HI Anthony is right. There are also considerations of how the glider performs at various loadings. For instance one of the golden rules that we used to stick when flying a Jantar was to dump 20 or 30 seconds of water on tow other wise it was difficult to handle. The Ls8 and SZD55 are different again and handle very well at the higher loadings. Over the last few years I have flown an SZD55 mostly. As a general rule on an average summer day in WA I use 45 kg/m2 and expect to get 3.5 to 5.5knots ave climb rates. If I expect to get better ave climb rates I will increase the loading to 48 to 50kg/m2.
The Polar10 spreadsheet that Todd has sent is very useful. However be careful to note the wing loading for the gliders (shown in brackets) some are set for max wing loading and others are not. Cheers, On 7/10/07, Anthony Smith <[EMAIL PROTECTED]> wrote:
There is a bit in Fred Thomas "Fundamentals of Sailplane Design" that discusses how to optimise aspect ratio and wing loading during the design stage. It shouldn't be too hard to reverse engineer it and work it out for a known design. I will have a look tonight for the relevant pages. The biggest problem is that you need to make some assumptions about the environment in which you are flying eg thermal strength, thermal diameter (and an idea of thermal cross section), distance between thermals and sink between thermals. The german models had 4 types of "average" thermals (basically combinations of weak, strong, narrow and wide) and did the optimisations based on those conditions. The end result is that there is no easy way to do what you want. In order to make a decision on how much ballast to carry, you need to have an idea of what conditions you are going to encounter on the day to get it right. Anthony > I'll be a bit more specific: I understand you can derive > the speed to fly by drawing the tangent from the > anticipated thermal strength to the polar. > > > > How do you determine the optimum weight and therefore wing > loading for particular conditions? (Or do you fill it to > the gunwhales and hope for the best :-) ) > > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Derek Ruddock > Sent: Tuesday, 10 July 2007 12:06 PM > To: Discussion of issues relating to Soaring in Australia. > Subject: [Aus-soaring] Block speeds and wing loadings > > > > Can anyone give some pointers for how to calculate the > block speeds and optimum wing loadings for a particular > glider? > > Examples from anyone who has already performed the leg > work would be appreciated > > > > _______________________________________________ > Aus-soaring mailing list > [email protected] > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
-- Regards, John Orton Mob: 0429357439
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