Launched my first two LPRs today! Both failed!

Discussion in 'Low Power Rocketry (LPR)' started by bigxmac, Mar 18, 2018.

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  1. Mar 18, 2018 #1

    bigxmac

    bigxmac

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    Estes Hellicatwith a C5-6 Engine
    ————————————————
    I was concerned that the parachute might not deploy because it was difficult to fit in there with the nose fins.

    -Result-
    The rocket went as high as it could. The parachute didn't deploy. One of the nose's fins broke on the inside, presumibly due to impact. The rocket broke into two pieces. I assume it's because the pressure buildup couldn't push out the parachute and had to go somewhere, so it went out the sides.

    IMG_2050.jpg

    Estes Mini-Comanche 3, launched with 2 stages, a A10-0 in the bottom stage and a A10-3T in the top one
    —————————————————
    My only concern was with the third stage, which I didn't launch.

    -Result-
    The rocket seemed to work at first. The second stage came off as planned and spun down to earth. The first stage however also broke and spun down (not supposed to happen). The streamer recovery did not deploy. The second motor still seemed to be in the second stage although it did burn. The rocket was hot and smoking. It has a strong burning smell not present in the Helicat.

    IMG_2047.jpg IMG_2048.jpg IMG_2049.jpg

    Could someone more experienced give some insight into what may have went wrong? Since both recovery systems failed to deploy there must be something I did wrong. Could I have used too much wadding? I'm really stumped on what went wrong with the Mini-Comanche 3 causing the first stage to break off and become charred.
     
  2. Mar 19, 2018 #2

    lakeroadster

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    Possibly the nose cones were way too tight or the chute got hung up on the shock cord mounts.

    Did you paint the section of the nose cone that fits into the body tube?
     
  3. Mar 19, 2018 #3

    bigxmac

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    I did paint the section of the nose that goes in the body on the Mini-Comanche 3, but not on the Helicat
     
  4. Mar 19, 2018 #4

    Cabernut

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    For the Comanche, was the top stage friction fit as well? My first thought is if the two were taped together for staging, but only the bottom was friction fit, then upon staging, the upper stage engine would be free to slide up out of the motor mount and fry the rocket from the inside-out.
     
  5. Mar 19, 2018 #5

    LithosphereRocketry

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    Did you make sure the shock cord wasn't tucked in the NC shoulder? I've had that happen to me...
     
  6. Mar 19, 2018 #6

    kuririn

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    We can only speculate, but sounds like the recovery gear was too tightly packed or the nose cone was too tight for both rockets. I have a Mini Comanche, the double streamer packs very tightly in the tube. Instead of rolling them together, you may want to consider rolling the streamers separate and packing them in one on top of the other. I actually fold my streamers, doubling them up until they are about an inch wide, then rolling them into a cylinder and packing it in. The burning of your top stage of the Mini Comanche might be due to the enclosed hot ejection gases not being able to immediately release. Another possibility is an engine CATO, though not likely. And yes, the trifold shock cord mount can obstruct the recovery gear and keep it from sliding out at ejection. Consider using a Kevlar shock cord mount for future builds.
    For parachutes in minimum diameter rockets, consider modifying your packing method to make a longer, skinnier "burrito" so it doesn't jam in the tube.
     
  7. Mar 19, 2018 #7

    MALBAR 70

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    On the Mini Comanche, Is it possible that the motors were accidentally reversed? The fin can looks like it was blow torched. That could happen if a -0 Delay motor were to be used in the sustainer by mistake.
     
  8. Mar 19, 2018 #8

    Zeus-cat

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    A rule of thumb for nose cones is that you should be able to pick up the rocket by the nose and shake it lightly and the nose stays on. With a little more effort the nose should come off. And the parachute and wadding needs to slide. You aren't packing another round to fire at the Yankees with your muzzle loader! Don't ram that stuff in there; pull everything out and repack if necessary.
     
  9. Mar 21, 2018 #9

    BABAR

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    Hmmm. The HeliCat is a “right sized” version of the Cosmic Cobra, meaning a much longer body tube. You should have plenty of room for wadding, chute, and the rotor blades ( packing the Cobra for me was always somewhat tight.) As said, we can only speculate but for an ejection charge to blow out the sides of a Rocket strongly suggests nose cone, chute, and/or wadding was too tight. For low power rockets, if packed right, without engine in place, you should be able to blow into the engine mount and pop out everything. If YOU can’t do it, engine ejection charge probably won’t do it either.

    HeliCat and Comanche are great rockets, not best choice for your first foray into Rocketry, however. Hope you don’t get discouraged. Try some basic streamer or chute single stage level 1 or RTFs. The miniT engine rockets and engines are inexpensive, usually easy builds and good small field fliers with the lower rated engines.

    Good luck!
     
    Last edited: Mar 21, 2018
  10. Aug 22, 2018 #10

    MoeB

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    One thing I can add is try not to become discouraged from these initial attempts. See that 2x upscale Mars Lander I'm holding? On its second flight the nylon webbing shock cord broke and the rocket free-fell from altitude thus ending its flying life. It was hard to watch and pick up the pieces but it didn't discourage me.
     
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  11. Aug 22, 2018 #11

    bigxmac

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    Haven't replied in a while or checked the forum, but I've since built and launched another rocket. It was a success, but unfortunately I lost it in the weeds/grass which had grown considerably since my last launch in late winter. Going to be busy with college the next few months, but definitely a hobby I plan on continuing
     
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  12. Aug 22, 2018 #12

    MoeB

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    Good to hear. College is very important! Try to get back to the hobby when you can...I've been in and out of it several times over the 43 years since my first launch in 1975.
     
  13. Aug 22, 2018 #13

    Rockyt

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    If at first you don't succeed....try, fly again
     
  14. Aug 22, 2018 #14

    Bat-mite

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    Discouraging, but we've all been there. I hope you do try again!
     
  15. Aug 22, 2018 #15

    DankMemes

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    Yeah, rockets come and go, but its still fun to fly, definitely recommend picking up some E2X or RTF rockets. If you know where to look like Hobby Lobby with the 40% off coupon or online at AC Supply co you can pick up many for less than ten bucks. Lets you experiment with different engines, and some even have booster combinations that let you practice flying and recovering without risking someting you spent a while building...

    Some really well flying e2x/rtf models I recommend are

    Alpha III
    Sky Twister
    Firestorm
    Helios

    Lots of fun and with the plastic fin cans I can speak from experience that all of these models can survive a failed chute deployment.
     
  16. Aug 22, 2018 #16

    SteveThatcher

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    Keep on trying. The old axiom I go by is "the lifetime for a rocket in your hand is at least one more launch..."

    I have a PML quasar that has seen numerable flights. I had a 3" phenolic rocket that I launched exactly once years go. It flew to 1000 feet, the parachute deployed, and I watched the knot unfurl and the bottom of the rocket came "crashing" down. I did safely recover the nosecone and parachute... :)
     
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  17. Aug 24, 2018 #17

    BABAR

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    Good to see you keep trying.

    Something to think about, go to Hobb Lobby and get the Viking Rocket Classroom Bulk pack with the 40% off coupon. Will run you $30 plus tax and you get 12 rockets.

    The Viking Flies on anything from 1/2A6-2 to a C6-7. An A8-3 is a good first flight choice. It is an easy build and recovers on a streamer, so doesn’t drift as far. Because it is cheap and doesn’t take a lot of time to build, you can play around with engine choices and not feel so bad if you lose one (or six!) It comes with 5 card stock fins, so you can play with 3, 4, or 5 fin styles, build it with fins swept forward or back, and because there is no balsa to fill, it paints up pretty nice without much prep work. Give one to a friend or sister or brother or mom or dad to build.

    Even when you go on to fancier and more expensive rockets, not a bad idea to fly one of these as a first launch of the day. Gives you an idea what the winds are REALLY like, and you can adjust your engine choices and launch rod angles for your more valued rockets accordingly.
     
  18. Aug 24, 2018 #18

    Alan15578

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    I can't really diagnose the problem any better than you can. However, this reminds me of my very first rocket flight. I knew nothing, other than what I read in the instructions. I knew nothing of this wadding, and I did not have any flameproof wadding. I did understand that something was needed to protect the parachute from hot ejection gasses. The only thing I could think of was like a spit wad. I whetted some TP and put that into the rocket. This damp tissue formed a plug that would not slide in the tube, so the rocket over pressurized and totally ruined the rocket. Lesson learned. My second rocket was a two stage Apogee II which had many successful flights. Don't give up.
     
  19. Aug 26, 2018 #19

    Andrew_ASC

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    8CDE79A8-C7F4-44F8-A443-46D81A617DED.jpeg
    Recovery is key.

    When you pack shock cord. Zig zag it neatly in the palm of your hand. It goes a long way to use the right techniques when packing shock cord. I’ve used dry toilet paper in a MPR Estes Conquest which flies on an E-12. Don’t form a tight plug for wadding, you want it to move with touching fingers to it, it’ll feel firm, but it slides easy while being large enough to protect the chute.

    You need to fold the chutes in a way they unfold easily. Start by folding it in halves, then bury the cord inside neatly in a upside down U, then fold halves again, roll, and roll the excess cord around it. You may find detailed burrito pictures on the recovery section.

    Sure you can buy fancier nomex squares at Apogee, but why spend more money for a low power rocket?

    Recovery failure is a common failure of even high power rocket launches when the wrong techniques are used by inexperienced flyers. Don’t give up.
     
    Last edited: Aug 26, 2018
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  20. Aug 26, 2018 #20

    rharshberger

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    First of all NEVER use toilet paper, it is not fire retardant, Estes wadding is. A cheaper alternative to Estes wadding is cellulose insulation (Green Fibre is one brand, no fiberglass), cellulose insulation will generally be referred to as "dog barf" ( get it wet and see what it looks like) is actually shredded and fire retardant treated paper.
     
  21. Aug 26, 2018 #21

    Andrew_ASC

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    Yeah I screwed up on the toilet paper part. Use Estes wadding.
     
  22. Aug 27, 2018 #22

    Woody's Workshop

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    My first thought was when I started reading the OP was too much wadding, and/or packed too tight.
    My beginning years I did that just once.
    I usually tear off one sheet at a time and loosely make a ball until it's big enough to fill the air frame.
    It should slide down fairly easy, and tap with a pencil or dowel rod (or launch rod) around the sides to seal against blow by.
    I've never used dog barf, I have tons of wadding from over the years...and igniters too.
     

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