"Starship" - L3 Build Thread

Discussion in 'High Power Rocketry (HPR)' started by Ben Martin, Mar 4, 2019.

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  1. Oct 12, 2019 #181

    jqavins

    jqavins

    jqavins

    Joseph Avins TRF Supporter

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    Ah, my work here is done.
     
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  2. Oct 13, 2019 #182

    Ben Martin

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    Update #26

    I tested the ejection charges today. I went with 2g for the drogue and 1g for the main. More testing will be done in two week, probably will increase the main charge.

    Video:
     
  3. Oct 18, 2019 #183

    Lukun7

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    Looked kind of underpowered for the main, but I don't have that mich knowledge.
     
  4. Oct 18, 2019 #184

    Ben Martin

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    I've heard that the main is just supposed to get the nosecone off since the nosecone will pull the parachute out of the payload bay. I'll probably increase it to 1.5g and see the results, but I think 1g would work great for flight.
     
  5. Oct 18, 2019 #185

    rfjustin

    rfjustin

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    I think that is a dangerous generalization. Is it possible for the nose to pull out the rest of the laundry, maybe, depends on how tight its packed and how much other volume you have in the chamber in question.

    IMO, retest at 2 grams for the main.
     
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  6. Oct 18, 2019 #186

    Ben Martin

    Ben Martin

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    I pulled on the nosecone with maybe a few pounds of force and the parachute slid right out after the test. What stopped it from coming out was the nosecone hitting the grass. I'm confident that it would have smoothly deployed. But I am going to test again with 1.5g as 2g is way overkill for the very small payload bay volume. The backup charge will be 150% of the final main amount I decide on, likely 1.5 or 2g.
     
  7. Oct 18, 2019 #187

    jqavins

    jqavins

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    Joseph Avins TRF Supporter

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    I know the general rule of thumb is that it's better to push a parachute out than to pull it. Maybe that rule or this situation carries subtleties that I'm not aware of.
     
  8. Oct 18, 2019 #188

    Ben Martin

    Ben Martin

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    It seems like the gas just went around the parachute and popped the nosecone off. I'll test with 1.5g next weekend and see if it has similar results, but I'm nearly 100% confident that it would have deployed reliably with only 1g. In addition, I have a backup charge to ensure the safe deployment of the main in case the flight does not go as tested.

    The calculator gives 1g as a bit over 10psi with 3 shear pins which is good. 2g would be over 20psi, which is dangerous in itself. 1.5 produces the upper end of the PSI range with 15psi, I'll have to test it to see if it's too much.

    The payload bay is only 4in x 15in with the parachute taking up 80% of the space. It has 3 shear pins for the nosecone.
     
  9. Oct 19, 2019 #189

    GalantVR41062

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    I use 1.4g in my 4" MC SDX3 with 2 2-56 nylon pins. I looked at my L2 flight data and the main was set for 500' and drogue decent rate was 45f/s. Main fired right on time but the air frame fell another 100' in about 2 seconds to get everything in line and slowed down to a slow 11f/s. Yes its good the nose cone came off, there is a chance the main would rattle out but that takes time, then it needs to inflate and slow the air frame down.

    ~John
     
  10. Oct 19, 2019 #190

    Ben Martin

    Ben Martin

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    My main is set at 900 with backup at 700 for the first flight. Depending on the results the main might be lowered to 700 and the backup at 500. This gives it time to fully open and settle. I'll test with 1.5g but will probably reduce the main charge to around 1.2-1.3g with the backup at 2g.
     
  11. Nov 10, 2019 #191

    Ben Martin

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    Update #27

    Successful launch!

    Launched Starship for the first time today.

    Main: 1.2g, 1.5g backup (900ft for main, 700ft for backup)
    Drogue: 2g, 2.2g backup (1 second delay for backup)
    Parachutes: 9ft main, 2ft drogue
    Motor: K535W

    All charges were set off by the dual Stratologger CFs set with full redundancy. Everything went flawlessly besides a tangled booster which will be easily fixed by moving the swivel.

    Video of launch:

    Pictures: Shown below. VideoCapture_20191109-231245.jpeg 1573350480264_13thPic00005.jpeg 13thPic00014.jpeg 13thPic00015.jpeg IMG_20191109_143303.jpeg IMG_20191109_143343.jpeg IMG_20191109_143409.jpeg IMG_20191109_143418.jpeg
     
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  12. Nov 10, 2019 #192

    JoeTekcor

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    Looks like it was a great day. I’m sorry I missed the launch. Hoping the weather is as nice in December.
     
  13. Nov 11, 2019 at 3:03 AM #193

    Ben Martin

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    It was a beautiful day. Perfect day to launch as the weather was great and best of all, no wind! You were attending something a "bit" more important. Hope to see you next month if the weather is nice!
     
  14. Nov 11, 2019 at 8:24 PM #194

    Ben Martin

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    More pictures from first launch. Screenshot_20191110-173148_Chrome.jpeg IMG_hkm48o.jpeg Screenshot_20191110-004013_Video%20Player.jpeg Screenshot_20191110-003930_Video%20Player.jpeg
     
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  15. Nov 11, 2019 at 8:34 PM #195

    Ben Martin

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    Video from our prospective:

    Launch pad camera:
     
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  16. Nov 12, 2019 at 11:51 PM #196

    JLebow

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    Impressive project. Based on some of the decisions you discussed in this thread (not launching in poor wind, and ground testing deploy charges), I think you have a bright future in rocketry and whatever career path you choose.
     
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