Canon EOS 5D Mark II
ƒ/9
100 mm
1/3,200
1250

My son designed this rocket from scratch, and this was the first test flight for stability with one motor, a Cesaroni Aerospace J360 with titanium sponge in the propellant.

It was a loud sustained roar into the sky, punctuated with throaty afterburner effects.

He plans to add three more motors at each of the outer edges of the fins, for a cluster launch. So the bottom section is not yet completed or painted.

The fins are honeycomb nomex sandwiched between fiberglass sheets. It has a cool aluminum boat tail and a reduction coupler for the strap-on videocamera.

He built a computer model (below) for this flight, and it would have gone supersonic were it not for the drag of the videocam (which took quite a beating but managed to capture the climb to max Q)

17 responses to “Custom Test Flight”

  1. jurvetson Avatar
    jurvetson

    Telstar Logistics Quad Rocksim

    Reply
  2. PhOtOnQuAnTiQuE Avatar
    PhOtOnQuAnTiQuE

    That’ s so cool !!! How did he felt about the all process of thinking, creating, and looking at his creation working and rising into the sky ? And how do you =)

    Reply
  3. karl.simpson Avatar
    karl.simpson

    This is brilliant, any plans to upload the video?

    Reply
  4. Leino88 Avatar
    Leino88

    I bet mr. J sr. is gushing pride at his son who’s gushing pride at his son!

    Reply
  5. jurvetson Avatar
    jurvetson

    Oh yeah! =)

    Photon: he was very excited. More than usual.

    karl: Yes! I just uploaded the video.

    The plan was to capture the launch of a chaser rocket once ours had deployed its parachute at about 8K ft. But the acceleration to transonic speeds slammed the batteries back against their springs losing power soon after launch. Will need to solder the connection with wires for next time. And rethink the attachment mount as the camera does a wicked downward tilt with acceleration.

    Reply
  6. Peter✔ Avatar
    Peter✔

    Incredible! How difficult is it to keep camera focus on the rocket during takeoff?And what lens did you use?

    Reply
  7. TomiTapio Avatar
    TomiTapio

    …did the rocket survive the test flight?

    Reply
  8. jurvetson Avatar
    jurvetson

    Yes, in perfect shape.

    Pete: 100-400mm. I shoot timing priority at 1/3000 sec or above (and adjust ISO for available light to get the aperture in a decent range). I do one shot focus while it’s still on the pad, and that fixed focal arc works for quite a while as the rocket climbs.

    Reply
  9. Gone-Walkabout Avatar
    Gone-Walkabout

    would the extra engines be serial or parallel? I’d be concerned about engines on the fins, supposing 1 didn’t fire or fire out of sync, & thus go off angle

    Reply
  10. Tamooj Avatar
    Tamooj

    I didn’t see any wobble on the fins (in the short time on the video) so "Bravo!" to your son. Ever since you posted about this project I’ve had some nomex sheets set aside in the shop just waiting to be cut and glassed.

    Curious; the video implies that the nomex fins are blunt on the leading edges. Is that an illusion (i.e. maybe some clear resin we can’t see) or are you getting serious drag from those edges?

    As always – post the rocksim file! 🙂

    Reply
  11. jurvetson Avatar
    jurvetson

    The fins are super rigid. Yup, you are seeing a bare nomex sandwich for this test flight. It was a risk reducing flight before he finishes the build. He added 2-part expanding foam in the tail body, and started epoxying 1/4" wood dowels on the fin edges last night. And then the 29mm motor tubes on each fin tip….

    Reply
  12. Tamooj Avatar
    Tamooj

    Ah – Now I see the need for extreme rigidity… his ultimate plan for placing engines in the fin nacelles. I hope he’s got a really really REALLY good plan for igniting them. 🙂 The 1/4" dowels is a pretty nice touch. Would love to see some work-in-progress pictures from him; my 16 y/o is watching this closely.

    Reply
  13. jurvetson Avatar
    jurvetson

    Been wondering about that…. Feedback and suggestions welcome.

    We were going to wire all four igniters in parallel and hope launch control has enough juice.

    The general plan is to have a powerful 54 motor doing most the work, so partial ignition of fin motors will be in the noise (so we tested a central CTI J360 and are planning G75 metalstorm motors for the fins). I have never seen a Cesaroni motor fail to light with the igniters they ship with their motors, so they seem pretty reliable.

    One idea we are considering is a poor-man’s hold down clamp. I wonder if a rubber band between rocket and pad would be enough to hold it down if only G motors ignite for some reason. The midsize rubber band(s) would be wrapped over a screw in-line with and below the GLR rail guides, which should not induce a torque on the airframe)

    To give more time for parallel ignition, we could use long wires taped to the body so they can lift a bit while still being in the proper position internally (to give a slow igniter a chance) but would pull away before leaving the pad (pre-measured length wrapped around an anchor point on the pad).

    (We were also thinking about using a flight computer for launch detect, but give the current draw there, it might only make sense to use it to launch the central motor once the G motors kick in. So 3 g motors on launch with on board ignition of the central 54mm… but, I think that is less safe given any time delays as the rocket might clear the rail with lopsided G’s only, and then the big motor kicks in. Yikes. So this is why we are thinking about ways to keep it from lifting off if only 1 or 2 G motors are lit.

    Reply
  14. melroberts Avatar
    melroberts

    That is a serious motor. CTI has an office in Ontario. Do you think I could get a solid fuel motor from them for a model rocket?

    Reply
  15. Broken Toy Shop Avatar
    Broken Toy Shop

    I don’t know much about this, but if there is an issue with multiple igniters not working when wired in parallel, then maybe just wire the centre/main motor, and use fuses between it and the fin motors?
    There wouldn’t be a spontaneous ignition, but the delay would be very small if you used the right fuses.

    Reply
  16. rocketaholic Avatar
    rocketaholic

    what millimeter diameter is the J360 from CTI?

    Reply
  17. rocketaholic Avatar
    rocketaholic

    I found the data. Its a 54mm 3 grain skid mark motor:-)
    Great photo

    Reply

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