Here is something from Tom Pastrick thta I got from the NARTARC forum...
A little known fact: 2- 18' chutes do not equal 1- 36" chute. It may not sound
right until you see them in action. The air spilling out around the chutes
causes a slight pressure increase between the chutes. Mom Nature doesn't like
this so she moves them apart until the pressure equalizes. This causes the
chutes to angle apart. The angle apart may sometimes be more than 30 degrees,
and depends on the size of the chutes.
Packing the chutes is no different than packing one. If you use the Estes style,
you have the shroud lines wrapped around the folded chute. If you fold
carefully, the 2 chutes should fit side by side inside the rocket. It is best to
have a perforated bulkhead below the chutes so that the 'g' acceleration doesn't
cause them to slide all the way down the tube. The perforations must allow the
ejection gases to push the chutes out. Each chute should have its own attachment
point on the opposite side of the tube. Chutes packed this way seldom tangle
unless the the shroud lengths are not uniform on each chute.
Two identical chutes is probably the best way to go. I have never tried two
chutes of different materials or two different sizes.
Two of the school Teams that I Mentor, have made their first chutes out of
plastic garbage bags. They made them with the shroud lines going over the top of
the chute. This makes a much stronger chute. They also used twice as many shroud
lines as an Estes chute.
Tom Pastrick
