I need a 24" chute for my custom built rocket, but i don't wanna buy one and
waste the money on shipping...can i just cut a 24 inch circle out of a white
cotton sheet and put 6 equally spaced holes around it's circumference and
put some shroud lines in...or should i ust use a garbage bag for the
material... any tips would be great!
-Vishal
For a questes sized model rocket plastic trash bag material is fine. THe
other good alternative is the colored mylar sheet material sold in party
stores. A 18x30" piece is good for an 18" and a 12", or two 15" chutes.
For heavier stuff, say from an Executioner up to a LOC IV, I've had good
results using a nylon dress liner material called Sunline or something like
that. A 1 yard piece (36" by IIRC 60") is about $3.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD"
>>> To reply, remove the TRABoD!
Yes, it is that easy. Here's a link to a picture of my Candy MIRV recovery.
formatting link
I have 10-12 2" sphere payloads with 18" chutes all of which are ejected
at the top. I made a hexagonal pattern out of cardboard, laid it on top
of ripstop nylon (sometimes available for $1.00 a yard at WalMart), and
cut around the template with a soldering iron. The holes were also
punched with a soldering iron. The shroud lines are braided mason's
line. Most hardware stores have it, but be sure to ask for braided line,
not twisted line. Twisted line unravels and doesn't work well. (Note
that the soldering iron will only work with nylon or other synthetics;
if you want to use cotton, use a knife to cut around the pattern.)
Making ellipsoidal 'chutes is more complicated, and requires a lot of
sewing. Still, it's doable with a standard sewing machine (sergers are
better, though.) Here's a link to pictures of a 5' and 6' .707 ellipsoid
I made. (Sorry, no ground shots.)
formatting link
The hard part is calculating the gore pattern; I wrote a program to do
it for me, and it can calulate any number of gores, for any shape of
ellipsoid. However, there are some simplified methods on the Internet.
Richard Nakka has one, or do a google search for 'hemispherical
parachute' and you'll find lots of links to sites that will do the
calculations for you. Some of these are kite sites, but hey, a parachute
is just a specialized kite. ;)
Hmm, observant readers will notice that there are too many lines on this
'chute for a hex; it's actually octoganal. How could I have forgotten that?
Mark E. Hamilton
NAR #48641-SR
ARSA #218
I've never seen any one use a cotton sheet. I bet it would piss off your
mother too!
The large plastic bags used at places like Target and Hobby Lobby would
probably make fine parachutes.
I happen to prefer the aluminized mylar sold in party stores, or Sunliner
from the fabric stores. And I prefer 8 shroud lines since it's easier to cut
via oragami-like folding, then one cut with the paper cutter.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD"
>>> To reply, remove the TRABoD!
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