Estes Spectra drifts 0.6 miles. :)

Discussion in 'Low Power Rocketry (LPR)' started by Bat-mite, Sep 10, 2018.

  1. Sep 10, 2018 #1

    Bat-mite

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    My daughter launched an Estes Spectra with booster on Saturday. D12-0 to C6-5. The pads were right in front of trees, which significantly blocked the ground wind. It appeared to be very calm.

    The rocket went up and arced over the trees. We recovered the booster. The chute came out above the trees, I don't know how high.

    We watched it drift with the stock chute until it was almost out of site. The winds aloft must have been about 30MPH, because we found it about 3300' away. Unfortunately, it landed in a newly seeded field, and we were not allowed to recover it.

    Spill holes in the chutes from now on!

    Spectra drift.png
     
  2. Sep 10, 2018 #2

    Forever_Metal

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    yikes...

    All of my lpr stuff has chute holes

    fm
     
  3. Sep 10, 2018 #3

    dhbarr

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    Note that a 20-25% dia spill hole has a hugely beneficial effect on stability, but a surprisingly small effect on descent rate.
     
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  4. Sep 10, 2018 #4

    Bat-mite

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    I wish I knew more about that kind of thing. If that is the case, then wouldn't it make sense to manufacture the chutes with holes already in them? What is the advantage of not having a hole?
     
  5. Sep 10, 2018 #5

    samb

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    I’d guess that the manufactures decided to forego the additional processing steps and associated cost that would impact product pricing.
    In this case I prefer reefing the shroud lines with tape to effectively and temporarily reduce the size of the canopy. OTOH I usually use a steamer in my LPR stagers ‘cause those little puppies get up there ! I prefer the risk of a broken fin on a recovered rocket to losing one over the horizon.
     
  6. Sep 10, 2018 #6

    Bat-mite

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    I have considered this but have been too lazy to buy/install them. :rolleyes:
     
  7. Sep 11, 2018 #7

    DankMemes

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    The RTF models are notorious for weathercocking with the boosters, I lost two firestorms on a 30 acres soccer complex this way, before I quit launching them with the booster there, am curious to see what they’ll do with the 18mm D -qjets when I get them in
     
  8. Sep 11, 2018 #8

    DankMemes

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    Lower descent rate without a spill hole, good for fragile rockets
     
  9. Sep 11, 2018 #9

    DankMemes

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    Exactly the rockets are less likely to cone on descent and reduces tangling in my experience
     
  10. Sep 11, 2018 #10

    Nytrunner

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    Since holes let the air out, the chutes don't tip and "dump" as much. If the right set of circumstances exist, a holey chute may actually descend slower than a solid chute that's dumping air
     
  11. Sep 11, 2018 #11

    Bat-mite

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    Next Q: what size TFR streamer for the Estes RTF kits (~2.4 oz. w/motor, loaded)?
     
  12. Sep 11, 2018 #12

    kuririn

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    Here's an easy streamer length calculator:

    https://www.rocketreviews.com/streamer-calculator.html

    But I'm scratching my head cuz you obviously are an experienced builder with thousands of posts. Don't you know this already? You're pulling our collective legs, right?
     
  13. Sep 11, 2018 #13

    Bat-mite

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    I know more about big fiberglass rockets than I do LPR. I never use streamers in my stuff. This is for my kids, and I honestly don't know the calculations. That link offers up sizes that seem way too big. It also doesn't make any indication of descent rate, or allow you to pick different sizes based on different descent rates.

    And, according to Tim van Milligan, "Figuring out the correct size streamer for your design is a bit more complicated than finding the right size parachute. It will take a lot of drop tests to dial things in and get good estimation of descent rates."

    I was hoping someone who uses streamers on a regular basis would be able to recommend a good size based on experience.
     
  14. Sep 11, 2018 #14

    KarlS

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    One of the benefits of a spill hole is the reduction of swinging/tilting. With no spill hole the parachute will tilt one way to dump air then keep tilting or swinging. On landing this will slam the rocket into the ground. With a spill hole there will much less or no tilting and the rocket will land almost straight. This will save the fins.
     
  15. Sep 12, 2018 #15

    dhbarr

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    One of the problems with trying to predict streamer descent rates in LPR is it very much depends on what kind and size of folding technique.

    For instance, assuming 1mil mylar at 6in*60in:
    - pure scorpion will unroll least / descend fastest
    - pure zigzag will be next
    - first ~48in zigzag remainder scorpion falls slowest
    - ( all these assume corner attach single reinforce )
     
  16. Sep 12, 2018 #16

    scott johnson

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    Estes chutes have dashed lines in the apex of the canopy as a cutting guide....Baby Bertha and Big Bertha come down much more reliably with the hole cut out.....especially Baby.
     
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  17. Sep 12, 2018 #17

    kuririn

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    Related thread:

    https://www.rocketryforum.com/threads/streamer-recovery-question.147913/#post-1813869
     
  18. Sep 12, 2018 #18

    BABAR

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    Glad it was an exciting flight.

    Seems like we are blaming the parachute (and considering modifying the chute on future flights) for a problem caused by the sustainer engine choice.

    From the Estes site for the Spectra

    Recommended Engines: B6-2 (First Flight), B6-4, C6-3, C6-5

    Recommended Engines with D12-0 booster: B6-4 (First Flight), C6-5 (requires booster accessory 2256).

    You ignite a C6-5 engine in a rocket that first is already up in the sky, but more importantly is already at or near Max velocity, now that C6 engine propellant doesn't have to accelerate the rocket off the rod and get it up to speed, all that power does is fight gravity and keep it going to MAINTAIN the speed it already has. Assuming straight trajectory, you are gonna get exactly what you did get, a really way up there chute deployment, possibly outside of visual range.

    Don't have much choice on the booster, but depending on your goals, reasonable to go small on the sustainer. Often when I am staging, the whole point for me is just to successfully stage, not to reach the greatest altitude (if I wanted greatest altitude I would go single stage and put a bigger motor in it.) For an 18 mm engine mount, an A8-5 does the job quite well. The larger nozzle of the A8 engine also gives more reliable upper stage ignition, although for non-gap or short gap stages the Bs and Cs do pretty well also. Ds also have a large nozzle and D sustainers ignite fairly reliably.
     
    Last edited: Sep 12, 2018
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  19. Sep 12, 2018 #19

    bobby_hamill

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    Bat-mite

    Looks like the land owner would let you walk between the rows and get your rocket.
    I have never seen a field covered in seed unless it was grass seed on a sod farm.
    Maybe a farm hand could have recovered it and held it for you ?

    Bobby
     
  20. Sep 12, 2018 #20

    Bat-mite

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    It was grass seed on a sod farm. ;)
     
  21. Sep 12, 2018 #21

    bobby_hamill

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    That is when you need a drone to snag the parachute with a hook and bring it back to ya :cool:
     
  22. Sep 12, 2018 #22

    Bat-mite

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    That's a great idea!
     
  23. Sep 12, 2018 #23

    KennB

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  24. Sep 16, 2018 #24

    samb

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    Not sure what a TFR streamer is so I can't answer that question. My 2 cents:

    Tim VanM is right, calculating descent rates for streamers is darn hard. So I don't do it. :) I'd let your daughter pick her favorite shiny mylar party streamer at <pick any party streamer retailer>. 5 feet sounds about right for a start. Z-fold about half the length and set it under some bricks, books, dumbell for a couple days to set the creases. Then tape it to the shock cord and go have some fun.
     
    Last edited: Sep 16, 2018
  25. Sep 17, 2018 #25

    Bat-mite

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    TFR = Top Flight Recovery

    Ripstop nylon streamers. They offer multiple sizes and colors. I picked up a few 2" X 20". We'll see how it goes. Seriously, though, those RTF and ARF kits almost need no recovery material; but RSOs may frown on tumble recovery.
     
  26. Sep 17, 2018 #26

    Normzilla

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    What did you use to track it? Or was it eyeballed for the map?
     
  27. Sep 17, 2018 #27

    Bat-mite

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    Eyeballed. We watched it sail out of sight, then later drove out in that direction until we saw it. Fortunately, on a dirt field, it wasn't hard to see.
     
  28. Sep 17, 2018 #28

    snrkl

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    I use ripstop nylon for streamers exclusively now. I bought a few meters of fluorescent yellow from the local fabric shop for $8, and cut what ever size I want using a metal ruler and a 40w soldering iron. The little hole in the metal ruler is great for making a durable hole in the streamer with the soldering iron, as it seals the hole.

    I also use streamers in my 2 stage LPR boosters - on my scratch BT60, it was held in a pod attached to the sustainer, but mounted around the MMT through the wall on the booster.

    On my sports scale Nike Apache, I used a rear eject pod in the booster with a 100mm wide streamer that worked a treat.
     
  29. Sep 18, 2018 #29

    samb

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    Cool. Nylon is certainly durable. Just never used one of those. So now all you need is another stager for your daughter.
     
  30. Sep 18, 2018 #30

    Bat-mite

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    Oh, we have several. ;) Awhile back, Estes had a sale where you got two ARF rockets and a booster for the price of one ARF rocket. We stocked up. :cool:
     

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