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  1. #31
    Join Date
    4th July 2015
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    London, UK
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    406
    Quote Originally Posted by ECayemberg View Post
    Tim, great insight! 'Tis true that this concept can be used as a transition; watch for that application in the future! Availability...I suspect it is *available* right now by contacting Loc.
    Great! Thanks for the heads up. Suddenly I'm seeing the 5.5" tubing that's been standing in the corner of my workshop for some time now with fresh eyes... ; )

    UKRA #1895
    EARS #1329
    L1 6/9/15 Custom built LOC Fantom 438 CTI H125
    L2 3/4/16 Same custom built LOC Fantom w/ DD EXL configuration CTI J410

  2. #32
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    21st January 2009
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    Manitowoc, WI
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    Quote Originally Posted by Tim51 View Post
    Great! Thanks for the heads up. Suddenly I'm seeing the 5.5" tubing that's been standing in the corner of my workshop for some time now with fresh eyes... ; )
    Nice! Here's a shot of the Stiffy before a bit of trimming. I'd imagine the tail as cut could go down to about 3.5" diameter...with the right amount of poking and prodding, I think a 5.5" to 3" transition/tail would be able to be programmed and burned.

    [IMG]20171118_195738[/IMG]

    Eric Cayemberg
    TRA 7783 L3
    TAP

  3. #33
    Join Date
    9th December 2009
    Location
    Wichita, KS
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    338
    Quote Originally Posted by ECayemberg View Post
    Per the "Goals" note, the intent is to maintain the same external dimensions as the original K-Load while adding the amenities of modern high power rocketry...plus having the option of add-ons to make the K-Load a "GT" model, or N-Load with the simple addition of a removable boat tail and a swap for the sleaker Long nose cone. Fly it on the coffee can K, fly it on the M2500 for a good kick in the pants, and fly it on the N1000 to see how high we can shove a 5.5" airframe! Can't wait!
    Eric,
    If you are looking for a venue to fly these three flights, I know of a pasture in Kansas that would love to provide support for them over the Labor Day weekend. Just sayin!
    Bob
    Hmmm !!!!

  4. #34
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    21st January 2009
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    Manitowoc, WI
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    Quote Originally Posted by BBrown View Post
    Eric,
    If you are looking for a venue to fly these three flights, I know of a pasture in Kansas that would love to provide support for them over the Labor Day weekend. Just sayin!
    Bob
    Hi Bob,

    It'll be there...with an N1000. Already on the flight log! Cannot wait sir; thanks for the invite and the hospitality!!!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  5. #35
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    21st January 2009
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    Manitowoc, WI
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    Booster Build: Part I

    Let's build a booster. She won't fly straight without some tail action!

    Booster Coupler

    One last coupler Assembly!

    Take an 11" coupler and a Stiffy.

    [IMG]C1[/IMG]

    Butter the ID of the Coupler tube with epoxy.

    [IMG]C2[/IMG]

    Insert Stiffy into Coupler. One of the ends of the tubes should be flush; this is easily accomplished using wax paper and pushing the ends flat against a flat work surface. Set aside for epoxy to cure.

    [IMG]C3 [/IMG]

    Now apply a bead of epoxy to the end of the Coupler/Stiffy assembly that is flush.

    [IMG]C4[/IMG]

    Press a Centering ring against the bead of epoxy. The outside of the centering ring should be even with the outside of the coupler. Wipe off excess epoxy; apply tape around the edges to center the ring if desired.

    [IMG]C5 [/IMG]

    Motor Mount Assembly: Part I

    The N-Load is supplied with 3/8" thick Centering Rings. Mark the Motor Mount Tube at 3/8", 12-15/16", and 13-5/16" from one end.

    [IMG]20171119_145332 [/IMG]

    If desired, lightly score the glassine along the visible spiral void and peel. Not necessary, but I prefer the bond to the furry fibers verses the shiny glassine layer. Alternately, one could kill the sheen on the glassine by sanding.

    [IMG]20171119_145437[/IMG]

    Peeling generally goes quite well and is therefore my preference. "Generally" means "darn near always...unless I'm sharing a build thread then it goes horribly wrong". In that case, a mix of peeling and sanding will suffice just fine. Maintain the marks at 12-15/16", and 13-5/16" despite the peeling, however...re-mark as necessary.

    [IMG]20171119_150101 [/IMG]

    Apply a bead of epoxy between the 12.9375" and 13.3125" marks. Slide a ring onto the AFT end of the motor tube (the 3/8" marked side) and up to the epoxy.

    [IMG]20171119_150625[/IMG]

    Position ring between the marks. Location and perpendicularity about the Motor Mount Tube is important here; so I used a few wraps of masking tape as a guide that the ring sits against until epoxy hits the "green" phase.

    [IMG]20171119_150830 [/IMG]

    Epoxy ONLY that centering ring at this time! Set aside to cure; I used 12 minute epoxy...so I didn't have to wait toooooo long!

    To be continued....
    Eric Cayemberg
    TRA 7783 L3
    TAP

  6. #36
    Join Date
    5th January 2012
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    Des Moines, IA
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    172
    Getting super motivated to finish mine.......
    Nice work Eric, I will follow this closely.
    Nik B.
    TRA 6035 L3

  7. #37
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    15th October 2016
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    Huntsville AL
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    1,879
    Question on the internal coupler reinforcing (which I totally dig since it allows me to put off fiberglassing):

    Is it possible to leave them unfixed so that they're removable for lower powered motors?
    Or when all is said and done, is the extra tubing and epoxy/woodglue not that much of a weight burden anyway?
    (or will unfixed tubes not provide relevant stiffening even when butted against bay/rings/nose and perhaps riveted?)
    Last edited by Nytrunner; 1st December 2017 at 08:57 PM.

  8. #38
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    21st January 2009
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    Quote Originally Posted by nraymondb View Post
    Getting super motivated to finish mine.......
    Nice work Eric, I will follow this closely.
    ....and more transitions coming up after this build. #1 off the line to Mr. Byra!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  9. #39
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    Quote Originally Posted by Nytrunner View Post
    Question on the internal coupler reinforcing (which I totally dig since it allows me to put off fiberglassing):

    Is it possible to leave them unfixed so that they're removable for lower powered motors?
    Or when all is said and done, is the extra tubing and epoxy/woodglue not that much of a weight burden anyway?
    (or will unfixed tubes not provide relevant stiffening even when butted against bay/rings/nose and perhaps riveted?)
    Possible yes, but I don't believe you'd gain the same strength in the airframe walls without the lamination. Assuming a gap-free continuous internal structure of couplers, you still get the added benefit of two surfaces carrying the mating surfaces (for example, the nosecone is supported at the lip by the OD of the cone, as well as at the base of the cone via the coupler)...this double support occurs with or without the added weight and complexity of epoxy.

    What you lose without epoxying the couplers in, is a bit of additional longitudinal and circumferential strength in the airframe. Think of it like a composite structure, where there are two outer skins with a core in between. The core ties the skins together and the outer skins work against each other in tension making for an effective structure. In the case of the double wall cardboard construction, the airframe works as the outer skin, the coupler works as the inner skin, and the epoxy acts as the core that ties them together. Now the composite purists will argue that epoxy is a poor core material and that the web between skins is minimal....TRUE, but the concept is there. Without the epoxy to tie the two together, I hypothesize that the resulting structure is weaker than with the epoxy bonding outer and inner together.
    Last edited by ECayemberg; 1st December 2017 at 09:29 PM.
    Eric Cayemberg
    TRA 7783 L3
    TAP

  10. #40
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    Teasers

    Teasers....why not? I've been slow playing you a bit. More fun stuff to come, but have a local launch to get ready for, so let's throw in a pair of teaser photos in the meantime!

    K-Load

    [IMG]20171124_115935[/IMG]

    N-Load

    [IMG]20171124_120150 [/IMG]

    Go Badgers!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  11. #41
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    Quote Originally Posted by ECayemberg View Post
    Possible yes, but I don't believe you'd gain the same strength in the airframe walls without the lamination. Assuming a gap-free continuous internal structure of couplers, you still get the added benefit of two surfaces carrying the mating surfaces (for example, the nosecone is supported at the lip by the OD of the cone, as well as at the base of the cone via the coupler)...this double support occurs with or without the added weight and complexity of epoxy.

    What you lose without epoxying the couplers in, is a bit of additional longitudinal and circumferential strength in the airframe. Think of it like a composite structure, where there are two outer skins with a core in between. The core ties the skins together and the outer skins work against each other in tension making for an effective structure. In the case of the double wall cardboard construction, the airframe works as the outer skin, the coupler works as the inner skin, and the epoxy acts as the core that ties them together. Now the composite purists will argue that epoxy is a poor core material and that the web between skins is minimal....TRUE, but the concept is there. Without the epoxy to tie the two together, I hypothesize that the resulting structure is weaker than with the epoxy bonding outer and inner together.
    Agreed on all points.
    I'm thinking the endgame of my design quandary boils down to: Can I retain internal skin removability by using ~8-12 Heavy rivets per coupler while not sacrificing too much bending strength by foregoing a permanent adhesive.
    It also boils down to being lazy and not wanting to dig out my Materials and Solid-mechs books and do a proper structure analysis lol.

  12. #42
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    Booster Build Part II

    Motor Mount (Continued)

    Take one of the centering rings and install a pair of screws; this becomes our aft centering ring. We'll use these to extract the ring after tacking the fins in place.

    [IMG]20171119_182425[/IMG]

    Slide on the aft end of the Motor Tube.

    [IMG]20171119_182449 [/IMG]

    The Motor Mount lines up with the booster tube like this. One ring at the front edge of the fin slot, one at the rear edge of the fin slot. Purdy simple!

    [IMG]20171119_182630[/IMG]

    Test fit the Motor Mount into the Booster Tube to ensure proper fit.

    [IMG]20171119_182744[/IMG]

    Happy with the fit, mix up a batch of epoxy. Apply a ring near the front end of the fin slots being careful not to get epoxy in the slots.

    [IMG]20171119_183126[/IMG]

    Slide Mount into airframe from the aft end.

    [IMG]20171119_183212[/IMG]

    Slide in until the aft end of the middle centering ring is just past the forward edge of the fin slot.

    [IMG]20171119_183319 [/IMG]

    The aft end of the motor tube should be recessed 1" in from the end of the aft end of the booster tube.

    [IMG]20171119_183312 [/IMG]

    Slide the Forward Centering ring onto the forward end of the Booster Tube TEMPORARILY to hold the Motor Mount in alignment until the epoxy cures. Do not push it in too far, do not epoxy in place at this time.

    [IMG]20171119_183427[/IMG]

    Allow epoxy to cure and we're ready for fins!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  13. #43
    Join Date
    21st January 2009
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    Manitowoc, WI
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    Booster Build Part III: Fins

    Now that we have a Booster Tube with a Motor Mount, let's add some directional stability appendages.

    The original K-Load had .125" G-10 fins, the N-Load has .375" Baltic Birch ply fins. G-10 is great, but at 1/8" thick, a span as large as we have here, and the velocity atop a full M or mid N, they'd be wobbling all over the place. The 3/8" thick ply is the right combination of strength and reasonable weight in this application. Without further ado, let's play with some fins.

    [IMG]20171119_192030[/IMG]

    [IMG]20171119_192041 [/IMG]

    Test fit fins to make sure it all fits together right prior to adding any pot-life limited gooey stuff. I like to use fin alignment guides made of foam board, cardboard, plywood, or whatever is available at the moment.

    [IMG]20171119_192343 [/IMG]

    Optional Step: Score the Booster Tube lightly with a blade, roughly 1/4" away from the edges of the fin slots.

    [IMG]20171119_192718 [/IMG]

    Peel up the glassine from the fin slot to your scored line. Epoxy adheres better to virgin fuzzy paper than to the glassine wrap....just sayin'!

    [IMG]20171119_192910[/IMG]

    Butter the root edge of one fin with epoxy. Install fin in slot, making sure the fin is fully seated against the Motor Mount Tube. Note: If you don't intend to do internal fillets, the "double dip" method of installing, removing, adding another layer of epoxy, then re-installing may be a good idea here. I'll be doing some internal fillets, so a single application of epoxy will suffice.

    [IMG]20171119_193459 [/IMG]

    If your jig is solid and/or you feel comfortable doing all three fins at once, proceed to do so. Otherwise tack a fin, let cure, tack a fin, let cure, etc. I did them all at once and made sure they didn't go anywhere. The fins fit in the slot perfectly, and I shoved a few mixing sticks in the slots in the foam fin jig to make sure everything stayed where intended.

    [IMG]20171119_193608 [/IMG]

    Allow fin root epoxy to fully cure before proceeding. I used 12 minute epoxy here, so didn't have to wait long...

    ...to be continued...
    Eric Cayemberg
    TRA 7783 L3
    TAP

  14. #44
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    Booster Build Part IV: Filleting

    Now that the fins are tacked, let's reinforce the airframe-to-fin and motor tube-to-fin joints. Remember, this is adding weight to the wrong end of the rocket, so a little goes a long way here...keep it light but strong!

    External Fillets

    It is wise to start on the external fillets. If there are any gaps for epoxy to leak through and you start with the internals, you may have a mess to clean up! Thus, let’s get a good seal on the outside, then make a mess of the inside!

    If there are any cavernous gaps between the fins and the edge of the airframe, it may be wise to fill them, as even the *best* filleting epoxies will sag over unsupported areas. As mentioned, the fins fit the slots perfectly; however with some bevels on the fins, there are gaps at the leading and trailing edges.

    These gaps are filled with epoxy filled with a bit of cabosil. All sides are done with a single batch of epoxy.

    [IMG]20171122_171207[/IMG]

    [IMG]20171122_171211 [/IMG]

    *Unless you have a super-stout filleting blend, perform one set of external fillets at a time to avoid sags*

    Clean the area to be bonded with a tack cloth to remove any dust or debris.

    [IMG]20171122_171218[/IMG]

    I'm using Rocketpoxy for the external fillets. Mix up a batch, plop it into place along the fin-to-airframe joint. *if you're concerned with excess, tape off the areas just outside the fillet edges to keep things clean; I skipped that step here.*

    Begin to smooth the epoxy with a filleting tool. Some use round rods, dowels, pipes, or oily fingers; I prefer the West System sticks mentioned earlier. For the first pass or three, the stick is held at a shallow angle relative to the length of the airframe; resulting in a deep fillet and a fairly even distribution of epoxy.

    [IMG]20171124_070832[/IMG]

    After the first few passes, the angle of the magic stick is increased, resulting in a smoother fillet, less epoxy, and the desired result. The steeper the angle, the more epoxy you're pulling around, and the more that may be removed from the fillet (that's a good thing!). Any epoxy that spills over the edge of the stick is removed by carefully scraping the other end of the stick along the spillover. For reference, I used a 20 gram batch of epoxy for each pair of fillets, with roughly 4 grams leftover from the scrapings, so roughly 8 grams per fillet.

    [IMG]20171124_070838[/IMG]

    The end result looks like this. Allow to cure in position so gravity doesn't cause your fillets to sag. As thick as Rocketpoxy is, it will sag courtesy of gravity until it reaches the "green" stage.

    [IMG][url=https://flic.kr/p/22dYCQt][/IMG]

    Internal Fillets

    I'm using the mid cure (12-20 minute cure) epoxy for internal fillets. The fin-to-motor tube joints and the fin-to-airframe joints will be epoxied in three batches; one for each 120 degree rotation.

    Remove the aft centering ring by pulling on the two screws installed earlier. Epoxy is mixed and a moderate amount is poured into the locations shown with red circles below.

    [IMG][/IMG]

    The Booster is placed in a nose-down position so the epoxy may flow down the length of the joints thanks to gravity's fine work. A thin dowel is used to help the epoxy along its path when and where necessary.

    [IMG][/IMG]

    After the epoxy beads have traveled the length of the fin's root, the rocket is returned to a horizontal position to allow the epoxy to self level and settle into the joints evenly. Allow to cure.

    Repeat for remaining two sides.

    More to come...
    Last edited by ECayemberg; 6th December 2017 at 03:52 PM.
    Eric Cayemberg
    TRA 7783 L3
    TAP

  15. #45
    Join Date
    26th January 2009
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    LAX
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    Quote Originally Posted by ECayemberg View Post
    a new product coming out of the Wonka Factory...errr Loc 3.0 Plant: a Build-a-boat tail! One of those items you have to play with to truly appreciate, this next segment is a fun one; I've enjoyed building this tail...and it's kinda sexy!
    I haven't had Jerry Irvine flashbacks this intense since... I think the last time I saw Jerry.

    But laser-cut gores? Nice!
    David Reese
    TRA 5590 TAP / NAR 64125
    http://davidree.se / http://www.wildmanwest.com

  16. #46
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    21st January 2009
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    Quote Originally Posted by daveyfire View Post
    I haven't had Jerry Irvine flashbacks this intense since... I think the last time I saw Jerry.

    But laser-cut gores? Nice!
    Now that's funny! Who needs transitions or nose cones when you can just bend them out of paper, right!?! Some examples of these USR jobbers on Ebay right now.

    Wait, did you just mention JI in a public forum? Love him or hate him, he was somewhat of a pioneer to renegade, or "progressive" rocketry! BTW...I may or may not have burned some Firestarter over the weekend.

    Cleaned up from last weekend's launch, time to finish up the booster!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  17. #47
    Join Date
    1st July 2011
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    Pittsburgh, PA
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    Firestarters? Nice.
    Kevin Wuchevich
    Tripoli Pittsburgh
    TRA 12238

  18. #48
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    15th October 2016
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    Huntsville AL
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    Did you remove a layer of paper from the stiffy?
    I'm examining mine, and it slides right inside the coupler with no issue. To the point that I worry it'd be too loose if I removed even a thin layer.

  19. #49
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    21st January 2009
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    Quote Originally Posted by Nytrunner View Post
    Did you remove a layer of paper from the stiffy?
    I'm examining mine, and it slides right inside the coupler with no issue. To the point that I worry it'd be too loose if I removed even a thin layer.
    Only on one of them....only if necessary! If it fits, no need to remove any material.

    Confession statement: The "new" owners of Loc are "old" friends of mine....we flew together in the late 90's/early 00's during the Yank Enterprises years, and it's just so darn cool that they're back, WAY better than ever! When playing around with prototypes, items that may be off spec tend to get used...something that doesn't cut the mustard for production runs, but works plenty well for protos! Some of the tubes/couplers/stiffys didn't always play well together for a while; think that's all worked out of the system now, however!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  20. #50
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    Factory seconds are always nice to get to play with. Not so nice to have something messed up though (bad order).
    Kevin Wuchevich
    Tripoli Pittsburgh
    TRA 12238

  21. #51
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    23rd March 2011
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    Germantown, Ohio
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    Eric, I have never thought of removing the glassine layer on either side of the fin slots. Brilliant!
    Gary Dickinson - Prefect
    Tripoli Mid Ohio #31
    TRA #5520 - L3 - TAP

  22. #52
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    23rd November 2016
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    Sheboygan, WI
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    Eric, you should come build mine too! I just got to moving all the parts finally!!! Even though it was just because I was cleaning... Never enough time to build! We appreciate the help!
    Get Up There!!!


    www.locprecision.com
    Dave@locprecision
    920-892-0557

  23. #53
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    21st January 2009
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    Thanks!

    Quote Originally Posted by cavecentral View Post
    Firestarters? Nice.
    Indeed. The original sparky???!?!?!

    Quote Originally Posted by cavecentral View Post
    Factory seconds are always nice to get to play with. Not so nice to have something messed up though (bad order).
    Agreed! These guys are doing a great job, IMO...eyes on quality!!!

    Quote Originally Posted by pondman View Post
    Eric, I have never thought of removing the glassine layer on either side of the fin slots. Brilliant!
    Thanks Gary! Happy to have you here. I'm certain you'll see this thing fly in 2018!

    Quote Originally Posted by LOC View Post
    Eric, you should come build mine too! I just got to moving all the parts finally!!! Even though it was just because I was cleaning... Never enough time to build! We appreciate the help!
    Right on, Dave! I appreciate the friendship; all in good fun! We can build yours sometime; let me get these instruction-type things done. Gettin' closer!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  24. #54
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    Booster Build Part V: Coupler

    The final structural component of the booster build is the Coupler Assembly. We previously epoxied the stiffy inside the coupler and a 3/8" centering ring on the forward end. Now to epoxy it into place.

    Place the Drogue Chute Tube forward end down on the floor. Slide the Coupler assembly into aft end of the Drogue Tube centering ring down.

    [IMG][/IMG]

    Push the coupler all the way in until it fully seats (against the coupler previously epoxied into the Drogue Tube). Mark a line around the circumference of the coupler where the Drogue Tube ends. A quick check shows just under 6" of exposed coupler tube.

    [IMG][/IMG]

    Remove the coupler for now. No glue shall be placed on the forward end of the coupler...this surface must slide in and out of the Drogue Chute Tube freely.

    [IMG][/IMG]

    There are MANY ways to attach a shock cord to a booster holding plugged motors. Even though I tend to rely upon the eyebolt in the forward closure of the motor regularly, having options is nice. For that reason, I'll be using the common glue-a-harness-to-the-motor mount setup here using 1" flat Kevlar strap. Tubular nylon would work as well. *Disclaimer: I don't know that this will come with the kit, some things are left up to the builder's choice...this may be one of them*.

    We start by taking a ~8' length of Kevlar strap and tying a Figure 8 knot in the middle.

    [IMG][/IMG]

    [IMG][/IMG]

    The forward end of the Motor Tube is prepared for bonding in two areas, 180 degrees apart from one-another. Areas are cleaned with a tack cloth.

    [IMG][/IMG]

    Epoxy is applied to the motor tube in both locations; no epoxy on the last ~1" of Motor Tube.

    [IMG][/IMG]

    Several inches of the ends of the strap are epoxied in place. Masking tape helps hold the strap in place until the epoxy cures.

    [IMG][/IMG]

    While the strap epoxy is curing, use a Dremel sanding drum or equivalent to remove material from the centering ring where the strap is to pass. After doing so, the strap is fed through the coupler...

    [IMG][/IMG]

    ...and test fit the Coupler Assembly in place. Make sure the Kevlar strap fits your newly made voids.

    [IMG][/IMG]

    With the strap firmly secured in place, mix up a batch of epoxy and apply to the first few inches of the inside of the Booster Tube (little wood stick at the bottom of the photo).

    [IMG][/IMG]

    Clean up any epoxy blobs or drips on the outside or ends of the booster tube.

    [IMG][/IMG]

    Slide the Coupler Assembly down until it slides over the Motor Tube, and STOP!

    [IMG][/IMG]

    With the Drogue Chute Tube forward end down, slide the Booster Tube into the aft end of the Drogue Tube. Watch that line you drew around the circumference of the coupler earlier.

    [IMG][/IMG]

    Slide the Booster Tube all the way until it fully seats against the Drogue Chute Tube. Allow to cure in a vertical nose-down position; so that coupler-centering ring assembly stays seated against the coupler epoxied in the Drogue Tube.

    [IMG][/IMG]

    Take a nap, have a beer, or something!
    Last edited by ECayemberg; 8th December 2017 at 05:51 PM.
    Eric Cayemberg
    TRA 7783 L3
    TAP

  25. #55
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    18th January 2009
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    Nice pic of rocket on the RR track...geeesh Eric, didn't your mom ever tell you not to play on the tracks?.....LOl

    Very nice build you have going on, been following since start.
    How are you finishing the transition? Just coat and fill or wrapping with glass.
    Hat's off to the LOC boys for coming up with that idea, me likey.

    If that's coming no need to answer, I'll just wait and see!

    Happy Holiday's to all the extended Cayemburg family.

    Cj
    Jim Hendricksen
    L-3 Tripoli 9693
    [ICBM, Orangeburg,SC R.I.P.] - QCRS ,Princeton ILL - MDRA , Price Maryland - Woosh, Bong Wisconsin- ROCC, Charlotte NC , ICBM Camden SC
    "Made" member of Chicago & Carolina Rocket Mafia
    Rocketry...........an exact science.......but not exactly !!!

  26. #56
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    Quote Originally Posted by blackjack2564 View Post
    Nice pic of rocket on the RR track...geeesh Eric, didn't your mom ever tell you not to play on the tracks?.....LOl

    Very nice build you have going on, been following since start.
    How are you finishing the transition? Just coat and fill or wrapping with glass.
    Hat's off to the LOC boys for coming up with that idea, me likey.

    If that's coming no need to answer, I'll just wait and see!

    Happy Holiday's to all the extended Cayemburg family.

    Cj
    Hi CJ!

    Great to hear from you and best wishes from the frozen tundra, buddy!

    RR Tracks: funny that you mention it. "Our" train comes midday Mon, Wed, Fri....slow moving and minimal freight. Anyway, it was a windy day when I took the picture, you can see my boys' shoes in the bottom left, they caught it when it fell over! Anyway, took the photo of the K-Load and were "switching over" to the N-Load by swapping cones and adding the boat tail when my younger one says "I think that's a train coming". Sure nuff, off day, creeping down the tracks, here it came! That's why the "N-Load" photo is off the tracks! We are careful; ironic that you called us on this one!!!

    Transition/Boat-tail: Glass-less: coming right up!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  27. #57
    Join Date
    21st January 2009
    Location
    Manitowoc, WI
    Posts
    2,221

    Booster Build Part VI: Details

    Let's finish the booster, shall we?

    This kit comes with three Centering Rings. We've epoxied two in place, time to take care of the third; happens to close up the rear of the rocket. Before doing so, we need to figure out motor retention. I AM a fan of AeroPacks and other snazzy retainers, but in this case, they just don't make sense. We'll utilize alternative, affordable, "classic" means of retention. That said:

    Remove the two temporary wood/drywall screws used to extract the aft Centering ring. Drill out the holes to accommodate an #8-32 T-Nut.

    [IMG][/IMG]

    Get out the hammer and pound them in place. Secure with a bit of epoxy.

    [IMG][/IMG]

    Apply a ring of epoxy around the inside of the Booster Tube just aft of the fin tabs. Also apply a ring of epoxy around the outside of the Motor Tube at the aft end. Be careful not to get any inside the motor tube or aft where the centering ring will rest on the body tube (need to fit the tail in there!).

    [IMG][/IMG]

    Position the T-nuts between the fins and push the Centering Ring into place until it fully seats against the fin tabs. The aft face of the ring should be flush with the aft end of the Motor Tube. Wipe off any excess epoxy.

    [IMG][/IMG]

    Stand the rocket on its aft end to allow epoxy to flow down onto the forward face of the ring. Meanwhile, on the front end of the booster, apply a fillet of epoxy to the Motor Tube-to-Centering Ring joint. Avoid getting epoxy on the Kevlar if possible. Epoxy on the Kevlar at a point where the Kevlar may flex may tear the material.

    [IMG][/IMG]

    Rail Buttons

    Pick your least favorite side of the rocket, this is where your rail buttons will go. Take a scrap piece of paper and mark the distance between fins (roughly 1/3 the airframe's circumference).

    [IMG][/IMG]

    Fold the marked distance in half. Crease and mark the middle.

    [IMG][/IMG]

    [IMG][/IMG]

    [IMG][/IMG]

    At the middle mark, measure and mark 1-3/16" from the edge of the paper. This puts you in the middle of the aft centering ring that occupies the space from 1" to 1-3/8" up from the aft end of the Booster Tube.

    [IMG][/IMG]

    Mark that spot on the rocket. (You kidding me, I can't do that and take a photo at the same time!)

    [IMG][/IMG]

    At that spot, drill and tap a #10-24 hole (or whatever size screw/button is used). The Loc big buttons use 10-24. If you're good, you'll hit wood!

    [IMG][/IMG]

    The next step is very easy, but it is apparent that this is a deceivingly difficult endeavor. Side story: Been judging Rockets 4 Schools Class 1 and 2 rockets for about 15 years now with some really fine folks from Rockets for Schools and TWA; out of the hundreds of rockets seen year after year, one of the criteria is "Are the rail buttons aligned straight". 93 out of 100 times, the answer is "Heck No"! So anyway, no mystery to many folks, but just in case....

    Now that you have one good hole, let's carry that line forward. Using a piece of angle iron (I use aluminum 1"x1"x1/16"), draw a line forward from the center of the hole while giving the audience the middle finger. It's a good idea to flip the angle around, draw from both sides of the hole, etc. to verify accuracy.

    [IMG][/IMG]

    On that line, drill and tap another #10-24 hole roughly .75" aft of the front edge of the Booster Tube. Drip some thin CA into both rail button holes and let dry for a few minutes. Install buttons.

    [IMG][/IMG]

    Friends, this is a SOLID booster!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  28. #58
    Join Date
    15th October 2016
    Location
    Huntsville AL
    Posts
    1,879
    Quote Originally Posted by ECayemberg View Post
    Friends, this is a SOLID booster!
    Any idea of the comparison with the weight of a similarly strong fiberglass booster unit?

  29. #59
    Join Date
    21st January 2009
    Location
    Manitowoc, WI
    Posts
    2,221

    Build-A-Boat Part II

    How about a little more tail action? I was going to wait, but Crazy Jim asked...so I gotta deliver! Now, I love glass; I love to glass, but I'm remaining faithful to the glass-less theme of this build. The goal is to provide a moderately sized and priced stocker airframe that the average joe can build without elaborate tools or tactics; and have it survive a myriad of J-N motors! I think we're on the right track! So, in order to fit that Aerotech 15360 hardware in this thing, we need to give it some tail action. Previously, we glued up a skeleton. Now, let's begin to smooth it out and make it pretty!

    First up, we add a 1/4" long ring of 5.54" airframe to the forward end of the Boat-tail's coupler. This is done by sliding in the Boat-tail assembly until it's fully seated against the motor tube and ring (1" recessed). Slide the 5.54" ring onto the coupler until it butts up against the airframe and epoxy in place from the aft end. No glue on the forward end...don't want this thing permanently attached! Sorry, no direct photos of this step. One could omit this step, but this gives me a surface that mates to the airframe's OD perfectly and acts as a sanding bumper.

    Next, another optional step! Mix up a batch of thin epoxy.

    [IMG][/IMG]

    Apply to the outside of the tail using a chip brush. In the following photo, you can see the darker color change on the left side where the epoxy has been applied and is soaking in.

    [IMG][/IMG]

    Fully coat the tail with a thin coating of unfilled epoxy. Again, optional step; my intent is to give a hard surface for the sanding process. Without this step, if I sand through the filler and onto the bare cardboard, a potentially fuzzy and primer absorbing surface may emerge.

    [IMG][/IMG]

    Once the epoxy dries, the cone gets a coating of Spot Filler Glazing Putty. I've tried a lot of fillers over the years, and this is by far my favorite. Bondo makes a similar product (NOT 2 PART Polyester based EVIL BODY FILLER), that is similar in nature, but the price has gone up while the volume has gone down...so this product it is. It's a one part, solvent evaporative curing product that dries quickly, sands beautifully, finishes smooth, and stands up to upper Mach 2's. Anyway, here's one coat application; haven't begun to sand it smooth yet....you caught up to my build progress!

    [IMG][/IMG]
    Eric Cayemberg
    TRA 7783 L3
    TAP

  30. #60
    Join Date
    21st January 2009
    Location
    Manitowoc, WI
    Posts
    2,221
    Quote Originally Posted by Nytrunner View Post
    Any idea of the comparison with the weight of a similarly strong fiberglass booster unit?
    Good question...closest size-wise I have built is a 5" glass Tarantula; I no longer have any 6" glass rockets. I'll weigh them both and post the comparison. Both have the ability to house and fly on comparable 98mm motors.

    Eric Cayemberg
    TRA 7783 L3
    TAP

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