Canon EOS 5D Mark II
ƒ/2.8
200 mm
1/5,000
100

We had a variety of strap-on video cams ready to fly at NASA Ames on Saturday, but alas, a peculiar string of ignition failures limited our flights. So this big bogey got away. =)

For this pink rocket, the likely culprit is my poor storage of this old F20 Econojet motor from 2003. I tried to scrape out the internal oxidation, and after the stock igniter chuffed, I doubled up with two igniters on the next try. Another chuff (i.e., the igniter fires just fine, with the signature puff of smoke, but propellant does not come up to pressure). So then I put a Aerotech high-power igniter in there, and got a lot of smoke, but still no go. I plan to disassemble that motor to see what was going on inside.

The rest of the stories are below.

6 responses to “Rocket Trial Balloon”

  1. jurvetson Avatar
    jurvetson

    My intrepid rocket crew took videos and aided in recovery
    IMG_5387

    So we moved on to the Starburst, with two F32 blue thunder motors… and one of two lit
    IMG_5425
    Luckily, this flight configuration survives a motor failure, as can be seen in the back end of my compilation video.

    (I expected this outcome here, because I had used up all of my wire igniters on the earlier pink rocket attempts and had to try to get a pair of copper laminate igniters wired in parallel with a small clip to hold them.)

    So, to regain our confidence, I tried to entertain the kids with a night launch of a cable spool with a G78 motor that burns in a bright neon green. This time, it was a fresh motor, straight from the air-sealed bag. The standard wired igniter fails. So I go for a larger Wilman igniter. Chuffs again. So I open another new motor. Standard igniter chuffs. I am using a wooden dowel to roughen up the interior after each attempt. So I finally try a Aerotech HPR igniter that barely fits up the central core. And it chuffs again! Ignoring the Starburst flight, I had eight igniters (of four different types, across three different motors) fire as expected, yet all failed to launch. Never seen anything like it.

    Open to suggestions from anyone who has seen something like this. I know the green propellant is hard to light, but I have not had any problems with the 15 or so green motors I have flown in the past.

    My first thought is to build a pyrogen-dip XXL igniter and scrubbing the oxidation out one more time…

    Reply
  2. telebyte Avatar
    telebyte

    What are you using to press the ignitor into thorough contact with the core?

    Reply
  3. solerena Avatar
    solerena

    Nice one, video is cute with rocket girls… Marissa will create a brand new Yahoo – some Y left there:) was curious about zeppelin above my head – keeps coming…

    Reply
  4. telebyte Avatar
    telebyte

    Perhaps I should note a small amount of TP (flammable – e.g. NOT flameproof wadding) carefully tamped in with a dowel worked best. Decades ago we used to make our own ignitors from nichrome wire allowing custom 3X loops & x-heavy coating with nail polish (the heaviest / most flammable coating). Cheaper & better.

    If you are planning to cut apart, suggest soaking the engines in water (safety procedure used for flares).

    Reply
  5. meta59361 Avatar
    meta59361

    I’ve had similar issues with old AP motors. Paul Pittenger has igniters that have worked on motors I couldn’t get to light, I suggest talking to him at the next LUNAR launch.

    Reply
  6. jurvetson Avatar
    jurvetson

    Ah yes, I used one of Paul’s for the final attempt.

    I think I needed to scrape more oxidation away. It’s the fresh G78’s that worry me.

    Reply

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