I had to truncate my first post because dinner was ready, and I don't like to miss a meal. I got the term span loading from some old articles read years ago, I believe it is a quantifiable relationship tied to aspect ratio. What I think I elude to is that after a certain size, wing loading ceases to be as significant as perhaps other parameters. I have had the pleasure and privilege to sit in on conversations with full scale designers of sailplanes. According to them, adding span is the easiest way to add performance, and aspect ratio close adjunct. But certainly it would seem that the higher RN achievable with larger long winged sailplanes would be of some significance.
I had a 1/3 fox with an eppler 373 that needed to be ballasted to 35 pounds to get it to fly right. (Perform aerobatic routines). Another 1/3 scale fox with a selig 6060, flew much better at 24 pounds and was able to do the same routines at much lower airspeeds as well as thermal rather well. With each I first dialed in what I felt was a correct tail incidence and CG. So obviously there are several things in play here. Overall wetted area, mass, span, aspect ratio, and airfoil? Many large scale ships use the Harald Quabeck series (2.5 to 3.0) due to their ability to utilize trailing edge camber and reflex. Not that others can't, just that these are what I often see on larger heavier ships. They fly faster at normal wing configurations, but can be slowed efficiently with the use of camber or thermal flaps. These ships all have "molded" wings (either sheeted Obeche pressed or GFK sandwich) lending to more accurate airfoils replication. JD Endless Mountain Models http://www.scalesoaring.com email: [EMAIL PROTECTED] > -----Original Message----- > From: Bill Swingle [mailto:[EMAIL PROTECTED] > Sent: Tuesday, November 30, 2004 7:01 PM > To: John Derstine; 'James V Bacus'; [EMAIL PROTECTED] > Subject: Size & Weight (was favorite topics) > > John has broached a good topic. There is some validity here. > > "Span Loading" No clue if this is an actual phrase but I think I see what > your alluding to. I think you mean "Bigger flys better." Which is > essentially true but with limitations. > > Why? Because RE#'s tend to go up. Speed tends to go up. Extra mass > smoothes > flight and tends to be easier to fly (less neurotic). Larger airfoils are > also often more carefully constructed. > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
