Thursday, December 21, 2017

Saturday, December 02, 2017

de Laval, shme Laval

screen snap via

Thursday, November 02, 2017

My Jolly Logic Chute Release issues

I have been pondering the last NARHAMS launch, specifically the flight that ended up in the trees. I decided to summarize all my JLCR issues so far. If for no other reason to reinforce what I learned.

1. Beware wind-free days. At the last launch, the ground level wind was mostly still. We had the crowd on one side, soccer fields to one side, and trees on the other two sides. Thus, we needed to angle the rods slightly towards some of the trees. There was some upper-level wind that was generally keeping the rockets away from them. My launch of the MLAS-S, between the angle and a little weathercocking, headed over the stand of trees. The ejection was on cue and the JLCR worked perfectly. Unfortunately, it fell almost straight down. In this case, not using the JLCR would have been preferable. I need to watch my angles better and, if there is no wind, consider not using the JLCR.

2. Be careful about really heavy nose cones. A lot of my rockets seem to end up needing nose weight. If the nose is heavy enough to lead the ejected rocket down, the release can let the chute open directly under the falling rocket, which means the body can fly into and snag the chute. On such rockets, I now add a leader so the chute bundle is adjacent to, or above the falling rocket.

3. Protrusions on fins look cool, but... I had one flight that had fin pods. After ejection, the body and the nose/chute bundle flopped around relative to one another and the chute ended up snagging a fin. Maybe a leader would help here too but this is harder to anticipate. This can happen even without a JLCR.

4. On the last flight of my upscale Estes Cluster Bomb, I stuffed in a huge chute protector. I decided for the first time to use a 60" chute. Afterall, if the JLCR drops it close, why not? Well, the rocket is a bit over 5" in diameter so a protector for a 4" tube seemed too small. Next up was one for an 8" rocket. I don't know if the size of the protector mattered or even why the chute snagged, but the protector went through the shroud lines after the JLCR released. The chute would almost open them the snag would deflate it. The rocket landed parallel to the ground and required a fin fix. I still can't figure out why it snagged this way much less how to avoid this failure mode.

Monday, October 23, 2017


In my earlier launch report, I mentioned having to use a long but heavy lineman's pole to recover my MLAS-S. I recently packaged the rocket recovery system in its own bag. I haven't programmed myself to grab the bag and, for the first time since I made it, didn't bring it to the launch. I'm still paying the price with joint and muscle aches. D'OH!

Saturday, October 21, 2017

Launch Report 2017-11 (NARHAMS)

Location: Mt. Airy
Weather: sunny; mid 70s; wind 0-3 
Total flights: Today - 12; YTD - 50
Total motors: Today - 12; YTD - 62
Motors by class YTD:  MMX-1; A-9; B-4; C-21; D-3; E-7; F-9; G-6; H-1; I-1

Man alive, another day of perfect weather. 2017 was most excellent in that regard (so far)!  The lines were nonexistent from the first couple of hours and I got all my LPR flights up in about one hour and 15 minutes. By the time I ate, the near soccer field cleared and I moved on to my mid-power flights. The first one, the MLAS-S, landed far up in a tree despite the use of the JLCR. It might actually have been better not to use it that time. It took over an hour to get it down. It was too high for me to wrangle it down using our lineman's pole, although I totally wore myself out trying. It returned to get a drink and enlisted a volunteer and his two kids to help. It came down and I rewarded the kids with rocket funds. It did save the JLCR and Alt 3. Getting old sucks.

My flights:
  1. 2nd Half on a C6-3 - Nice flight as usual. I'm down to just a few of the Quest C6's :(
  2. Mini Patriot on an A10-3 - CATO! I have never had an A10 blow it's top before. I will fill out the MESS form.
  3. House of Blues Tetrahedron on an A10-3 - Good flight.
  4. Half Spool Jack-o-lantern on a C6-3 - Nice up part, but the CD lid broke. I will replace it for next Roctober.
  5. CornRoc on a C6-5 - Good flight but this one needs a -3.
  6. GI Joe on a B6-4 - I built this with my son in the late 80's and the last time it flew was in 1998. The rubber shock cord seemed ok bit was too short so I extended it a bit. It flew great.
  7. Boyce Saturn V on a C6-3 - This went cruise missile and landed hard. No damage but I think this will be a display model going forward. The previous flight at MDRA went OK. Maybe there was too little wind today? LOL.
  8. Art Applewhite 13mm Stealth on an A10-P - Nice flight.
  9. MLAS-S on an F15-6 - CR@200' - Great flight to 821'. As noted above,  it landed in a tree. I have a few dings to fix.
  10. F in Rocket on an F15-4 - CR@200' - I found my Alt3 no longer was recognized by my phone. I wonder if it got whacked by the recovery pole on the previous flight? The ejection was at apogee and it headed down awfully fast. The JLCR did its thing and saved the flight. The plastic Estes chute held together somehow but needs repair.
  11. AeroTech J1600 SU on an F15-4 - CR@200' - This 13oz rocket flew nicely on this motor.
  12. Estes Ventris on an F59-5 - CR@200' - Fast flight and good recovery!
NARHAMS 10 21 2017

Tuesday, October 17, 2017

AeroTech J1600 SU build (not what it sounds like)

There was a recent TRF thread that asked if people save the tubes that motors are packaged in and if they ever built rockets out of them. The answer is, of course, YES! I replied that I had used them on some oddrocs, including my Saturn V SA-666 and SA-667 induction rockets. I also used one such tube (either AeroTech or CTI, I forget) to rebuild a damaged AeroTech Cheetah that I inherited. Perfect match!

Well, that thread planted a mind worm and I have started building a rocket out of them. It used three AeroTech 38mm packing tubes and one 29mm tube. These are larger than the size motor that they hold but, for simplicity, I will refer to them that way.  The lower body used two of the 38mm tubes and the payload section one 38mm and the 29mm. The couplers, nose section shoulder, and 38mm-29mm spacer were made from sectioned CTI tubes. The nose cone is a damaged hand pumped/launched water rocket. It fits in the  29mm perfectly. The initial sims say it will fly nicely on an F15-4 or -6.

Here is the progress to-date:



The rocket's name reflects the rough equivalent of the four motors that contributed to this build: two H550s, an I357, and an H182. The tool on wasn't updated for the H550 or H182, so I winged an estimate.