US Composites

Discussion in 'Mid Power Rocketry (MPR)' started by roytyson, Mar 15, 2019 at 10:45 PM.

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  1. Mar 15, 2019 at 10:45 PM #1

    roytyson

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    Ok, so this is another epoxy thread, sorry. I have been trying to figure out what epoxy to use on my injected internal fillets for my L3. I ended up with West when I ran out of Rocketpoxy, but then seen where people do not recommend it for its low melt temp. So I got some US Composites 150 thick. Yes, I know I bought thick, but it may be thicker than I anticipated. Can this be injected with 1/4" chop fiberglass? Or should I have gotten the thin? Kind of mad at myself now, but I wanted the best strength and chickened out of the thin.

    Thanks for your feedback.
     
  2. Mar 15, 2019 at 10:52 PM #2

    timbucktoo

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    I use the 150 thick with the 3:1 hardener with chopped carbon fiber for injected internals no problem.
     
  3. Mar 15, 2019 at 11:17 PM #3

    rharshberger

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    I use both the 150 (adhesive) and the 635 (laminating), both are "neat" (no fillers), the 150 is about the consistency of honey, you can inject it but I recommend using the 1/16" fibers or 1/32" milled glass fibers. The US Composites epoxies are a much better value than the other common epoxies used in rocketry and work just as well as other epoxies of the same type. In order to get the thickness of Rocketpoxy and Proline it is necessary to add some type of filler like cabosil, but for injection fillers are not needed. With the exception of bonding the fins of my L3 project with System Three T-88, most of my rockets have been built with US Composites and the epoxy has yet to fail me. Below is an epoxy comparison sheet based on Technical Data Sheets, while its not a definitive list and or actual testing (there has been a limited amount of it done but US Composites was not one of them). My opinion is that for almost all rockets commonly built US Composites is an excellent choice, if I were building Minimum diameter speed demons I might reconsider and use a more expensive epoxy like a Hysol or Cotronics product, however the laminating of the tip to tip would still be US Composites 635.

    https://www.rocketryforum.com/threads/epoxy-comparisons-and-technical-data-sheets.138953/
     
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  4. Mar 16, 2019 at 11:56 AM #4

    David Schwantz

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    Hey Roy, just a thought, but do you have to inject the fillets? What is the dia?? MMT? I have left the top and bottom CR off for this reason. I will use them to line up everything when gluing in mmt, then I remove them after glue sets. This way I can run fillets about normal on the inside, you can even get them on the inside of the airframe tube and not just the mmt. when it is time to install the CRs again, I will mark the location and apply a bead of glue so that when they now are pushed into place it will from the internal fillet on them. I like to use Hysol 9462 for my glue. It is very thick also, so maybe this might be an option.
     
  5. Mar 16, 2019 at 1:49 PM #5

    MikeyDSlagle

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    I don't see how 1\4" chopped glass can be injected at all. Mixed with epoxy it is pretty difficult to work with. I suppose maybe with a large syringe it is possible. But I've never had the need to inject fillets.
    I'm right there with Rich. I use both of their epoxies along with multiple fillers and their Fastek epoxy glue.
    I started with their thick stuff (150) and now I use their thin stuff (635) more often. I didn't like the 635 at first but the more I use it the more I like it. Main reason for the switch is I can laminate with the 635 (which I rarely do) and add fillers to thicken it; that and my 150 is running low and is now difficult to get out of the bottle. :D
    Either use a smaller filler, such as those Rich mentioned, or grab some Cabosil (fumed silica); that stuff makes a nice creamy paste that should inject nicely, or inject without a filler. When injecting, the fillet should be able to self level anyway shouldn't it?
     
  6. Mar 16, 2019 at 3:15 PM #6

    jderimig

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    internal fillets are over-rated. Skip the chopped glass, do it easy and quick. Don't spend excessive time and bother for little added value.

    (Was that too opinionated?)
     
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  7. Mar 16, 2019 at 3:24 PM #7

    Wallace

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    Not at all. I personally appreciate it when a person speaks their mind..
     
  8. Mar 16, 2019 at 3:59 PM #8

    jsdemar

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    I use US Composites for most builds. The thin resin with all sorts of fillers is strong and versatile.

    I use chopped fg and silica for fillets to the mmt, building it as a subassembly without the aft cr. I cut fin slots all the way to the aft end of the airframe to allow sliding in the mmt with fins already glued.

    Kevlar pulp is great for an initial small fillet for min diameter rockets. Then a smooth fillet. And tip-to-tip fg or cf over that.
     
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  9. Mar 16, 2019 at 5:52 PM #9

    aerostadt

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    Or don't cut the fin slots all the way to the end, but still do epoxy from the aft end with the aft CR not present. This eliminates the need to drill holes in the airframe or maybe cut down on the number of holes drilled. Perhaps, the build might be a little bit heavier, but maybe that isn't an important concern for the builder.
     
  10. Mar 16, 2019 at 6:41 PM #10

    jsdemar

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    It depends on how much room there is between the mmt and main body id. And how critical the strength is for the max speed of the rocket. For a 4" with a 3" mmt and 5" with a 4" mmt, I can do a better job with the mmt and fins outside the main tube.
     
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  11. Mar 16, 2019 at 7:13 PM #11

    blackjack2564

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    It's all about what type of flier you are building and the stress/heat requirements. Most rockets are way overbuilt.
    Only large motors in 54mm minimum's and up really need high stress/high temp glues, and that's for extreme 54's.
    In reality only 3 in and up min. need high temp glues. IMO.
    I quit adding chopped carbon to internals yrs ago and have not seen any difference.
     
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  12. Mar 16, 2019 at 11:18 PM #12

    Wallace

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    Jim: You have more personal experience in this area than most will gain. What bothers me is being "harassed" for potential safety issues for both under and overbuilding. Without holding your nuts to the fire, give us an honest opinion.
     
  13. Mar 17, 2019 at 4:22 AM #13

    blackjack2564

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    Ok [now I get the PM..lol]
    Problem at hand is specifics....each project must be built to handle the required load/stress for flight parameters.
    i.e. size weight mach # heat soak recovery stresses.
    Each project must be assessed for what it is. Without knowing what's being discussed, it's nigh impossible to recommend.

    That being said: most glues we use today [when properly used] are stronger far in excess, of the materials being joined together.
    Majority of builders use "what I heard" or so & so 'told me" to use.
    With Google it's fairly simple to research the tig [heat] and shear strength of all glues out there. Problem is the average flier doesn't take the time to figure this stuff out, and resort to "more is better" mode. Heck just go to company web site for info...it's there.

    As far as safety issues that's where I can tolerate some overbuilt issues better than under as far as survivability.
    After all this is "Rocket Science"!
    Short of teaching how to build for novices...I don't know what the answer is.
    Most all fliers I know that have been at this any length of time and are successful at it, all have the same thing in common.....'"common sense"...knowing how to build not assemble..and basic use of power tools. We take the time to figure out what's needed to accomplish our goals [whatever they may be, sport or Xtreme projects] research strength of materials or ask someone who has. Not "well I heard" which is sooo common on the forum.

    For sport flying, which is 90% of flights any epoxy will suffice short of 5-20 minute. Even those will work for many things. I've repaired L-3 rockets and flown M's in them no problem.

    It's not a simple answer, requires building skill to choose correct glues for materials being used. Evidenced by all the epoxy threads & controversy over the years. There are many more fliers out there,than I, more experienced in Xtreme builds....guess I'm just more vocal lol. Built a few, been around a lot, asked many questions of those more experienced than myself AND don't trust hearsay.....''trust data"

    If anyone harasses you over potential safety issues regarding build...tell 'em to get off your field, and go fly somewhere else!

    roytyson what are you building for L-3?
    By the way...what issues temp wise have you "heard" about West? Unless you are building something going stupid fast you should be fine. I've used boat glue to M2.5 and been fine.
    West specs on tig are more honest than many..they consider heatsoak over several minutes. When we fly the motor is already burned out for duration of majority of heat soak by time it gets to glue joints.. Read West website for correct data and explanation.

    Edit: I hate getting into glue threads, they are like politics and religion. Most have their minds already made up and ain't changing regardless of the facts..lol
     
    Last edited: Mar 17, 2019 at 4:11 PM
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  14. Mar 17, 2019 at 6:11 AM #14

    roytyson

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    My first line I mention I was not wanting another glue war thread. As Jim said I learned almost everything I know in rocket building from reading threads and posts.

    I am building a 4” Madcow Frenzy XL with a 75/7680 M1850. Nothing stupid fast.

    Again I read several post where people discouraged west for any internals because of its low melting points. One even said to keep it out of the summer sun if built with west. Do I know this is fact. No. But several agreed. So I took some stock in it.

    Edit: I don’t have my mind made up. That’s why I ordered US Comp. I was wanting to try west then read “the bad things”. I would probably order ground unicorn horn powder if several people said it was the best option. I, like many probably, don’t want my rocket to be the test vehicle for experiments.
     
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  15. Mar 17, 2019 at 1:43 PM #15

    Wallace

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    Well done! Thank you Sir.
     
  16. Mar 17, 2019 at 1:55 PM #16

    Wallace

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    I've used quite a few different epoxies myself and short of the quick hobby brands have yet to reach any of their limits (possibly due to lack of sufficient funds:)). I've found myself going with what I find easiest to work with for the most part. I do like the US Composites for cost and working properties and will probably switch over to it for almost everything. If West truly couldn't be left out in the sun I'd expect to see a whole lot of sunken boatso_O.
     
  17. Mar 17, 2019 at 5:04 PM #17

    blackjack2564

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    Well Roy, that's a mighty fine kit ya got there. Should supply you with many years of fun flying ...so long as the fins don't come off from wrong glue choice.............

    .....just kidding!!!

    I just get my feathers ruffled a bit when I hear the old....''it melts in the sun, it melts in the sun"
    So here's the skinny on how all this temp related ratings work with low and behold West as the test subject!
    Excerpt from pdf:

    "We have glued two blocks of mahogany together with WEST SYSTEM® epoxy, allowed it to cure for one week at room temperature,
    and then exposed the whole assembly to 200°F for 3 hours before forcing a chisel into the glue line to fail the joint. When the joint
    was examined closely, we found that the primary failure was in the wood and not the epoxy.
    Experience has also shown that while heat tends to soften epoxy while it remains warm, if WEST SYSTEM epoxy is not exposed to damaging heat (exceeding 230°F for extended periods), it will return to full strength when cooled to room temperature."


    By the way if you post cure your rocket with heat oven [or even in a car with windows rolled up in sun and heater going full blast, or redneck curing oven as we call it down here..lol] you increase the temp failure another 40-50 degrees. [ 45 minutes or hour]
    But note the lab heat soaked these joints FOR 3 HOURS, not the 30seconds to 1-2 minutes a rocket experiences during flight.

    This pdf will enlighten you a great deal on epoxy function with heat range to failure. It took me an hour to find it and I have posted this many times over the years during the many "great epoxy debates" hope it helps you in your epoxy future choices.

    Good luck with your L-3 and hope ya have great flight/success!

    Ps this is not my recommendation for only using West, just a defense for all the bad propaganda it gets. I too use many epoxies for various projects. It just is easier to buy West when something is needed "now" due to all the West Marine stores everywhere. For Xtreme use I swear by Hysol [proven over mach 5 flights] but very expensive and not needed for most applications. I use Aero-poxy...West...Proline ...3M...Rocketpoxy.... US Composite thin..Bob Smith 10 minute among others. I prefer to use additives to modify epoxy to use at hand....adhesive...laminating...structural.
    If truth be told, there are only 3 major manufactures of epoxy. All the brands we see are formulated to spec by distributers.
    Some where I did a thread about all this.
    Hopefully time I spent researching all this will be worth it, if just one builder learns something from it.:cool:
     

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    Last edited: Mar 17, 2019 at 5:22 PM
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  18. Mar 17, 2019 at 5:18 PM #18

    Wallace

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    Very interesting paper, thanks Jim. Btw, if anyone ever has any doubt's, a simple test with a heat gun and a thermometer will give you first hand results. Or you can just fly West built projects at night;).
     
    Last edited: Mar 17, 2019 at 5:33 PM

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