dirk8037 wrote: ↑Mon Apr 25, 2022 9:19 pm
Hi Fluidity,
How do you approach the wing design?
Do you take a foil and add the tubercles so they are bigger/thicker than then main foil
or do you rather carve out the in between the tubercles so you have a thinner edge than normal.
Cheers Dirk
Hi Dirk,
I think I do it differently than most other people. There are a couple of good programs out, finfoil.io and winghopper for example but I do my design with openscad which is a programmer's 3D design tool. So I create my wing surfaces from conditional equasions. There are a lot of sine waves in my wings. The tubercles for instance are currently a simple application of a repeating sine wave to the chord with no adjustment for thickness, it follows the chord proportionally. The sweep, the taper, linear and sine functions.The wingtips, a power from a set % of span function. The mid chord thickness for fuselage, a sine wave applied with adjustable limits, but only from a selected distance from the centre of the wing and inwards. There are aircraft wing modelling programs out in which you can likely do very similar things as with finfoil.io and winghopper but I've not investigated. I like that I have complete control of the algorithms so ultimately I have no limits, so long as I can conceptualise a requirement, I can design it. Today I spotted another programmer's design tool, cadquery. I'll download it and see how amenable it is to my sort of designing. Openscad doesn't do 3D fileting, cadquery is supposed to work with a more advanced rendering engine.
I believe the key with tubercles is to break up wing partial stalls to provide a chance for recovery before a stall spreads to the whole wing. Most useful in turbulent and aerated waters which I'm sure humpback whales encounter regularly.
My latest wing doesn't have them but that's for 3 reasons: 1. ease of manufacture. 2. uniform structural loading(1.33 meter span, short chord). 3. I'm designing it purely for pumping efficiency.
Graham