Recent content by mz-


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  1. mz-

    Did the Sparrow Hawk become the Sadler Vampire?

    Why is it a mid wing? Wouldn't a low wing enable you to put the wing further forward and thus enable putting the passengers very close to the center of gravity? Would it then have too rear CG problems with the engine placement? Putting the battery at the nose wouldn't compensate?
  2. mz-

    A wooden PIK-26 Mini Sytky

    For everyone, here's the page describing the crash during inadvertent takeoff in taxi testing D-EPIC PIK-26 homebuilt aircraft I'm sorry for your loss, but it is most important that you are alive!
  3. mz-

    Flaps or No Flaps?

    The Icon's flaps were quite extraordinary - some flexible thing that comes out of the wing, to enable a very large surface area IIRC.
  4. mz-

    Exhaust Extraction on a Pusher

    Actually, there are and were boats with forward tractor propellers too: icebreakers. :) At least in one case back somewhen on an old icebreaker, they found that actually routing all the power to the rear propellers made it more efficient, which was a surprise. It's a special case anyway -...
  5. mz-

    homebuilt twins

    Of course there's the new standard from Colomban: Twin-R Two 100 hp Rotax 912 ULs and 450 kg empty mass means something. Four seater. 175 kts at 75% power. It's not pressurized of course so none of that turbo or high cruise stuff.
  6. mz-

    Why we still use old engine technology

    The problem is, that bike from the seventies is still around and beats 90% of the new bikes available. Certainly all at the $100 price. At least I ride one. Though I'd really love to upgrade from a 1975 entry level model to a 1979 racing model with much less weight. Most of that cheap stuff...
  7. mz-

    Why we still use old engine technology

    You have to include the social aspect into it somehow to make it more popular (again in some places). Also, style is not to be underestimated. Something else than Cessnas, please! Either vintage planes or very light but cool planes or then sleek composite machines. And lower the cost so you get...
  8. mz-

    Books about wooden gliders building...

    That is very good, gery, thank you very much!
  9. mz-

    windshield material

    It's a Grumman XP-50!
  10. mz-

    UltraLight airships can be homebuilt?

    Yeah I guess one can say that alpha rays and thus earth helium is just "reliberated" helium - its protons and neutrons were hydrogen or helium originally after the big bang and were fused in a star to a heavier atom's nucleus, which then later broke up again, but these atoms had bunched up into...
  11. mz-

    Questair Venture canopy design

    You could make the whole plane out of PE of course. Even the control cables. Kayaks are made often from PE, they're not much heavier than glass fiber ones. The more expensive PE kayaks use sandwich materials. You can get PE foam too but it doesn't have that good of a strength to weight ratio...
  12. mz-

    UltraLight airships can be homebuilt?

    Earth's helium is from decay of radioactive unstable nuclei and it is being created constantly inside earth. Alpha rays are just helium nuclei without their electrons. Helium is so light that it doesn't stay in the atmosphere, it reaches escape velocity at thermal energies (hydrogen too but it...
  13. mz-

    Interesting propeller

    Yes, like increasing wing chord has sense for increased lift... but not for efficiency. I realize I typed it really unclearly.
  14. mz-

    Interesting propeller

    Force = Mass Flow * Velocity Change hence a larger mass flow gives more thrust for less velocity change. You achieve a larger mass flow with a larger prop. I don't know much about prop theory per se but if you think about the air parcel whose velocity is changed, the chord doesn't matter -...
  15. mz-

    HELP Finding an engine...

    For minimum energy per distance you want to minimize weight per L/D. I wonder how you'd do with thermaling. Probably takes too long though to travel with anything too ordinary glider (might just work for a UAV) like with really low power, and encountering head winds will make you move backwards...