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Roger wrote:
Eric, can you explain span loading as opposed to wing loading? Span loading = weight/span. I don't have a good technical reference for it, but it accounts for aspect ratio effects to some extent. Consider two gliders with the same wing area and weight, giving them the same wing loading. The one with the higher aspect ratio, and consequently lower span loading because the span is greater, will thermal better. It's weight could be increased until they climbed the same, but it would now have a higher wing loading and cruise better. I mentioned it because it seemed likely you were thinking of 15 meter ships flying around empty in the weak winter conditions at about 7.5 lbs/sq ft, and wondering how an 18 meter glider could possibly keep up at 8.5 lbs/sq. On Oct 21, 8:13 pm, Eric Greenwell wrote: Roger wrote: Eric, some places fly all year and if the pilot is 200 - 250 lbs the wing loading in a motor glider is near max.Have you considered a sustainer glider instead of a self-launcher? That removes 100 pounds or so. I've found my 18 meter glider climbs as well as a typical 15 meter glider that has less wing loading. Span loading is an important number, so don't go just by wing loading. In the winter this means the non-engine folks have a much easier time staying aloft, and the motor glider in on the ground watching the pure gliders having fun.Start the engine, climb a bit, and go back to soaring. You will be able to do cross-country flights on the days the unpowered folk don't dare leave the field. The engine is your portable towplane, and even in weak conditions you might find, as I have, that you don't need it as much as you thought you would. Starting the engine might be the of competition or badge flight, but it's not the end of the flight or the fun. A few of my most memorable flights involved weak conditions and low cloud bases, but I had good soaring flights because I knew it wasn't going to end in a retrieve. Not that retrieves can't be fun, but after 20 years of them before I got the motorglider, my wife and I aren't missing them much! To the 26E, 808 list I'd add the Antares, and the Apis and Silent gliders (electric and gas versions). Lots more choices today than 10 years ago. -- Eric Greenwell - Washington State, USA Change "netto" to "net" to email me directly "Transponders in Sailplanes" on the Soaring Safety Foundation websitewww.soaringsafety.org/prevention/articles.html "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org -- Eric Greenwell - Washington State, USA Change "netto" to "net" to email me directly "Transponders in Sailplanes" on the Soaring Safety Foundation website www.soaringsafety.org/prevention/articles.html "A Guide to Self-launching Sailplane Operation" at www.motorglider.org |
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