NAR HPR Recovery Systems & Deployment 3 — Questions and Answers
Question 1: Which type of pyrotechnic device is most commonly used to separate rocket sections for recovery deployment?
- Black powder charge in a sealed charge cup (Correct answer)
- Road flare
- Estes igniter in open air
- Thermite brick
Correct answer: Black powder charge in a sealed charge cup
A measured black powder charge in a sealed cup or bulkhead produces the controlled gas pressure needed to separate sections and deploy parachutes.
Question 2: What does 'apogee deployment' refer to in high-power rocketry recovery?
- Firing the motor at maximum altitude
- Releasing the drogue chute at or near the peak of the flight (Correct answer)
- Opening the main parachute at ground level
- Jettisoning the motor casing at burnout
Correct answer: Releasing the drogue chute at or near the peak of the flight
Apogee deployment releases the drogue parachute at peak altitude, stabilizing the rocket for the remainder of descent before main chute deployment.
Question 3: A recovery harness rated for 1000 lbs is used on a 20 lb rocket. Which scenario could still cause harness failure?
- Slow parachute opening with gradual load
- Shock load from sudden snatch force exceeding static rating (Correct answer)
- Correct packing with a deployment bag
- Flying in calm wind conditions
Correct answer: Shock load from sudden snatch force exceeding static rating
Snatch force — the sudden jerk when a parachute fully inflates — can create dynamic loads far exceeding the static weight, potentially overloading rated hardware.
Question 4: What is the primary advantage of using a deployment bag (D-bag) for main parachute packing?
- It eliminates the need for a drogue chute
- It controls staged canopy inflation to reduce snatch force (Correct answer)
- It allows the parachute to deploy at apogee safely
- It increases descent rate for faster recovery
Correct answer: It controls staged canopy inflation to reduce snatch force
A deployment bag retains the canopy until the suspension lines are fully stretched, staging inflation and dramatically reducing peak snatch force.
Question 5: Under NAR HPR rules, a rocketeer's recovery system must return the rocket to the ground at a speed considered safe. What is the commonly accepted maximum descent rate for the main canopy phase?
- Under 5 mph
- Under 20 mph (Correct answer)
- Under 50 mph
- There is no specified limit
Correct answer: Under 20 mph
NAR guidelines target landing speeds under roughly 20 mph to prevent damage to the rocket and injury hazards to spectators.
Question 6: Which of the following best describes a 'tender descender' or similar line cutter device in a recovery system?
- A pyrotechnic that severs the main chute riser at a set altitude
- A device that cuts the drogue loose to allow main chute deployment at a preset altitude (Correct answer)
- A GPS tracker mounted on the harness
- A reefing ring that slows canopy opening
Correct answer: A device that cuts the drogue loose to allow main chute deployment at a preset altitude
A tender descender or line cutter severs the drogue attachment line at a set altitude, freeing the main parachute to deploy without a separate ejection charge.
Question 7: What is the correct procedure for testing black powder ejection charges before flight?
- Fire them in the assembled rocket at the range
- Ground test with the rocket sections mated and parachute loaded to verify separation pressure (Correct answer)
- Test with an empty tube and no parachute
- Never test — rely on manufacturer calculations
Correct answer: Ground test with the rocket sections mated and parachute loaded to verify separation pressure
Ground testing with sections mated and parachute packed verifies the charge produces enough pressure to separate the sections under real flight conditions.
NAR HPR Recovery Systems & Deployment 3
Which type of pyrotechnic device is most commonly used to separate rocket sections for recovery deployment?