TARC frustration: advice needed

Discussion in 'Competition Rocketry' started by neil_w, Feb 14, 2019.

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  1. Mar 8, 2019 #211

    neil_w

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    Anyone have an intuitive guess (or experience) whether properly-packed eggs are likely to survive a 15 G launch? Seems kind of rough.
     
    Last edited: Mar 8, 2019
  2. Mar 8, 2019 #212

    boatgeek

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    15G is a little steep, but I've seen 10G with absolutely no problem. If they're in the soft foam casings, they're probably fine.
     
  3. Mar 8, 2019 #213

    neil_w

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    It does seem steep. Could add a couple of ounces to the rocket to get it down to 13 G. Hmm.
     
  4. Mar 8, 2019 #214

    Ez2cDave

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    Impact breaks far more eggs than acceleration does . . .
     
  5. Mar 8, 2019 #215

    neil_w

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    Yeah, but I figure there's gotta be a limit on acceleration before problems crop up. Trying to guess whether an F67 would work here. Now that I think more about it, I wonder if we'd even be able to tell if the eggs broke on the way up or down?
     
  6. Mar 8, 2019 #216

    Steve Shannon

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    The force when the chute opens may easily be more than 15 gees.
     
  7. Mar 8, 2019 #217

    neil_w

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    Ah well that would seem to answer it....
     
  8. Mar 8, 2019 #218

    boatgeek

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    You'd have to CSI the pattern of how the yolk ran, down into the base of the rocket or up toward the nose. Or, in the case of our TARC team from years ago, ejected at apogee into the top of a tree, exploding into a fine mist covering our NAR witness. :oops:
     
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  9. Mar 8, 2019 #219

    JJSR

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    Neil we'll be at the field tomorrow, if the girls want to come and try..
    We'll also be there the 16th and 23rd for other teams that have testing this weekend.
    Get them to come out at least to see how it all works.
    Our Lodi team will be there tomorrow, they've hit within the top 100, 5 out of 6 or 7 years they've been flying with us.
     
  10. Mar 8, 2019 #220

    neil_w

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    Definitely hoping for one or two of those days, although tomorrow will be tough.
     
  11. Mar 8, 2019 #221

    Ez2cDave

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    PLEASE tell me you have video of that . . .
     
  12. Mar 9, 2019 #222

    Trip Barber

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    "Anyone have an intuitive guess (or experience) whether properly-packed eggs are likely to survive a 15 G launch? Seems kind of rough"

    I have never seen properly-cushioned eggs break from launch acceleration in a TARC rocket. They break from slapping into each other internal to the capsule at the time of the shock of ejection or landing due to insufficient between-egg padding, from getting poked by an altimeter or other piece of hardware inside the capsule that is not isolated from contact with the eggs by a disc or padding, or from the shock of landing when the capsule hits sideways rather than end-on since padding is normally thinner on the sides of the egg than on the ends. Of course when a rocket augers in for a crash with a failed recovery system all bets are off! I have watched four or five thousand TARC rocket launches.

    Trip Barber
    NAR TARC Manager
     
  13. Mar 15, 2019 at 4:13 PM #223

    Ez2cDave

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    So, 30 days later . . . What's going on with the team, Neil ?

    Dave F.
     
  14. Mar 15, 2019 at 4:19 PM #224

    afadeev

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    I don't think Neil owes us, or anyone else, and update on this.

    There is a fine line between a Good Samaritan outreach, helping out someone else's kids, and flipping that into an suicide mission obligation with status updates to total strangers.
    That's way too weird, and too far down the "no good dead shall go unpunished" trail.

    a
     
  15. Mar 15, 2019 at 4:34 PM #225

    neil_w

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    I don't mind giving an update here, mainly because I'm feeling ever so slightly optimistic at the moment. :) This has been a bit of a rollercoaster (and afadeev has been on the other end of a lot of my venting).

    Anyway, I spent some time with them and went through all the fixes I thought would be required to make the rocket safely flyable (including but not limited to: installing the altimeter + making holes, shortening and securing the payload section, adding a parachute to the lower half of the rocket, cleaning up the parachutes of the top half of the rocket, and cleaning up the upper rail button). All of them have now been implemented. Unfortunately it's basically one girl working at this point, being helped by her parents. Not much of a team.

    I suggested that the team should do some experiments to figure out how much reefing the chutes need to ensure they'll come down in a reasonable amount of time. According to my sims dual-21" chutes will be way too slow. Don't know if they've done that yet.

    The main thing is that the rocket seems to be flyable now, to my eyes anyway. They've acquired a couple of single-use F20s that should get them to 800+ ft or thereabouts. Their plan (I think) is to use those motors for practice, then buy a couple more for qualification attempt if the rocket survives. Finding a flying opportunity will be the challenge now; unfortunately they are not available on the next couple of Saturdays when RadRocks will be open for TARC flying. Their schoolyard is quite small (about 400' square) so I'm not too hopeful of them getting back the rocket if they fly it there unless it's a *really* calm day, and those tend to be in short supply in March.

    But at minimum, they (she) learned a bit more about the various things that go into a working rocket, and some techniques. I am told she has come out of this more interested in it than before. I'm crossing my fingers that they can get some flights in now.
     
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  16. Mar 15, 2019 at 4:37 PM #226

    JJSR

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    We had quite a few teams show up last Saturday. (Some unannounced and a surprise to our BoD.) I'm not the only mentor at our club, so I didn't meet everyone that showed up, not sure if this particular group of kids showed.
    We will be out this weekend again for a TARC ONLY launch, due to some schools having testing last week.

    The invitation is still open for them to come. Like I've said, even if they only come the see the other teams fly and how it all works. They will be able to come away with vital info for next year.
     
  17. Mar 15, 2019 at 4:39 PM #227

    neil_w

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    Sadly they have an unbreakable conflict the next two Saturdays. It really is a bummer, going up there to fly would be by far the best thing for them.
     
  18. Mar 15, 2019 at 4:41 PM #228

    JJSR

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    Would a Sunday work ???
    I CAN make that happen!
    We try our best to get any team flying for TARC
     
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  19. Mar 15, 2019 at 4:46 PM #229

    neil_w

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    It might! I'll continue this in PMs.
     
  20. Mar 16, 2019 at 12:38 AM #230

    Ez2cDave

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    I don't think anyone appointed you to any position of authority here . . .
     
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  21. Mar 16, 2019 at 12:44 AM #231

    Ez2cDave

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    While things certainly aren't great, at least some progress is being made.

    As to the number of kids on the team, were there more initially and they lost interest or was there not much "genuine interest" at any point ?

    I really feel bad for these kids . . . It's a shame they got short-changed by their teacher.

    Thanks for the update.
     
  22. Mar 16, 2019 at 1:42 AM #232

    JJSR

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    What makes you think they got "short changed " by the teacher?
     
  23. Mar 16, 2019 at 3:35 AM #233

    Ez2cDave

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    Joe,

    This may require you to actually read the thread for content . . .

    A brief summary . . . Teacher has no rocketry skills ( Post #1, Post # 17, Post #21, ) . . . Reused an old design ( Post # 1 ), meant for another set of TARC requirements, didn't follow up with the NAR Mentor or seek out a new on if the Mentor "dropped the ball" ( Post #80, ) . . . ( Post #57, Post #59, Post #63 ) =, etc, etc, etc

    ( Post #2 - How'd that work out ? ) . . .

    ( Post #154 - Why bother starting the thread, then ? )

    ( Post # 159 - I list the Mentors . . . Post #161 - Well ??? )

    ( Post # 168 - You don't ) ( Post #171 - Post #172 )
     
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  24. Mar 16, 2019 at 1:05 PM #234

    neil_w

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    Looking ahead to the finish line right now, not interested in rehashing what got us here.

    The girl(s) will do a practice launch on Sunday, thanks to a way-above-and-beyond effort by jjsr.
     
  25. Mar 16, 2019 at 3:52 PM #235

    Ez2cDave

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    Neil,

    Good deal . . . Best wishes to them !

    If possible, post up some pics of the rocket and video.

    Dave F.
     
  26. Mar 16, 2019 at 4:49 PM #236

    neil_w

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  27. Mar 17, 2019 at 12:42 PM #237

    Ez2cDave

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    It's Sunday . . . Time to fly !

    Wishing the team much success !

    Dave F.

     
  28. Mar 17, 2019 at 7:01 PM #238

    neil_w

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    Executive summary: a bit breezy but manageable. Got 3 flights in (1xE16 and 2xF20), all parts recovered with no (or minimal) damage. One broken egg. Altogether a *very* successful day.

    Full report later.
     
  29. Mar 17, 2019 at 7:48 PM #239

    JJSR

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    Over all a good day for all the teams.

    Neil, those girls are interested, even if next year at HS they don't have a rocketry team/club.
    I reminded them all extracurricular activities start with someone having interest and finding others to join in.
    I'm pretty sure the dad will be back. lol
     
  30. Mar 17, 2019 at 8:40 PM #240

    neil_w

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    Thanks again to you and the club and the farm for providing launch venue (and igniters!). I dunno if the girls will want to continue, but I think for sure they had a good successful experience today to motivate them.

    Full report:
    Weather forecast said 8 mph winds, it felt stronger than that though, and the girls were cold. So we did as much prep as possible inside the warm car. As the day went on the sun got stronger and it got a bit more comfortable. Wind direction was not optimal but not terrible. Recovery would mostly be in fresh fields, with a healthy amount of mud.

    Here's a team picture with the rocket. That's me over on the left.
    tarc-team.JPG

    First flight: Estes E16-6, only the frontmost egg loaded. We reefed the chutes in the payload section about 6" to get started. We had some igniter troubles but Joe provided some of his own hand-dipped igniters and they worked great. It was a slow takeoff and flight, but straight and true; the E16 is just *barely* enough to lift that rocket. Slightly late deployment, but fine. The payload section landed on sod (woohoo!); the booster section didn't fare so well and splashed down in one of the ditches. Fortunately only the tail end went into the water, and we were able to get the motor out and dry everything off. Altimeter said 400-something feet, quite a bit lower than OR estimate. So I prepared for the following flights to be low as well.

    Second flight: AT F20-4W, fully loaded with eggs. We left the chutes as before, because we had insufficient data to know what adjustment to make. Flight went up pretty well, a bit waggly probably because of the 3 small fins. The payload parachutes were very late to open for unknown reasons; eventually one of them opened fully but the other stayed closed. The booster deployed fine under its 18" chute and landed on the road. All parts recovered, frontmost egg broke however. Altimeter said about 720', flight time was 20-some seconds due to late deployment.

    This is a not-very-good video of the "up" part of the flight:


    Third flight: for this one I let the girls do most of the work, although they still needed a bit of help. We adjusted the way we packed the eggs, and moved the reefing up a few inches on the payload parachutes, and reefed the booster section chute about 6". Again on an F20-4W, flight looked very similar to the first except this time everything deployed *perfectly* at apogee. The two parts of the rocket came down right next to each other, and landed quite close to each other in a nice dry field. All eggs survived. Total flight time a very good 50 seconds, but only 680'. For qualifying we will get some stronger motors, and move the reefing up even more on all chutes to decrease the descent time. Here's a crappy still from the video of the third flight, which is not worth watching:
    launch-still.JPG

    I don't know when exactly they'll get a chance to attempt their qualifying flights, but they had a darn good day of flying today, and the rocket performed well enough.
    I had about as much fun (maybe more) as when I fly my own stuff. The fact that we got everything back intact definitely helped. :)

    Footnote:
    Of the four rockets flown by the teams at her school, this is the only one that was recovered successfully and flown more than once. Yesterday one team flew their rocket in the schoolyard with an E12-8 (I kid you not), and unsurprisingly it lawn darted before deployment.
     

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