Mach One “Alien Interceptor” build

Discussion in 'Mid Power Rocketry (MPR)' started by downhill_D, Sep 3, 2018.

  1. Sep 26, 2018 #61

    downhill_D

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    So in retrospect, I would highly recommend adding your rail button (1010 in this case) before your forward CR is dry. I thought I would be able to manipulate the end of the fiberglass tube to allow enough room between the motormount and body tube for the button to slide up into place after it dried. This proved most difficult but luckily I did get it installed. I also had rounded the button back (convex) to try and reduce the metal sticking out so much inside and match the curve if the body tube (more important for the forward button). Here it is installed-tight fit. I used a magnet to draw it up for install.
     

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  2. Sep 26, 2018 #62

    Normzilla

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    Not sure if you mentioned it; are ya using those tiny guides that came with the kit or using the larger, more common sized, guide?
     
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  3. Sep 27, 2018 #63

    downhill_D

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    I am using 1010, not the micro rail guides they sent. My club uses 1010-good looking out for me though! Thanks!
     
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  4. Sep 27, 2018 #64

    Normzilla

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    I'm going to do the same.
     
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  5. Sep 28, 2018 #65

    swatkat

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    I used 1010 on mine as well, no issues with them fitting between the fins.
     
  6. Sep 29, 2018 #66

    downhill_D

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    Next up: mounting/aligning the fins. I took two approaches to prepping the body tube and fins-I sanded with 100 grit and then last night prepped the fins and body tube with an X-acto “crosshatching” cuts into them. Here is how mine looked afterwards-this surface should take to epoxy very well!
     

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  7. Sep 29, 2018 #67

    downhill_D

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    I have always aligned fins by eye and babysitting them until dry so I am gonna keep this approach BUT I will tack with 5 min epoxy with internal fillets of 30 min (motor mount fillet and body tube fillet internal) then JB fillet the fins externally.

    I wanted to cut out my own wooden fin alignment guide (using the online guide they have on their website glued to thin plywood) but find a temporary pencil line drawn up the body tube also works well for me and I really didn't feel like cutting the wood guide yet.

    I might skip the 2 part foam around the motor mount as the strength on this motor mount (2 forward centering rings with JB weld and 1 aft with 30 min) with epoxy should be plenty strong. I have a AT 29/240 casing now - it should be perfect for this rocket.
     
  8. Oct 1, 2018 #68

    Normzilla

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    Hey does anyone have an .ork file for this kit?
     
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  9. Oct 1, 2018 #69

    Normzilla

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    I ended up at a 22.5 oz build with paint and AV bay.

    Built a little heavy but built to last.
     
  10. Oct 1, 2018 #70

    downhill_D

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    Yes. Steve sent me one but I dont use .ork, I use rocksim
     
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  11. Oct 1, 2018 #71

    downhill_D

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    I currently am at 1lb 9 oz with bay no paint yet. Definitely built to last
     
  12. Oct 2, 2018 #72

    Normzilla

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    I attached the .ork file sent to me by Mach 1 after I've asked for the CP and the file; what an outstanding company they are.

    The builds are solid and really well taken care of, and the customer service is really great. This kit won't be my last. 38mm MMT on a 38 BT coming up next!


     

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  13. Oct 2, 2018 #73

    downhill_D

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    Nice! I will attach my rocksim file to this thread once I have finished the rocket. I only have built it in rocksim...it was not too difficult. My next one is the antigravity!
     
  14. Oct 2, 2018 #74

    Normzilla

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    I could be wrong, but if you change the extension from .ork to .rkt (or what ever the rocksim ext is), it'll open in rocksim.
     
  15. Oct 2, 2018 #75

    Eric

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    I know rkt file will open in openrocket. But I dont think they work the other way. I have mostly gone to openrocket.
     
  16. Oct 2, 2018 #76

    downhill_D

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    That is good to know, our club Vp said he uses three diff sims to see the differences...I feel rocksim is as close as it gets to accurate (no data just personal opinion ;) ) but it would be good to have other features that are more user friendly at times.
     
  17. Oct 2, 2018 #77

    downhill_D

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    The fins are internally bonded with 30 min bsi slow cure epoxy. I did have to inject the epoxy from the aft of the rocket and just tilted it vertically so it would run down. due to the close to minimum diameter spacing I used a 1.5” needle 18 guage syringe (3 actually) to inject my internL fins from the AFT end of the rocket. NOTE: My aft centering rings are not installed yet. I mixed the epoxy right in the syringe with my secret rocket building multi tool lol a 300mm bicycle spoke. :D

    I stuffed a thin bit of cotton over my kevlar cord inside to prevent the epoxy from curing on it and then injected 1.5 mL into each fin root along the motor mount “trough” where it is tacked. This proved to be enough to coat the upper and lower of each root side all the way down.

    Now for the fillets and the aft centering ring next!
     

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  18. Oct 2, 2018 #78

    downhill_D

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    Almost ready for paint just needs fillets on the fins and the recovery set-up. The E-bay I made is inside the payload. Since everyone seems familiar with the “Graduator” from Loc Precision I am using it as a visual scale here-this is my level 1 graduator (hopefully) next to the Mach 1 “alien interceptor”-this is a BIG rocket-it’s gonna make great flights!
     

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  19. Oct 6, 2018 #79

    downhill_D

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    This is by far one of my most challenging kits but I am enjoying the heck out of it. I want my real numbers now, the data. I need to know my Cd now so I can really tighten up the simulation! Working out the parachute sizes in simulation I really want this bird to ride slow at the main chute-it took a long time to build so I figure somewhere around 10mph should be ok-my wife and I are going to build some 48" and 36" chutes BUT for this rockets first flights I will use a commercial set of chutes. I have a rocket man 18" which slows it to about 25-30mph I think and then I am using a 48" to slow somewhere in the 9-10 mph around the 300-500ft mark. Still refining the sim with both chutes.
     
    Last edited: Oct 7, 2018
  20. Oct 6, 2018 #80

    downhill_D

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    Ok-I’ll save recovery for later discussion. The rocket now has the motor retainer (aeropack) JB welded on AFTER the aft motor retainer was epoxied behind the fins. The fit is clean and I am very happy with the aft position of the motor. I have ~.25” of retainer and motor behind the aft of the airframe. I spent a good deal of time planning each move of install at this point-JB weld inside the body tube is not good as I have about 3mm all around to get JB weld on to the motor mount and not impede the retainer closure screwing on. A clean straight piece of bicycle spoke was used for epoxy application and a qtip for cleanup BEFORE the retainer (male side) went on. I had no room for build up for the retainer closure (female) to fit into the airframe. If your patient and careful, it is a perfect fit with the aeropack retainer!

    I ordered rocketpoxy with the chute for the fillets...I could not resist trying a small 8oz package for the fin fillets and the next fiberglass build at a good price.
     

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  21. Oct 6, 2018 #81

    Andrew_ASC

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    Rocketpoxy is good stuff. Used it on two HPR builds. I trust it to M1.4. Nice clean thread and rocket you have.
     
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  22. Oct 7, 2018 #82

    downhill_D

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    Thank you!

    Yes, I have heard too many good things about rocketpoxy to not try it!
     
  23. Oct 7, 2018 #83

    downhill_D

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    Ok so aside from rocketpoxy I have a 48” chute coming that should slow this bird down to about 9mph-that should do. 18” drogue from rocketman and a 48” main ripstop nylon generic from apogee. Additonally, I started messing with making my own chutes to test with cheaper rockets at low altitudes. Just made my own 18” ripstop with a woodburner and light/thin kevlar shroud lines! Wife is gonna show me how to use the sewing machine.
     
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  24. Oct 9, 2018 #84

    downhill_D

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    chutes show up today! I will post pictures of the rocket with all attached pieces, basically finished just need to fillet the fins with the RPoxy that shows up today as well! I have to say this is one really cool looking rocket with a lot of canvas for paint! Can’t wait to launch this bird.

    Once this project is complete I will post my rocksim file and some data from a flight or two possibly next launch from the JL2 altimeter. I am still trying to settle on a flight computer, I like the simplicity of the JL2 a lot but made a beautiful payload bay that needs to be filled with a camera, lights (night launches) and circuit boards! The payload could be even longer if you were able to 3D print or carve out of wood (in my case) something that could go down into the coupler cavity.

    On the note of light-it is a great possibility that if you leave the frame unpainted you could see light through the fiberglass. It is very thin and might be a cool effect. Maybe I will look at RC car lights if I have time to add some and leave that section of payload unpainted. Hmmmm
     
  25. Oct 11, 2018 #85

    downhill_D

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    Rocketpoxy, 2 parachutes and an H97 showed up yesterday. The apogee branded 30” chute is really nice! It’s made of ripstop but feels like silk...really nice chute for a budget chute-i got a 30” to roll up nice on a JLCR last night inside the BT-60 tube no problem. Breath test ejection deployed everything no problem. Fillets go on the Alien Interceptor tonight!
     
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  26. Oct 11, 2018 #86

    downhill_D

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    For the record-this Mach 1 rocket will not be flying on the H97J-10. The H97 is reserved for my graduator Level 1 flight-I want to see it, not send it, the first time. :) but I do have two/three other motor options to fly with.

    Mach 1 Alien Interceptor:
    A G77-7 R/L is my planned 1st flight-it shows a nice flight and not too high...then a H180 or H220 with the JLCR (assuming my rocket passes the H flight...it will). I will do my best to get video, it will be a day and night launch so I might get to do a Redline night flight. I have never flown at a night launch so this is exciting.

    I will try and see if a 48" standard ripstop chute will fit in this bird with a JLCR...kind of doubt it at this point...we'll see.
     
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  27. Oct 14, 2018 #87

    downhill_D

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    Ok! Got a coat of paint on the Alien interceptor-went with Metallic Black and it will look really good with the decals in a few days. You can make out the kevlar on the side in one of the pictures because the metallic paint goes on thin. I will give it another coat, decals and then a clear coat over the next few days with ~48 hours between coats. This bird looks awesome and will fly in two weeks! If I decide to use an eggfinder mini later I will just change out the nose cone to a non-metallic paint. For now, this rocket will see lower altitudes with a cool paint job.
     

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  28. Oct 14, 2018 #88

    crossfire

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    Not sure what you heard about rocketpoxy but it is great stuff and very east to use.
     
  29. Oct 15, 2018 #89

    downhill_D

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    All good things-that is why I got it! :)
     
  30. Oct 15, 2018 #90

    downhill_D

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    Built a parachute last night using a rocketMan chute style. This is a 28” chute that will have 4, 300# kevlar lines and is Halloween friendly for this months launch.
     

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