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Recent content by mafa

  1. M

    DGR PDs -> Thanks For Playing!

    Apparently Timko does know (occasionally) what he's doing since JR's and mine arrived today! Well done, 6 days from U.S. by USPS is totally unexpected and unasked for speed of delivery, probably eligible for some kind of record title. Matti
  2. M

    Distance increasing with temperature!

    8000 km NE from Florida, temperature 2 C and relative humidity 100%? Matti
  3. M

    Distance increasing with temperature!

    Please do not confuse absolute and relative humidities. As Monocacy said, at 30C air can only hold 3% per weight water. Calculated examples at 1000 mbar actual air pressure: Air densities at 30C with 10% and 100% RH are 1.15 and 1.13 g/l respectively Air densities at 15C with 10% and 100% RH...
  4. M

    Distance increasing with temperature!

    I don't think this is correct. For air density, temperature and air pressure are significantly more important than humidity. Sure humidity has a non-negligible effect but it's small. If you look at the varying conditions people disc golf (-20 F to 120F) and 0 ft to 6000+ ft elevations, the first...
  5. M

    Maxing out @ 300ft...

    Avery shoots from the left pec but anyways... Matti
  6. M

    Maxing out @ 300ft...

    Second this. From what I've learned from here and tried to conclude myself: There definitely should be active elbow extension involved. There's also passive extension happening due to the "stopping elbow". They combine for the "late acceleration". _Timing_ the passive and active extension is...
  7. M

    FPS Question

    If you look at his right hand in the follow through, his middle finger is extended. I have no idea why or how this happens. As if he's not gripping with middle finger at all. Is this one of the known grips? Matti
  8. M

    FPS Question

    Yeah, frame rate gives you smoothness. The slow motion videos I have posted here at DGR are shot at 250 and 300 fps depending on the camera used. Since ~25 fps gives illusion of smooth motion, 250 fps can be slowed down 10x. On the other hand, slower frame rates can also provide useful data...
  9. M

    From The Archives: Drive Comparison

    Here's a compilation of mostly unpublished slow motion footage from last summer. This time I decided to have pairs of drives side by side so you can try pick up the similarities and differences between some of the top arms. Each pair is first shown real-time then 2.5x, 5x and 10x slowed down...
  10. M

    Disc Physics

    JHern, I think I see your point but please keep in mind that velocity has squared influence on lift. Throwing disc with 1.4 times its cruise speed will lead to lift force of twice that is needed to keep the disc aloft. That converts to one g of radial acceleration which rapidly renders initial...
  11. M

    Disc Physics

    Let the discussion start: In literature pitching moment does change sign but as a function of _AoA_, not speed. This has been stated for all kind of airfoils I have this far found, not just frisbees of which there are much less research results available. In the frisbee studies ( i.e. Potts &...
  12. M

    Disc Physics

    JHern, Really can't wait for your results. I've also been thinking for some time now of putting up some sort of simulation/simulator for inspecting and understanding better how discs fly. Having a "live" disc flight chart is a great goal. I am really interested on your thoughts on how to model...
  13. M

    How to adjust spin vs. speed

    Did part of my homework and quickly measured flight plate thicknesses of the discs in my previous study. I had to measure quite close to the rim since the micrometer I was using does not allow over 30 mm distance from the edge of the disc. From Star Destroyer to Dx Aviar, flight plates went...
  14. M

    How to adjust spin vs. speed

    To clarify: D is the distance from inside of the rim to the center of the disc. It's not diameter of the disc which I did not need in my calculations. Just measured from the inside of the rim to the center of the disc. To JHern and Bradley. Putters having thicker flight plates explains why...
  15. M

    Ken Climo in Finland 2009 slo mo and real time

    Man, DG's not child porn. Matti
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