The J340Metalstorm is Aerotech’s new sparky reload for the popular 38/720 casing, which also takes the classic J350 White Lightning casing – the most common motor for Level 2 certification. I was happy to see that Aerotech got into the sparky motor market, but did something different than the black-smoke-with-sparks available through Loki and CTI. The new Metalstorm propellant is basically White Lightning with sparks.

When Ken at Performance Hobbies said he’d be getting a bunch of H170M, J340M, and K540M reloads in time for Red Glare, I shot him an email right away letting him know I’d like an H and a J. Turns out he only got a small shipment in time for RG8, so I’m glad I ordered mine in advance. I saw several G75M’s and H170M’s fly at Red Glare, but I don’t remember seeing any other J340’s and no K540’s.

Motor assembly was normal. Now that the ATF lawsuit is over, propellant slugs are packaged together – in this case, already placed in the liner – instead of in the normal, laughable plastic packaging necessary to have keep the grains packaged ’separately’ for legal purposes. The J340M reload also came with the new 14A delay – max of 14 seconds but adjustable downwards. The same delay adjuster works for CTI, Loki, and Aerotech motors (though you have to be careful to double check which setting is which to get the correct delay length) and I had no problem with assembly. I assembled the motor in identical fashion to how I’ve assembled all my others – and I’ve successfully flown multiple J350’s in this same casing.

Don Bryant of D. Bryant Photography was on hand and happened to be standing next to me on the right side of the flight line while I was waiting for the launch, so I asked him to try and get a few liftoff shots. He definitely exceed my expectations, and got a pretty incredible selection of shots in the 2.2 seconds of powered flight.

Zero to 391 mph in 2.2 seconds. Here are a few of the highlights:

The boost was perfect – powerful and straight despite the wind. Somewhere between burnout and apogee she slipped into a cloud, so I waiting anxiously to see a chute emerging so that I could track her down. The flight was simmed to go 3,358 feet so I was expecting quite a walk with an apogee deployed chute, with a 42-inch chute to bring her in faster than normal.

But there was no ejection charge. When Lunch Money emerged from the cloud, she was coming down in a fast flat spin – and luckily not in a ballistic dive. If the latter had happened, I probably would have gotten the motor casing and fin can back, but that’s about it. Instead, she was spinning rapidly around her central axis, and also rotating horizontally around the center of gravity. I was crossing my fingers hoping that she wouldn’t finally get out of the wind and assume a ballistic trajectory, but luckily that didn’t come to pass. Lunch Money hit hard enough – fin first – to bounce at least 5 feet in the air, maybe more, so I knew there’d be damage. That walk out to the field was a long one.

The damage was bad, but it could have been a lot worse. Of the 6 fins, one of the rear ones is toast, and one of the front ones has cracked fillet. There’s also a big crack in the Quantum Tubing where the nose cone goes into the payload bay. The airframe damage is more easily repairable than the fin damage – I’m still not sure how I’ll fix the fins.

A shot of the rear fin damage:

Aerotech was on site, so I took the recovered rocket over to them immediately after recovery, and one of their people was very helpful with the motor dissection and failure analysis. The delay grain burned all the way through, and the black powder was still in place in the ejection well, in contact with the burnt-through delay grain. Most of the black powder was loose, but some of it was a bit clumpy, which they said indicates it had grease mixed in with it. Looking at my o-rings, they said I was using way too much grease. Having suffered a blow-by before, I’ve always erred on the side of too much grease rather than too little, and I didn’t know that it could cause a failure. During assembly I didn’t notice any grease in the ejection well, so my best guess is that the extra grease on the o-rings and around the delay element (all within the motor forward closure) moved forward once the motor pressurized, mixing with the black powder enough to prevent its ignition. A user error to be sure, but one that I had never encountered before (or heard of) so frustrating nonetheless. I’ll know to use less grease next time. I’m certainly glad she didn’t lawn dart!

While the boost was beautiful, we all know the “down part” is often more difficult than the boost, and now I’ve got to figure out how to repair my flagship. But part of the thrill of rocketry is the risk that it won’t go well, and in this case I think I got off relatively easily.

Finally, here’s a slideshow of all of Don Bryant’s Lunch Money shots:

The discussion is interesting because it explores one of the least pleasant aspects of hobby rocketry. Our hobby has an excellent safety record, in large part because we have rigorous safety codes and self-police our launches to ensure that, for the most part, random idiots don’t ruin it for the rest of us. But even while following those safety procedures, things can go wrong. By all accounts, the flight being discussed was in a very well-constructed rocket build by a world class rocketeer. Yes, the motor is new, and is causing some problems (of the 6 flights I’ve heard of, two CATO’d and one shredded), but it was the unexpected that’s causing a stir: while rocketeers often leave nose weight loose so it’s removable or less likely to come down in one solid, heavy chunk, in this case the loose nose weight compounded the problem by causing damage to a number of cars instead of just one (or none).

In the end, no one was injured, and the property damage is being worked out. But incidents like this make me think that some sort of personal injury or worse is inevitable. And there are worse failures, like seeing an 80+ lb N-powered rocket whistle in ballistic at Red Glare 7 last fall, which could have easily killed someone if not for the sheer improbability caused by a big field and people being spread out. In some ways, rocketry is a much safer hobby than many activities that feel much safer. But as more and more people fly rockets, the crowds of spectators get larger, the motors get more powerful, and the rockets get heavier… sooner or later probability will catch up with us in a bad way.

Here’s a great example: Terry Leright’s Gladys, a minimum diameter N-3180 to N-1100 two-stager. Terry documents the construction, including kevlar and carbon reinforcement on the tubes and fins, the stage coupler (the sustainer motor casing, which has a flush rear closure, extends backwards into the booster airframe). Here’s the interstage coupler:

The finished rocket (actually, he built two of them, but that’s another story):

On the launch pad at Black Rock Desert – I swear I’m gonna make it there someday:

And here’s the liftoff on the N3180 (photo by Ken Adams):

One of the coolest aspects of this flight is that Terry’s electronics – an R-DAS (the same unit I obliterated in my second USLI rocket) – maxed out on its pressure and flatlined the altitude. Terry knew the flight went a lot higher because the R-DAS data showed the rocket was still going 1200 feet per second when the altitude flatlined – that’s over 800 miles per hour.

Rocketeer and math whiz David Schultz took a look at the data and calculated that Gladys maxed out at about 70,000 feet. His methods are definitely worth a read!

Finally, here’s video of the flight, showing just how massive the acceleration was (Gladys flies around 3:40):

(Construction photos by Terry Leright, launch photos by Ken Adams)

There are a lot more awesome build threads at the TQC forums. Also recommended: Predator L3, Project Vertigo, and Ultimate Wildman build threads.

From left to right:

PML 2.1″ AMRAAM (29mm motor mount) – this one lost the front of its main body tube a while back (windy, underpowered launch on a chuffing G33). I simply need to graft some phenolic tubing onto the front, and finish it to cover up the surgery.

My 2.6″ Fat Boy has a 38mm motor mount and is basically a fiberglassed version of the Estes kit. The reinforcement on the fins and parts of the nose cone is a bit spotty (fiberglassing plastic = poor choice) and I need to figure out how to pull off recovery and nose weight, so this one will require some work.

Above the Fat Boy is the body for a 1.6″ diameter Mosquito (the “Arkansas Skeeter”) with a 29mm motor mount – not the most sane of projects, and no clue when I’ll get it done and feel comfortable risking my hardware.

LOC Aura (painted black). I completely forgot that I had ever built this rocket until I went home to Arkansas for Christmas. I mailed it (along with some of these other rockets) up to DC so I could figure out a recovery system and start flying it – seems like it will be great for F, G, and H flights.

The short, dark tube with a long white tube is the genesis of a new project. The bottom section was originally to be an Estes Big Daddy – but with 4 29mm motor mounts. However, I’m not comfortable enough with my ignition skills to want to explore composite clusters on a rocket this short, and I’m not really that partial to the Big Daddy design. So, I’m going to extend this into a more traditional length 3″ diameter rocket. Maybe I’ll build in a timer bay so I can do air starts – maybe liftoff on 2 H128’s with 2 G64’s starting after a delay.

The next three tubes are for my as-yet-unnamed 3″ project. One potential name is I Lied About the Motor – just for the laughs I’d get at the flight line, and the uneasy questions I’d get at the RSO table. On the left is the remains of the crashed booster section, and on the right is the main parachute bay and nose cone – significantly shortened from a nasty zipper that’s been mercifully amputated. In the center is a 3″ coupler and a section of grey tubing I discovered while home in Arkansas for Christmas. Very luckily, this is a section of tubing that was reinforced with the same wraps of fiberglass and epoxy as the other tubes, but cut off to reduce excess length and then saved. I was quite happy to find this piece as it will make the rebuild much simpler, as this tube is already the same diameter as the other two.

Finally, on the far right is a scratch-built rocket I have yet to fly. It’s 2.6″ in diameter, built from LOC components, and has a 38mm motor mount and plywood fins. The unique aspect of this design is that it’s missing a section of the 2.6″ tubing above the fins. The 38mm motor mount has a total of four centering rings – two attached to the lower body tube and two bonded to the top, main body tube. More on this project later, but one potential name (with a paint design that would play off the rocket’s gaping hole) is Zombie Bite – Grab the Vaccine! It’s going to be a good winter building season!

One of the most extraordinary amateur rockets flown in the last decade was the Civilian Space Exploration Team’s Go Fast rocket, the first amateur rocket to reach space. It flew 72 miles at a max speed of Mach 5. (Documented at Derek Deville’s website.)

The Go Fast rocket was 10″ in diameter, 21 feet long, and weight 724 lbs, of which an impressive 435 pounds was propellant. In hobby terms, the motor came out to an S50150.

To get an idea of how high 72 miles is, check out this diagram, which shows the highest commercial airliners, highest military aircraft, and how high Go Fast went. Wowser.

Many projects this size are never recovered, or end up buried far underground. Go Fast’s payload section was fully recovered. The manpower involved in finding the space vehicle is covered at Stratofox, along with some fascinating analysis of the sonic booms created on reentry.

The video on YouTube includes these technical details from Derek Deville:

The motor produced a peak thrust of 16,000 lbs accelerating the vehicle at 23 g’s. At 10.5 seconds into the flight the vehicle was at about 40,000 feet and traveling at 3,420 mph (Mach 5) setting an amateur speed record. After motor burnout at 49,000 feet the rocket continued to coast upwards for an amazing 330,000 feet over 145 seconds before reaching apogee. All portions of the vehicle were recovered.

And, liftoff:

It gets better. Bob tried again and caught the smoke trail of another rocket flying on a longburning 54mm J90W.

But the best footage came from a flight of the Mirage on an H180, followed closely by a rocket from a Steve T on a Cesaroni green K motor. The results are impressive, making you feel like you’re in the video rocket with a much larger rocket being launched directly at you:

And here’s the slow-motion version of the same footage:

I’ve never seen anyone try onboard video with chase rockets before, so Bob and Steve may just have invented a new niche for high power rocketry. I hope we see many more of these. And eventually – if this becomes the next cool thing – maybe we’ll all get to see the chasing rocket shred, or even a highly improbable mid-air collision… but not with Bob’s rockets we hope!