L2 Certification
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In order to understand high power rocketry enough to launch and successfully recover an L1 rocket, please make sure you have already read the L1 Certification page, and all related pages.
Level 2 certification allows fliers to fly high powered rockets with a total installed motor impulse of up to 5,120 newton-seconds. The recovery system for the rocket can be either motor ejection or duel deploy, however in general SSI Rockets members use a duel deploy to gain experience with altimeters while getting an L2 cert.
Requirements
See: TRA L2 certification info and NAR L2 certification info.
Written Test
The written examination for level 2 shall be passed prior to a level 2 certification flight.
Airframe
The rocket must be built by the flyer. The rocket shall have a display on the exterior identifying the calculated center of pressure. The rocket must be of “conventional rocket design”. “Odd Rockets” including flying pyramids, saucers and flying spools will not be allowed for any certification flight. The rocket may be either a kit or scratch built. Scratch built rockets may contain commercially built components.
Recovery
Standard parachute recovery is required. Non-parachute recovery methods (e.g. tumble, helicopter, gliding, etc) are not permitted for certification flights. If the rocket is using dual deployment, the first recovery event may be via drogue-less or streamer as long as the main or second event uses a standard parachute. Note: NAR does not list this requirement on their site, as they say "the member must use an active recovery system for their certification attempt, which usually includes parachute recovery" More about what active recovery means can be found here: NAR Definition of Active Recovery
Motor
The certification flight must be with a single certified J, K, or L motor (tested total impulse between 640.01 and 5120.00 n-secs). Staged and/or Clustered rockets may not be used for certification flights. The flyer shall be observed by the certifying member or their designated representative during the assembly (if a reload or hybrid) and preparation of the motor.
Electronics
Electronics are not required for level 2 certification flights. However, prior to attempting level 3 certification, the flyer shall successfully fly at least one rocket in the Level 2 impulse range using an electronic device as the primary means of recovery system deployment. This may be their level 2 certification flight or any subsequent flight.
Certification Flight
Level 2 Certification flight may take place at any insured launch. The certifying member (i.e. Prefect, TRA Director, or TAP Member) must be present and witness the certification flight. The certifying member must witness the rocket ascend in a stable manner and descend in stabilized manner controlled by the recovery system.
Post-Flight Inspection
The rocket must be presented to the certifying member for inspection. If the rocket cannot be recovered, but can be inspected in place (power lines, tree, etc...) this is acceptable. The certifying member shall inspect the rocket for excessive damage. Excessive damage shall be considered damage to the point that if the flyer were handed another motor, the rocket could not be put on the pad and flown again safely. Damage caused by wind dragging will not cause a disqualification.
Non-certification
Any of the following will result in non-certification for a certification flight:
Motor Cato Excessive Damage No recovery system deployment or tangled recovery system deployment Rocket drifting outside the specified launch range Components coming down not attached to the recovery system. Any other violation of TRA safety code associated with this particular flight. Any other legitimate reason the certifying member deems merits non-certification.
Duel Deployment
Dual Deployment, in general terms, means that two parachutes are ejected out of the rocket. The first parachute is a small one (often called a drogue chute), and is ejected at apogee. As the rocket descents, a secondary ejection charge is fired (typically between 500 and 700 feet) and a full size parachute is ejected, bringing the rocket down to a much lower descent rate that will not damage the rocket upon hitting the ground. The advantage is that the rocket falls fast for most of the descent and doesn't drift very far. It is also called "close-to-the-pad" or "close-proximity" recovery.
The Key to the system is the electronics, specifically, the altimeter (See: Altimeters) The Altimeter senses the altitude of the rocket and then sets off two different ejection charges at the appropriate times. As the rocket takes off, the altimeter is constantly calculating the altitude of the rocket. When it senses apogee, the altimeter sends a pulse of electricity to one of the igniters. This igniter sets off a small charge of black powder, which pressurizes one section of the rocket (usually the back end) and spits out the drogue chute.
While the drogue chute brings down the rocket quickly, the altimeter is still measuring the altitude of the rocket. When it descends to a pre-programmed height (which you control), it then triggers a second charge. This charge pushes out the main parachute (usually stored in the front part of the rocket). Since the rocket is now closer to the ground, the wind doesn't have the time to push it downrange too far. So it lands slowly, but much closer to the launch pad.
In most SSI L2 cert rockets, the avionics bay is riveted to the bottom half of the upper airframe. It acts as the coupler between the upper and lower airframes, with a either a friction fit or shear pins. The rocket separates in two (but is still connected by a shock cord) at apogee, deploying the drogue. The main chute is deployed from the top of the upper airframe, pushing out the nosecone with it, similar to an L1 ejection.
See also: Apogee Rockets dual deploy page