Gonna put the ‘HV’ in HV ARCAS

Discussion in 'High Power Rocketry (HPR)' started by Theory, Dec 6, 2019.

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  1. Dec 6, 2019 #1

    Theory

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    So I’m kind of a sucker for nostalgia. ...and a deal. So when I saw a Black Friday deal that centered around an Aerotech HV ARCAS there were few options. I built the same kit back in 1993. I was 13 and this was my first “big” rocket. I love it. Flew it mostly on the larger 24mm F motors and F25s as I didn’t push things very hard back then. She was in my fleet till I moved away from the hobby in the early 2000s.

    here I am with the HV ARCAS at the fall Culpeper VA launch in 93’. Im wearing the ever so stylish red sweatpants :/

    28011991-B7B5-4FE8-9F73-8C1053CC37F3.jpeg

    fast forward to now. I have picked up the same tried and true kit (though now with rail guides and a screw on motor retainer) along with some other strategic parts with the goal to fly this thing on some large 29mm motors, H268 and the 29-360 case pictured along with the rest of the parts.


    9D045E1B-E2FF-4910-B8E7-D444E36F1B3A.jpeg

    The idea is to sleeve major parts of the airframe with couplers, add two ply centering rings to “double” the fore and aft ring, modify the booster-payload coupler with a LOC stiffy in the same fashion as my caliber build, incorporate a Kevlar lower harness with nylon shock cord, and also delete the mesh baffle in favor of a nomex blanket. I will also add a JLCR for extra high flights. Going to hit up Mark for some high end lettering and will likely opt for a high gloss light gray in place of the white when finishing.

    Not going to do a full build thread as most of this will be a regular Aerotech build, but wanted to share the project.

    Things get underway this evening!!!
     
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  2. Dec 6, 2019 #2

    mbeels

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    Very nice, that looks like a fun project.
     
  3. Dec 7, 2019 #3

    Mugs914

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    This is going to be fun! Aerotech's Arcas is one of my favorites too.
     
  4. Dec 8, 2019 #4

    Tyler P

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    When I first got back into rockets a few years ago, that one caught my eye and it's still on my list to get.
     
  5. Dec 8, 2019 #5

    Mugs914

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    Are you planning to beef up the fin can at all? I think the fins themselves are pretty bulletproof, but it seems like the tabs might could use a little help if you get to going REAL fast.

    Of course I could be all wet about that, it has been a while since I put one of these together!:rolleyes:
     
  6. Dec 9, 2019 #6

    Theory

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    Motor mount is complete and will be installed shortly along with the two couplers that will sleeve the upper part of the booster

    B7980466-863D-4CBA-BE68-FC42A91B303E.jpeg
     
  7. Dec 9, 2019 #7

    Theory

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    @Mugs914

    not planning on doing much other than securing the fins in the “locks” with quality epoxy

    even the 6XL loads stay well sub sonic so they should hold up well
     
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  8. Dec 9, 2019 #8

    blackjack2564

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    I built one and made coupler an av-bay so I could dual deploy. Opened up the fiber centering rings to hold 38mm motor mount.
    Stuck rail buttons on with screw and CA.
    Flew 38 5 grain I.motors no issues. !-284's i -315's etc/ went around 5500-6000 ft. No other beefing up.
    CA fins as per instructions but added small epoxy fillets.

    It will be just fine. Good luck, have fun!:cool:
     
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  9. Dec 9, 2019 #9

    Theory

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    Thanks Jim, and yes if yours survived an I284, and I200 or I224 shouldn't be an issue! I contemplated setting this up for DD, but opted for the JLCR recovery method instead.


    last night I got the MMT in and completed the coupler sleeves in the booster and payload. I wanted to move on to the fins tonight but noticed that one is fairly warped. Going to work it over with a head gun and some weight to see if I can straighten it out. With the performance I'm shooing for, I cannot have a warped fin!
     
  10. Dec 9, 2019 #10

    farsidius

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    Happy Building! Nostalgia is a hell of a thing. The Aerotech Arcas was my first "big rocket" also.
     
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  11. Dec 10, 2019 #11

    Andrew_ASC

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    ARCAS.... HV for High Velocity. In all seriousness glad you stepped it up to H class motors. You shouldn’t have any pesky delay grain issues like on that WAC and those Aerotech G class motors lol.
     
  12. Dec 10, 2019 #12

    Theory

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    I tell ya, that whole WAC experience is definitely a low point in my rocketry year, and really in my rocketry "career." With that much time and effort expended, and when you do everything right and get burned by something that is totally out of your control that really should have never happened... oh well.

    Yes, the one will see a steady diet of smaller H motors 29/180s and also some 29-40/120 G motors. My issue is not at all with G motors as I truly believe that a full 'G' is a very solid motor that will turn in a very respectable flight. More that the mass produced "economax" motors have a manufacturing flaw that, while easily checked for, renders the ejection charge 100% unable to fire. Hence why most all of my flights since have been relaods, as I have 100% control over how the motor goes together.

    Its really too bad too as the G74 is a hot little motor and great for small fields. Who knows, I may buy a few more and be extra diligent about checking them.
     
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  13. Dec 12, 2019 #13

    Theory

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    got the warped fin straightened out last night. nothing a heat gun and two scrap pieces of granite couldn't fix! its not 100% perfect but more than good enough for this build.

    moved on to installing the fins. opted for a generous amount of slow CA in each fin-lock and also some on the root edge where the fin meets the motor tube. set everything aside to set up overnight.

    next up is the cosmetic fin can and then the rail guides.

    if all goes well she will be ready for primer by the end of the weekend.
     
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  14. Dec 12, 2019 #14

    Andrew_ASC

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    Awesome.
     
  15. Dec 21, 2019 #15

    Theory

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    Got the primer shot and sanded with 400 grit. The spirals are still there but I’m not concerned with that

    F394DDD4-2E01-4F7E-A349-DC1F777659A3.jpeg

    Warmed up the garage. Started running the heater early as I knew it would take some time. I try to start shooting at 65+. Can’t run the heater while I’m painting, don’t want to blow myself up, so 65+ allows for some cooling during the painting process

    F61E5121-82D8-4C7C-BB33-6D5171B21F4A.jpeg

    Laying down 7 - 8 very light costs. Need to let this cure for a LONG time before moving on to the red

    D74BFB71-6048-4C68-A166-082D760BC205.jpeg
     
  16. Dec 21, 2019 #16

    Theory

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    Not bad at all

    C3EC2B42-4A67-47B6-94AE-69BB28327117.jpeg
     
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  17. Dec 23, 2019 #17

    Theory

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    Spent a good deal of time yesterday looking over the gray and its not as smooth as I would like it to be. Contemplating "blocking" it with some 800 grit then 1000 before hitting it again to see if I can smooth it out. Not 100% sure on that though as this is where I often get myself in trouble. I get a finish 80% of the way there and then, while seeking that last 10-15%, I find a way to mess something up and then spend a good deal of effort to get back to where I started from...

    Good news is that I have a good deal of time between now and her first flight. Fingers crossed that it turns out!
     
  18. Dec 23, 2019 #18

    Andrew_ASC

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    Your paint finish looks way better than mine. I’d say if you want that last 10-15 percent go dig around for Nathan’s advice or whatnot on TRF. I think he uses ultra high grit numbers.
     
  19. Dec 24, 2019 #19

    Theory

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    Thanks Andrew! It is good but not great and as I have time I'm thinking I shoot for great.

    Yes I have "painting the magg" saved along with Jim Jarvis's document on carbon and several of ECayemberg's LOC threads. tons of very valuable info in all of those.

    Really thinking that the issue is the way the primer was "finished" prior to paint. This is also the first time ive used rustoleum "paint and primer in one." Not sure if that is the issue, but it could be part of it. I am going to sand it with the 800 grit / 1000grit combo then let it continue to cure for 24-36 hours prior to painting. To accomplish this I use our basement bathroom with a small space heater and hold it at 85 degrees or so for several hours. Want to be 100% sure that the solvents have evaporated off as to not have any issues with the next coat.
     
  20. Dec 26, 2019 #20

    ksaves2

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    If you don't do anything to the fins and fly on anything more powerful than an H123, you "will" have fin flutter problems. I know for a fact with mine. I put an H165 in mine, there was a "bauble" and short buzz mid flight and a couple of fins were cracked after a nominal landing with an oversized parachute. Converted mine to dual deploy during construction. After repair, I limit mine to 1400' flights with an H123. Don't do too good a job on the paint if you're going to push the motor size up because if you lose fin(s) due to flutter, you will likely lose the rocket. I mean look at how floppy those plastic fins are. I thought they could take an H165 but I was wrong. Looks like you're too far along as I was going to suggest glassing the fins to make them more resistant to flutter. Good luck. Kurt
     
  21. Dec 26, 2019 #21

    Theory

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    thanks, and its very surprising that they flutter with an H165. a quick thrust curve sim (accurate as a "back of the envelope" sort of calculation) puts it at 458 ft/sec. thats with a weight of 30oz which is my best estimate at the moment.

    458 ft/sec is MUCH slower than the H268 that i had planned. that sims to 759 ft/sec.


    hhhhmmmmm...
     
  22. Dec 26, 2019 #22

    ksaves2

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    Be careful if you want to be able to fly the rocket a long time. Mine I use to demonstrate DD to spectators. Can see all the events nicely. Uses an older AIM USB deployment electronics that recommend against using an Rf tracker. Perfect place for it as the rocket doesn't go higher than 1400' and not likely to need a tracker. If I worry, I'll put a screamer on it. Kurt
     
  23. Dec 28, 2019 #23

    Theory

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    Had a nice warm day so I figured why not finish her and shoot the red. Masked it off and went to town.

    Overall I’m happy.

    BBEC521F-4B4D-4DD2-89C4-F1E8016CD5E8.jpeg

    The transition leaves something to be desired but when I’d gettin hammered by an H238, no one will notice.

    081AACBA-5389-4341-AEB2-47EA9BC47868.jpeg 116AB489-8944-4CAD-8ACC-B94327511C00.jpeg

    Next step is to paint the very aft end (aft centering ring area) black, then install the motor retainer
     
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  24. Dec 28, 2019 #24

    g.pitts

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    Looking good!!
     
  25. Dec 28, 2019 #25

    mbeels

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    Yeah, that came out really well, I think that transition looks fine! With an H238, that'll do a disappearing act off the pad.
     
  26. Dec 28, 2019 #26

    Mugs914

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    The gray and red looks fantastic! Very nice...
     
  27. Dec 28, 2019 #27

    Andrew_ASC

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    Got any clue on fin material?

    Also...
    Prefer the following length data in inches.

    Body tube Od.
    Fin Span.
    Fin Sweep.
    Fin Root.
    Fin Tip.
    Fin Thickness.
     
  28. Dec 28, 2019 #28

    Theory

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    Andrew... No idea what you are talking about.
     
  29. Dec 28, 2019 #29

    Theory

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    she is home

    if all goes to plan she will take to the sky’s at Battle Park next weekend or the weekend after


    9045F4E5-70C1-4779-8663-E6639C6A922E.jpeg 6B9B36B3-D9E2-4ACB-9A65-B31243CAB8AB.jpeg
     
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  30. Dec 28, 2019 #30

    Andrew_ASC

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    So you wanna try M 0.67 and you don’t know if fins flutter...

    Gimmie Data I give you Flutter Sim Result.
     

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