2018 IREC

Discussion in 'Competition Rocketry' started by jnelson, Jun 10, 2018.

  1. Jun 10, 2018 #1

    jnelson

    jnelson

    jnelson

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    The 2018 IREC / Spaceport America Cup is just over a week away. Fortunately, it looks like we won't be roasted like last year.

    My team is almost ready. The airframe just needs a couple finishing touches. We'll be doing the 10k SRAD category again.

    So, who's going?
     
  2. Jun 15, 2018 #2

    Eat, sleep, and Fly

    Eat, sleep, and Fly

    Eat, sleep, and Fly

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    Purdue's team is prepped and ready, we're competing in the 30K COTS division with a minimum diameter CTI N5800 (wish us luck). Now we just have to drive the ~27 hours one way to get there. If you're there definitely stop by and say hi at the range or poster session.

    It should be a really great week at an awesome venue!
     
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  3. Jun 19, 2018 #3

    Aksrockets

    Aksrockets

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    Now with 8% more aluminum

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    DFEBE94F-446B-46DF-94BB-93E165A08FA3.jpeg Yeah, i got a 100k shot going on some time this week. Presentation tuesday at 4:00



    Casper
     
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  4. Jun 19, 2018 #4

    ChrisAttebery

    ChrisAttebery

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    That looks wicked Casper. What motor are you using?

    Good luck with your flight.
     
  5. Jun 25, 2018 #5

    jnelson

    jnelson

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    Just got home... event was significantly better than last year, but they've still got some work to do... I might expand on that later. I took video of almost every flight except for 2 or 3... I'll post that later.

    I saw it, nice job. I heard your team call out a few of the altitude readings on the way up, but what was the max altitude?

    I made sure to be there for the presentation and really enjoyed it, any plans for next year?
     
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  6. Jun 25, 2018 #6

    stealth6

    stealth6

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    While I understand that the new venue is vastly more appropriate, I gotta say I miss this event being in my backyard. Was a favorite of mine to go hang out and spectate at.

    Alex!! Launch report please.

    s6
     
  7. Jun 25, 2018 #7

    jnelson

    jnelson

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    Agreed. I'm part of the SUU team. Our first year was the last at Green River. We sure miss the 3 hour drive (now 12).
     
  8. Jun 25, 2018 #8

    Eyesinthesky

    Eyesinthesky

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    Uploaded a few videos and images from SAC 2018. This rocket from Oronos Polytechnique went to about 30,100 feet and shot at over 1,000 fps.


    This was the first flight of the event by a team from Turkey. Footage was shot at just under 2,000 fps.
     
  9. Jun 26, 2018 #9

    stealth6

    stealth6

    stealth6

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    Doug's camera/launch-tower rig is simply awesome.
    Another thing I miss about my "backyard" location....I was sometimes helping Doug (and MotoJoe) out a bit on their rig.

    s6
     
  10. Jun 26, 2018 #10

    Rocketjoe13

    Rocketjoe13

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    You missed out on another epic IREC. Pitch mounts and rail cameras worked overtime - those Chronos cameras are way kool!
     
  11. Jun 27, 2018 #11

    Eat, sleep, and Fly

    Eat, sleep, and Fly

    Eat, sleep, and Fly

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    We overshot the altitude quite a bit, AFAIK we had the highest at the launch. Hit ~42K at mach 2.5 pulling 31G's. We intentionally overestimated sims assuming it would underperform, sims said ~33 Mach 2.2 and 21G's. Still not sure what happened there, but if we were going to essentially disqualify ourselves that's the way to do it.

    My best guess is that there was a pocket of inactive turbulent air surrounding the body. We had a fincan lip which was intended to act as an altitude and speed inhibitor, and I'd be willing to bet we weren't feeling the effect of that. We'll have to wait until we get back to school and can throw it in some CFD to confirm that theory. I'm just glad it held together. A successful minimum diameter N5800, even a heavy one, is no small feat.
     
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  12. Jun 27, 2018 #12

    djs

    djs

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    Congrats on this! Better than having to shoot your rocket while it was on the pad, like A+M.
     
  13. Jun 29, 2018 #13

    RGClark

    RGClark

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    How did your flight go AKSrockets? Flights to 100k are quite an accomplishment.

    Bob Clark
     
  14. Jun 30, 2018 #14

    jnelson

    jnelson

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    Okay, here's the compilation video. I got almost every launch.

     
  15. Jul 20, 2018 at 5:32 AM #15

    sean_journot

    sean_journot

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    Our rocket is at 32:30 in that video (Washington State University). It looks like it has two wind cocking events during launch, either that or we had stability issues; What do you think? I was standing at the cross road 90 degrees out from the video's point of view and it looked like it went straight up from my perspective. was a multiple diameter rocket (6" payload bay, 4" main chute, motor section) which used a fly away rail. Main chute deployed and we had a bearing to (telemetry failure) it but after ten hours of searching we gave up and didn't recover.
     
  16. Jul 20, 2018 at 6:18 AM #16

    AlphaHybrids

    AlphaHybrids

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    Sean - I'd guess that you had stability issues, probably partially due to the two diameters that you had. The larger 6" portion was partially shadowing the fins so they weren't as effective as simulated. That is a disappointment you weren't able to recover the rocket. Does it have identification information in case someone walks upon it in the future?

    Edward
     
  17. Jul 20, 2018 at 7:34 AM #17

    sean_journot

    sean_journot

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    Our team number and school logo were painted on the fins, I doubt anyone will find it out there. They would have to walk within 20 feet of it to spot it.

    Using openFOAM in-compressible solvers it appeared that the fins were far enough back that they were not being affected by the payload bay; our max velocity was around 900 ft/s however and there could have been shock waves running around the nose cone but if that caused an instability it should have shown up just before and after motor burn out.

    I think that either the rocket was over-stable and passed through a wind sheer or marginally stable at lift off. After studying the concept of stability I don't have faith in the cardboard cutout method anymore and believe that center of pressure is an oversimplified metric for stability. I have an idea of how I can go about developing a 6 degree of freedom simulation that determines stability from a data set derived from CFD simulations; if the rocket is ever found comparing actual flight data with such a simulation may reveal what actually happened.
     

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