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Model Rocket Recovery
Model and high-power model rockets are designed to be safely recovered and flown repeatedly. To accomplish this, the model rocket recovery system is designed to bring the rocket back down to earth gently so the rocket can be recovered for future flights. The most common model rocket recovery methods are parachute recovery and streamer recovery. The parachute is usually blown out when the engine's recoil creates pressure and pops off the nose cone. The parachute is attached to the nose cone, making it pull the parachute out, and make a soft landing.
Tumble recovery
A simple rocket recovery method appropriate for small rockets—or rockets with a large cross-sectional area—is to have the rocket tumble back to earth. Sometimes tumble recovery is called by other names, like featherweight recovery. Any rocket which will enter a stable, ballistic trajectory as it falls is not safe to use with tumble recovery. To prevent this, some such rockets use the ejection charge to slide the engine to the rear of the rocket, moving the center of mass behind the center of pressure and thus making the rocket unstable.
Streamer recovery
Recovery by Streamer recovery for model rockets is used most often in small rockets for rocket recovery. It uses the ejection charge of the motor to deploy, or push out, the streamer. Typically, a ball or mass of fireproof paper or material is inserted into the body before the streamer. This allows the ejection charge from the model rocket engine to propel the fire-proof material, streamer, and nose cone without damaging the recovery equipment. The streamer provides enough air resistance, slowing the rate of the rocket's descent, to allow the rocket to land gently.
Parachute recovery
A parachute is used for model rocket recovery most often in small to medium size model rockets, but can be used with larger rocket models given the size of the parachute greatly increases with the size of the rocket. It uses the ejection charge of the model rocket engine to deploy, or push out, the parachute. Typically, a ball or mass of fireproof paper or material is inserted into the body before the parachute. This allows the ejection charge to propel the fire-proof material, parachute, and nose cone without damaging the recovery equipment. Air resistance slows the rocket's fall, ending (hopefully) in a smooth, controlled and gentle landing. Care must be taken to compensate for wind, as many parachute recovered rockets descend rather slowly, allowing any slight wind to carry the model rocket far away from the intended landing zone.
Glide recovery
In glide recovery, the ejection charge either deploys an airfoil (wing) or separates a glider from the motor. If properly trimmed, the rocket/glider will enter a spiral glide and return safely. In some cases, radio-controlled rocket gliders are flown back to the earth by a pilot in much the way as R/C model airplanes are flown.
Helicopter recovery
The ejection charge, through one of several methods, deploys helicopter-style blades and the rocket autorotates back to earth. The helicopter recovery usually happens when the engine's recoil creates pressure, making the nose cone pop out. There are rubber bands connected to the nosecone and three or more blades. The rubber bands pull the blades out, and let them 'copter down.