Need Maths help to make a parachute!

[KatyMac]

I have 6.35 m by 1m

I am lazy

I want to make the largest parachute like fabric with as little sewing as possible

It wont be a circle it'll be a hexa/deca/poly-gon

So on the most basic level if I use 1m by 1m I can make a lopsided 12 sided shape just by cutting it like triangle sandwiches

But is there a more elegant solution

I think you are right, cutting 1m squares diagonally, then stitching the 1m sides together, will produce something a bit bowl shaped. My maths isn't up to fitting 2 dimensional shapes onto curved surfaces any more (if it ever was). Can you make some 10cm paper squares, cut them diagonally then a bit of nifty work with a stapler or sellotape will give you and idea of what the finished product will be like. Or with a lot more sewing, you could use smaller equilateral triangles and make part of a geodesic polyhedron. A polygon with 12 sides is a dodecagon, a regular dodecahedron is a solid with 12 faces all of which are regular pentagons.

That's umm very advanced maths and my brain gave up! I'll read it againvtomorrow

Paper may be the way to go!

Rethinking, that doesn't work. Put simply, if a right angle triangle has 1m sides the other side is about 1.41m (pythagoras), a circle with a circumference of 12x1.41=16.9 has a radius of 2.7m which is much bigger than 1m. So a circle radius 1m has a circumference of 6.3m, if you want some sort of dish shape you need the circumference to be less than 6.3m say 5m, so your triangles need to be isosceles, with sides 1m,1m and 0.4m. It may be possible to cut your cloth to make bigger triangles in the same proportion. This is all a bit approximate because I've assumed the dodecahedron is a circle, the more triangles you make the better, as long as the circumference of the polygon is less than 2piradius. That's cured my insomnia for tonight anyway.

i really need some sleep. The isosceles triangles, stitched together, will produce a 12 sided cone with a point, which may be ok. My alternative, cut about 20cm off the pointed end of the triangle (or fold and pin it out of the way, the triangle is now a trapezium, stitched together they produce a truncated cone, so cut a circle of cloth, my estimate about 33cm diameter,and stitch that to cover the missing part of the cone. If you cut 30cm off each triangle the disc of cloth needs to be about 50cm diameter- I think that would be a more parachute type shape.

Do you want your parachute flat or domed? Is this for kids to play parachute games or something else?

Sorry my brain imploded! I think im following

It's for games - im fairly sure making a square and cutting a circle wont work for floatyness

The triangles do need to be isosceles I think

Do I cut them running down the length of the piece nesting them backwards and forwards? Not triangles but trapeze? (I lose half a trapeze at the start and finish?)

Ok it looks more like a lampshade, but you can see the principle, it would work better with cloth I'm sure. That was with a scaled equivalent of 30cm cut off the point, Original triangles 1m,1m, 40cm. The circular lid is about 55cm diameter. No idea how you lay it out, possibly pointing up/down alternately,

That's amazing, im sorry you had a bad night!

I'll play a bit more with measurements, I think, but trapeze are the way to go!

Not a job for today, that is a wedding skirt and a lot easier!

Version 3, looks a bit more like a parachute. The dimensions shown use all most all your material. The trapeziums are 100cm high, the short sides are 66cm and 14cm, the piece for the lid needs to be about 60cm diameter. It should lay out on the material alternate up and down. leaving a bit at the end for the lid. The whole process has proved that Pythagoras, geometry and similar triangles have a use, then add in a bit of tech drawing.

Im trying to remember my old one - i think it was flatter

I can't believe your skills thanks so much i have a much better idea of what to do

If you want it flatter you need to increase the bottom of the trapeziums or reduce the top. Obviously you still need to fit into the material available, so that may mean reducing the height of the trapezium. Thinking about real parachutes, they do tend to be not as flat, more like version 1, or maybe I've seem to many fast jets landing on short runways. It was a bit of fun to do, the model makes it much easier to understand what is happening once I'd realised why the original solution didn't work.

for parachute games, you want a big flat area, not a dome. I got a cheap double sheet, painted a pattern on and it worked fine.

Maybe they should use this piece as it is for ripples/waves & i should buy a sheet for the parachute?

What type of fabric is it? Does it need hemming to stop it fraying?

I would be tempted to cut it in half and the reattach so it is 2m wide and 3m long. Much more useable to play with.

Then add some webbing around the edge to make it look more finished /not fray (bend it in half to cover the edge and zigzag stitch). If you want to be fancy you could then add some webbing loops to make handles.

eta webbing link

ChatGPT offers this umbrella like shape. (Image uploading)

Arghh the edit didn’t work.

here is a link to webbing Amazon link cotton is much easier to see than polypropylene.

The umbrella was my original idea but im leaning towards the rectangle with loops to hold

I have plenty of webbing/tape

Sorry @Somersetbaker - I mentioned the laziness at the beginning 😥