Monday, November 16, 2015

A tragic weekend...

This weekend was tragic...

Not only for the horrible events in France, which are beyond belief, but also for an accident some deemed inevitable, but yet took over 55 years to occur...

A scout leader was killed on Saturday when a rocket came in ballistic and struck him in the head.

As I sit here writing these words, I must admit to feeling a bit shell-shocked. In the several hundred million launches of hobby rockets since things started back in the late 1950's, there have been a minuscule few accidents in which people have been hurt, but none seriously. My hobby was - and still is - just about the safest one on the planet. The safety code and best practices that have guided us throughout decades have enabled rocketeers to fly without major incident over and over again. So what happened?

Facts are sketchy, especially given the lack of knowledge the media have about hobby rocketry. Some initial reports said the scout leader was struck by a "bottle rocket"; others say it was a "homemade rocket." In all likelihood, it was a model rocket assembled from a kit, but even that is currently speculation. What appears to be consistent is that the rocket was launched at an annual Boy Scout event, the scout leader lost track of the model, and it came in ballistic, hitting him. A terrible case of an extremely low probability event having disastrous consequences. There is no evidence of a safety code violation, no indication that carelessness played a role - facts are few, and it will take time for them to come out, if they ever do.

However, I have been in the hobby a long, long time and attended many launches. And I know that with the increased popularity of high power rocketry, the safety emphasis has shifted to the large 10 foot beasties flying on L motors; you can just look at them and know that if one of those came in ballistic on a vehicle or, heaven forbid, a person, it would be a very bad day. Model rockets, because they are smaller, made of cardboard, balsa, and plastic, and use lower impulse motors, are not really considered much of a risk in today's environment. I myself have fallen into this mode of thinking on occasion - a few years back, I was greatly concerned that one of the high power rockets flown at the NASA Student Launch Initiative could make a hard landing among the crowd of spectators. calculations showed that this was a very low probability event, and it was easily mitigated by angling the launch rails so that a rocket coming in ballistic would impact down range, well away from the attendees. In my mind, big = dangerous, so I never bothered to quantitatively consider the risk posed by my model rockets.

That changed last night - after all, I am a scientist, and I need numbers. I wondered how one could quantify the danger posed by a model rocket coming in ballistic.

I quickly made up my mind to focus on the rocket, not the probability of a ballistic model hitting a person. That would be very variable, depending on the number of spectators, the size of the area in which they are located, and so forth. So I considered the energy possessed by a rocket coming down at terminal velocity, and how this energy compared to other non-rocketry impacts on humans. There were two obvious extremes - the case of being tackled in a football game, which seldom causes major injury, and being shot with a 0.38 caliber bullet, which is obviously very bad. I also looked at the U.S. military's lethality limit for explosive fragments, figuring they had put a lot of effort into establishing this. These numbers were fairly easy to find through Google, and here they are (I have converted the units from the obscure imperial system to metric, which is how I think - the imperial ones are in parentheses).

Lower lethality energy threshold for explosive fragments: 78.6 joules (58 foot lbs)
Energy of 0.38 caliber bullet: 163 joules (120 foot lbs)
Average energy involved in a tackle: 610 joules (450 foot lbs)

You can see that energy alone does not tell the whole story - if it did, the bullet would be much less lethal than a football tackle, which has the greatest energy of three. Obviously, there is another factor to be considered, and that involves the area over which the energy is applied. The tackle spreads out the energy over the cross-section of the human body, whereas the bullet concentrates it into a very tiny area. So let's compute a new number to characterize lethality, one in which we divide the energy by the area over which it is concentrated. Doing this for the tackle and the bullet gives

Lethality of 0.38 caliber bullet: 630,000 joules per square meter
Lethality of football tackle: 547 joules per square meter

This makes much more sense - it is over 1000 times easier to be killed by a bullet than a football tackle. So where do model rockets fit into this framework?

To figure that out, I used the Rocksim simulation program to generate results for 3 rockets - the Estes Alpha, Big Bertha, and the diminutive Mosquito. For maximum altitude, C6 motors were loaded into the Alpha and the Bertha, and an A10 into the Mosquito; the simulations were then set not to have an ejection charge so that the rockets would virtually crash into the ground at terminal velocity. I then used the mass of the rocket, its frontal area, and the impact speed to calculate the impact energy and lethality. Here are the results:

Estes Mosquito (A10 motor): 1893 joules per square meter
Estes Big Bertha (C6 motor): 14,500 joules per square meter
Estes Alpha (C6 motor): 25,200 joules per square meter

It was the difference between the Alpha and the Bertha that surprised me; even though the Bertha is bigger and more massive, the more streamlined Alpha had a larger terminal velocity and a smaller diameter, which accounted for its greater lethality. However, the main point is that model rockets can be dangerous if they come in ballistic, and the Alpha can have a lethality closer to that of a bullet than a football tackle, by a factor of 10 or so.

These numbers have convinced me to redouble my safety awareness at all launches, even if they involve "just" model rockets. In particular, I think there are three established practices to religiously implement:

  • Angle rods away from the crowd for ALL rockets. No one can be hit if the rockets are flying in the other direction.
  • Keep everyone 'heads up" whenever a model is launched, regardless of size.
  • Consider restricting motors to keep the models visible throughout the flight.

Hopefully, we will never have to give our sympathies to another rocket accident victim. The world is tragic enough.

Saturday, October 31, 2015

A short Halloween launch...

HARA had scheduled an afternoon Halloween launch today at Pegasus field, but the threat of impending rain moved the launch time up from 1 PM to 10 AM. A good thing too, 'cause this afternoon has sucked in a weather sense. Duane and I arrived promptly at 10 and helped Chuck, Woody, and Art set up the range - a rail, Woody's tower, a mid power pad, and a single LPR rack. Everything was ready to go in just a few minutes, but we discovered problems with both HARA controllers when we tried to launch the first rocket. After dinking around for a few minutes with test lights and multimeters, it was decided the batteries were low on juice, which forced us to use Duane's hand held controller for the launch. It was switched from pad to pad - not very ideal, but it got the job done.

Some friends of Woody's also showed up with their kids, who were very excited to recover the rockets. This was fine with me, as I have been not feeling my best this week - thanks to these young folk, I did not have to chase after a single rocket. I know... It ought to be considered cheating and beneath a true rocketeer, but being tired, old, and fat should occasionally allow one a little slack. The recovery team was very fast and efficient; all rockets were returned undamaged, and I was most appreciative at not having to schlep my ancient rear across the field.

Duane's Death Star was first off the pad, riding a C6 motor in a long arc to the southeast. It did its usual break apart into streamered fragments upon ejection, which elicited oohs and aahs from the kiddos. My Target bowl saucer was next on a C6-0, followed by Woody's 29 mm scratch built on a composite D. It truly got up and left - burst mode caught only a single frame of it in the tower, and it was gone in the blink of an eye to us human watchers. I don't know how Woody managed to keep track of the rocket, but he did, and was able to direct the recovery crew to its landing spot.

Duane's Death Star lifts off for Alderaan (Click to
My Target saucer on a C6-0 (Click to enlarge).
Normally most creative fall rocket kudo goes to Chuck and his flying corn rockets, but this year Art Woodling gave him a run for his money by creating a "pumpkinik" - an orange hobby store craft pumpkin perched on top of 4 long orange dowels. It had two stable flights, albeit with a tendency to fly nearly horizontal after motor burnout. Chuck did fly a corn rocket - a plastic corncob perched on top of a long green body tube with leaf like fins; however, the F motor may have been a bit too much, as the rocket lost a couple of fins on the way up. The parachute deployed, but the motor casing was kicked from the rear and still lies somewhere on the field. Not to worry - I am confident that with all of the TARC activity at Pegasus, it will be found fairly soon.

Art's "Pumpkinik" rises on a plume of fire (Click to
The F motor in Chuck's corn rocket ignites (Click to
One of Woody's friends flew a nekkid payload model on a C motor, followed by Vince's venerable Big Bertha. I am always impressed by the serene and stately flights produced by the Bertha; it is truly a classic design. Vince also had good luck in the flight of his skull-topped "Death's Head", which surprises me with nice straight flights despite its ungainly looks. However, his luck ran out with a reflight of his Rocketarium Mega Vortico, which he put back together after it was rekitted by an E motor CATO a couple of months back. This time he chose to fly with an ancient Estes E15, a now discontinued motor notorious for its failure rate. The motor lived up to its reputation, erupting into a spectacular fireball just above the pad. The failure ripped the motor casing in half and blew the Mega Vortico into many small pieces. I had great sympathy for Vince as he picked up the fragments from the field, knowing that there was no way he could rebuild it this time.

Vince's trusty Bertha turns in yet another flight (Click
to enlarge).
The recovery crew in action (Click to enlarge).
Vince's "Death's Head" gets going (Click to enlarge).A Woody rocket clears the rod (Click to enlarge).
I had brought 7 Halloween-themed rockets to the field. The Target candy bowl was followed by my Estes Zoom Broom clone on an A10-3T motor - old Witch Hazel was happy to spend some time in the air after a year of resting on the shelf. The Goony Ghost jumped off the pad after Chuck's corn rocket flew, the B6-4 powering it to about 400 feet. A B6-4 was also the motor of choice for the "Ecto 1", a Ghost Buster-themed Red Max; it flew like an arrow into the overcast skies, and landed softly on a ripstop nylon chute. My Quasar One Spooktacular blasted off the rod on a C6-3, immediately followed by a clone of the Estes "The Bat", which flew on an A8-3. My final flight of the day was the newly-built Goblin, which performed spectacularly on a C11-5 (I don't want to think about flying it on a D12).

Witch Hazel goes for a ride (Click to enlarge).The Goony Ghost bemoans another flight (Click to
Ecto 1 awaits launch (Click to enlarge).The Spooktacular climbs out of the smoke
(Photo by Woody - Click to enlarge).
The Bat spreads its wings on an A8-3 (Click to enlarge)My Goblin starts its maiden voyage (Click to enlarge).
There were several other flights, many of which I did not image because my phone ran out of memory (stupid thing - it should simply expand its storage to accommodate my hundreds of rocket pics). Chuck flew a saucer and his "Crappernaut" Porta-Potty a couple of times on F motors; I always love seeing it deploy the toilet paper streamer along with the parachute. Duane flew his treasured Cherokee-D on a B6, and brought the launch to a close with a flight of his yellow and black "Beast" rocket from last year's TARC season. All-in-all, it was a pretty good day; outside of Vince's shredded Mega Vortico and Chuck's engine casing, we didn't loose anything. The only real negative was the failure of the HARA launch gear, which will receive some attention over the next few days. Plenty of time for a fix, though - our next club launch is in March.

Duane's Cherokee-D sets out to poke a hole in the
clouds (Click to enlarge).
The Crappernaut emits noxious smoke
leaving the rail (Photo by Woody - Click
to enlarge).
The F motor in Duane's "Beast" gets it moving (Photo by Woody -
Click to enlarge).

Friday, October 30, 2015

I fly a few during TARC practice...

The skies were overcast last Saturday, but that did not stop me and Duane from joining Nate and his two Liberty Middle TARC teams at Pegasus field. We showed up around noon to find the young folks already hard at work prepping their rockets to fly. As with any TARC practice, there were some things that went right, and some that went wrong. A couple of the rockets had fins that were too small, making them marginally stable - they were noticeably squirrelly when they flew. Good altitudes though; one flight turned in an altitude of just over 870 feet, and another achieved a phenomenally good mark of 848 feet, just 2 feet shy of the goal! Recoveries, though, were another matter - there were several separations, resulting in damaged rockets and broken eggs. The Jupiter VII rocket was sufficiently damaged that the team was talking about building Jupiter VIII (one wonders what the Jupiter model number will be by the end of the season). This was a shame, because it was the only Liberty TARC model with the proper size fins. One team also learned - the hard way -that you do not use snap swivels to attach the parachute to a heavy TARC rocket; they just cannot take the stress.
The "Atomic Bomb" TARC rocket. The name would prove to be prophetic when it fell from the sky after a
 parachute separation (Click to enlarge).

Liberty TARC team members prep their rockets for flight (Click to enlarge).
Why you do not use a snap swivel to attach a parachute to a TARC rocket (Click to enlarge).
A TARC bird takes to the air on an Aerotech F32-8 (Click to enlarge).
I was not going to pass up the opportunity to launch a few, so while Liberty was launching TARC birds, I put up 5 of the 6 rockets I had prepped the night before. First up was the Quest Astra, making its maiden voyage on a Quest A6-4. It reached a nice altitude under the cloudy skies, but the streamer did not deploy. Fortunately the model was light enough that it still made a soft landing in the grass, and inspection showed that I had a melted streamer - too little chute wadding. The Squirrel Works pirate-themed Vulture was next on a B6-4; its flight was very nice, with no spin, and a nice recovery on the 12" ripstop nylon parachute. Encouraged by the fact that both rockets had landed relatively close to the pad - and by the presence of an eager young recovery crew - I launched the Semroc Centurion on a C6-3. Another good flight, and a soft landing under a 15" parachute. I really appreciated the kids helping me recover the rockets, though I must confess to a wee bit of anxiety seeing them approach the models at a fast run. I do not deny visions of crumpled body tubes and flying painted balsa occasionally danced through my head.

The Quest Astra's A6-4 motor ignites (Click to enlarge).The Vulture starts its first flight (Click to enlarge).
The Centurion is a blur leaving the pad on a C6-5 (Click
to enlarge).
The recovery crew in action (Click to enlarge).
The Aerospace Specialty Products NEO Standard rocket was the next bird to leave the pad; it flew surprisingly high on the Quest A6-4, landing to the south under a 12" parachute. I then ended my part of the day's launch by launching my Estes Avenger clone. Powered by a B6-0/B6-4 motor combination, this two stager achieved my best altitude of the day, and landed undamaged under a full parachute. I was very glad of the recovery crew, as the upper stage drifted about a hundred yards downwind; it was beginning to drizzle and I was eager to get my rockets into the SUV before they got wet. Everyone began to pack up, but we did launch one of the Liberty kid's Laser Lance as the final flight of the day. It too turned in a good flight, despite the launch lug being held on by tape.

First launch of the NEO Standard; the bright orange of
motor plume provides a contrast to the dull day (Click to
The Avenger clears the rod (Click to enlarge).
We managed to get everything loaded before the rain worsened, and then Duane and I then caught a bit of lunch at the closest Rotten Ronnies (McDonald's). I was pleased - 5 rockets up, 5 back with no damage. One of my better tallies.

Saturday, October 24, 2015

TARC session at the University of North Alabama

Time to catch up on blog posts - work has been kicking my rear lately and I haven't felt like writing when I get home. The rain outside is providing some motivation today :)

Lee Brownell starts the ball rolling at UNA's first TARC session (Click to enlarge).
Last Saturday, the University of North Alabama located in Florence (over in the NW corner of the state - about an hour and a half drive away) hosted a session for all interested TARC teams in north Alabama. It had a threefold purpose:
  1. Acquaint newbies with the basics of building a rocket
  2. Introduce TARC to first time teams
  3. Highlight a competition that UNA is conducting using current TARC rules. Basically, it's going to be a launch where kids fly their TARC rockets, with the best score(s) winning a prize. These launches can also be one or more of the teams' qualification attempts.
At least half of the three hour meeting was spent going over basics. After that, each team built a rocket - the ASP NEO Standard - which was flown in the last 30 minutes of the session. Chuck, Duane, myself, Vince, and Woody had a primary job of setting up the range in the very small, tree lined field near the building where the meeting was held; some of us also helped the kids construct the rockets, which was done with superglue because of the lack of time. I must confess I was surprised that things went rather well, as I fully expected the usual messy stuck fingers and motor mounts locked only halfway in, but that happened in only a few instances. Most of the 20+ rockets were completed without much trouble.

Members of the world champion Russellville TARC team demonstrate the basics of the Open Rocket design
software (Click to enlarge).
Building rockets! (Click to enlarge)
Once all the rockets were built, the kids brought them outside to the RCO station to receive motors and igniters; they were then sent over to the launch pads, where Woody showed them how to connect the clips to the igniters. The launch went rather smoothly - there were the usual igniter misfires, but no rockets disintegrated, though several did land on the roof of the building (they were later recovered). It is most fortunate that only A8-3 motors were used in the rockets - anything more powerful would have resulted in many tasty snacks for the rocket-eating trees.

A perfect day to fly! (Click to enlarge)
My Quest saucer kicks off the launch on a C6-0
(Click to enlarge).
A NEO Standard heads skyward on an A8-3 motor
(Click to enlarge).
We packed up around 3:30 and headed back to Huntsville. We had eaten lunch at an Arby's about 1 mile from UNA on the way in; as we passed it on the return journey, we noticed that it was surrounded by fire trucks and some firemen were hosing down the building. Apparently the place had caught on fire while we were launching our rockets (Note: we were WAY too far from the Arby's for any rocket on A motors to reach it). I suppose we might have jinxed the place by eating there - maybe next time we should eat lunch at a place we don't like.

UNA is doing an excellent job in motivating the schools down the TARC path. They are planning to have a follow-up session in December, and are nicely supporting the local teams; expect great things out of northwest Alabama this season.

Sunday, October 4, 2015


The weather has positively sucked the past several days - dreary, dismal, and wet. Our Fall seasons are normally very nice, but this one has started out poorly. The forecast shows some potentially better weather tomorrow, Tuesday, and Wednesday, so I am hopeful that I will be able to get through some of the painting backlog. I have a Squirrel Works Vulture and Estes Vampire clone awaiting paint, and two Der Red Maxen needing primer. I need to get these guys finished and off the bench.

The poor weather hasn't stopped me from building though. Last night I put together an Aerospace Specialty Products (ASP) NEO Standard. It's one of their 18mm starter kits, and I must say it is very nice. High quality parts - a strong body tube with practically no seams, thick laser cut fins, a kevlar shock cord attachment, and an appropriately long sewing elastic shock cord (those in most kits - especially Estes - are way too short). The motor tube protrudes about an inch from the bottom, which gives the rocket a somewhat unique appearance. Here's a pic of it tacked together:

Nekkid NEO Standard - Der Red Max to the left, Vampire clone in the
background right, and another Red Max's fin visible at right edge. The
work bench is crowded (Click to enlarge)!
The NEO went together fairly quickly, but you do need to pay a little attention to the well-written instructions to make sure you get the centering rings in the right position on the motor tube. A lot of beginners like to use super glue when they build a rocket - this one is a white/wood glue bird, at least when assembling and installing the motor mount. You definitely do not want things to get stuck in the wrong place.

A finished NEO Standard from the ASP web site. I will try to duplicate this
paint/marking scheme (Click to enlarge).
There was some big news from Estes this week, which sent ripples throughout the universe of rocket geezers. The old 1/45th scale Centuri Little Joe II is one of the most sought after kits in Rocketdom, commanding prices of hundreds of dollars when they make rare appearances on eBay. Well, those prices are about to get lower, because Estes is planning on re-releasing this kit in December, for the bargain price of $49.99! I say re-release, but it's really not - John Boren, the chief designer for the big E, says that the only things used from the old Centuri kit production were the molds for the capsule and tower; everything else is new for this model. He posted some pics on the forums and on Facebook, and the rocket looks absolutely beautiful!

Upcoming Estes Little Joe II (Click
to enlarge).
Closeup showing detail (Click to enlarge).
I NEED a couple of these - Santa, are you listening?

Saturday, September 26, 2015

Soggy Scout launch....

The alarm went off this morning at 5:15 AM, giving me just enough time to ready myself and my stuff to meet Woody, who pulled up around 6:15. The day was a wet mess, and we experienced drizzle and light rain throughout the 2 hour drive to Camp Westmoreland, which is over in the northwest corner of Alabama. The poor weather had us both convinced that we would be dealing with just a handful of kids, so imagine our surprise when we pulled into the camp and found at least a hundred milling about. Checking in with the scout leaders, we found that they were expecting at least a hundred more, very close to the 250 cub limit they had placed on this event. Woody and I exchanged glances, both of us realizing we were going to be working our rears off for the next few hours. 200+ rockets is an awful lot to launch in a morning, even in sunny weather!

Fortunately, it was not just the two of us - the leaders informed us that the U.S. Space and Rocket Center had provided someone to help with the rocket construction, which left us free to focus on the launching. We also found out that Tracy and Lee from Russellville were out at the launch area trying to assemble some launch gear. The rain had slacked off, so Woody and I moseyed over there, only to find our Russellville colleagues starting to assemble some Estes Porta Pads. I must confess that I fought down a smirk at the idea of launching over 200 scout rockets using single pads and individual launch controllers; it could be done, but it would be an unholy chaotic mess, and take much longer than the 3 hours or so we had in the launch window. Lee and Tracy were much relieved at the sight of the HARA launch equipment, and thanks to their help, we had the range set up in no time. Sometimes the presence of a well stocked rocket club is a wonderful thing!

Akela 1's motor ignites (Click to enlarge).The candy bowl saucer starts its journey (Click to enlarge).

The selected clear area was small and surrounded by trees, but it was just big enough to accommodate the scouts' Estes Dinks on 1/2 A motors. Red barricade tape cordoned off the pad area, and we placed some more around the battery packs and cables to indicate a no walking zone. I launched my Akela 1 rocket on an A8-3; it reached about the same altitude we expected of the Dinks, and recovered comfortably within the field. Knowing I was going to be really busy very soon, I also launched the Target Halloween Bowl saucer on a C6-0. My colleagues were impressed by how straight the ungainly purple oddroc flew. After these flights, the range was declared operational around 8:50, and we settled in to await the first wave of Cub scouts, expected around 9:20.

But the rain came first...
Waiting out the drizzle (Click to enlarge).
A light rain set in, continuing for the next 40 minutes. The first group of launches would involve scouts who had built their rockets in advance; they lined up under the porch of the camp bathhouse to receive their wadding, motors, and igniters. The rain was getting less, but even so, the first rack of 15 rockets was launched in a light drizzle - umbrellas were in much use when loading the pads. Scout Wave 1 involved launching 3 racks, about 45 rockets in all. By the time rack 3 was completely launched, the rain had finally stopped; I suppose it had deemed things were sufficiently soggy and decided to move on. The rockets in this first group were well made, and there were no parts falling off or ballistic returns.

Loading the final rocket of the rack (Click to enlarge).
A full rack of Cub scout rockets (Click to enlarge).
There was a lull of a few minutes before the next wave of scouts, who were the first to build their rockets in the camp activities building this morning. We expected two more groups after that, but what actually happened is that we had a more or less continuous influx of scouts for the rest of the morning. You could tell these rockets were built in a hurry - some had fin cans that fell off and had to be re-glued, while others had shock cords that were dangling. 11 more racks of rockets would take to the air, and while most performed well, some would not survive the morning. About 3 were lost in the trees, and 5 landed on building roofs; 4 came in ballistic, a couple re-kitted themselves at ejection, and 3 caught fire on the pad when the igniters pulled loose, igniting the plastic fin units. I felt particularly bad for one determined young lady; after 3 misfires, her 4th attempt resulted in the rocket catching fire, melting the fin unit and burning the lower portion of the body tube. I gave her one of the spare Sky Duster ready-to-fly rockets I bring to these events, and we were able to get this one up into the cloudy sky, which made her happy.

This video gives good idea of the pace of the launch

We were finished right about noon, and Lee and Tracy helped pack the very wet equipment back into Woody's SUV. I didn't take many pictures, because we were constantly occupied with pad duty, loading motors, and launching; there simply wasn't time. This launch was busy, even hectic at times, but it was good fun - the scouts thoroughly enjoyed themselves, and we put a bunch of rockets into the air. This is enough to satisfy any old rocketeer, even one a bit on the damp side.

Sunday, September 20, 2015

An hour with the B sisters...

After the scout launch yesterday, Duane warned me that he might head over to Pegasus field this afternoon for a couple of practice flights with his geezer TARC rocket. When he called about 3 to let me know that the warning would become reality in an hour, I immediately started looking over the fleet to decide which rockets would make my first flights at Pegasus this season (Pegasus field has been overgrown all summer, and they finally cut the weeds a few days ago). My new black-and-yellow Big Bertha caught my eye; next to her stood Beulah, also awaiting her first launch. Inspiration hit... It was time the three B sisters - Big Betty, Big Bertha, and Beulah - had a Sunday outing. Dragging out the range box, I prepared them for flight.

A B6-4 pushes Big Betty off the pad (Click to enlarge). Duane's Goth rocket on an Aerotech F32 (Click to enlarge).

Duane and I quickly set up his launch rail and my LPR camera tripod pad after arriving at the field; Big Betty would be up first, and she left the rod around 4:15, soaring to a couple hundred feet on a B6-4. Duane then launched his black-and-red Goth geezer TARC rocket, which had its flight recorded by a family friend from Texas. She was a complete rocket novice, having only flown water rockets in her youth, and was very interested in the goings on. It was nice seeing the enthusiasm and answering her questions - very different from the usual "rocket smack talk" normally heard at our launches. Anyway, the Goth rocket reached 815 feet and was down in about 40 seconds. Not too shabby, but Duane was determined to do better, so he started prepping for flight #2.

Bertha lifts off to an audience (Click to enlarge).Beulah is a blur as she clears the rod (Click to enlarge).
Big Bertha was loaded with a B6-4 and placed on my pad; she reached about the same altitude as her sister and recovered very nicely on a 15" green rip stop nylon parachute. I then fit a C6-3 into Beulah's motor mount and slid a Jolly Logic Altimeter 3 into her payload bay. The Altimeter 3 uses Bluetooth to talk to a phone or tablet, and I had re-paired this one with my Kindle - Apple does Bluetooth in a funky way, and I occasionally experience problems with the Altimeter 3/iPhone 6 combination. The Kindle communicated flawlessly; recording by the altimeter was started, and I quickly loaded Beulah on the pad. Flight was straight, with a good parachute deploy and a recovery about 25 yards downwind. The altimeter data was downloaded into the tablet, which showed she had reached 321 feet. Kind of low for a C6, but Beulah is a heavy girl - basswood fins, baffle, interchangeable motor mounts, and paint, plus the weight of the altimeter.

Beulah's flight profile as reported by the Jolly Logic Altimeter 3 (Click to enlarge).
Duane ended the launch with another flight of his Goth, which overshot the target altitude, hitting 905 feet. The parachute also failed to deploy, resulting in a very quick descent; luckily, there was no damage to the rocket, or to the eggs in the payload section. I have to hand it to Duane - his molded egg protectors are the cat's meow. The loading of the SUV was accomplished almost in the blink of an eye, and I was back at the apartment by 5. Five flights in one hour, no losses... A nice Sunday outing!

Saturday, September 19, 2015

Boy Scout build and fly...

I dragged myself, my range box, and four rockets outside at 6:30 AM this morning to meet Chuck and Duane in the parking lot. After loading the stuff into the back of Chuck's SUV, we headed out to the Hardees in Scottsboro, where we linked up with Woody and three Boy Scout leaders. This morning's mission - help the scouts at Camp Jackson build and fly a few rockets. Sounds pretty easy, but nothing is easy for me early on a Saturday morning.

Camp Jackson was just a short drive across the river from the Hardees; like many scout camps, it's a rather scenic place, being right on the river in the midst of some gently rolling hills. We set up the pads in a small field next to the lodge and a small picnic shelter. I immediately took note of the potential rocket hazards - a few power lines and trees ringing the field except for the river on the east side. Fortunately, there was very little wind, and, despite my expectations of hanging a few in the trees, or rocket splash downs in the water, no rockets would be lost this day. It's not often this happens.

Setting up the range at Camp Jackson (Click to enlarge).
While the scouts were assembling, I took the opportunity to fly three of the four rockets that had journeyed from Huntsville. The BMS School Rocket was up first, making its maiden flight on an Estes A8-3 - straight up, with a nice parachute deploy, and best of all, it drifted back into my outstretched hands. Definitely a good start for the day. I followed this with my Estes Snitch on a C6 motor. This rocket delighted some of the scouts, who were intrigued by its unconventional appearance; clearly they had never seen a saucer fly before. The Snitch is showing its age, being rather battered after lots of flights - one of the plastic supports for a landing leg has cracked. Repairable, but I'm afraid this rocket will not be able to handle many more launches. My final flight was the venerable Der Red Max on a B6-4. Outfitted with a keychain camera, it also put in a textbook performance and returned a not too shabby video. I particularly like the part just after landing, where you can see some scouts running up to the rocket.

Video taken from Der Red Max

The scout leaders had this event organized pretty well, with the first step being rocket assembly in the lodge. The chosen rocket was the Estes Dink, repackaged for the Boy Scouts as the "Scout Voyager". Because of the limited time available for this activity, construction was done using super glue, which got the job done, albeit with lots of sticky fingers and mess. Fortunately, the leaders had ample quantities of nail polish remover (acetone) to help clean things up. After the scouts built and prepped their rockets, they moved on to an outside station, which had some space-related crafts. The final stop was the launch pads.

Scout Voyager rocket
(Click to enlarge).
Building rockets (Click to enlarge).
We had set up three racks, each containing three pads; all were tied into the trusty HARA launch controller. Duane acted as the LCO, with Chuck, Woody, and I acting as pad managers; each scout would get to press the fire button to send his rocket on its way. Launching went smoothly, with no mishaps. Several rockets did not fully deploy a parachute or streamer, but none came in ballistic or were lost. All in all, about 30 scout rockets took to the air (three and a half sets of nine), and everyone had a most excellent time. I was approached by a couple of parents afterwards asking where they could get rocket supplies so they could fly with their kids - always a good indicator of a successful launch.

Demonstrating how to connect igniters (Click to enlarge).Woody powers up the pads (Click to enlarge).
A Dink gets going (Click to enlarge).Up, up, and away! (Click to enlarge)
Dink drag race (Click to enlarge).
Woody and I get to repeat this at another scout camp in Florence this coming Saturday. Since it's a bit farther away from Huntsville, I will have to get up even earlier...