Canon EOS 5D Mark II
ƒ/7.1
100 mm
1/3,200
500

My son designed and built this 4-engine cluster rocket from scratch, with GLR nomex honeycomb fins, and an Aerotech Metalstorm engine on each fin edge, and a reduction coupler for the strap-on camera, and RF tracking inside.

And get a load of this – all three metalstorm motors at the ends of the fins are actually lit and coming up to pressure. In this frame, none look lit, but they all are. Below, you can see the sparkles from the titanium sponge mixed into those motors.

A whole series of events led to the loss of the upper half of the rocket. Will post analysis below, thanks to photo tracking into the sky

Here is the HD pad-cam video. Since it’s a fixed videocamera at the pad, the visual action is brief, but the soundtrack is fun. The Cesaroni J355 Red Lightning central engine just roars off the pad.

13 responses to “Epic Cluster Launch”

  1. jurvetson Avatar
    jurvetson

    The first fin motor to light, on the right, ruptured under pressure spilling its propellant grains. Single use motors usually do not CATO like that. Suspected cause was the pull back of the igniter from the top of the motor, igniting toward the rear of the motor:

    Epic Sky 1

    Then the other two fin motors come to pressure properly, and the rocket spirals into the sky, with the asymmetry of 2 of 3 fins lit, the 3rd having been destroyed:

    Epic Sky 2

    The instability goes into a bucking bronco ride in the sky, and the body segments separate, ripping the shock cord (my fault for letting the shock cord be a combination of Kevlar and wide elastic from a mid-power kit, the latter of which is not strong enough for these mishaps):

    Epic Sky 3

    So the black upper body tube and strap-on cam can be seen in free-fall here (the black specks in the blue sky) and the thin wisp still heading up is the bottom red half of the rocket. Luckily, most of the expense and labor of the rocket build is in that bottom part, and it was unharmed from the fall. The only repair it needs is one new fin motor tube to replace the rupture from the CATO.

    In building a new upper body tube, the plan is to leave room for a computer bay… as this is a fairly complex project to rocksim for motor ejection as he has been doing so far…

    Reply
  2. Leino88 Avatar
    Leino88

    6 mach diamonds?? way cool!
    how did j-jr take the … unfolding of events?
    i think the design is stellar! and even more impressive knowing who thought it up, and made it happen! KUDOS to him! (and u) – u must be gushing with pride. 🙂

    Reply
  3. Rocketman8911 Avatar
    Rocketman8911

    What igniters were you using to light the G75M’s?

    Reply
  4. drona Avatar
    drona

    Way to go, Dad!

    Reply
  5. jurvetson Avatar
    jurvetson

    heh – it was all him. I just armed the video cam at the pad given my height. He designed it, built the computer simulation model, built 100% of it (with supervison), and prepped it and wired it for launch.

    Leino: thanks! Look at you, spotting the clarity of the thermoplastic burn. =)

    To your question, he was especially excited about the wiring, RF tracking beacon, and riding on the roof during the recovery drive through the fields.

    A Stanley: We used the igniters that came with the motors. One other factor in the cascade of events: we painted the big central motor with pyrogen… For safety, we wanted to make sure it ignited, but in retrospect, it lighted too fast, and the fin motors started a full 1.5 seconds later (!!!! measured by camera frame rate in autodrive) after the rocket left the pad on the central motor.

    Do you know if G40Ws light more quickly?…. We have three of them for the next launch.

    Reply
  6. drona Avatar
    drona

    Amazing, how quickly he has grown, in so many different dimensions! Congrats Dad (and Mom!)!

    Reply
  7. In Memoriam: jerryfi_99 Avatar
    In Memoriam: jerryfi_99

    Was the on-board video recoverable? That would be spectacular, I would think. Interesting that there would be 1.5 sec delay in ignition. Nice work, fun test.

    Reply
  8. Dr DAD (Daniel A D'Auria MD) Avatar
    Dr DAD (Daniel A D’Auria MD)

    How did your son make out throught the whole escapade? Disappointed, or just anxious to get back to the drawing board?

    Reply
  9. Vanita Avatar
    Vanita

    A Homer Hickam without all the homelife baggage.
    So very cool.
    ‘-}

    Reply
  10. marhawkman Avatar
    marhawkman

    ouch, and this neatly explains why being a rocket scientist is hard. 🙂 So many variables, so many things that can go wrong. So why is the later ingition of the secondary thrusters an issue? I would think that as long as they ignite at the same time it should be fine.

    Reply
  11. jurvetson Avatar
    jurvetson

    Yeah – just ask SpaceX. =)

    Mark Canepa sent me some of his photos. Here is the makeshift prop we used to make sure the main motor would fry the rubberbands… Erik’s Chapstick

    Jurvetson 210699

    And he caught the adults watching the spectacle unfold overhead…

    Jurvetson 710704

    Next time, we might ignite the three fin motors with a similar holddown, and use an on-board computer to ignite the main central, once movement starts.

    Reply
  12. marhawkman Avatar
    marhawkman

    Hmm… what’s SpaceX?

    anyways, did you consider launching from a flat pad instead of tying it to a stick?

    Reply
  13. marhawkman Avatar
    marhawkman

    Okay, I looked it up on wikipedia.

    they seem to be doing decently well.

    Reply

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