Recycling Container Oddroc

Discussion in 'Oddrocs' started by JLRockets, Jan 7, 2011.

  1. Apr 22, 2011 #21

    JLRockets

    JLRockets

    JLRockets

    Just Judy TRF Supporter TRF Lifetime Supporter

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    After a long absence, JLRockets is pleased to introduce . . . . the centering rings! We have three freshly cut rings made of ½ inch Baltic birch. The top two are 18 inches in diameter, and the bottom started as 18 inches in diameter before the sides were cut to accommodate indents in the bottom of the bottle. All three have a 7.5 inch hole for the stuffer tube.

    Jackson and Augie cut the rings with the help of Augie’s father Frank. I forgot to bring the camera to Frank’s shop, so you’ll have to make do with photos of the finished product. After a great deal of measuring and re-measuring, the boys rough cut the rings with a jig saw. Then they trimmed to size with a shaper. When we liked the fit, they used the jig saw to rough cut the 7.5 inch center hole in one of the rings. Then, they got the inner hole perfect using an oscillating spindle sander. That became the template for the other two. They used the template and a router to cut the center holes on the remaining two rings. They also cut the hole in the bottom of the bottle with a router. The best part is, they both still have all 10 fingers! Job well done boys.

    Although we have the basics for the core, we can’t start the attachment until we finalize the fin design. More on that later.

    Photos are: the core of the rocket beside the bottle; the finished centering rings; the motor hole in the bottom of the bottle; the bottom centring ring fitted into the indents; dry fit view from the top.

    bottle_aside_core.jpg

    fresh_cut_centering_rings.JPG

    bottle_bottom_with_hole.jpg

    bottom_centering_ring.JPG

    dry_fit_from_top.jpg
     
  2. Apr 22, 2011 #22

    SMR

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    Nice looking rings. And, yes, keeping all your fingers IS the most important part. Great job!
     
  3. Apr 25, 2011 #23

    JLRockets

    JLRockets

    JLRockets

    Just Judy TRF Supporter TRF Lifetime Supporter

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    After much deliberation, hemming and hawing and back and forth, JLRockets has – finally - chosen a fin design.

    The credit for this design must be given, in large measure, to the newest member of our project advisory team, Judy’s father Florian, a retired aeronautical engineer who has designed parts of the F-series fighter jets. After reviewing the challenging aerodynamic situation, Florian solved the problem with a single utterance: “winglets” (like most engineers, he’s a man of few words).

    Some of you may have noticed that the winglet idea is already in use by fellow bottleteer Sather (SMR). Great minds think alike. The winglet solution clearly goes back to their shared history – Florian has designed fighter jets, and Sather has flown fighter jets. So, the winglet connection is not just a random coincidence. Apparently, winglets were the tool of choice to fix post-production aerodynamic problems in the days before simulated flying. (Okay, we’re just copying Sather. After all, this whole bottle thing was all his idea.)

    Lexan is too heavy and has too many flap issues (even with the winglets), so we have officially abandoned lexan. No more pretending that our oversized rocket is not really a rocket, just a flying soda bottle.

    After considering every single conceivable fin material, we have settled on making our own fin material by laminating thin pieces of G10 onto a piece of foam. These fins will be much lighter than lexan fins, and even lighter than plywood fins. With the lighter fins, we may even be able to keep it light enough for a skid.

    Because of the winglets, the span on the main fins will be small enough to get the rocket into the minivan. We figure if we make the winglets removable (they will bolt onto the main fins), we can get away with permanently attaching the main fins. This clears up a number of engineering challenges.

    So, the final fin design is: permanently attached winglet-ed fins made of foam core G10 laminate.

    Up next: results of the scale model test

    View attachment RB G10-foam fins side.pdf

    View attachment RB G10-foam fins base.pdf
     
  4. Apr 25, 2011 #24

    JLRockets

    JLRockets

    JLRockets

    Just Judy TRF Supporter TRF Lifetime Supporter

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    My apologies. I attached the RockSim drawings as pdf's, not jpg's, so you have to click on them to see them. Here are the jpgs, which will display even if you don't click.

    Final fin design: permanently attached, winglet-ed fins made of foam core G10 laminate.

    RB G10-foam fins side.jpg

    RB G10-foam fins base.jpg
     
  5. Apr 25, 2011 #25

    JLRockets

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    To test our fin concept, Jackson built a one-eighth scale model. We chose one-eighth because we had 2.6 inch tube sitting around, and that scales to one-eighth of the recycling bottle’s diameter. We built the model so that the stability parameters would exactly match those in the current design. That meant a margin of .6 loaded. The CG was 46% from the top of the rocket in both the scale model, and the predicted real thing.

    We had to add about 10 ounces of nose weight to get the CG in a comparable spot on the model. Check out the fancy nose weight technique – Jackson put large washers into the soda top and held them in with clay. An interesting look with a clear nose cone.

    Our first test did not go well. We had major skywriting, and off angle flying soon after leaving the rod. I was convinced that it was a stability issue, but Jackson held to his conviction that we didn’t use a powerful enough motor. Combining what we had in our motor stock with the available field size that we could assure was empty on the first nice day after a run of bad weather, we went with an Aerotech E20 White Lightening. The motor package said max weight was 16 ounces – the exact weight of our test rocket. But Jackson’s later calculations showed that to be only a 4.45 thrust to weight ratio. That’s why we pay him the big bucks to be the Chief Engineer (okay, we don’t pay him anything, but the job has some good perks.)

    So, we put it up on an Aerotech F32 Blue Thunder. Straight as an arrow! A perfect flight – except that the rocket is not retrievable. We can see it, so its technically not lost, but we can’t get at it. No need, though. Its served its purpose. Our design is stable. QED

    Just the same, we may extend the fins out a bit, just to give a better margin of error in case we’re too heavy in the build.

    Winglets rule!

    scale_model_small.jpg

    scale_model_base_small.jpg

    scale_model_on_pad_small.jpg
     
  6. Apr 28, 2011 #26

    SMR

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    Well, let's give credit where credit is due... Marc was the original bottle advocate. Technically, we're all just copying him. And to add the proper perspective, he's using it for his L3 cert, whereas the rest of us are just having fun! :)

    Sather
     
    Last edited: Apr 29, 2011
  7. Apr 29, 2011 #27

    JLRockets

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Yes, its true. This was all Marc’s idea. But since our entry into the fray came as a response to an email from you, Sather, its your name that gets mumbled under our breath when the going gets tough. :)

    But your right, we are having fun. And Marc’s design is an engineering marvel. Marc, if you’re out there, do us the favor of posting your design!
     
  8. May 10, 2011 #28

    SMR

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    I like your idea (and implementation) of testing a scale model. And keeping the Cp and Cg in corresponding locations. Very well done.

    As clearly demonstrated by the Beech 1900. How many aerodynamic band-aid add-ons can we count on this airplane?

    raytheonb1900d_ave_800.jpg

    Beechcraft-1900-PrivateFly-AA1511.jpg
     
    Last edited: May 10, 2011
  9. Jun 29, 2011 #29

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    The scary thing is that our winglets are not aerodynamic band-aids, but rather are the center piece of our design. It may time be to get a second opinion! Although its actually too late for that. We have moved irrecoverably forward with the winglet design.

    Although we’re behind in the postings, we have made some headway on the fins. Back in May (sorry, the posting has been really slow), we headed out to the Wildman’s workshop to get a tutorial on how to use our new vacuum bagging supplies. The customer service that Tim Lehr of Wildman Rocketry provides is unsurpassed. Thank you, Tim. Its people like you who make rocketry fun. We left Tim’s house with our first block of fin material. Two sheets of thin G10 (1/16) with about ½ inch foam sandwiched in between. The fins are strong and, in contrast to the lexan, do not wobble at all, despite being 15 inches by 21 inches before shaping. At 3 pounds for the uncut fin material, we should come in about where we had hoped with respect to weight.

    We made the other three fin blocks at home. Clearly, we had a bit of a learning curve. The next two fins looked pathetic compared to the one we made at Wildman’s. Turns out, we had melted the foam with the heat lamp that we used to speed up the cure. After the first bad fin, the cause of the odd indentions in the foam was still a mystery. But, there’s nothing like doing something wrong twice to help you figure out what you did wrong. We nixed the heat lamp for fin block number 4, and that did the trick. We re-made the two bad ones. Now, we have four usable pieces of fin material, each 15 inches by 21 inches.

    Next up, cutting the fin material into actual fins.

    Jackson laminating fin.JPG

    fin lamination in action.JPG

    curing fin mtl.JPG

    finished fin mtl corner.jpg
     
  10. Jun 29, 2011 #30

    SMR

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    I hope you don't think I was being critical of your design... I think it looks and will fly great. I am actually fond of winglets, since Jayhawks, Fireball XL-5, and TIE fighters all use them. Your fins are looking good.

    (I do agree with your father, and I WAS making fun of the Beech 1900, though.) :wink:
     
  11. Jun 29, 2011 #31

    mannyskid

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    This is looking great Judy! I cant wait to see it fly. Are you going to fly this monster at ECOF? LDRS would be a great venue for this project too. One thing that you have failed to mention is the motor you will be using. Will this get another one of those sweet M3700's? I regret missing that flight of your Darkstar. From the TWA photos it looks like there were about 4 or 5 M's that day. I like the looks of those winglets, how are you attatching them to the fins? Just west systems and a big old fillet? Good luck with this project! Talk to you soon.

    Manny
     
  12. Jun 30, 2011 #32

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    :wink:
    Of course we don’t think your being critical of our design. After all, we’ve copied your design!:wink:
     
  13. Jun 30, 2011 #33

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Eat Cheese or Fly is the official unveiling day for all of the recycling bottle rockets. We’ll have to hustle to make it, with Jackson’s busy summer schedule, but we’re doing what we can.

    Thanks, Manny, for giving me the opportunity to brag about the M3700 flight. It was a good one. For those who were not there, team JLRockets launched our Ultimate Dark Star on a Cesaroni M3700, in honor of Jackson’s birthday. That white thunder propellant has a very sweet kick off the pad. Here’s a link to the on-board video from the flight:
    http://www.youtube.com/watch?v=3RirTkRh7-Y

    If you’re going to use the M3700 - and I do recommend this - don’t forget to get hold of a copy of the “double secret instructions” – the hidden addendum to the instructions that is not included with the motor, but nonetheless contains essential information for a proper build. I’m not sure why Cesaroni is hiding this little gem, but JLRockets will not be stopped. We were able to thwart their impeccable security to obtain the classified information, thus ensuring the proper use of glue in the build. Where there’s a will, there’s a way.
    http://www.pro38.com/pdfs/Pro75_notes_V1.4.pdf

    We won’t be using the M3700 in the bottle, because it is too long, especially since we own the 6XL case and not the 6 grain case, so we used it with a spacer. We have, however, considered the smaller M3100 and the bigger M3400. Jackson wants to use a Skidmark to get that sparkling soda affect, but I don’t think we’ll build light enough for a sparky.

    After the results of the test flight, we’re leaning towards a greater than 5 to 1 ratio. The scale model did poorly with just under a 5:1 ratio, but great with a 7:1 ratio. The 75’s are longer and distribute the weight up into the rocket, thus helping with the stability. So, we’re looking at 75’s with good initial thrust, but not so many newtons so as to launch this giant garbage can into outer space. The M2250 C-star is a strong contender, as is the L2350 or the M3100. But with either white thunder or c-star, we’ll have to build strong. These are powerful propellants.

    Which brings me to your last question. The primary attachment for the fins will be the poured or injected internal fillets between the motor tube and the fins (both fiberglass) and the internal tube and the fins. We’ll do this with pour-able epoxy, so it will be Pro-line mixed with chopped carbon fiber. All of the strength will be internal. The bottle will be something like a dress that the rocket wears to the launch for appearance sake. However, it will have to be firmly attached as well. We will attach the centering rings to the bottle with the black tar epoxy that comes with Wildman’s blackhawk rockets. I tested it, and it does attach to the bottle. But, just to be sure, we will also bolt the centering rings into the bottle. We’ll also use the Blackhawk epoxy to make external fillets between the bottle and the fin. Our chief engineer is skeptical, but I’m asking him to consider plywood struts along the side of each fin on the interior wall of the bottle (attached to the centering rings). Then, we could add one more internal fillet that attaches the fin to the backside of the bottle that would hold with a high degree of reliability.

    UltDS_on_M3700_small.jpg
     
  14. Jul 3, 2011 #34

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Sorry, Manny. It looks like I did not actually answer your last question. You asked how we are going to attach the winglets, not the fins. We are currently planning to bolt the winglets onto the main fins using L-brackets. We expect the winglets to break on landing, and want to have a way to easily replace them. Also, we think we can get the bottle into the minivan more easily with the winglets off.
     
  15. Jul 3, 2011 #35

    stickershock23

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    YOu guys, that is look wa cool so far. wish I could be there to see them in the air!

    I want to try and get my R2D2 Cooler ready for MWP... but I doubt it.
     
  16. Jul 4, 2011 #36

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Mark, we haven't forgotten about you. The label is just one of the many things that we are behind on. Since we are currently exiled from the workshop (some people call it vacation), we are just now taking the time to make some decisions on the label.

    If this thing survives its maiden flight at Eat Cheese or Fly, and if we can get it to Kansas, we plan on flying it again at LDRS.

    How will you get the R2D2 into the checked baggage for MWP?
     
  17. Jul 5, 2011 #37

    stickershock23

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    No rush I am here whenever you are ready.

    We are thinking about driving out this time. I want to actually FLY some rockets this time.... and I have a special project in mind.... If I can do it in time.. I was given some 7.5" tube couplers motor mount and a nose cone... its perfect for an upscale Estes "re-release" of a Exotic kit....
     
  18. Jul 7, 2011 #38

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Ok, I finally downloaded the pictures of the fin cutting process, and can take care of this past due post. With the four pieces of fin material in hand, we headed back over to the workshop of Frank, the father of Jackson’s friend Augie. With Frank’s guidance and Augie’s help, Jackson cut each piece of fin material into an actual fin.

    We made a slight change to the fin design before fin production. The fins will now go through the wall all the way to the motor tube, instead of just to the internal 7.5 inch tube, as we had previously planned. We are planning to pour or inject internal epoxy fillets at both the motor tube attachment and the stuffer tube attachment, although we haven’t yet hammered out the details on the method. Attaching the fins to the motor tube this way will make assembly more complicated, but it will strengthen the internal structure of the rocket.

    Each fin is 15 inches tall and extends 13 inches from the bottle. The fin tab for each fin is 7 inches deep. In the picture with Jackson and Augie holding the fins, the fins are sideways. The part that is on the table is the part that will attach to the motor tube. The fin tab extends to the place where the angle begins. Each fin weighs 29 ounces (not counting edge finishing and winglet).

    The next step is to finish the edges of the fins. We plan to use pre-made balsa leading edge (balsa sticks with pre-rounded top used on wings in model airplane making). We will attach with epoxy, and then fiberglass over the leading edge to enhance attachment and strength of the balsa.

    setting up the saw.JPG

    straight cut.JPG

    angle cut.JPG

    cut fin.jpg

    four cut fins.JPG
     
  19. Jul 21, 2011 #39

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    We finished off the fins with balsa leading edge, glassed on with fiberglass tape.

    Next, Jackson cut the fin slots. This was messy and unpleasant work. The black plastic dust sprayed hot off the dremel, burned Jackson’s hand and disseminated itself everywhere. Lucky for us, we decided to do this part of the work on the day the cleaning lady comes. Due to her heroic efforts helping us clean up, we have decided to officially include our cleaning lady as part of the project team. We're not sure what this means, other than further opportunities to help us clean up, but we're very greatful.

    fin edges with balsa.jpg

    Jackson cutting external slots.jpg

    messy fin slot.jpg

    jackson finishing exteranl slots.jpg
     
  20. Jul 21, 2011 #40

    JLRockets

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    Just Judy TRF Supporter TRF Lifetime Supporter

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    Next up was cutting the fin slots on the inside 7.5 inch tube. It was necessary, but difficult, to get these to be perfectly lined up with the outer slots. We ended up cutting them a bit wider than optimal. To accommodate, we will glass the internal fillets that attach to the 7.5 tube (poured epoxy would drip out of the excessively wide slot). We will still pour/inject epoxy for the fillets where the fins attach to the motor tube.

    internal fin slots.jpg
     

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