Stage-a-saurus, a first HPR staged rocket

Discussion in '[Unrestricted] Staging, Airstarts & Clusters' started by boatgeek, May 2, 2019.

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  1. May 2, 2019 #1

    boatgeek

    boatgeek

    boatgeek

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    Introducing Stage-a-saurus, my first HPR staged rocket and another terrible, terrible dad joke. Hey, they'd take away my Dad's union card if I didn't make them, so here we are.

    This is a fairly basic staged build. The genesis was realizing after the disastrous flight of Big Bird last year, I need to work on my staging before I do such an ambitious cluster project. Baby steps and all. The high school TARC team I mentor had an oddball tube between 38mm and 54mm that someone had donated. Since it wasn't really useful to the team, they were gracious enough to let me have it.

    Motor mounts are 29mm on both the booster and sustainer. The nose cone is 3D printed, as is the AV bay that holds an Eggtimer Proton and an Eggfinder Mini. A JLCR will minimize drift. In an ideal world, the nose would have been a little longer, but I was limited by borrowed printer capacity. The coupler that holds the interstage is a custom fiberglass layup. It happens that a 1 1/4" PVC pipe in the basement was just the right size for a mandrel for that.

    I'll have some pictures up tomorrow. In the meantime, a sim to look at. An F79 (24mm 3G CTI smokey) to F36 (29mm 1G CTI blue) is about the lowest possible altitude at 500m apogee. I would like to work up to an H163 (29mm 3G CTI white thunder) in the booster and either a G54 red or G33 mellow in the sustainer. Those top out at 1500m. 5000 feet isn't too shabby on full H/baby I total impulse!
     

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  2. May 2, 2019 #2

    boatgeek

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    And here's a couple of pictures--the full stack and the AV bay. Because I didn't have a coupler that fit exactly, I didn't want to put any more breaks in the airframe than I had to, so the AV bay acts as an extended baffle, with a flat on the back side. I may yet put the apogee ejection charge from the Proton above the AV bay. The AV bay is probably longer than it needed to be, but it seems to work OK.

    IMG_1989.JPG IMG_1990.JPG

    Fins for both the booster and sustainer are custom layups. The booster's are 1/8" balsa sheet with a thin layer of fiberglass on each side. They are cut square and are pretty draggy to aid separation. The sustainer's fins are two layers of carbon fiber. They're pretty thin so I didn't need to bevel/airfoil them.
     
  3. May 2, 2019 #3

    Nytrunner

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    Hopefully it won't pull a Fantasia and meet its end at the hands of Terrain-asaurus Wrecks
     
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  4. May 6, 2019 #4

    Ian A Dalton

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    You win best comment on this forum.
     
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  5. May 6, 2019 #5

    boatgeek

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    Nytrunner, if you are ever adopting a child and they ask for proof of your suitability to be a parent, just show them this joke. It is truly a thing of beauty. :)
     
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  6. May 6, 2019 #6

    Nytrunner

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    Like lawn darts, some jokes just fall into place :cool:
     
  7. May 6, 2019 #7

    K'Tesh

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    Where's the Thagomizer?

    [​IMG]

    Rest in Pieces Thag...
     
  8. May 6, 2019 #8

    boatgeek

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    The booster section is now officially named Thagomizer. I love that the Far Side cartoon name became the official unofficial description of the tail spikes.

    [edit] Now seeking names for the sustainer section. I can't have one part named and the other not named. Terrible puns are much appreciated.
     
    Last edited: May 6, 2019
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  9. Jan 20, 2020 #9

    boatgeek

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    Stage-a-saurus and Thagomizer have now earned their paint. I flew on a boosted dart configuration (G126WT to nothing) last weekend to 1305 feet, about 4% lower than OpenRocket predicted. I was surprised that it needed the separation charge, since the interstage fit seemed pretty loose and Thagomizer has fairly thick fins. A tiny bit of BP did that job just fine. I also had another small charge to simulate ignition of the sustainer. Both charges burned, so it looks like everything is hunky-dory for a full up flight later this year.

    Any suggestions for paint schemes are welcome, though the fins will just be clear coat on both. No sense hiding the CF or the balsa grain.
     
  10. Jan 20, 2020 #10

    mbeels

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    Nice, and I love the name :D
     
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  11. Jan 20, 2020 #11

    ebruce1361

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    For the sustainer stage, you could name it after any of the cavemen in the Far Side comics thus keeping with the theme, but to satisfy the predilection for terrible puns, I suggest "triSOARatops" given that it has three fins. Another option is to name it Pterrobledadjokyl. Bonus points if you can get the LCO at your local club launch to pronounce it correctly.

    As for paint schemes, it would seem dinosaurs would be the ideal theme. I'm thinking greenish gray with scales for a more serious look, or magenta and lime green for that classic Barney vibe.
     
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  12. Jan 20, 2020 #12

    dhbarr

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    I mean, obviously it should be Simmons....
     
  13. Jan 27, 2020 #13

    boatgeek

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    Flight summary from the Proton:
    Proton_319AB9 1.02Q

    Flight Summary

    Flight No.: 1
    Flight Status: Landed

    Apogee:.........1305
    Time to Apogee.....8.80

    Max Velocity.....345
    Time to MaxVeloc.....0.90

    Max Accel.....14.0
    Time to MaxAccel.....0.25


    LDA Alt.........255
    Time to LDA.....1.30

    Low V Alt.......1251
    Time to LowV.....7.05

    Nose_Over Alt...1290
    Time to Nose-Over.....9.80

    Boost #1
    ...@Time: 0.05 secs
    ...@Alt: 7 ft
    ...Duration: 0.85 secs
    ...Avg G's: 12.5
    ...BO@Time: 0.90 secs
    ...BO@Alt: 148 ft

    CH1: Airstart
    Status: Fired: OK
    Altitude: 285
    Time to Firing: 1.40

    CH4: Airstart
    Status: Fired: OK
    Altitude: 484
    Time to Firing: 1.90

    CH6: Drogue
    Status: Fired: OK
    Altitude: 1290
    Time to Firing: 9.80

    Flight Time.....39.80

    ASL Alt.........-214
    Temp. F.........55.0

    The official CTI burn time for the G126 is 0.93s, so everything looks spot-on. Channel 1 was the separation charge, Channel 4 was the simulated airstart, and Channel 6 was obviously the chute ejection. I used a Chute Release on the 30" main chute, set at 300'. It took about 150' of descent distance to fully open, so I probably want to re-visit that altitude for future flights. That's especially true for higher flights in bigger recovery areas, so I have a better chance of seeing the chute after it opens.
     
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  14. Jan 27, 2020 #14

    boatgeek

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    One more discussion item from the flight data: deviation. I used the recommended 15% deviation qualification for the airstart. This basically compares the accelerometer distance traveled to the barometric altitude. If there is a significant difference (in this case, over 15%), the upper stage will not fire. Cris has said before that there is a lag between the accelerometer data and the barometric data at the start of flight. I definitely saw that here, with the altimeter finding significantly higher altitude than the accelerometer for the first second or so, even though the flight was dang near vertical. After the first second, they got back in sync fairly well. You can also see a little lag after burnout. This is the data from this flight, in the time between burnout (0.9s) and nominal upper stage ignition (1.9s):

    Flight time BarometerAlt/AccelAlt
    0.9 1.11
    1.0 1.05
    1.1 1.02
    1.2 0.99
    1.3 0.98
    1.4 0.98
    1.5 0.77 (see below)
    1.6 0.95
    1.7 1.04
    1.8 1.08
    1.9 1.10

    Barometric data around 1.4s flight time was wonky because I had an empty casing with masking tape over the top in the sustainer motor mount. From the data, it looks like the separation charge caused a pressure spike in that time, which monkeyed with the data. In a flight with a motor in place, that wouldn't have happened.
     

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