Wing Work….
This week I haven’t had too much time to dedicate to working on the SF-1. I am still spending a lot of time attempting to understand structural design. Based on some YouTube videos from the Ultralight Aircraft Workshop and Stress Without Tears I working out some calculations through excel (I’ll attach an excel screenshot). I bumped up the weight to 1500lbs just in case my aircraft weights more than I originally intended. I can’t know the exact weight or really close to it until I continue further down the design process. Luckily, with Fusion 360 I can get the weight of every component provided the right material properties are selected for the component. I also bumped the max g load up from 3.8 to 6 just for some kind of safety margin. I personally don’t care for doing aerobatics, but eventually (and dreaming) if someone else were to build my design I would like that to be an option.
In Fusion 360 I designed the spar caps and spar web from the data I got in excel from the calculations. Something I am confused about is a tapered spar. Right now the sheer web decreases as you go outboard on the wing (mostly because the wing chord and thickness decreases along the span. This is something I’ll have to look into further as I calculated the shear and moment along the wingspan thanks to one of Ultralight Aircraft Workshop’s YouTube videos.
I ended up cutting and making some ribs with 1ft spacing. I have no backup or calculations to the spacing and thickness of the ribs. I used .032 for everything except the spar caps. This is just a place holder for now. Ideally the wing ribs will be milled from sheet metal. The tabs bent, holes drilled and then riveted to a L-bracket that attaches them to the spar. I am thinking a rear spar will be needed to provide more support for the ailerons, flaps, and back of the wing.
The ribs will be milled probably in two sections and connected to the spar and rear spar. The skin thickness is .032 as well. Again, no calculations done on anything except the main spar. So far the total weight of the wing is 65.5lbs. This is without rivets, flap, aileron, fuel tank, landing gear. I have no idea if that weight is too heavy or not. Originally in Xflr5 I used 175lb for the total wing inertia which is excluding fuel.
With the landing gear I WAS going to mess with it, but I decided to keep focusing on the wing instead. I did upload a YouTube video of the initial super rough design of the landing gear. It’s really just a concept. I am contemplating building a scale model of it. More to follow.
