A non-flammable filler material placed in a model rocket airframe to protect the parachute or streamer from the hot ejection gases of the ejection charge. They can also act as a piston.
Recovery wadding has been around since the birth of Model Rocketry. Parachutes needed protection from the ejection charges of the rocket motors. In the original patent drawings from Orville Carlisle we see a paper wrap used to protect the chute. The paper wrap can be seen here labeled as #50
In the very first Estes catalog the following quote can be found
“RECOVERY SYSTEM WRAPPERS AND PROTECTORS: Since many missiles designs do not require wrappers for parachutes and streamers, they are not included herein. They are easy to make by cutting out a piece of typing or similar quality paper adequate to completely cover on all sides and ends the plastic parachute or streamer. Completely wrap the plastic in the wrapper and insert in the missile before attaching the nose cone.”
The first mention of Wadding for sale is in the 1964 Estes catalog. It is listed as the RP-1 Pack of Flameproof Recovery Wadding.
The Centuri 65 catalog shows chute protector wadding as a product.
Carlisle sued Vern Estes over including a “parachute wrapper” with certain rocket kits in the 65 timeframe. Estes was printing the wrapper on the motor instruction sheets. Carlisle lost the suit.
A good wadding must be both flameproof and biodegradable.
Types of common wadding:
Flameproof Tissue wadding: from Estes since 1963-64. This is the common toilet paper like tissue. The original flameproof tissue was made from toilet paper. Vern once said he wondered what all those truck drivers thought when they pulled up to Estes Industries with truckloads of toilet paper. I’m sure there were a great many jokes about that.
Quest tissue wadding – thinner than Estes, more like tissue paper
Cellulose fiber– commonly known as Dog Barf. Probably the most widely used wadding. Used in both LPR and HPR. Sold as Cellulose insulation and readily available at your local hardware store. A $7 bail will last you a lifetime of rocketry.Cellulose is composed of 75-85% recycled paper fiber, usually post-consumer waste newsprint. The other 15% is a fire retardant such as boric acid or ammonium sulphate. Cellulose has the highest recycled content of any insulation available.
Common alternatives to Wadding:
Plugs – the is the most common wadding replacement in FAI competition style rockets. Foam plugs are made from the pink/blue closed cell construction foam. This can be done by making a cutter from a piece of body tube of the size plug you need. Take the tube piece and CA around the circumference of one end. This will be the cutting side. Take the tube and put it on top of the foam and slowly spin the tube while applying pressure. This will cut the plug from the foam. Plugs act like many piston and effectively help “push” out the chute in competition models.
Pistons– Pistons are like plugs but usually created with a solid sliding bulkhead that is connected to motor mount tube by means of a shock cord/nylon tubing etc. Pistons effectively eject the parachute.
Baffles– Baffles are means of taming the hot ejections gases of the ejection charge. They can be made of steel wool, a mesh material or a series of mis-aligned tubes. The devices trap the hot gases while allowing the ejection pressure to continue throught the containment. Click the links to see common LPR baffle kits from Semroc and Fliskits