Saturday, February 28, 2015

The airframe printed but with issues

I had hoped the airframe would have sufficed for a test flight but there are some layer splits that would likely fail. As such I've switched slicers and it's reprinting for another 15 hours. :)

Friday, February 27, 2015

V2 nosecone... PRINTED!


I found a flaw in the source model only after printing (note that ring/gap near the top).  I've since fixed the flaw but this 8-hour print will suffice for test flights.  The airframe is printing in black ABS now now and should be done tomorrow morning.  Yay, printer.

Sunday, February 22, 2015

More OctoPrint goodness

It turns out that OctoPrint also provides a real-time preview of the GCode toolpath in the 3D printer:

The solid black line is the current bead in progress and everything else translucent is the previous layer.  Nifty!

Saturday, February 21, 2015

It's aliiiive!

I've struggled with a learning curve since Tuesday but, with perseverance (and significant assistance from Alex on the forums), I'm now up and 3D printing at home!  I started by sending just the motor mount from the full-size V2 to test motor fit. Oh and all the print data moves wirelessly thanks to the brilliant Octoprint!  More soon.

Sunday, February 15, 2015

Updated^2: Lucerne on 2/14/15 with M3700 viciousness

I finally got around to crunching some data so I'm updating this entry. Here's the video you might have already seen but go ahead and watch it again anyway  (:

I'm astonished and pleased to note that I experienced two Saturdays in a row of impeccable flying weather. Holtville and Lucerne were similarly windless and a comfortable mid-70s all day.  It turns out that I've had this CTI 6800M3700 White Thunder reload in storage since November 2009.  Oops... tempus fugit!  I was throughly committed to preventing additional aging so I packed only that necessary to fly this vicious motor in my trusty DarkStar Extreme.  I bonded the grains into the liner the night before but, despite that and getting to the lakebed by 8:30AM, I still didn't fly until 11:30AM.  I was totally on my own and was unable to shoot photos but Gerald Meux was LCO and he and I agree that must have been an ~10' flame during the blistering ascent.  I lucked out for once and dual-deploy put 'er down less than 1/4 mile away from the pad:
I couldn't get the GPS transmitter working for some reason so you'll have to take my word for it.  The ARTS2 (table, graph, motor analysis, CD) and Raven3 250G(table, graph) averaged to the following maxima:
  • Altitude, AGL: 15,846' (3.00 miles!)
  • Velocity: 1,792 fps (1,222MPH, Mach 1.1... really?)
  • Acceleration: 44.7 Gees (Raven3 = 54.4, ARTS2 = 35)
  • ARTS2 Motor Performance: 7065M3605
The RocSimulation predicted a mere 15,300' AGL so I'm very happy with that altitude.  I'm surprised by the velocity of only Mach 1.1 but that must be due to the short 1.8s burn time and 28.3lb liftoff weight.  Finally there's quite a difference between the two altimeters on acceleration. The ARTS2 maxes out at 50Gees so I'm inclined to believe the Raven3 with it's 250Gee max.  
     The December launch at Lucerne was cancelled due to rain.  Two months later there remained some photogenic puddles so that's one benefit:


Addendum: David Reese captured a liftoff shot and kindly shared the link to his Flickr site:
It's not quite a 10 foot flame as I originally thought (rocket - 8.5 ft.) but I'll take it!  And he caught a proof-of-recovery shot as well:

Thanks for all you do, David!

Friday, February 13, 2015

M3700 grains are interesting...


...and now all four find themselves cozily bonded to their liner for tomorrow's flight!

Mini 3D print of a slightly larger 3D-printable design

Here's an earlier 3D print test of my 3D design below:
And here's a later test print in-hand:

This latter print came from a pair of replacement extruders we installed at work last week and they're working better than ever! I also received the ship notice on my home 3D printer and it should arrive soon. Stoked! In preparation I bought some clear polycarbonate filament from GizmoDorks.com as well as some glow-in-the-dark HIPS filament cause they're friggin' awesomely print-ready. Clear polycarb V2 anyone?  Oh and the HIPS polymer is soluble in D-Limonene so it's a highly reliable structural material that can double as support material for complex and gravity-challenged designs.

Wednesday, February 11, 2015

Holtville February 2015 launch report

OK so that was another epic launch at the Holtville.  Zero wind, cool peeps, and hawt flyin' akshun!

I'm psyched that Frank Hermes made an appearance to inadvertently, if viciously, topple my GoPro with his clustered liftoff and perfect flight and recovery.  Thanks a bunch, Frank!  Darrel flew his J595 successfully and it too, was awesome.  Finally Ron Rickwald flew a roaring M1315 in his Armageddon and good times were had by all.  I posted my photos here and, if Google lamely redirects you to Google+, look for the thumbnail of the white arrow on the green background.
     I had only two flights but both were on new motors from CTI. The first was my Polecat Aerospace 4" V2 on a Pro54/2G 699J145 Skidmark moonburner for an astonishingly stable liftoff and ascent on this long-burn beast of a Skidmark:

This motor ships with a 19 second delay but my 54mm delay adjustment tool only goes to -10 seconds.  The shortest possible delay would be quite long for many rockets so... what up wid dat, Cesaroni?  I adjusted to ~10.5 seconds and that was perhaps about 1 second too long but still ejected within the apogee window.  Once again, without any wind, it felt like I walked a mile but let's check the geotag on my cell photo... and, in doing so, I discovered a use for the Maps feature in Lightroom 5.x!! Any image with embedded GPS coordinates can be imported and reverse-geotagged using Lightroom's map (click to enlarge):

I'm sure there's some clever HTML5 method to allow you to click on regions of the above but I'll just quickly walk through the features and employ those antiquated yet familiar hyperlinks instead:
That's about all I got.  Fun review?

Monday, January 19, 2015

...and a UV-mapped render seems in order


I wanna fly it now!!

Initial V2 modeling complete

This morning I added a shoulder to the nose cone and a shock cord attach hoop that's smooth to reduce stress points:

I also built a rail guide by downloading the .dxf cross section from 8020.net and extruding a virtual rail within which I could bevel/extrude:

The larger hole of the three near the motor mount will be the Kevlar shock cord attach point.  I'll just tie a square knot or two in one end as an anchor and thread the cord up through the airframe to the nose cone.  The two smaller, opposing holes in the base are guides for the wood screws to retain the motor. Finally I improved the leading edge taper of the fins and sharpened up the bottoms to maximize adhesion to the heated build platform.

The airframe alone will require 15 hours to print at 0.3mm layer height or 25 hours at 0.2mm layer height (!) so I want to minimize the risk that the part will pop off before it finishes.