Recent content by b7gwap


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  1. b7gwap

    Engine options for my Lazair

    Slightly off topic, but how long has the OP had his Lazair? And what is the best venue for used ultralights? Does everyone just watch barnstormers or is there somewhere else I can watch the market for used ultralights? I think the Lazair is a unique and neat little airplane. Eh I mean powered...
  2. b7gwap


    To bring this thread back on topic, has anyone heard any news about Earthstar or the Thunder Gull lately? It really is an attractive little ultralight.
  3. b7gwap

    Wing Covering Material

    Doesn’t Peter Sripol use structural coroplast in his ultralights?
  4. b7gwap

    modern equivalent to doped canvas?

    I have a kayak like that I built in the 1990s. Plain canvas sealed with latex house paint. Still floats.
  5. b7gwap

    Are tube spars an insult to the engineering community?

    The single biggest advantage to tube spars is that they come pre manufactured as an extrusion. Part of the pioneer, Knievel-seque spirit of ultralight design is the TLAR nature of a tube ladder wing with external bracing. I doubt very many of those designs ever underwent a FEA/FEM, or even a...
  6. b7gwap

    Bolt holes, burr and fatigue life effects

    TL,DR :) breaking sharp edges is extremely important, no matter the material, although some are more sensitive to it than others. Just don’t take so much that it becomes a chamfer and now you have reduced bearing strength and bolt bending issues to consider.
  7. b7gwap

    Laser cutting aluminum questions

    But you said tubes not sheet stock. I still think you’d be better served by traditional machining techniques here.
  8. b7gwap

    Laser cutting aluminum questions

    A router table has to cost less than a laser table. Yeah your kerf is wider but with the correct speeds and feeds, you need not worry about HAZ. At a laser price, you could even look into an NC punch press.
  9. b7gwap

    Human Powered Flight

    It’s a fascinating subject. A testament to human ingenuity. It also humbles me to remember just how little power even our strongest muscles produce in comparison to internal combustion and electric motors. I think of a Hirth F33 as a minimum power plant, but it’s got something like 50 times or...
  10. b7gwap

    Hi I whant to buy aircraft like this or aircraft no more than 70 kg

    The motorized Pig is called the Bloop, and has some other significant design changes like a single empennage, motor mount and nose section update. I believe Mike says his weighs 195 lbs or thereabouts, so ~88kg.
  11. b7gwap

    The Future of Air Travel

    Ron pointed out that sub orbital is slower than orbital flight. Also keep in mind such a trajectory is by nature parabolic, you’re kind of going more up and out and then back down, not trying to establish a free fall ellipse around the planet. G forces are a real thing, and any manned space...
  12. b7gwap

    Glues for foam to alloy tube?

    Not cheaper, but west systems 105 epoxy will bond foam to aluminum with proper substrate preparation.
  13. b7gwap

    UL spars?? Tube or plank?

    Care to share a quick napkin sketch of your proposed spar design? it would help the group better envision what you have in mind. is this to be a cantilevered or externally braced type of wing? most ultralights use externally braced circular tube spars at the leading edge and at the aileron...
  14. b7gwap

    Alternative to turnbuckles

    As an outside admirer of the Zenith lineup (A “someday it might be fun to have a CH750” sort of admiration), have there been similar structural concerns with their STOL designs? Or were the in flight break up issue relegated to the 600-series low wing airplanes?
  15. b7gwap

    Alternative to turnbuckles

    Yikes on the live hinge ailerons. That’s nice they did a test, but was the engine running so as to incorporate vibration and fretting loads? Someone also pointed out flight loads. I’ve put live hinges in model airplanes that were composite-skinned. Composites have insane fatigue lives. Fatigue...