I ran a wing weight estimation using the equation Raymer provides in Simplified Aircraft Design for Homebuilders (p. 108) and got strange results: 282 lb--way too heavy for this little sub-1,300 lb plane (details below). Raymer also suggests a metal wing could weigh 1.1 to 2.0 times the area (exposed planform) which would result in ~140lb. I triple-checked my math, then checked his Aircraft Design: A Conceptual Approach--same equation provided (p. 460). Hmm, no typo in the equation. I then checked what Gudmundsson had to say in General Aviation Aircraft Design. He reproduced Raymer's equation but also supplied one from Nicolai. This equation provided a much more favorable estimate of 137 lb.
Anybody else get wacky results from these statistical methods? I didn't expect they'd be perfect; I'd be happy with +/- 20% but +/- 200%...? I would chalk this up to some mistake on my part but I did it manually and using Excel. If anyone cares to wade through it and point out what I'm missing here I'm all ears.
Anybody else get wacky results from these statistical methods? I didn't expect they'd be perfect; I'd be happy with +/- 20% but +/- 200%...? I would chalk this up to some mistake on my part but I did it manually and using Excel. If anyone cares to wade through it and point out what I'm missing here I'm all ears.