Rockets 101 Update: A story of preparation and clever hacks

Yesterday was the last launch day of the season at TORC (it turns out the farmer needs his field back to grow corn during the summer, go figure).  So, it was my last chance to test out the draft Rockets 101 Manual content under live conditions (and to get my NAR Bronze flights certified while I was at it).  I would love to be able to report that everything went according to plan, but that just is not the case.  However, as is often the case, I think the lessons learned from the complications that came up yesterday are far more valuable than those that would have come out of the day just going according to plan.

I spent the night before reviewing the requirements, packing my rockets and materials, and updating the course manual.  When I got to the field, I decided to start with the non-timed flights (in testing the timed flights were the harder ones to achieve success on, and I wanted to get some early momentum going).  As expected, my first two flights went off without a hitch, and allowed me to quickly get half way through the Bronze certification objectives.  The details of the flights are as follows:

  • “D” size or larger flight

    Rocket: Big Daddy

    Preparation: 7 squares of wadding

    Motor: D12-3

    Notes: Successful flight, achieved Bronze objective.  However, there was some minor melting of the parachute.  Should increase wadding on next flight of this rocket.

  • 2-Stage flight

    Rocket: Aztec

    Preparation: 3 squares of wadding, streamer recovery

    Motor: B6-0/B6-4 (taped together and friction fit with tape per kit instructions)

    Notes: Successful flight, achieved Bronze objective.  Some minor dings to the booster stage.

With two great flights under my belt I moved on to the first of the two timed flights, the 30+ seconds streamer recovery.  The spec’ed rocket for this flight is an Estes Hi-Flier.  This rocket always performed well in testing, so I felt confident it would pass the requirements.  There is just one minor detail I failed to consider.  The Hi-Flier is a very small rocket, and the launch site is a VERY large cornfield.  I’ll let the flight log below tell the rest of the story.

  • 30+ sec streamer recovery flight

    Rocket: Hi-Flier

    Preparation: 3 squares of wadding, streamer recovery

    Motor: B6-4

    Notes: Flight lasted 43.6 sec.  Rocket landed beyond line of sight.  Over an hour of searching failed to turn up the rocket.  Bronze certification requires recovering the rocket; objective not met.  Check with Greg to see if he used a B6-2 for his flight.

So, this was a problem.  First, I had failed to meet the requirement for the third mission.  Second, the Rockets 101 Manual calls for using the Hi-Flier for both duration flights.  I now had a choice to make.  I still had a B class motor rocket I could fly, namely the Aztec upper-stage.  But testing had shown time and again that most rockets could not meet the streamer recovery times.  So, I could either fly the Aztec upper-stage in an unlikely attempt at the streamer flight or go home.

I decided to go ahead and try the Aztec.  Worst case is I lost it, too, but I already had my 2-stage flight certified, and it is not a very expensive rocket.  Turns out it missed the time by 3.5 seconds, as shown in the flight log below, but that is not the end of the story.

  • 30+ sec streamer recovery flight

    Rocket: Aztec Upper-Stage

    Preparation: 3 squares of wadding, streamer recovery

    Motor: B6-4

    Notes: Flight lasted 26.5 sec.  Rocket landed close to launch site.  After the flight, another NAR member at the site asked if the rocket had a motor clip or used tape to friction fit the motor.  I answered it used tape, and he replied, try it without the tape so the motor will eject and lighted the returning rocket.

Talk about a clever hack.  The suggestion from the observing NAR member to simply let the motor eject so the rocket would weigh less on its descent was brilliant.  And it was just what I needed to get the last few seconds for the streamer duration flight.  So, quick turn around and then I tried again.

  • 30+ sec streamer recovery flight

    Rocket: Aztec Upper-Stage

    Preparation: 3 squares of wadding, streamer recovery; motor inserted without any tape so there was very little friction in the fit.

    Motor: B6-4

    Notes: Flight lasted 33 sec.  However, the rocket landed further away and it took nearly 45 min to find it in the field.  Rocket was undamaged, Bronze certification requirement accomplished.

Finally, after nearly two hours spent on recovery operations, and some clever hacking, the first of the two timed trials was complete.  The last flight was actually a breeze.  I again flew the Aztec Upper-Stage, this time swapping the kit’s streamer for a 12 inch parachute.  I continued to exclude the tape from the motor mount.  I also chased the rocket while it descended so I would not run the risk of not being able to find it, and I was able to recover the rocket in just a few minutes.  However, this meant I did not know the duration of the flight until I got back from my recovery…  At which point, I learned it had flown for 76 sec, easily achieving the 60 sec requirement.  Woot!

  • 60+ sec parachute recovery flight

    Rocket: Aztec Upper-Stage

    Preparation: 3 squares of wadding, 12″ parachute recovery; motor inserted without any tape so there was very little friction in the fit.

    Motor: B6-4

    Notes: Flight lasted 76 sec.  Chased rocket down during descent.  Rocket was undamaged, Bronze certification requirement accomplished.

So, there you have it, all four requirements for NAR Bronze certification achieved in one day.  Based on the performance of the Aztec Upper-Stage, I think it is worth it to conduct some additional testing to see if it is reliable enough as configured to be the spec’ed rocket.  It would be very exciting to shave an entire rocket off of the build list for the Rockets 101 curriculum.

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