Model rocket recovery methods
Model and high-power rockets are designed to be safely recovered and flown repeatedly. The most usual recovery techniques are parachute and streamer. The parachute is most commonly 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.
Featherweight recovery
The most basic approach, which is only appropriate for the tiniest of rockets, is to allow the rocket flutter back to earth after ejecting the motor. This is slightly not the same thing as tumble recovery, which relies on some system to destabilize the rocket to prevent it from entering a ballistic trajectory on its way back to earth.
Tumble recovery
Another simple approach appropriate for small rockets―or rockets with a huge cross-sectional area―is to have the rocket tumble back to earth. 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.
Nose-blow recovery
Another very simple recovery technique, used in very early models in the 1950s and occasionally in modern examples, is nose-blow recovery. This is where the ejection charge of the motor ejects the nose cone of the rocket (most commonly attached by a shock cord made of rubber, Kevlar string or another type of cord) from the body tube, destroying the rocket's aerodynamic profile, causing highly-increased drag, and reducing the rocket's airspeed to a safe rate for landing. Nose-blow recovery is commonly only suitable for very light rockets.
A typical problem with parachute recovery.Parachute/Streamer
The approach used most usually in small model rockets, but can be used with huger rocket models given the size of the parachute greatly increases with the size of the rocket. It uses the ejection charge of the motor to deploy, or push out, the parachute or streamer. Generally, a ball or mass of fireproof paper or material is inserted into the body prior to the parachute or streamer. 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 in a smooth, controlled and gentle landing.
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.
Some rockets (generally long thin rockets) are the proper portions to safely glide to Earth tail-first. These are termed 'backsliders'.
Helicopter recovery
The ejection charge, through one of multiple techniques, deploys helicopter-style blades and the rocket autorotates back to earth. The helicopter recovery most commonly 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 they provide enough drag to susually the landing. Very usually the blades will break.