Model Forum / General / Rockets / October 2004

They're available for, and popular in, larger rockets as well.
(Perhaps even more so - wadding is one of those model-rocket
things that doesn't "scale up" all that well.)

-dave w

I tried wadding instead of a nomex protector in a 7.5" diameter rocket
once.  The ejection gases basically got absorbed by the wadding and the
rocket didn't come apart.  Luckily, the rocket recovered okay because it
went into a flat spin and the main came out okay at 600 feet.

I had forgotten the nomex protector at home.  The nomex protector sort of
acts like a piston to push the rocket apart.  I won't be using wadding
again except on the little bitty stuff.

Brian Elfert

I've been trying numerous things to replace the one-time-use toilet paper
wadding, and have had some difficulties.

soft cloth nomex will burn thru if placed in close proximity of ejection
charges (fat boy with 36" chute)
military nomex (another soft cloth) metls and burns also
the hard canvas nomex I've used sparingly on my LOC IV seems to work well. I
wish i could find this in bulk.
Airbags tend to work well, but will melt/burn and shrink (still testing)
most people will tell you pistons stick in differing tempatures, which makes
me think that someone should come up with a soft piston. take some hard
canvas nomex, willit with (something) to make it like a pillow the size of
your body tube. shouldn't stick, should block hot ejection gasses, and
hopefully get your shute out like it should.

only problems I see is that it would take up space in your rocket, but come
to think of it, probably much less than wadding does.

I'm baffled by all this discussion of wadding :-)

    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"
        >>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf
   www.encompasserve.org/~kaplow_r/    www.nira-rocketry.org    www.nar.org

    26-October, 2001: A day that will live in infamy
    Support Freedom: http://www.indefenseoffreedom.org/

    Voting for "the lesser of two evils" is still voting for evil.

I use flame shields from Sphereachutes in my HPR birds, and they hold up
really well.  In my 3" Thor, they sit up against the ejection charge - no
burn thru, no melting.

Hint for cheapskates: buy a fiberglass ironing board cover (not the
cheaper coated cotton)for about $18. Peel off the polyester flocking
from the back and cut into parachute protectors to suit. Yields 6 to
12 protectors depending on size. Hem the edges if you're a neatnik,
otherwise use as is. I've used them many times without burnthrough.
Not quite supple as nomex for packing in small tubes, but more
durable. My nomex protectors eventually look moth eaten.

PEN

According to chris m  <gn15101@somenewsserver.com>:

In larger diameter rockets, the risk with wadding is that you may
have a narrow "blowthru", and if the chute isn't plugging the
tube, the chute might not get chucked out with sufficient force
to avoid hangup.  As long as the BT separates, you _should_
have enough yank to get the chute the rest of the way out, but
sometimes, maybe not.

I used wadding in my 6" (very heavy J) rocket, but I had a tethered
disk of plywood (somewhat smaller diameter than the BT) under the wadding
to make sure that it gave the chute a good shove.

I'm not fond of pistons.  Way too finicky.  I think we have
to remove the piston on our IO to fly it again, because we'd
have to sand off most of the piston to fit in the quantum BT with
the sorts of weather we deal with.

In most cases, the nomex/chute "blob" acts as your piston, and
is nowhere near as finicky as real pistons.  Fewer things
to go wrong.

As for scorch, we had just had a aerotech F20 (in an almost
minimum diameter) blowthru the top closure (thing let go about
half way thru the burn), and the nomex sheet is hardly marked
at all despite being in an AP blowtorch.

The BT on the bottom end got thoroughly scorched.  The
nomex, chute and shock cord (except the bottom few inches)
unscorched.  The chute shredded...