Wing Design 4: Now, Where Were We?

Well, it’s been over a year since my last post and not a week minute has gone by without me thinking about this blog. I’m trying to punch holes in the cavernous void of ignorance, and leaving this blog unfinished simply will not do. Thus: onward! For glory! And knowledge! Also to crush the lingering sense of guilt due to unfinished business

Good news: I made a spreadsheet to tweak the design, and our wing can now carry the entire model’s predicted 0.74kg load. Yay!

Bad news: the wing is bigger, heavier, and now has a 3 degree angle of incidence. And our minimum flying speed just shot up. Boo!

Remember how the wing was originally going to look? 1.25m wingspan, 0.21m chord length, and with a target cruise speed of 6m/s? It’s now standing at 1.5m span (up 20%), 0.27m chord (up 30%), and has a target cruise speed of 8.2m/s (up 37%). Plus the 3 degree angle of incidence means we have less breathing room with pitch angles.

It might not be pretty, but it is necessary. Now the wing can lift a shade under 0.77kg. Throw in 3.333% loss in lift due to 3 degrees of dihedral (see the Dihedral bit in Wing Design: Part 3), and we have just over 0.74kg. Neat!

Which leaves us (minus the tips, which we’ll CAD in later) with this:

Our new wing. Wing tips are super awkward to model in XFLR5, so I’ve left them out. They’ll only have small effects on lift and stability, so not modelling them shouldn’t skew results badly.

 

Now for the part where I try to remember where I was going with this last year… ah. I have some re-reading to do.

 

---

 

Holy crap, I wrote all that? What… oh hey, we’ve actually got a wing design mostly sorted now. We just need to sort the flappy bits out. In fact, we’ll do that in the next post, because I am lazy. In the meantime, rest assured that I intend to continue this project to its completion. Who knows – I might even build the thing eventually! I’ll be shifting my approach so posts will be lighter but more frequent. Hopefully this will make posts less of a faff to write and less of a pain to actually read.

Right then. Until next time!