FORUM: Level-3

“Level-3” (L3) is the most advanced certification level that an amateur rocketeer can achieve from the Tripoli Rocketry Association (TRA:, or from the National Association of Rocketry (NAR: Only those rocketeers possessing L3 certification are authorized to fly the largest classes of motors.

Rocket motors are broadly categorized by the total energy produced ( From least to most powerful, the rocket motor categories, and their motor designations are:

• Low-Power or “Model” (A, B, C, and D motors);
• Mid-Power (E, F, and most G motors);
• High-Power, Level-1 (some G motors, and H and I motors);
• High-Power, Level-2 (J, K, and L motors); and
• High-Power, Level-3 (M and larger motors).

The alphabetical designation (A, B, C, etc.) of a motor indicates its total energy. Rocket motors in category “A” produce the least total energy. The total energy produced by a rocket motor doubles with each alphabetical designation.

For example:

• a B motor is twice as powerful as an A motor;

• a C motor is twice as powerful as a B motor, and a C motor is 2 x 2 = 4 times more powerful than an A motor;

• a D motor is twice as powerful as a C motor, 4 times more powerful than a B motor, 8 times more powerful than an A motor; and so on.

Legally (punitive and insurance aspects), in order to fly rockets on Level-1 (L1) motors the flier must be L1 certified. I was certified L1 by TRA.

In TRA, after an L1 candidate has constructed a presumably L1-capable rocket, L1 certification first requires passing a two-part multiple-choice exam evaluating high-power rocketry technical (theory, methods) and regulatory (statutes, insurance) knowledge. This test is taken at the rocket field, and it must be passed for the L1 certification process to continue.

The candidate next presents the L1 rocket to the range safety officer (RSO) for safety evaluation. Completing this station the candidate advances to the launch pad manager who assigns the rocket to a specific launch pad.

At the pad a launch pad official assists the candidate in loading the rocket on the launch rail, and setting the preferred orientation of the launch rail for flight. The candidate then turns on electronics which control drogue and main parachute deployment and confirms they are performing nominally; inserts an initiator into the motor nozzle; attaches launch system leads to the initiator; and assesses electrical continuity. The rocket is now ready for flight and the candidate retreats to the flight line.

The launch control officer then takes control: the first rocket in the rotation is described; the field and sky are checked to make sure it is safe to fly; and the rocket is counted down and launched. Once nominal status of the rocket under parachute is established, the next rocket launch waiting in the que is initiated.

The rocket must be recovered by the candidate and returned to a Tripoli Advisory Panel (TAP) rocketeer at the launch, who will inspect for damage.

This L1 certification procedure assesses if the candidate demonstrates the minimum quintessential rocketry requirements—the knowledge and skills required to build, and safely fly and recover rockets which fly L1 motors.

Legally flying Level-2 (L2) motors requires L1 and L2 certifications. Application for L2 certification requires candidates to be L1 certified. L2 certification requires the flier to successfully build, fly, and recover undamaged a rocket flown on a L2 rocket motor.

Flying L3 motors requires much more work by the Flier. The certification process begins with a written prospectus for an L3 rocket designed to fly a specific L3 motor. The proposal covers theoretical design, build, electronics, propulsion, recovery, and safety issues. The proposal and later the rocket booster is inspected by the Tripoli Advisory Panel (TAP) rocketeer assigned to evaluate and supervise the rocket proposal and build.

A pinnacle of “high anxiety” is the L3 flight, which is a delight for everyone at the launch: the dream of a rocketeer sits on the pad, offering promise of imminent ignition of a mighty rocket motor and a sizzling flight—no matter what the end result. Everyone in the field is required to stand and watch the L3 rocket fly (a “heads up” launch)—just in case not everything goes as planned. Once spotters declare the field is clear and the air is clear, the rocket receives a countdown.

L3 certifications are hard-earned achievements, remembered and celebrated by the rocketeer and the friends and family at the flight line, for a lifetime.

Navigating the path to a successful L3 certification requires cognitive, emotional and physical strength expressed over a substantial period of time. The journey is humbling and long, and is impossible for most rocketeers to complete without consulting publications on a wide variety of subjects, abundant experience building and flying high-power rockets using weaker motors, and help from rocketeer chat groups, club members (especially L3 fliers), TAP advisors, hardware store experts, and specialty venders.

Most L3 rocketeers whom I’ve spoken with expressed pride and happiness regarding their L3 project, and were happy to discuss details about it, from conception until the present (and beyond).

I enjoyed overcoming the challenges that L3 certification projects present. Thus far, I have undertaken three separate L3 attempts—two for official TRA L3 certification, and once for fun and to prove a point. They are described below in the order they occurred.

First Attempt: Half-Scale Nike Smoke (Smokin’ Rockets), October 1, 2000

I didn’t want to experiment by flying my own “scratch built” design (though I’d scratch built more than 100 rockets, from hobby through L2-class) until after I was L3 certified, because the certification process is involved and it requires substantial time to schedule and to complete. Thus, I wanted to get a successful “L3 cert flight” in my first attempt.

I purchased a ½-scale Nike Smoke kit (Smokin’ Rockets) for three reasons.

First, I was familiar with and admired Nike missiles, having lived near missile bases as a child (Dad was a mathematical statistician working on missile guidance systems). I liked the idea of building a Smoke—a large and handsome rocket, even at half-scale.

Second, the Smoke was used in NASA research studying high-altitude winds (the nosecone contained a smoke generator), and I was a NASA supporter.

Third, when I decided to use the Smokin’ kit for my L3 certification attempt, I knew of three other rocketeers who’d already certified L3 using a rocket which was built using the same basic kit—indicating that the kit’s design and components were of high quality.

After I was ready—plans, parts, approval, it took three months to complete the build, working at least a bit every day. The rocket is 106” long (8.8 feet), the airframe is 7.625” in diameter, and the assembled rocket weighs 40 pounds ready to fly without the rocket motor installed.

The rocket uses two-stage recovery. At apogee a 12”-by-120” custom Top Flight high-visibility fluorescent pink nylon streamer is deployed to slow the rocket and initiate a flat spin. At 1,200 feet above ground level (AGL) a charge fires to deploy a 14ft Rocketman R14C-B X-form main parachute. A second, larger backup charge is fired at 900 feet AGL to ensure parachute deployment. Electronics included an Adept ALTS25 main altimeter, and an Adept DDCS-25 secondary altimeter.

My L3 attempt took place at the Danville high-power rocket field in central Illinois.

The leader of the TRA high-power club at Bong Park in Wisconsin, of which I am a member, who has helped me an uncountable number of times in my journey from beginner ( to L3, helped me to carry the Smoke to the pad, and prep it for flight.

The rocket flew an Aerotech M1419W motor, achieving maximum velocity of 510 MPH, and apogee of 7,548 feet AGL (pre-flight simulation predicted 7,595 feet).

This motor is loud and growly: it emits a great deal of fire and smoke during the burn and is a true crowd-pleaser. After motor burn-out a smoke charge is ignited to aid tracking the rockets path. The rocket was recovered in perfect “fly again” condition: L3 certification granted.

Here are photos of a medium- and high-magnification of a photo of this L3 cert flight, taken by my friend and fellow L3 club member Brent (sadly, most of my physical/digital photos and paper files were destroyed in various moves and disasters).

This image has an empty alt attribute; its file name is smoke-1.jpg

This image has an empty alt attribute; its file name is nike-smoke-2.jpg

I later took the Smoke to the Quad Cities club field, to fly on an Aerotech L1500T motor that produces thrust more rapidly than the M1419W motor used in the L3 cert flight. In this flight the rocket had maximum velocity of 453 MPH, and apogee of 4,938 feet AGL (pre-flight simulation predicted 4,940 feet). Here is photo of three photos of this flight.

This image has an empty alt attribute; its file name is smoke-2.jpg

In the left-most photo, Mike  (“505”) on the left (, and I (“525”) stop for a photo on the way to the far-away pad.

The middle photo shows lift-off. Note how this high-performance L-class motor has a more focused thrust spike than the M1419W motor shown earlier, and the flame color differs in the two motors due to the different metal used in the propellant formulations.

The final photo shows the Smoke on the way back down, with all recovery system components deployed. At the top in the photo is the parachute, attached to the nosecone. A long recovery strap attaches the cone to the sustainer (a piece of black fire-proof fabric protects the parachute and recovery strap from the ejection gases used to remove the nose cone at a pre-programmed altitude). The sustainer is attached by recovery strap to the booster, and the streamer, released at apogee to bring the rocket down in a controlled flat spin, is located midway between booster and sustainer.

Second Attempt: Three-Bagger (Scratch-Built), June 9, 2001

Not long after my successful L3 certification, I heard a rocketeer certified L1, L2 and L3 “using the same rocket.” Initially I thought this meant that one single rocket was flown on L1, L2 and L3 motors. Later I learned that two different versions of the “same” rocket were flown: a smaller version flew L1 and L2 motors, and the larger version flew the L3 motor. Nevertheless, the idea of obtaining L1, L2, and L3 certifications using a single rocket seemed like an excellent project, which I decided to undertake.

I named my solution “three bagger” because that was the rocket’s mission: bag all three high-power certifications in a single day. The scratch-built rocket was 96” long (8.0 feet), and 4.0” in diameter. The assembled rocket weighs 15 pounds ready to fly a 75mm L3 rocket motor, and a half-pound more ready to fly a 54mm L2 or 38mm L1 motor (the greater weight is attributable to adapters used to fit the smaller motors in the booster). The rocket had a ten-foot diameter Top Flight hot pink round main parachute, and had a 8”-by-80” Top Flight hot pink streamer for apogee deployment. The electronics were an Adept ALTS2-50K (with deployment set for 1,200 feet AGL), and an Adept ALTS25 (back-up charge set for 900 feet AGL).

I flew the rocket in reverse order: because I was a current L3, this exercise was “for fun,” and L3 motors are definitely the most fun.

First, I flew a 75mm Kosdon M1015DH motor. The flight was perfect with maximum velocity of 802 MPH (Mach 1.05), and apogee at 11,836 feet (2.24 miles), 6.4% less than was projected (12,647) due to greater than simulated wind (flying rockets turn into the wind—a behavior called “wind cocking”).

Next, I flew a 54mm Aerotech K550W motor. The flight was perfect with maximum velocity of 379 MPH, and apogee at 4.062 feet (0.84 miles).

Finally, I flew a 38mm Aerotech I435T motor. The flight was scary: maximum velocity of 151 MPH, and apogee at 846 feet (0.16 miles), 5.3% lower than projected (893). In the final hundred feet of the ascent the rocket struggled against gravity to keep climbing, in a manner reminiscent of the way that a top waggles when it is almost ready to topple.

As planned, both altimeters fired the moment that the rocket started to lose altitude. This happened because the altimeters are designed to fire a recovery charge if apogee is lower than the rocketeer-specified deployment altitude—and both altimeters were set to deploy at an altitude that was greater than was simulated or actually achieved.

In my haste to complete three flights I forgot to attach the booster recovery harness to the sustainer! In retrospect, I should have compulsively used the checklists created when making my plan. Not making an excuse, explaining what happened, time urgency got the better of me on the last flight. Flying an L3 rocket three times, prepping twice, in one day, is a lot of work for one person to accomplish. In my time urgency to make the final flight I obviously didn’t use the checklists properly.

When the chute blossomed the sustainer went for a very gentle ride, and the booster fell 700 feet (the height of a 70-story building) onto a grass field. It sustained cosmetic damage.

Forgetting to attach the harnesses is a “very bad” mistake, and it could have ended tragically. Fortunately it ended well, and I proved that the concept of using “one rocket for all three high-power certification levels” was indeed feasible. Maybe I’ll do it a again (I’d like to), but this time using a carbon fiber ultra-performance super-rocket.

I don’t have photos from this launch, but I do have a photo of three-bagger lifting off on an Aerotech M1315W motor at the Midwest Power-1 launch. The flight and recovery were perfect, with maximum velocity of Mach 1.22, and apogee 2.74 miles AGL.

This image has an empty alt attribute; its file name is 3bagger-m1315w.jpg

Third Attempt: Son-of-Three-Bagger (Scratch-Built): Midwest Power, Halloween, 2014

I changed my residence. In the time that it took for me to move out, and back in, and get everything set-up, my application for annual TRA membership renewal came due. By the time I received the letter, I missed the window to renew membership. By rule, my TRA certifications were terminated, and I could no longer fly L1 or larger motors.

So, I had to start over again. I flew older rockets for the L1 and L2 flights.

For the L3 flight I built a new and improved version of three bagger—lighter (12.5 pounds without the motor), shorter (7.4 feet), and stronger (tighter tolerances). I named it Son of Three Bagger. It flew on a slow-burning M900LR Loki 75mm M motor to apogee at 14,983 feet (2.84 mi) AGL, achieving a maximum velocity of Mach 1.19.

Speedy (who drives a Dodge Viper) recorded and posted a video of the liftoff and recovery of my L3 flight. In the beginning of the video, my L3 TAP for this flight, Rocket Rev is on the mike introducing the rocket (filmed using a telescopic lens, the rocket is more than 200 yards away from the camera). A slow burner, the motor takes a few seconds to come to pressure after initiation. When it pressurizes the rocket flies exceptionally straight, easily breaks Mach, and disappears. The motor smoke element used to track trajectory doesn’t burn quickly enough to lay thick tracking smoke.

After a few seconds the video switches to the recovery portion of the flight.

Our buddy Front Page is heard on the video, saying that he spotted the main chute (it is shocking pink). The chute drifts into view (as a pink spot that is getting larger). The secondary charge fires, and is visible as a small white puff of smoke that increases in size.

The rocket comes into view with the recovery system fully deployed. Note that the streamer clearly indicates wind direction and speed, allowing rocketeers heard speaking in the video to correctly ascertain that the rocket would miss cars and a corn field. The rocket gently lands in the launch field, a contender for “closest to the pad landing” award.

A rocketeer’s “dream come true.”

Here is the video.

A High-Altitude Rocketeer’s Prayer
for Maximum-Power Courage

Today’s air is so fair I’m compelled to fly high!
I must therefore dare to aim straight at the sky.
No motor to spare in such calm Midwest blue!
Please grant me my prayer to fly closer to You.

525, “Quarter”
Paul R. Yarnold, Ph.D., Level 3
January 6, 2021

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s