Bird? How?

    AR, thanks for all clarifications! Ok, those two pins are at each side (ends) of that bar or just at one side while other is smooth? Red arrows in sketch... What is middle (blue arrow) pin, just to secure command horn (red horizontal bar in sketch from my previous post) to the bar? Yes, got...
  18. Birdman100

    Upper Wing laminating with twill

    If it is same fiber type and weave, I dont see any problem. If properly stored (dry place) and undamaged carbon doesnt have limited shelf life.
  19. Birdman100

    Stabilizer Twist

    I doubt that designer of Carbon Dragon could calculated angles so accurately to account for that twist and to finally gain something. Without real-scale experiments or CFD it is very hard if possible at all. That said, I wouldnt be surprised if it happens that flat tail even improves...