How good is this stuff and does it really work as good as they say it does?
Doesn't The Home Depot sell it? Isn't it just fiber glass insulation? I would imagine you can get a pretty big bag for cheap?
No, it MOST CERTAINLY IS NOT fiberglass insulation!!! NEVER use fiberglass insulation as recovery wadding in a rocket-- the stuff drifts down free of the rocket and wherever it lands, unless you specifically hunt it down and pick it up, assuming you can find it, it will be there FOREVER. It doesn't rot or break down from the elements... even buried it will remain intact. Pillow ticking or mattress stuffing or other such "non-flammable" artificial fiber materials are the same way. Anyone flying on *my* land using that stuff would be disinvited from ever returning, period, and the club could be looking for a new flying field!
"Dog barf" is actually SHREDDED NEWSPAPER (recycled paper waste) broken down into fine bits and then treated with a boric-acid fire retardant material (same stuff basically used to make commercial "Estes" type recovery wadding. Law requires that this insulation material, which is "blown in" to the wall cavities of old homes using a special blower device after cutting a hole in the upper part of the wall between studs with a hole saw, must be treated with fire retardants so it doesn't pose a fire hazard. Note that "flame resistant" materials such as this WILL smolder and char when exposed to a high-temperature ignition source (open flame, etc) but will self-extinguish when the ignition source is removed... they won't support combustion or continue to burn. Essentially, think of it as shredded up Estes wadding.
The stuff comes in big blocks or "bales" wrapped in plastic, and is sold at most big-box home improvement indoor lumberyard type places, as well as traditional lumberyards and building supplies. A damaged bale can usually be had at half price or less-- I got one that a (presumably) dumb kid had speared with the forklift and torn the bag for less than $4 once... A bale of the stuff will last the average rocketeer YEARS if not DECADES... practically a lifetime.
To use it, you usually want to fill a big freezer bag with the stuff to carry it to the launch-- that's probably all you need depending on the size of your rockets and how many flights you expect to get in that day. To use it, I usually just scoop up a handful of the stuff and dump it into the open end of the body tube until it's at least 2-3 times the body diameter deep in the tube... Occasionally you'll have to poke your finger down the tube a bit to get it to drop down, no biggie... You can push it down a little bit, but don't PACK it in TIGHT into the tube-- you want it to be somewhat loose-- loose enough to blow out of the tube when the ejection charge fires, dislodging the nosecone and ejecting the parachute or streamer...
When the ejection charge fires, the loose particles of the shredded paper will capture and trap any burning BP particles, which will cause the bits of paper to char, but they won't "ignite". The shredded paper will capture the hot gases from the ejection and the mass of the dog barf will be blown forward by the ejection charge gas blast, pushing out the parachute and nosecone, then they will usually fly in a thousand directions just like confetti, and gently waft down to the ground on the breeze. Unlike regular Estes "sheet wadding" which remains in a wadded up state like used Kleenex, the dog barf disperses over a large area and practically NOTHING of it is visible on the ground after landing, even when used in LARGE amounts in LARGE rockets... that's the beauty of it (although it deprives me from picking up a supply of used sheet wadding after a club launch on my fields and putting it in my own wadding bag to use myself for the next launch... and yes used wadding is perfectly fine to use again and again until it's too "holey" to be used much anymore-- I generally put the most badly burned stuff on bottom and new(er) sheet wadding on top, when I use sheet wadding-- dog barf can be hard to use in small diameter rockets) That's hardly a bad thing-- not having to clean up the field is pretty nice). Due to the smaller particle size (bits of paper instead of wads) the cellulose insulation (dog barf), like confetti, drops down through the grass to the soil surface, where natural dampness and fungi and bacteria rapidly start decomposing it back into the humus in the soil... even if it lands on top of the grass, rain and wind will easily wash or move the particles down under the grass to the soil surface where it will decompose. Sheet wadding "wads", being larger, will of course take a LOT longer to be washed down or blown down to the soil surface, and be decomposed, which means it's basically a litter issue until it decomposes or is removed. Neither of course hurts the environment, unlike fiberglass insulation or pillow ticking type materials when used for wadding-- in fact, the borate fireproofing solution used to flameproof the dog barf or sheet wadding is water soluble and will wash into the soil, where it's a valuable micronutrient, as most soils in the United States are actually deficient in boron (at least for crops).
Some folks like a little additional 'insurance' using dog barf, and push a sheet of wadding down the rocket first as a "cup" to hold the loose dog barf... if you use 2-3 body diameters long layer of dog barf though, it should be completely unnecessary... some folks will also wrap the parachute in a sheet of wadding, in lieu of the "sheet wadding cup" method (or sometimes as an adjunct to it!) Largely unnecessary...
We've had a number of discussions on reusable and alternative materials and methods for recovery wadding replacement here on the forum-- from leaf lettuce or cabbage or green grass from the field itself, to reusable pistons or plugs, baffles, even Teflon pom-poms and flameproof treated pieces of cloth...
Later and hope this helps! OL JR
