Sunday, May 15, 2016

Lucerne... Punisher... K1440... redemption!

I'll augment this entry soon but here's the video of yesterday's K1440 flight to 13,932' with full recovery ~1 mile North of the pad (shocker):

Friday, May 6, 2016

Holtville - April 2016 launch report

In looking at my todo list in the entry below I must admit I recall little from the February launch but I remember much about last month's launch.  Here are a few photos of Ron Rickwald's M flight, my M2080 Skidmark, and Larry Hermanson's L1000.  Thanks to Mark Treseder for shooting the away photos.  And here's the GoPro vid of Ron and my flights:

In honor of Mike "Sparky" Jerauld's lengthy service to the DART club many folks flew Skidmarks, Dark Matters, or Metalstorm motors.  I elected to bust out the CTI Pro75/6GXL 6827M2080 Skidmark purchased during last fall's Wildman sale.  As always the prep took much of the morning but I felt good about the setup.  Thanks to Darrel for helping out at the pad and that was a fine, joltingly quick liftoff:
GeeMuneh_4GS18138.jpg M2080Liftoff-blog
Mark Treseder later shared that he thought the motor had cato'd but I had used the stock CTI igniter and I'm guessing it was the high aspect ratio, 7G motor that caused the quick pressure up.  I never saw it after burnout but had GPS lock from about 14,000 feet until it landed. Later Darrel and I drove right up to it on the concrete runway about three feet North of the dirt.  It was clear that the apogee ejection had worked but there had been no main ejection at 800 feet.  Having flown this rocket based on a recipe that had served me well for about nine flights I was shocked and saddened at the recovery failure.  I forgot to shoot a photo but the booster was on the runway painfully close to the dirt (which would have saved it) and the payload section was in the dirt.  I'm guessing that the payload section had bounced off the concrete, however, as it's nearly totaled as well.  The booster clearly landed at an angle as the AeroPack motor retainer has a huge dent in it, the epoxy sealing the retainer in is mostly fractured out, and I can see that the casing itself is dented.  I will publish a separate entry on the failure analysis but I'm quite certain the new M-tek 'initiators' are to blame.  Kenny Harkema spoke to the folks at electricmatch dot com and they told him there was a defective batch of pyrogen material for these new matches.   Friggin' sheer awesomeness.  I should note that their J-teks have never failed me.
   The flight had sim'd to 14,800' AGL.  I still need to pull the ARTS2 data but the Raven 2 and Big Red Bee Beeline GPS appear to have survived the impact:
Tomorrow's Holtville launch will be small but I'm gonna head out anyway in search of better luck.  Wish that for all of us. Thanks for reading.

Saturday, April 9, 2016


Hi, all.

Sorry for the lag but I've been in Swift/iOS app programming mode for work since January so XCode overrides blog authoring time when I return home.  I had planned to attend Lucerne today but it was cancelled due to inclement weather.  I vow to catch up soon and owe:

  • February Holtville launch report
  • 3D printing update
  • April Holtville launch report including a special failure analysis focus.  Grrrr....
Thanks, onward, and upward!!

Saturday, January 9, 2016

K185 = cable cutter test

I got a late start during last Saturday's packing because I could not find three important items and arrived at Holtville about 9:30AM. The AT 1417K185 did indeed fly...
...but there were several issues during prep and the primary reason for the flight, the cable cutter test, failed.   This was the first flight of what was supposed to be a super robust, carbon-fiber-overlaid, minimum diameter 54mm design.  I built this very high aspect ratio rocket to take any 54mm certified motor but the K815, while cool, would not be pushing any aerodynamic limits that day.

I specifically designed and 3D-printed the black caps [below] to fit in this rocket's electronics bay and cut a length of 1/4-20 all-thread that morning to hold the caps in place.  However, upon assembly, I discovered that the all-thread rod was ~2" too short.  I still have no idea how that happened as I'm somewhat familiar with ruler use.  I was about to give up but this was my only planned flight for the day so I quickly decided to shorten the already too long coupler to fit the all-thread assembly.  I bought a DC Dremel tool and that made quick work of the modification.

So now everything fits together as originally planned and the rest of the prep goes relatively smoothly.  The booster segment is only 36" long so a K185 with even a shortened coupler doesn't leave much volume for the recovery goods.  With Darrell's help I was able to get everything packed in and two pieces of masking tape seemed to hold the payload section into the booster.

Out at the pad I armed the Raven 3/Power Perch with the large magnet but rather than the expected "high high low low" dual-deploy beep pattern Darrell and I heard only "low low low pause high" (I think).  I admitted that I had not powered up the altimeter after prep as a test but this setup always works as expected so I had become overly confident.  In any even we agreed that something was wrong and pulled the rocket.  We undid all the careful packing work and checked the connections only to hear the same odd pattern after several iterations.  Once again I had planned to scrap the flight... defeatist!  Coincidentally I started talking to Russ Sands afterward who offered that it sounded like my LiPo battery below a safe voltage threshold.  I always charge my batteries the morning of a flight so I was skeptical but swapped to a different battery anyway.  Lo and behold it powered up with the expected dual deploy beep pattern! Well done, Russ, and thanks for the input.  I'll need to charge and test all my Raven batteries before the next launch.

OK so I crammed everything back together, got the rocket on the rail, armed the Raven 3, and loaded up the stock AT igniter.  Darrell was kind enough to launch for me but there was no ignition on this first try.  I've always found these Aerotech 54mm moonburners difficult to ignite and should have proactively metered some thermite.  Instead I used one of my older, dipped igniters on the second try.  There was a small puff of smoke upon ignition and then about 10 seconds of smoldering before the motor finally pressured up.  I was a bit worried about the moon burning thrust vector and minor curvature in the 4' long payload section but did everything I could to balance those forces during prep.  Ultimately the ascent was straight, true, and out of sight.  I used a 12g CO2 cartridge at apogee so there was no visible event at the top.  Luckily the Comm-Spec tracker signal boosted once the antenna was free from the carbon fiber shell so I knew I had separation.  Darrell and I walked right up to the rocket about 1/3rd mile away using the tracker.  Everything had separated but the main parachute's "burrito" remained intact with the cable cutter still in place.  D'oh!

I suspect that some of the BP leaked out of the cutter's cylinder despite a relatively thick wire to the ematch.  I had used a sealing o-ring around the wire in the previous night's test but it didn't seem to fit over the black wire I used for the flight.  Just in case I had plugged the cap with wall-tack clay but apparently that didn't help.  I suppose I'll force the o-ring over the wire next time and the new MTek leads are of apparently smaller diameter.

The bottom ebay cap had hit the ground and cracked another inch off of the coupler despite internal carbon fiber reinforcement.  This impact also  knocked the baro sensor off the Raven 3 and I have yet to be able to power it back up.  I might try to have it fixed but, with two abusive flights on it, the unit could be dead.  Good rocket science-y times!

Friday, January 1, 2016

Some 3D printing success

Over the holiday break I got my CreatorBot 3D printer up and running again and completed the following in the last few days:
On the left is the 3D V2 mark II with numerous improvements over my first design.  Unfortunately I still haven't built a lid for this large, open-top printer and you can see several warp/layer splits in the fins.  I can patch that before flight and the mark III should benefit from a laser-cut lid.

The middle two pieces represent my electronics solution for the Polecat Aerospace 7.5" V2 with 75mm motor mount in progress.  Before this design the two leading choices were to cut an door out of the airframe (not a fan) or add an E-bay tube in the nosecone tip.  The new alternative is to mount two Raven Power Perches into the smaller half and bolt that to the larger half in contact with the ID of the airframe.  There's a 3/8" static port to the outside, two 1/8" side outlets for ematches, and two top holes for screw eyes to minimize stress on the Power Perch's wire mounts.  I also increased the radius of the smaller half slightly so the bolt's threads will be loaded under a bit of force to prevent vibrational unthreading of the nuts. I may be able to refine the design some but this first one seems like it will do the trick. Here's the smaller half model detail: V2-PowerPerch-ebay-smallerHalf
Finally the two black ebay caps on the right are prints I completed at work on our Makerbot 2X.  I've been getting some very clean prints on the 2X lately as I added 4 mil thick Kapton tape to the heated bed and increased its bed temperature to 120˚C.  This mostly eliminates warp with ABS and gives a highly uniform glossy finish to the base of the part(s).  These caps will enable the aforementioned minimum diameter K185 flight tomorrow at Holtville.  I'll reiterate that every high-power rocketeer needs a 3D printer and a modicum of modeling/CAD skill!

Thursday, December 31, 2015

Test of Archetype Rocketry's Cable Cutter

I bought Archetype Rocketry's clever and compact Cable Cutter a couple of years ago because it enables dual-deploy from a single volume.  After struggling to find it all day I finally ran the following test tonight:

They recommend 0.1 ml of Pyrodex but all I have is black powder.  I could probably get away with 0.05 ml but, considering the parachute "burrito" will be outside the rocket when the cable cutter fires, I think I'll stick with 0.1 ml just to be sure.  I plan to fly a minimum diameter AT 1417K185 on Saturday using this system so wish me luck and [almost] Happy 2016!!

Sunday, December 6, 2015

Holtville Launch, December 2015

Here are the photos but I was having trouble with the GoPro and only caught three liftoff videos:

I was the first flight of the day for the first time with the CTI 260H194 Red Lightnin', helped Darrel with his perfect CTI 2771L990 Blue Streak flight, and socialized a bit.  The FAA just bumped our waiver from 10k to 15k so I need to get on that!  The only hitch is that we need to launch from the corner of the runway so that's quite a trek.  I could hear Paul Snow doing the remote countdown over the PA at the launch site and also on Darrel's phone about 1.5 seconds earlier.  We didn't specify which was the fire countdown so I was late on the button in the photos.  Also, when we got out there, my GoPro would not power on so I missed Darrel's epic liftoff.  Duh.

Saturday, November 14, 2015

Wow I'm a shiftless varmint

My maternal grandfather, Hank, used to call people of questionable drive "shiftless varmints" [vemin] and that's how I would classify myself in the last several months in the rocketry context.

I last flew at Lucerne in June and at Holtville in October.  I sort of took the summer off from flying because we're making the planet nearly unbearably hot.  Yes its true.  We are changing our planet's climate.  We should reject the disinformation created by the fossil fuel oligarchy and disseminated by corporate shills beholden to them in our government.  But I digress... I couldn't make the November Holtville launch because of an amazing cause.  I was planning to attend Lucerne today as it's no doubt amazing up there but I wasn't sure what to fly as of yesterday.  As such I started designing and 3D-printing electronics bay caps for what remains of the Viciously Mean Machine.   After struggling for a few hours trying to make nylon adhere to the printer's bed I reverted to trusty fluorescent green ABS .  Here's what I modeled in Modo:
And here's the 3D-print preview in Simplify3D:
And here are the final prints from my CreatorBot 3D:
These 3D-printed electronics bay caps are not quite what I modeled...
Not quite what I modeled right?!  I think a raft would have remedied the edge curvature near the base but the curved edges at higher elevations confuse me.  I think it's time to re-level my heated bed and try again.  With a little sanding/drilling those caps probably would have worked with an AT 1417K185 today but, by the time I finished the two E-bay caps last night, it was too late to start packing.  Now, at 8:47AM, I can't fathom the concept of driving up there through Saturday morning traffic to hurl a couple of sport flights.  I will commit to doing more rocket building and repair this weekend and hope to post more updates soon.

Tuesday, October 6, 2015

Holtville Launch / October / 2015

You'll find this launch was slash-a-rific:

I realized that I don't have a ton to add here except that:
  1. My pictures of the launch reside here.
  2. The CTI 1115J530 Imax is a friggin' beast... as are all Pro38 6GXL reloads?!
  3. I'm a dunce and somehow reduced my delay about 4 seconds too short.  The rocket felt so heavy as I was prepping but there was no wind so I'll take responsibility for 2 seconds of that.  The other 2 seconds continue to perplex.
  4. That delay shortage caused a 1.5" zipper in the tube and also flung my AltimeterTwo somewhere in the desert; lost on its maiden flight no less.
Did I mention that it IS rocket science?

Friday, September 11, 2015

So I had this idea for a Punisher fin alignment jig...

Modeled in Modo, sliced in Simplify3D, printed in white ABS on a CreatorBot 3D:
So I had this idea for a fin alignment jig...
I'll give 'er a shot tomorrow.  And I wish these and their inhabitants hadn't fallen victim to subjective indoctrination: