Recent content by aivian

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    Struts on a Glider

    Off the top of my head I think it is partly cultural and partly technical. (I've never designed a micro-lift sailplane, done market research for one, etc. apply a suitable number and size of salt grains to this opinion) Cultural: Sure, some of it is probably that "modern gliders don't have...
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    Trailer Design - Resources?

    I don't have any design resources, but I've had the misfortune to deal with a variety of home built sailplane trailers and fortune to deal with a number of name brand ones. Regardless I rig and derig almost every time I fly (now from a "homebuilt" Jiran half-clamshell which is the best of the...
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    Dynamic Soaring Blows My Mind

    Lord Rayleigh's observations of albatrosses "The Soaring of Birds" from 1883 is generally thought to be the earliest study of dynamic soaring. His analysis was largely qualitative but clearly lays out the basic ideas of dynamic soaring. As you show, the early literature of soaring is mostly in...
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    Using only GPS as your EFIS inputs??? Why u do dat?

    What do you mean by "EFIS" and "useful?" Any system which has attitude requires sensors other than GPS, and anything with a PFD requires pitot-static data. If any system is displaying a PFD based on inertial data I think we would agree that is not an appropriate thing to do. Focusing on...
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    Using only GPS as your EFIS inputs??? Why u do dat?

    The point I was trying to get at is that AHRS is improved by GPS. Adding GPS to a silicon MEMS system reduces attitude error by roughly a factor of 10 (even more for heading). That is the why. It is possible that some EFIS does this poorly but that is a mark against a particular implementation...
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    Using only GPS as your EFIS inputs??? Why u do dat?

    The solid state "gyroscopes" in these electronic AHRS systems are not gyroscopes in the traditional sense. They indicate angular rates, not attitude. To get attitude from them you could start from a known attitude and add up the angular rate over a series of small steps in time. Unfortunately...
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    Side Hinged Rudders - Any Known Issues?

    Coincidentally I had the rudder off of my H201 recently for overhaul of the "rudder gimbal drive." Here are some pictures, although they were taken to guide reassembly so they may not illustrate operation perfectly. A centerline(ish) pushrod actuates the first gimbal which then drives the...
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    Low Drag Cabin Air Exhaust - Whats Optimum?

    I've seen a few configurations in sailplanes, though never a comprehensive analysis of alternatives or trades on ventilation approaches. Here are the approaches I've seen. Exhaust through the tail area using the rudder horn fairings, a dedicated vent, or natural leakage. Some of these work well...
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