Big Daddy Lawn Darts... Show of Hands Please.

Discussion in 'Low Power Rocketry (LPR)' started by K'Tesh, Feb 1, 2016.

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  1. Feb 3, 2016 #31

    Daddyisabar

    Daddyisabar

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    Lawn darting your Big Daddy is a right of passage, a great honor. You love it so much and fly it so much that sooner or later you are going to do something stupid, a part is going to fail, or a combination of factors will lead to a lawn dart. It is a stubby rocket with a big nose cone and shoulder on a thin LPR tube with LPR components. Why should I not expect nothing less than awesome perfection?

    With the thousands of BP SU motors I have used the only ejection failure was in my first Big Daddy and it lawn darted. With Der Grosser Vatti I had driven all that way and by Jove I was going to launch it, blast the wind! An E9 4 that had a bit of a wimpy ejection (The top clay plug was about 2/3 in tact) coupled with the wind and a highly arched flight path that resulted in a lawn dart. The Horror. Time to use the recovered fin can from Der GV and my repaired first Big Daddy for a hacked together two stager! Now that was only a semi-stupid idea because I was just on the edge of what the D12-0 could lift. Tried two flights and got mud on the nose cone both times. Had to retire it even though the Pad Fuehrer thought I could get it to work, I was just too scared.

    Now is it just my stupidity, expectations, poor maintenance/techniques or bad luck? NO. It has to be a fundamental design flaw!:rolleyes:
     
  2. Feb 3, 2016 #32

    Crazyrocket

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    I've had two lawn darts. One got turned into frankendaddy on the repair (see my avatar) and the other had no damage luckily. Most likely it was my fault due to bad packing of my chute and nomex that was too tight for the limited space.
     
  3. Feb 3, 2016 #33

    ThirstyBarbarian

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    The time I stuffed the nylon chute and oversized nomex in my Big Daddy, causing a tight fit and failure to eject the nose cone, it was at a club launch. The rocket arced over and started coming down like a bomb toward a nearby creek bed. The LCO sounded the horn and started warning everyone, "Looks like it's coming in ballistic. Heads up, everyone! Heads up!" And at the last second he shouted, "LOOK OUT, KIDS!!!"

    Exciting times!
     
  4. Feb 3, 2016 #34

    Daddyisabar

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    I just might have to go with fundamental design flaws. A fat, short stubby rocket with four huge fins that likes to weathercock even in a slight breeze. Thin plastic nose cone that expands in the heat with a thin paper tube that can swell in the humidity. And what about all the tape you have to use when it is real cold but then it warms up as the launch day continues? Motor ejecting out a small 24mm area into a huge body tube diameter with tightly packed wadding and recovery gear, hard to get a good piston effect on the nose cone base and shoulder. Very suspect shock cord mounting, and a short, flimsy rubber shock cord at that. It is a first time rocket for many that just screams for all the cool mods and equipment upgrades I read about here on the forum, but can the design handle all the mods and upgraded recovery gear? Can the design handle the occasional weak ejection charge? Just a little damage to the short thin body tube and that darn big shoulder on the cone gets real tight, hard to repair. Constant cleaning and sanding of the cone's shoulder is right out. Like the early M16s in Nam the awesome design should work all the time without cleaning. Wow. I feel much better now and can start to remember all the good flights and not focus on the horribly embarrassing lawn darts that all but shattered my fragile BAR confidence. My next one will be called Big Daddy Warbucks and I will do the Dr. Evil "It's A Hard Knocks Life Rap" when I take it to the pad.
     
  5. Feb 3, 2016 #35

    rharshberger

    rharshberger

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    Sure it can take all the design mods we like to do, it just won't fly on 24mm D and E motors very high if at all. :)
     
  6. Feb 3, 2016 #36

    Rex R

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    they don't weather cock noticeably if you fly them on an F39-6 :).
    Rex
     
  7. Feb 3, 2016 #37

    rharshberger

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    Nope, they teleport!
     
  8. Feb 4, 2016 #38

    Fishhead

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    A seven day delay?!?!?!
     
  9. Feb 4, 2016 #39

    rharshberger

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    There a few MD's that might need a delay that long.....
     
  10. Feb 4, 2016 #40

    Fishhead

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    My Big D gave me two flawless flights back in 2001 before post-holing on the third flight. All three flights were D12 powered, but the first two had very distinct ejection charges while the charge for the ill-fated third flight was inaudible. It landed out near the edge of the field, mere feet from skewering the Mazda 323 of a fellow rocketeer. (He thought that would have been "AWESOME!") Post-mortem inspection showed only minor discoloration of the dog barf, leading all to believe that the ejection charge was underpowered. The top of the body tube was crushed fairly thoroughly and the entire bottom of the nose cone shoulder was cracked. Despite all this it could fly again, and now that I think of it, it just might. I don't have any pictures of any of the first three flights.
     
  11. Feb 4, 2016 #41

    MALBAR 70

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    Had several wonderful flights on my Big Daddy. I was starting to think that all this stuff about the NC not popping off was a bunch of hooey. How wrong I was. At a club launch the end of last summer I put my BD up on an E 12 4. Weather it was a weak ejection charge or too tight a nose cone I'll never know. The Big Daddy came whistling in fast and completely buried it's self with an audible "whump" along with my favorite CATO chute in the soft soil of the pumpkin patch opposite the flying field. We searched for about 45 min. but no luck...RIP Big Daddy...
     
  12. Feb 4, 2016 #42

    loopy

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    Stupid auto-correct....
     
  13. Feb 5, 2016 #43

    rstaff3

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    When mine darted, Jim's did too. I have 2 others, both of which have modified nose cones. These were modded for other reasons, but it fixes the lawndart issue too.

    8861277512_12e46c9fba_o.jpg
     
  14. Feb 5, 2016 #44

    Fishhead

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    I thought that was what you used at NSL.
     
  15. Feb 5, 2016 #45

    kcobbva

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    Your blue one looks just like mine did in 04. Recognized the Stubbier look immediately!
     
  16. Feb 5, 2016 #46

    loopy

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    I hate you...
     
  17. Feb 7, 2016 #47

    Sooner Boomer

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    I didn't do a lawn dart, more like a parking lot prang. My fault. Wimpy motor with too long of a delay. Ejection charge went off and blew the nosecone into the asphalt, just as the chute fully inflated and stripped the shrouds. It did everything but catch on fire and sink into the swamp.

    One thing I was playing with is a cardboard cup that holds the parachute. The Daddy is so short, is there any way to build a baffle into one?
     
  18. Feb 7, 2016 #48

    rharshberger

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    With its size it would probably be easier to build a piston into it.
     
  19. Feb 18, 2016 #49

    Kruegon

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    Been there, done that. Lost mine last month. I believe it was the 6th flight. She whistled in very nicely. You could see that the nose cone was only 1/2 way out. I talked to my club president about it. He's seen at least 4 of her flights. All flawless. He believes that my particular problem was in a weak ejection charge. I told him of the discussions here. He suggested I contact Estes regarding it.

    ImageUploadedByRocketry Forum1455768346.704409.jpg
    ImageUploadedByRocketry Forum1455768366.820685.jpg


    Sent Estes an email on it. Told them what happened and what the club president said. I received a replacement kit and a pack of motors.

    To be honest, a weak ejection or a design flaw in the nose cone is manufacturer error. I'm not sure how I feel about getting the free replacements. Continuing to fly a rocket with known lawn dart issues seems almost operator error. Not to mention that it could be argued that flying a risky rocket technically breaks the NAR MRSC.
     
  20. Feb 18, 2016 #50

    impulse09

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    It's been a while since I built one of these, but would it help to shorten the NC shoulder and extend the motor tube a bit?
     
  21. Feb 18, 2016 #51

    Trident

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    Well, by all means keep us updated on when you plan to launch it. Most items on my bucket list are vacation-oriented, but I'm willing to add performance art to the list ...
     
  22. Feb 18, 2016 #52

    Daddyisabar

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    If the wind is calm, which it is forecast to be, come to the launch Saturday morning. Will have just one scout pack to get through and then I might have the courage for the Roachworks Hercules and the MIRV for some skywriting. Will have to watch Austin Powers again for the hard knocks lyrics.
     
  23. Feb 19, 2016 #53

    Kruegon

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    Shortening the shoulder seems to be the only requirement.
     
  24. Feb 21, 2016 #54

    Trident

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    I could not make the launch today but will be at the next. I'll also have some new stuff to fly, if the weather holds for awhile. I'm trying to get everything out of the "primer-only" stage, and get them painted. And if not, I have about 25 others I could fly ... :)
     
  25. Feb 22, 2016 #55

    Daddyisabar

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    Sorry you missed it. It was a great day with periods of nearly calm wind and totally cloudless sky. The biggest bummer was there were no Big Daddy's (that I saw) launched! We did get to see an awesome Estes V2 lawn dart as there might have been a bit too much grease on that AT delay. They said the nose cone was in a good four to five inches. Looked like there was enough body tube to salvage the fin can. Tough rockets those Big Daddy's and V2s. Just pull 'em out, hack away and start the repair. It is OK for the big kids to cry over their crashed rocket too!
     
  26. Feb 23, 2016 #56

    Barkley

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    We had a high powered V2 lawn dart at our last launch, but... the nose hit tarmac. That's a battle it just couldn't win.
     
  27. Feb 24, 2016 #57

    Trident

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    I have an old Estes V-2 (2.6") primed and ready to paint. Will bring to next launch. I also bought some Red Max type decals for a Big Daddy (Sandman's Der Grosser Vati decals) but haven't started that one yet. I should have my Interceptor-E done, and possibly my Saturn 1B, although that would require amazingly warm weather to get painting done.
     
  28. Feb 28, 2016 #58

    jqavins

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    OK, BDs lawn dart a lot. The right question is: do BDs lawn dart more often per hundred flights than other models? More than other models with the same nose cone? It's a popular model, so one should expect that lots of flights will yield lots of darts. (I've build two, one heavily modified, flown each once, and no darts.)
     
  29. Feb 28, 2016 #59

    John Beans

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    It's been said before, but I think the big ramp on the nosecone base around the tether point is a mistake, because the nosecone can vent the ejection charge after just a little bit of travel.
    Coupled with the fact that there's not a *huge* amount of length to the fuselage to put parachute in, I'd advise cutting off the nose cone base right where the angle starts and replace it with a bulkhead and an eyebolt.
    for extra chute space, mount the bulkhead up inside the nosecone a ways.
    And by customizing it, you can get clever and use the space in the nose cone for an altimeter.
     
  30. Feb 28, 2016 #60

    Oberon

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    Has anyone ever lawn darted a Leviathan or an Executioner? Seems like if it's just the cone, those birds ought to suffer the same issue.
     

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