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  1. addaon

    Boeing Aims To Bring Flying Cars To Asia By 2030

    (This is the four-seat newer generation of the two-seat Wisk I worked on for ~4 years.)
  2. addaon

    Switching Options of Essential Equipment

    And this is also where latent fault analysis comes into play. If your pre-flight is consistently able to determine if a diode has failed short, then the probability of a diode-short failure during the flight is MTBF * flight duration * number of diodes, which should be a small number. But...
  3. addaon

    How to get diameter wooden propeller for gasoline engine 7hp = 208cc

    As mentioned on the last thread where you wanted to use two 2 hp engines...
  4. addaon

    Electric Aircraft Manufacturer Electron Secures Orders from Air2E, Hopscotch

    There's two factors here, at least -- the first is indeed thermal. It's sort of inherently true that fast charging means pushing the thermal limits of the battery; if you're not, you can charge faster. For a given lifetime target -- say 500 or 2000 cycles to 80% of nameplate capacity -- you will...
  5. addaon

    Electric Aircraft Manufacturer Electron Secures Orders from Air2E, Hopscotch

    I'm curious what battery chemistry you're assuming for this guess. Assuming it's pretty closely related to NMC, and the cells are closer to power-optimized than energy-optimized, generally you'd assume about 15 or 20 minutes until the elbow at 80% charge -- this matches Teslas, and many other...
  6. addaon

    Electric Aircraft Manufacturer Electron Secures Orders from Air2E, Hopscotch

    Where are you seeing this on their page? I'm trying to think of a battery chemistry that would meet their range/speed requirements and wouldn't comfortably charge in 30 minutes or less, and really can't come up with anything sane... I don't see any indication they're using a flow battery or...
  7. addaon

    Anti-ice for experimental.

    Yes, but besides all that, it might also make things worse, depending on where refreezing happens. So not just difficult, heavy, and bad; also maybe worse than nothing.
  8. addaon

    Sandlin Gliders: Builds, mods, flights

    The other advantage of a safety link is that you know where the break will happen. I’d rather have the pro in the tow plane deal with the line than deal with half of it hanging off the glider.
  9. addaon

    The Great FreeCAD Thread

    I have no experience at all with FreeCAD, but modern CAD programs should just slow down with increased complexity until they (rapidly) become unusable, not fail to show a subset of the geometry. I suspect it’s more likely that something else is going on than that FreeCAD is atypical here… but...
  10. addaon

    Cheapest / least expensive plane to build

    This is true, but the magic of paragliders is that failure to maintain OML isn’t a big deal — something between No Effect and Minor impact in aircraft terminology. Collapses happen. Recovery happens. Keep flying. (Sufficiently asymmetric collapses can approach Major… but I think in hundreds of...
  11. addaon

    Electric Dreams... Pipistrel’s gift to general aviation.

    Depending on exact chemistry choices, well-treated cells these days (NMC, LFP, etc) are good for thousands of cycles from 98% - 20% (using the standard lifecycle definition of 80% of nameplate capacity remaining). It’s easy to choose to not charge that last couple percent (for NMC, go to 4.190 V...
  12. addaon

    Electric Dreams... Pipistrel’s gift to general aviation.

    They’re producing axial flux motors, which does add quite a bit of manufacturing challenge — maintaining the rotor/stator gap really is harder. But yeah, agreed that they come across as a manufacturer making very reasonable claims with good data to back it up; I’d absolutely be comfortable...
  13. addaon

    Achieving The Best Reflexed Airfoils for Flying Wing use in the Small Plane Categories

    No. The static margin does not change with AoA. Sure, if you want to take into account movement of fuel with CG, maybe it changes be a fraction of a tenth of a percent... and certainly for an aircraft with a high fuel weight ratio it will change with fuel burn, but this is with a time constant...
  14. addaon

    Achieving The Best Reflexed Airfoils for Flying Wing use in the Small Plane Categories

    I'm not sure I'm quite understanding the question. Static margin is a function of the neutral point of the airframe and the position of center of gravity; unless the CG changes (or is significantly far from the neutral point vertically, which can introduce a sin(AoA) term), it doesn't vary...
  15. addaon

    Achieving The Best Reflexed Airfoils for Flying Wing use in the Small Plane Categories

    Really don't have a preference. But again -- what static margin to trim to? I used 5% for the stable design because the +Cm airfoil I was using won't really trim past that, but 5% isn't really considered flyable for most purposes. With a 50" chord I assume you're looking for a minimum SM of...
  16. addaon

    Cheapest / least expensive plane to build

    Yeah. Designing a paraglider wing is way more complicated than designing a fixed wing. On day one you're dealing with aeroelastic effects, even in the normal operational range; and you have major portions of the envelope (launch and collapse recovery) where the wing is not fully pressurized, has...
  17. addaon

    Cheapest / least expensive plane to build

    Earlier (< 2008 or so) beginner wings are much less safe, especially for a beginner, than a modern beginner/intermediate wing. The improvements in both performance and safety of paragliders in the past ~30 years are closer to the performance and safety improvements in fixed-wing airplanes from...
  18. addaon

    "We just hit a Drone!" | Windshield Damaged on United B737 MAX at SFO

    Or, glow engines and balsa no longer represent a significant chunk of the hobby. Electric motors, foamed ultralight filaments for 3D printed wings, ardupilot taking RC capabilities far beyond what was previously imaginable... might not be what you want from RC, but sure represent a large and...
  19. addaon

    Ultimate SI for u/l, EAB

    Nah, the UAV-designed heavy fuel rotaries really are crap (in terms of efficiency). They run a fuel/oil mix (with pretty much any fuel), crappy compression, deliberately worse sealing, and are usually designed to 100 - 250 hour TBO. They also get well over 2 hp / lb and are pretty much...
  20. addaon

    Universal electronic ignition options?

    Be very, very careful with confirming your environmental specs. This sort of board is not made to any realistic standards for use in the real world -- heck, they're not even conformally coated -- and you're proposing to put it in an environment with wide temperature swings (unless your aircraft...
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