So we are now trying to build envelope coming with shape around something like this:
As you may see it is quite simple concept of joining two ellipsoids with interlaced cylinder reaching maximum diameter of 2m. So the front part is traditional ellipsoid with w=2.5 (A), followed by a central cylinder w=1 (B), closed by another ellipsoid of w=3 (C). The plan is to buckle in the ellipsoid A so it will all end up being ~6m long.
The idea is to do a 5:1 scaled model and send it to Windreiter guys for review and a quote. To be able to do so, we actually need to draw parts which we can glue together next. Here we’ll be using classical pie/rugby-ball seems method, hoping that it will all work out when inflated.
Having a radius of 1m, maximum circumference comes to 6.28.
Divided by 6 to get height of each part we are getting h=1m. Scaling down 5:1 this is 20cm + 2cm for seem we have the first parameter 22cm.
With the W – part A this is going to be half-ellipse of -> 52cm (scaled 2.5m/5 + 2cm for seems), part B is a simple cylinder of 20cm and part C is -> 62cm (scaled 3m/5 + 2cm for seems).
To get this transformed this onto a paper, I prepared myself a tiny Excell helper (with another help from here). Where X is calculated with =B$2*COS(RADIANS($A5)) and Y =B$1*SIN(RADIANS($A5)).
Of course we’ll use just a part of those ellipses getting:
Now let’s get practical!
6 thoughts on “Envelope Demo – preparations”
Sounds like the wrong approach. Why not a plain cylinder – vastly more volume, vastly less complicated, and since you’re not pushing through any air (rather – tunneling the air through it) a cyl would be more efficient as well, right?
Thanks Chris, well the aim of this exercise is to prepare “how to” for the Windreiter guys to get us a proper envelope. So while cylinder would probably do, I though that giving it bit more blimpy shape would be better. 🙂
FYI – That’s called the “sheet metal workspace” in Fusion360 – which also lets you do the overlapping seams, folds (which you can fold or unfold to work on in the software), and so forth and can output to a laser cutter when you’re ready to glue…
Yep! I saw something similar in Blender and it wasn’t good at all, but I assume that Fusion 360 will be much higher quality. Can’t wait to give it a go! 🙂
co zkusit kostku? 😁