NAR HPR Recovery Systems & Deployment 2 — Questions and Answers
Question 1: Which altimeter feature is most critical for ensuring dual-deployment reliability in high-power rocketry?
- Single-event firing output
- Redundant independent pyro channels (Correct answer)
- Bluetooth telemetry
- GPS position logging
Correct answer: Redundant independent pyro channels
Redundant independent pyro channels allow separate drogue and main chute events to fire independently, preventing a single point of failure.
Question 2: A barometric altimeter fails to fire the apogee charge. What is the most likely cause in a properly wired system?
- Parachute was packed too tightly
- Battery voltage dropped below altimeter threshold (Correct answer)
- Motor ejection charge fired first
- Nosecone was not vented
Correct answer: Battery voltage dropped below altimeter threshold
Most altimeters have a minimum voltage requirement; a weak or depleted battery is the most common cause of failed pyro channel firing.
Question 3: What is the purpose of a 'shear pin' in a dual-deployment recovery system?
- To hold the nosecone until ejection pressure shears it away (Correct answer)
- To secure the altimeter in the avionics bay
- To prevent the motor from moving during flight
- To lock the main chute until ground impact
Correct answer: To hold the nosecone until ejection pressure shears it away
Shear pins hold the nosecone or payload section closed until sufficient ejection pressure breaks them, preventing premature deployment.
Question 4: When sizing a drogue parachute for a high-power rocket, the primary goal is to:
- Land the rocket as quickly as possible
- Slow the rocket to a safe speed for main deployment while limiting drift (Correct answer)
- Replace the need for a main parachute
- Ensure the rocket tumbles to dissipate energy
Correct answer: Slow the rocket to a safe speed for main deployment while limiting drift
The drogue slows the rocket from near-apogee speeds to a velocity safe for main chute deployment, while keeping descent fast enough to limit drift.
Question 5: NAR safety rules require that all recovery system wadding or baffles must be:
- Rated for at least 2000°F continuous exposure
- Flame-resistant and prevent hot gases from reaching the parachute (Correct answer)
- Made of fiberglass only
- Replaced after every flight regardless of condition
Correct answer: Flame-resistant and prevent hot gases from reaching the parachute
Wadding or baffles must be flame-resistant and protect the parachute from hot ejection gases to prevent melting or ignition.
Question 6: What effect does high altitude (lower air density) have on parachute descent rate compared to sea level?
- Descent rate is slower due to less drag
- Descent rate is faster due to less drag (Correct answer)
- Descent rate is unchanged
- Descent rate depends only on parachute diameter
Correct answer: Descent rate is faster due to less drag
Lower air density at altitude reduces drag, resulting in a higher descent rate for the same parachute at altitude versus sea level.
Question 7: In dual-deployment, the main parachute is typically deployed at what altitude to minimize drift?
- At apogee
- At 500–1000 feet AGL (Correct answer)
- At 5000 feet AGL
- At motor burnout
Correct answer: At 500–1000 feet AGL
Deploying the main chute at 500–1000 feet AGL limits the time under a large, slow-descending canopy, reducing wind-driven drift.
NAR HPR Recovery Systems & Deployment 2
Which altimeter feature is most critical for ensuring dual-deployment reliability in high-power rocketry?